Vorshlag Miata LS1 Alpha Project

[mk2tmr2]

Sexy!

[vejatabul]

Has there been any talk about possibly using a Jerico trans?

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Has there been any talk about possibly using a Jerico trans?

Nope. Jerico race transmissions use straight cut gears with no synchros. We are building this kit around more of a dual-purpose street/track car, with a synchromesh transmission.



But our LS1 kits are often used with major changes like this. Our E36 LS1 customer above used a Jerico in his BMW with our kit - just made his own driveshaft. It was a competition only hillclimb car.

With enough effort anything is possible.

[jeff_man]

Sweet, when do I get to drive it?

[vejatabul]

I have been on the lookout for a good used Jerico for one of my project cars for a while. I am certainly interested in the straight cut gears, and after driving a Jerico equipped car a few years ago, I was hooked.

[Fair!]

Project Update for January 4, 2014: Wow, over a year without an update? Yikes. While it looks like I have been avoiding this build thread, we have been plenty busy working on this project and many others over the past 14 months. Most of the work we have been doing on this project over the early part of 2013 had to do with upgrades to the shop and building fixtures we needed to delve further down the rabbit hole on the Miata LSx swap. Later in 2013 we also tried a number of oil pans, designed and built a new tubular front crossmember, did all of the geometry calculations then mounted the new front suspension bits, and then we finalized the wheel and tire package. We also worked on a lot of other customer cars in that period, built a few race cars, developed our BMW E36 LS1 swap kit extensively, released our BMW E46 LS1 kit, and a number of suspension development projects in the same time period.


All pictures in my posts can be clicked for higher rez versions

We also had a very busy racing schedule in 2013, running 15 events with NASA (among many other groups' track and autocross events) in our TT3 prepped Mustang, shown below. We won 13 of those, got one 2nd and one 3rd, setting 8 track records along the way, while testing all sorts of aero and suspension work (we race to test, and test to race). Another project that kept us busy was developing a new set of NA/NB Miata shocks shown below. These are custom built with Bilstein Motorsports components, using massive 46mm monotube pistons, machined and assembled at Vorshlag, then custom valved by Maxcyspeed & Co. We just finished our final round of track testing last weekend, testing the latest valving package for a dual purpose street/track set-up. I had a blast hooning around in the tester's 2001 Miata below at Eagles Canyon Raceway. These dampers should be in production in Q1-2014 and we will have more information about these in the New Damper Offerings forum thread.



One thing to note about this post: starting in early 2013, I started making ALL of the pictures in all of my forum posts click-able for larger sizes. With a photographer like Brandon on staff it is a shame to only show the little "small" versions in our posts. So if you see an image you like, click it for a higher resolution version of the same image.

Before I get going on this update I wanted to shout out to V8Miatas.net - Just found this forum recently, which looks to be a great resource for all sorts of V8 Miata swaps, as the name suggests. Our Alpha LS1 build thread was added there today at this location. I have already learned a few things reading other threads there, so if you have plans for any sort of V8 swap in any generation of the MX5 chassis, you should head over there and sign up.

Shop Upgrades Lead To LSx Swap Progress




So one of the things we needed to work on this Miata LS1 car was a 4 post lift, which we finally ordered and installed in early 2013. This made it easier to do drivetrain mockups. We quickly realized that we also needed a chassis dolly to make the Miata easier to move around once the subframes were out. So we built that in summer 2013, and soon modified it to fit two other chassis. Now that dolly thing gets used on a daily basis (should have built one of these sooner) to move a car around the shop that has no suspension, crossmembers, or wheels.



Believe it or not, the lack of the 4 post lift and chassis dolly were big impediments to this Miata LSx project. Since we are still in a somewhat small shop space we couldn't afford to have the Miata stuck on one of our lifts for more than a day or two, which kept us from pulling the front subframe out for more drivetrain mockup (ever try to move a car around without even subframes in it?).

The Real Engine Swap Work Begins



Once the lift and chassis dolly were built we rounded up the hardware needed to get the TKO-600 transmission mounted to another LS1 block we have, then put that mockup drivetrain in the car for some testing with the REAL transmission. Before we had eyeballed the TKO in the tunnel but not while attached to the block. This helped us see what the next piece was in the way...



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After we did that round of LS1+TKO mockups we quickly realized that the OEM front crossmember was a HUGE hindrance to this swap, as even heavily modified and hacked up it would be in the way of the engine, oil pan and exhaust headers. We refuse to accept the huge compromises that come with "block header" exhaust headers on any of our swaps, so a new tubular front crossmember was going to be required.



You can see above some of the structure of the frame fixture that bolts to the body dolly, which Ryan built for the NB Miata. There's actually a lot of steel rectangular tubing you cannot see in this pic. The rolling cart attaches to this frame fixture from underneath the lift. This fixture was built to allow the car to sit at the desired ride height w/o suspension while sitting directly on the lift, with the rectangular tubing setting the chassis height. He then mocked up some 265/35/18 tires at both ends for a quick look. If you shove them in hard enough they almost fit under the fenders, heh.



Choosing Tires and Suspension To Build Around

We knew early on that we wanted to upgrade all of the factory (and very weak) 4 x 100mm NA/NB hubs hubs to 5 x 114.3mm RX8/NC hubs. The 4 x 100 hubs are a common failure point up front on Miatas that see any track time, and keeping the rear 4 x 100 hubs would limit the halfshaft strength greatly. Going to 5 x 114.3 bolt pattern opened up a lot more wheel and brake choices as well. Doing this "hub upgrade" is more work than you might think - this meant new uprights and control arms, so the NB suspension pick-up points on the crossmember were no longer sacred... so we might as well ditch it, right? Well we tried to keep the stock crossmember, probably far too long into the swap development. We tried cutting it to make room for this or that (like some of the kits are fond of doing), modifying the pick-up points, but it was getting weaker and more customized.



Meanwhile we had been mocking up this RX8 front control arms and uprights and even tried an 18x10" wheel and later a wheel and tire. Ryan put in several days of work, and with Jason's help, they did a lot of measurements and calculations and got the front suspension sorted out fairly well. At this point we knew we would be able to re-use the RX8 front spindles, brakes, and control arms. I was worried we would need to fabricate control arms, but it all fit very well with the forged aluminum RX8 arms. Small victory.


Video we made for the customer, showing the RX8 suspension and 18x10" wheel in action

In the video linked above we were showing the customer the current location of the wheel and suspension with the big 18x10" wheel, to which we later mounted a 285/30/18 tire. This video shows the front 18x10" wheel turning at ride height, and we later made some adjustments to clear that wheel at full lock, inboard (obviously the fenders will need to be cut and flares added to cover the tire). Our customer has had regular e-mail updates every 2-4 weeks, showing all of what you see here and more. We send these email updates with pictures and videos to all of our long term project customers - basically anyone that has their car in our shop for anything more than just "day work".



Later a set of 18x8" Mustang wheels (from my 2013 Mustang GT) were installed, shown above left. We noted that these barely fit under the stock fenders, but they didn't have enough positive offset. We might pick up some higher offset RX8 18x8" wheels (above right) and tires, which would sit farther inboard. This could possibly avoid the need for cutting and flares for some folks. Luckily, our Alpha customer is going with the 285mm tire option. Why so much tire? Well the LS1-based 5.7L motor that was built for this car will make 425-450 whp, and in a 2600 pound car with a short wheelbase, that is downright hair raising... we felt that a 285mm tire (Hoosier!) was going to be barely enough to keep it on track when the loud pedal is cranked up to 11.



One thing that had me a little worried during our wheel and tire mock-up was tire height. Most NA/NB Miatas are using a 23" tall tire, which is SUPER SHORT and only come in sizes out to about 215mm or the occasional 225mm. We went away from the typical 14-15" wheels to clear larger RX8 front "sport" rotors, which at over 324mm diameter are too big to fit inside a 15" or 16" wheel. Then tire width choices started to come into the picture... there just wasn't anything wide enough in 14, 15, 16" or even 17" diameters (the last two diameters tend to top out at a 255mm tire width for most brands), so we jumped straight to 18" - which currently has the most options for wider tires in both street and race compounds, covering widths including 275, 285, 295, 315 and beyond.

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We're building our TT3 Mustang around a 345/45/18 in the 2014 season, for instance. You can almost never have too much tire width on a race car...



Turns out there wasn't any tire anywhere near 23" tall once you left the skinny options in the 14-15" wheels, so we chose the shortest tire that is also wide that we knew of - the 285/30/18. This tire is normally the magic solution to "going wide" on track or autocross cars, and we've used this 24.9" tall monster tire on lots of BMWs (see above right, which has a bit more tire height room), EVOs, Subarus, and more. They even are used on RX8s and NC MX5s, but those cars have a lot more "wheelhouse" room than the NA/NB chassis. So we will likely cut the front upper frame horns for more clearance at full bump travel (then add back more structure with welded steel tubing). The above left picture shows the suspension at about 1.5" of bump, which isn't enough. Oh well, using a 2" taller than stock tire causes some problems we will have to overcome, but they aren't anything we haven't tackled before on other chassis.

New Crossmember Development

Once the tire was chosen and the front hubs and suspension components were tested and mocked up, we were ready to start burning in the pick-up points onto some sort of crossmember - either the stock piece or a custom design. At this point it was obvious that the OEM front crossmember was the next big stumbling block and it had to come out, once and for all. We just couldn't save it (it was already cut-up so much to clear the engine that it would need major reconstructive surgery), we didn't need it (we were changing all of the suspension pick-up points), and it was just in the way. So first the Vorshlag crew fabricated a crossbar that held the front of the engine from the top, which rested on a part of the upper chassis that wasn't going anywhere. Then they made a similar and also temporary rear transmission crossmember that was bolted in place, so the driveline position and angles were set. In the step above you can see the OEM crossmember out of the car for a bit, but now it was time to be fully replaced.



Now that the drivetrain was where it needed to be we connected the dots to build our new front crossmember. Using lengths of 1.75" diameter x .120" wall DOM steel tubing, Ryan measured then mandrel bent the new fore-aft frame members. These tubes were spaced inboard enough to maximize exhaust header space as well as set the final lateral and vertical locations for the RX8 lower control arms, which had geometry already determined above. These main fore-aft tubes bolt at both ends of the engine bay, onto factory chassis mounting locations that have substantial strength. Unlike the stock front crossmember, which mounts at the rear of the engine bay and at the midpoint (where the suspension parts mount), the new tubular design would mount at those points plus forward at the front tow hook tie down mounting plates. Our crossmember should make for a more rigid chassis when it is completed, with less cowl shake and more stable suspension mounting.



You can see Ryan welding the front mounting position of the crossmember tubing at the tow hook mounting plate, which is a beefy piece of plate steel bolted to the front of the chassis with plenty of bolts on both sides. With these two main crossmember pieces in place several things were then test fit. First, 3 different LSx oil pan designs were fitted to see which provided the best clearance to the lateral tubing member that was still needed as well as clearance to the NB Miata steering rack.



Each oil pan design had some advantages and disadvantages, with the total depth of the pan's sump driving how low we could get the drivetrain in the chassis, and the front section of the pan limiting where the steering rack would end up. In the end we chose the oil pan from the 1998-2002 Camaro, which is commonly available from the aftermarket. The Holley swap pan and the GM Muscle Car swap pan both had issues that could not be overcome. Luckily we didn't have to settle on a fabricated oil pan (these always seem to leak), the GTO double-hump pan (we have used that one and do not like it) or another cut-up OEM pan. There are good baffle/trap door kits made for the Camaro pan (Improved Racing's unit is preferred) and we have a lot of miles on track with this oil pan and baffle in BMW E36 LS1 swaps.


This is our prototype front NA/NB engine swap crossmember - additional gusset plates and tubing will be added before final welding

The final LSx oil pan we picked ('98-02 Camaro) is shown above, after the lateral tubing member was tack welded in place. Two vertical tubing members were also added, welded mid-way from front-to-rear and landing on some plate steel that bolts to the stock crossmember front mounting holes (which doubles as the upper control arm inboard mounting point). This makes for a completely bolt-in tubular crossmember, with extra mounting bolts/locations, once we get it into production (we will replace the OEM tow hook tie-down plates with a new, Laser Cut plate version). It also has a LOT more room for the engine and exhaust headers, so we can develop real exhaust headers - which can make upwards of a 50 horsepower difference on an LS1 V8 over the block-hugger super shorty headers some kits are stuck with. And this crossmember could work with a LOT of other engines as well.

We weren't going for the "lightest crossmember on the market" here, as I cannot count how many lightweight tubular crossmembers I have seen bend or fail. No, we wanted the STRONGEST possible fabrication we could come up with. The .120" wall thickness on the 1-3/4" DOM tubing we used might be overkill, and we could step that down to .095" wall on a later prototype piece (we will surely make some tweaks to this design before it is ready for mass production), but when it is completed we will weigh this first tubular unit vs the stock OEM stamped sheet steel fabrication and see where everything shakes out. A crossmember is not somewhere you want to skimp on.

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Throttle Body Clearance, Air Cleaner Routing, Possible Hood Ducting?



Of course before the oil pan and engine heights were finalized we tested with an intake manifold and throttle body on the mock-up LS1 engine, then tested with the stock hood in place. We had plenty of room up top, but realized that due to the short length of the Miata engine bay the intake inlet tube would have to go "over the top" of the radiator support (yes, this means we have to lose the factory hood latch).


We've done this type of air inlet re-routing before, like on our TT3 Mustang shown below.



This was one of the many custom tweaks we had to do on that car to make room for a deeply ducted hood, which vented the back of the radiator and made the front splitter much more effective. This had an accidental side effect of offering a lot more cooling capacity (and front downforce) to that car, so we might do something similar on this LS1 Miata, and of course use a bigger radiator at the same time.


Ducting the Mustang's hood made the front splitter we built MUCH more effective, both for cooling and front downforce

There are plenty of Corvette style air filter housings we can choose from, which was the air filter we ended up with on our TT3 Mustang. So after the intake manifold was fitted the Miata's engine height was locked down, and the driveline down angles were set at the transmission. Next up it was time to burn in the RX8 suspension mounting points to the new crossmember...

Final Welding of Suspension, Brakes Added



Our fabricators Ryan and Olof made some steel mounting plate sections on the bench that were then fitted to the tubing and tack welded in place on the crossmember. Then the suspension was mounted up, the wheels were added, and everything was set to ride height... to re-check camber, caster, toe, and then camber and caster change with suspension travel. Obviously you don't want caster change with suspension travel, so that was dialed out.



It doesn't look like much but dozens of hours were burned getting these mounting points welded in, measured, moved, and tweaked. Mazda-sourced eccentric bolts are used at the same suspension mounting locations as the RX8, to be able to adjust camber and caster. And while some of you suspension savvy readers might point out that the upper arm's mounts aren't perfect (we wish they were about an inch higher), they are as perfect as we could make without cutting the frame out of the NB chassis or going to custom control arms.

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There's a lot to be said for re-using OEM forged aluminum arms, which can make for easier service and maintenance down the road. We checked the dynamic camber change and it turned out to be pretty reasonable, too. Remember: Vorshlag specializes in suspension development, so this was an area we really made sure to get right. And we could see something in track testing that might make for future changes before this kit goes into production, too.



Seeing the old front suspension and brakes on the shop floor next to the new stuff is quite a difference. We're upgrading from a 254 x 20mm vented front Miata front rotor to a 323 x 24mm RX8 Sport front rotor. Going with RX8 hubs gives us a lot of Big Brake upgrade kits to choose from down the road, if needed. This customer wants a car he can track, autocross and street drive across country - and it will have 450+ hp and sport 285mm tires, so it will have some extraordinary braking requirements for an NB Miata.



These RX8 calipers and rotors are all Centric premium units that we sourced new, so it should make for a good starting point for track and street testing. We will also add front brake ducting, at a minimum, before it sees any track testing. That makes a huge difference on most road course cars we deal with, and it doesn't cost a lot nor does it have any downsides for street driving.

What's Next?



With the front crossmember, brakes and suspension nailed down and in prototype form it is time to move to the rear suspension. The front bits had so many variables that all cross over each other, but without steering involved we're hoping the rear will go more smoothly and quickly. As you can imagine the customer is getting anxious to drive his car, and wants to run events this year, so we've got to get crackin!



None of the OEM rear control arms, brakes, and hubs will be re-used. Again, we felt that the small-ish rear hub's inner spine size would limit the power capability of any halfshaft that could be built for these cars. I've seen fellow racers shred axle after axle in LS1 equipped Miatas, and I don't want to get stuck with those limitations on our swap. So this means it all has to come out and we get to start over. Yay.



The diff housing we are using is of course the 31 spline Ford 8.8" aluminum IRS casing that was used on the 1999-2004 Mustang Cobra. This was also the same housing used in Lincoln MarK VIIIs, and steel versions were used in the Thunderbird and Explorer chassis. The new S550 Mustang chassis looks to have the aluminum version as well (we should have one of these Mustang's soon for chassis/suspension development in late 2014 and a full season of racing in 2015). All this means is these diff housings are both common and affordable, not to mention strong as an ox. Aftermarket choices abound for gearing and internal differential options, too. We also have the rear uprights chosen, which are a commonly used unit for Cobra kit cars.

For now we will use the OEM rear subframe to mount things to, at least during mock-up. Once these uprights and the diff housing are mounted and set at the right heights and locations, we will fabricate upper and lower control arms, check the suspension geometries, then move to the halfshafts. This will entail a lot of fiddly work, measuring and calculations, of course, but compared to the front bits (which had to have an engine, transmission, suspension and crossmember all mate up) it should be a little less work.

Until next time, thanks for reading.

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Project Update for June 25th, 2014: Long time no post on this project once again, but with some recent changes and progress we have regained some lost momentum and we are pushing to get this prototype LS1 NB Miata on the road by this Fall. After a spurt of work in January and a little more in April, some real time was spent on this project in May. Let's get caught up.



The biggest progress of late was a new milestone that was started and finished since the last post - the rear subframe and suspension was constructed. Right now the car still sits on 18x10" wheels and 285/30/18 tires at all 4 corners, with the new RX8 front suspension tacked up as well (see above). The front obviously needs more negative camber (and more adjustment range), which we're working on next.


Ryan, that started fabrication on this project has left us (left) but our new fabricator, also named Ryan, is on the case (right)

We had a few delays on this project in the months since the last post, due to a few unforeseen changes here at Vorshlag. For one, our lead fabricator Ryan B (above left) left us after almost 3 years of great work to pursue his college degree full time. He was working here part time for the past year and whenever we had to steal him for major fab work at our shop he didn't get to focus on the Miata swap often or for long. After he left we searched for over a month and found another great fabricator to join us, Ryan H (above right), who joins us with lots of race preparation and fabrication experience from a Daytona Prototype team and other previous race shops.



As soon as Ryan H started here we buried him in fabrication work on a customer's V8 swapped race car, then he spent 100 hours working on the Pikes Peak Subaru above. Once those pressing deadlines were passed he got to spend about a week and a half working on the LS1 Miata and a lot of progress happened, back in late May.

Custom Rear Subframe Construction

We weren't sure which way the rear subframe and suspension would go until we just dove in and started mocking up parts. We knew the factory rear hubs were going away, as we wanted to fix the problems we've seen in our V8 swaps to this chassis when we made ours - namely, busted halfshafts out back and fragile hub bearings at both ends.



There wasn't much to start with when Ryan got to the back of this 1999 Miata. We had looked at using part of the old factory rear subframe structure and cutting it up to fit the Ford 8.8" aluminum center section. The problem was the new diff was so large that most of the top of the old subframe had to be removed and very little structure would be left.



The stock differential housing, rear subframe and rear control arms were removed so we could mock-up the new parts we wanted to add. The rear hubs/uprights were ordered then we mocked up the Ford 8.8" IRS diff housing...



There was no way that 75 pound aluminum diff housing could fit without hacking the stock rear subframe beyond recognition, so it was set aside intact and fabrication of an all new rear subframe was started. The Ford diff housing was mocked up using some straight tubing passing through the new rear hubs and uprights we chose for this new set-up. These were chosen for their "high torque capacity" sizes on the hub bearings and the splined size for the halfshafts. Nothing that uses the OEM rear NA/NB Miata hubs or input spline can live much beyond about 250 ft-lbs of torque for very long, at least not with grippy R-compound rubber. The LSx motor that has been built for this Alpha car will make more than double that (450 ft-lbs+)

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The uprights (below) we used are aluminum, very strong and work with the 5 x 114.3 mm bolt circle hubs shown above. This rear hub will work with the same wheel bolt pattern we're using up front, which we borrowed from the best OEM Mazda front bits. The entire front suspension is based on the beefier RX8 hubs, uprights, brakes and forged aluminum upper and lower control arms.



We also switched to a different rear cover for the Ford 8.8" IRS housing, which is shown above, deciding not to use the 2004 Mustang Cobra cover. This dual ear "winged" mounting style cover used is similar to the style that comes on the BMW E36 chassis and somewhat like the C4 Corvette Dana 36/44 housing - both cars we have worked with and raced hard for many years without issue. This style cover is easier to work on and mount to than the "clamped center mount" '99-04 Mustang Cobra rear cover used in our earlier mock-ups. This newer cover also has both fill and drain plugs on the cover, for use with a possible differential fluid cooler (common for heavy road course use).



The goal was to be able to use stronger OEM based and commonly available hubs, brake parts & other consumables (not one-off fabricated or race-only parts), and have the same wheel bolt circle front and back. This way if you blow through your brakes or wear out hubs at a track event, you can run to a local parts store to get replacements fast.

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Ryan jumped into the new rear suspension and subframe design with both feet and spent a full day making measurements (see above) and checking suspension geometry using 3D node software, to check camber change through suspension movement. Using the short upper and long lower arms and moving the pick-up points in computer space, then checking the camber change under movement. The final pick-up points and geometry chosen looked great and the dynamic camber change was well within normal parameters.



This is major fabrication work coupled with suspension design, and not something usually done by just "anyone that can weld". Luckily it wasn't too challenging for our crew - we are primarily a suspension shop and all of us are racers - and the new subframe and suspension design was knocked in a little over 70 logged hours.



The start of the upper structure of the rear subframe is shown above and left. The beefy new subframe unit will bolt to the 6 factory mounting studs in the rear of the chassis, without any cutting or welding. Once it is finish welded I will share the final weights vs the OEM bits, but it should add little to no weight over the stock rear assembly. The picture above right shows some of the tubular steel custom rear lower control arms going together. These are adjustable and feature polyurethane mounting bushings for some cushion but nowhere near the slop of a rubber mount. This should be suitable for a dual-purpose street/track car, but we could also make these arms with spherical ends for track-only set-ups.



These hub-mounted stands worked well during geometry checks and suspension mock-up and fabrication. Lots of fixtures and welding jigs were built to be able to make the parts uniformly and mirror imaged from side to side.

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Here you can see the aluminum 8.8" diff housing starting to be fitted to the tubular steel rear subframe structure. Polyurethane (red) bushings were used in the front and rear mounting locations for this housing.



The front diff mounting brackets are shown below at right. There is a gusset to add on each side but otherwise that section of the subframe is finished.



You can see the rear chassis studs and bolt holes that the new subframe mounts to, below. There are some scalloped areas that will be added for more bolt/nut clearance, and small tubular gussets here and there, but this is the final layout we're going with.



There are a few gussets to be added, then final welding can be done and the subframe removed for powder coating.

What's Next?

We've already had started on the front subframe and it was mostly done. Now we are tweaking the front geometry to allow for more camber and caster adjustment, using the RX8 eccentric bolts/washers and OEM style "cages" around these bits. Once the front subframe is completed we will design and build the LSx V8 motor mounts (takes about a day and a half). After that the prototype header fabrication and a driveshaft can be built. We have an aggressive schedule to finish this car this year, so stay tuned for more updates. We will be making production runs of both subframes, for use with LSx V8 swaps as well as racers with boosted Mazda engines that want the reliability and durability of the higher strength hubs, halfshafts and diff housing we're using.

Thanks,

[karter74]

Impressive!!

Curious though, for the people who may buy your rear end kit for the strength, will you be integrating some sort of PPF mounting solution? Or developing a transmission mount for the factory transmission?

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Project Update for December 17th, 2014: We've been busy on the Miata over the past few months but I've just been too busy to get caught up on the forum updates. We just finished construction and a big shop move for Vorshlag, doubling our available space, which ate up a lot of my time. This move has made for some extra room to work on projects like this, to add some new fabrication equipment, and just this past week for two CNC machines (lathe and mill) to finally make our machined Vorshlag products 100% in-house.



Right after the move in November a majority of Vorshlag folks also went to SEMA and then we were competing in OUSCI (Optima Street Car shootout) in our TT3 Mustang. Then Jason went to the 2014 PRI show and took 100 pics of cool new parts. Ryan stuck around at our new shop in Plano, Texas, and worked on the Alpha Miata V8 and made some really good progress. Then he found some more days in late November and early December as well. Anyway, we have all been slammed, but big progress has been made on the Alpha Miata.


The 2014 SEMA show and the OUSCI competition were fun but ate up a lot of time I where could have been updating various build threads

Front Suspension Follies!

Last time we updated this build thread, Ryan had finished re-checking the geometry on the rear bits, tweaking the rear subframe and making new rear control arms. That was back in June. In August he was freed up a bit and finish-welded the custom rear rear control arms. They are ready for shock mounts, cross bracing and custom half shafts at that point, but the rear subframe still needed to be final welded. He wanted to tackle the front before "locking down the design" (track width, ride height, etc) out back.



Now we move ahead to some time he had in August, when he moved to the front, to re-run the 3D geometry on the RX8 spindles/arms that we already had mocked up and tacked in place to the custom tubular front subframe. Well... while it looked fine to the naked eye, once the wheel was at the proper ride height (now visible with the RX8 hubs mounted to the new hub-stands, shown above) the geometry was less than ideal. Once the pivot points were input into suspension analysis software it was obvious that anti-dive and bump steer were terrible. Still, I wasn't giving up on keeping the suspension/brakes "all Mazda" up front, so I had him stick with the RX8 bits a little longer and try to move the pick-up points to try to dial some of this out.



Ryan cut off the previous pick-up points and made new ones, then rolled the mounting points as far as he could within the constraints of the stock front Miata tub and the RX8 arms. After sourcing some factory Mazda RX8 eccentric bolts and making the new control arm mounts that mimicked the factory subframe mounting points, it looked great and had the adjustments we needed, but the geometry still wasn't getting much better. He did some 3D measurements, saw some room to improve, then yanked the subframe and started over - making an all new front subframe section, from scratch, to gain some room for our the RX8 suspension at the lowered ride height and to fit with the big tires we had in mind. Two steps forward, one step back - that's how it works sometimes. The second, new subframe was tack welded together and had several improvements, and we would end up sticking with that through the next suspension iteration.



After he re-installed the RX8 bits it still wasn't good enough, so our engineer Jason and I asked Ryan to just fabricate new control arms to use with the RX8 uprights and hubs, but after an exhausting search the OEM style ball joints for the RX8 (very funky taper and size - nothing like anything supported by the aftermarket) were not available separately, so this was a dead end. Bah! I finally pulled the plug on the RX8 spindles and pretty aluminum control arms. We had already acquired brand new RX8 brake parts, too. Oh well, some ideas just don't pan out. Lots of fabrication hours were wasted based on my notion of using OEM RX8 spindles, brakes and front control arms.

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After this latest wild goose chase we had Ryan stop working on the car for a few weeks while engineer Jason and I regrouped, to look for other front suspension and spindle solutions we could utilize. After this debacle we realized that swapping in another set of control arms wasn't going to work inside the narrow confines of the Miata without several miracles, so instead we focused our search on a good OEM uprights that was made for a double-A Arm suspension. The result was we found something much better than the RX8 bits - lighter, forged aluminum, even more common to find, with tons of aftermarket support, beefy front hubs, and dozens of OEM and aftermarket big brake options. So, what did we use?

When In Doubt, Just Use More Corvette Parts

Corvette C5 spindles were the chosen upright this time (C6 are virtually interchangeable, too) and the first one we purchased looked great - and proved to be significantly lighter, too. And honestly we don't care where the parts come from, if it meets the criteria for use on a hybrid build like this: use the best parts available, that can be purchased at the best price, with good aftermarket support, easily procured consumables, and the best materials/strength/design.



The C5 aluminum upright was 5.6 pounds (13.96 pounds, with hub and ball joint installed - and the unit bearing hub is BEEFY!) compared to the 15.5 pound RX8 steel upright and hub. The nice thing is that the front and rear spindles on a C5 (and C6) are interchangeable (RF and LF are the same, LF and RR as well), which doubles your chances of picking them up second hand. Once we had one of these forged C5 spindles on hand, new ball joints were ordered next (we first made sure first that they were available separately!) and Ryan started making a whole new set of upper and lower control arms.



These would be tubular, the right lengths, and after some analysis, end up with better geometry, and have more range of alignment adjustment than the "eccentric" bolts of the RX8 arms. We could now adjust camber and caster through a larger range and achieve proper geometry at the ride height we wanted without cutting up the Miata tub. The lower arms would house the C5 ball joints and the upper arms would accept the matching C5 upper. The ends we chose were firm polyurethane bushings and the lengths were to be adjustable. A lot of pieces were ordered, many more were custom machined, and a lot of hours were spent calculating, fabricating and measuring.



Making this car as a one-off build would have been SO much easier - we would have just notched out part of the frame and made the RX8's control arms pick-up points fit in space where they would work for the geometry. But we have been going to great lengths to keep this subframe and suspension a reproducible kit, and to keep it a purely bolt-on set of parts, which meant not chopping a chunk out of the front frame section to move the upper control arms upwards. In the end we found that the C5 spindles, with the OEM ball joints aimed as they are, allows for the geometry we needed within these MX5 chassis constraints, using these custom control arms. BOOM!

Steering Rack Placement + New Steering Shaft

Once the new front control arms were fabricated and tacked welded, then geometries rechecked (both manually/visually and in software), it was at a good stopping point. Ryan then began to tackle the front steering rack mounting.



The NB Miata steering rack was placed in the ideal location for the slightly altered wheelbase and new front Corvette spindles, keeping in mind the necessary oil pan clearance. We have a half dozen different LSx oil pans around here to test with, so we worked with those to find the right combination to clear the steering rack without adding bumpsteer. The final rack mounts were fabricated and tacked to the crossmember.



This new rack location (and the small wheelbase change) would mean we would need new, slightly longer intermediate steering shaft assembly in the engine bay. Luckily we're used to making those for all of our BMW LSx swaps, so this is another bolt-on solution. What you see above is a mock-up - with one of the two aftermarket steering U-joints installed with a piece of 3/4" Double D shaft, to check lengths. The final solution will be a proper 2-piece collapsible steering shaft assembly like our many Vorshlag BMW steering shaft assemblies (see below). We make these to improve header clearance for V8 swaps on various BMWs, improve the heat resistance of the U-joints (the OEM steering shafts on LHD cars with inline engines are not meant to see exhaust heat) as well as to remove nasty rubber "rag joints" (steering shaft isolators) in the shaft, for better steering feel. We even sell a lot of these steering shafts to BMW racers who keep the BMW engine, just for the improved feel.



Olof took a fresh NB steering rack core and converted it to a de-powered rack (we do this work on NA/NB Miatas often), welding up the bits necessary. We will use no power steering in this car initially, then switch to an electric assist solution if it is deemed necessary.

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Front Drive Accessories

Running no power steering pump will create some headaches but also solve some potential problems. Hydraulic fluid power steering assist is always a hassle in any car; the system can make for a huge mess when it leaks, and requires an engine-driven hydraulic pump, reservoir, cooler, and high end hoses on a tracked car. This system is the number one cause of on-track fluid leaks and underhood fires, so taking hydraulic power assist out of the equation is fast becoming part of our track-worthy upgrade list for all cars. Many OEM cars these days are coming with "EPAS" systems from the factory, which makes for aftermarket electric steering assist solutions that are numerous and proven - since many are just re-purposed OEM systems. This means they can even be cost effective. And lighter. And no longer based on flammable, high pressure fluid that robs power from the engine to pressurize. Win!


A recent LS1 mock-up (October) with a set of accessories that does NOT have a power steering pump

And while it might seem simple to run any old LSx engine without a power steering pump, it was actually pretty tricky. This particular accessory drive arrangement was figured out on our FR-S LS1 Alpha swap, with some help from the itnernets plus some custom machined bits made here at Vorshlag. That car has an electric assist in the column, so it did not need the pump.



We couldn't find a factory set of LS series engine accessories without the P/S pump, so we went with a proven version that had GOOD front clearance (shown above on the FR-S LS1) and narrow packaging, then the normal main serpentine belt routing was changed to bypass the missing power steering pulley. To accomplish this an extra idler pulley was added, and things were moved around to give proper belt wrap on each pulley - especially the balancer (SFI unit secured with a massive 12-point ARP bolt). We took some measurements then borrowed this set of accessories from the FR-S and test fit onto the built Miata LS1 motor, it fit great (see images above), so we're replicating that set-up now for the Miata. It took a few iterations but we finally got the right length belt (these were the "almosts")

Motor Mounts and Transmission Crossmember Design - With A New Twist

Once the newly modified, de-powered NB steering rack was mounted to the subframe with some beefy, fabricated brackets (see above) we wanted to then lock down the designs for the motor mounts and transmission crossmember. But now that the tubular subframe was built and the rack was tweaked to fit the C5 spindles, Ryan saw some extra room and tried something I didn't expect... he put a Tremec T56 6-speed behind the LSx mock-up motor and stuck it back in the car. Again. Yes, after all the testing and trouble we went through to make the Tremec TKO600 5-speed fit, he went and stuck a T56 in there.



I had told Ryan when he came on board at Vorshlag that the T56 would never fit this car, both because we tried this transmission before (with the OEM crossmember, and then a cut up OEM crossmember) as well as the fact that all of the other LS1 swap kits for the Miata require cutting the tunnel to make the T56 fit this car. "Waste of time."



Thankfully, I was wrong this time. Now the bigger, stronger T56 did fit - and fit with room to spare! Apparently in our previous T56 testing the Miata's OEM front crossmember was the limiting factor. That big, bulky plate steel structure moved the drivetrain up significantly, which is why the T56 never fits the Miata tunnel on most swaps without cutting the tunnel to make room.


Left: The initial LS1/T56 mockups were a bust with the OEM crossmember in place. Right: With the tubular crossmember we have lots more room

This is because the LSx/T56 drivetrain is being moved upwards inches from where we have our drivetrain. With our latest (version 2.0) bolt-in tubular front crossmember, the engine sits lower and so does the transmission, so now it fits. It still has ample ground clearance to the oil pan, which is tucked up just above the bottom of the crossmember and bottom of the Miata tub. The T56 shifter location lines up perfectly with the factory Miata shifter hole. Moving this drivetrain down worked another miracle, and it lowers the CG, too. Win-win.

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That big transmission change threw me for a loop, but so be it! A brand new Tremec T56 Magnum costs more than the TKO600 new, but not by much, and its a more popular trans so we called up our Tremec supplier and we had a brand new close-ratio T56 Magnum on hand the next day.


Tremec T56 Magnum - close ratio version - rated to 700 ft-lbs of torque!

If you know anyone that needs a GM-style TKO600, brand new, we will have it listed for sale here until it is gone, for less than they sell for now. We still have to get the correct flywheel, clutch and pressure plate for the T56, but those bits are already on order and should be here next week. During all of the transmission testing our crew removed the mock-up LS1 motor for the last time and installed the built 5.7L LS1 that the Alpha customer purchased for this build, made by the masters at HK Racing Engines.


Left: The built LS1 with borrowed accessories and LS3 intake in the Miata: Right: LS1 with same accessories and balancer in FR-S

This motor has a built bottom end, CNC ported heads, big lumpy cam, proper valvetrain, and all sorts of race parts inside. Should make in the neighborhood of 450 whp on pump gas. Ryan chose the 98-02 Camaro oil pan during his testing, so we ordered an Improved Racing oil pan baffle kit to fit this pan and that's in place. We won't build a track-duty car with an LSx without an oil pan baffle from Improved Racing. After talking to those guys at SEMA they realized how many of these LSx baffle kits we've used over the years and made us a dealer, so we'll add these to our website shortly.


Left: The accessory arrangement we used has ample room for an A/C compressor, as shown. Right: Improved Racing oil pan baffle will be used

Once the oil pan and accessories were locked down, then Ryan could start to build the motor mounts (see below left), which he knocked out in about a day. These look like many of the designs we have used on BMW E36, BMW E46, BMW E30 and the FR-S/BRZ swaps done here at Vorshlag.


A production set of similar mounts for our BMW E46 LS1 swap, black gloss powder coated. We make these in-house with CNC laser cut pieces

When you have a robust, proven design that has been made 100s of times, you use it. These make for a strong, reliable, low vibration mount that has no movement when torque is applied. These then bolt to a gusseted, plate structure welded to the tubular subframe (see below right).



To make the transmission crossmember required a bit of extra work, at least on this Alpha build. Like on the FR-S swap (after we made room for the longer T56 Magnum XL we used on that car) this NB Miata chassis has no transmission crossmember mounting on the chassis. The front mounting points of the "PPF" on the NA/NB Miata is the transmission mount (which is similar to Corvettes from C4-C7), but we ditched that since the T56 Magnum had no provisions for mounting this ladder frame to the back of the tail housing. Modifying the transmission to fit the factory PPF would be a nightmare to reproduce in kit form.

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Left: The heavy stock dash was removed to make room to pull the carpet. Center: Inner plate brackets. Right: Shifter lines up very closely

To make room for the next step, the dash was removed. Why? Two reasons. First, we wanted to see how much the entire NB dash structure weighed. 49 pounds is the answer. Second, to remove the OEM carpet intact the dash has to come out. We needed to add some backing plates inside the tunnel under the carpet, to hold the transmission crossmember brackets inside the tunnel, so the carpet was pulled. For the kit version we'll have templates for where to drill holes and you can slit the carpet to slide the plates under the carpet without removing all of this, hopefully. Mazda just makes it extra hard to remove the carpet on these cars - dash and everything is in the way.


Left: Outer tunnel reinforcement plates. Right: The transmission crossmember bolts to inner tunnel reinforcement plate mounts

As we did on the FR-S swap, mounting plates were bolted to the chassis on both sides of the transmission tunnel. These can stay in place, and the crossmember then bolts to the inner mounting bracket plates. This sandwich of plates (one set inside the tunnel and the matching plates inside the cabin) makes for a strong mounting arrangement which we've used in the past. The removable crossmember bolts to those inboard mounting plates and this, in turn, is what the transmission bolts to.



The raw steel crossmember shown above is semi-finished; we will add more gussets when we final weld the assembly. It has lower reliefs that could clear up to two 4" diameter exhaust tubes, but we will build this car with a dual 3" exhaust - which still has massive flow potential. We used our proven red polyurethane transmission mount bushing from other T56 swaps in this set-up, but we also make a machined Nylon busing for a pure race car.

Subframe Final Welding - Times Two



After the drivetrain mounting was designed and built, the motor was once again removed and the tack welded front subframe came out for final welding. This step took two solid days, as welding fixtures had to be built and then additional gussets had to be made and welded in place as Ryan went through the tacked joints and TIG welded everything. The end result is shown below, and is a very strong work of art. Production fixtures would key all sorts of CNC laser cut pieces into place, and that is much more elaborate, but we will make those when we blow the car apart for the last time.



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