Power Frame Support

[trackdog]

I did not want this response to get buried at the bottom of the last thread.

On the PPF support, notice the comments were from those that do NOT have it! Your complete drive train is held in basically by 4 points of isolation, two at the motor and 2 at the differential. You probably have about 900+ lbs. in your car moving one direction on another every time you accelerate or decelerate, this is called Polar Mass. The engine torques left and right and the differential torques up and down and your poor little Power Frame unit takes all of the abuse!

I would recommend the PPF support for normally aspirated and FI cars. No matter what your power level is your drive train movement is changing your CG as you accelerate and decelerate. If you are going though a turn and you let the gas off suddenly, what is that 900 lbs. doing? It is shifting and this can upset the car. Those that do not have good strong drive train support would consider this normal because that is how they have learned to drive. If you can reduce this polar mass movement then your handling will improve. A daily driver may not notice it until he drives it really hard in turns, but a good driver can notice the difference.

The Track Dog PPF kit also includes urethane inserts that go into the rear differential mounts. Personally, I prefer the insert over the MS replacement differential mounts as they provide more support in reducing movement. The PPF kits urethane insert has fingers that feel the void in the rear mounts to reduce significantly the differential movement. Reducing this movement can eliminate wheel hop and increase traction.

We put a customer's car up on our lift one time and watched the PPF as it was being torqued by the engine and the differential at the same time and it was amazing that the PPF does not crack under stress!

The second part of the Track Dog PPF kit adds a brace that installs right in the middle of the PPF where the most torque is being applied. Installation takes about an hour.

Thank about what I said next time your are driving aggressively and maybe you will understand why this product is beneficial on all cars.

Gary

[Tim the Teacher]

Thanks Gary for the info. I sent you a pm.

[Titus]

Gary, you know I have TONS of respect for your opinions on all things Miata, but as I said in my other post, "If someone does plan on installing one on an NA Miata, I would like to help with the install to feel any before and after change. I need to see it to believe it, otherwise it is just added weight."

Do you really feel that the PPF goes near the top of the list of things to do? It seems to me that there are too many things that would be a higher priority. I know you have a chart of recommended upgrades to go along with a SC (of which PPF isn't listed), but I would love to see a good analysis of upgrade priorities to help the guy starting out. Perhaps we can do a little scenario. You just bought a new bone stock Miata. Your wife (sorry Tim, I had to) will let you buy and install one part per month, and only one. What are ALL of the upgrades you would do, and in what order. Would you rather have better brake pads a few months before better motor mounts? Would you upgrade your radiator first, or would you rather have a set of Teins first? Another thing to consider would be weather or not the list would be different for different Miatas. Perhaps a 1.6 Miata would get a brake upgrade and extra bracing earlier than a 2005 Sport that comes pretty well braced and brake equipped.

[trackdog]

Excellent idea Todd and I will most definitely make a recommend list on our website and perhaps repost it here. Thanks for looking after us, again.

Gary

[icepenguin66]

Yep, nice idea Titus. I haven't taken a ride in Gary's NA car yet with the PPF and such to tell any difference, but it is way up there on my list of things to do next for my 90. IMO, anything that will increase the stiffness and structural rigidity of any Miata is a good thing, especially on the earlier ones.

As for the list being different for different year Miata's, installing the rear sub-frame brace was one of the best mods I've done. I could certianly feel a difference and for the better. (FYI, the FM rear brace is 100x better than the RB one) I for one would put that ahead of most mods for the 90-91 Miatas and the brake upgrade/pads as well. Those are noticable mods that make the car ride/brake better. A stock Miata still handles great so if the shocks/tires are still good, then I would recommend the above first.

just my

[Flyin96M]

You are right I do not have one on my car, but did not say that there was no gain to be had. I just do not believe that it is one of the first things I would be adding if I were starting from scratch. I recomended the clutch first simply because you would have to remove the PPF brace to install a new clutch so why add this first? Will I add one of these down the road...possibly, but it is not at the top of my list.

I would be interested in seeing some before and after tests the next time you install one. May be interesting to remove the hood and video tape how much the motor moves before and after the install. If I could physicaly see how much it helped I may reconsider it's position on my list.

I base most all of my purchases on facts that are well documented. I hear what you are saying and you know I have great respect for your knowladge, but I have a hard time seeing it. I'm your friend and if I have a hard time seeing it then how do you think others that don't know you think? I in no way mean any disrespect or am saying that it is all in your head, but I am just trying to make a point

Facts will sell this product.

[Billy Blaze]

I noticed reduced wheel hop on take off, and it seemed to rev a little better after mine was installed.
just my two cents.

[tailchaser]

Yep, nice idea Titus. I haven't taken a ride in Gary's NA car yet with the PPF and such to tell any difference, but it is way up there on my list of things to do next for my 90. IMO, anything that will increase the stiffness and structural rigidity of any Miata is a good thing, especially on the earlier ones.

As the owner of one of the stiff NB chassised cars, I've got to say that gary's NA car is probably the most solid Miata I've ever driven. That stiffening is a huge improvement on the older cars.

[altiain]

I would recommend the PPF support for normally aspirated and FI cars. No matter what your power level is your drive train movement is changing your CG as you accelerate and decelerate. If you are going though a turn and you let the gas off suddenly, what is that 900 lbs. doing? It is shifting and this can upset the car. Those that do not have good strong drive train support would consider this normal because that is how they have learned to drive. If you can reduce this polar mass movement then your handling will improve. A daily driver may not notice it until he drives it really hard in turns, but a good driver can notice the difference.

Gary

Gary, I'm just curious what you're basing this assumption on. Polar moment of inertia is based on where the major mass centers of the vehicle are in relation to the axis of rotation. For example, mid-engine cars tend to have a lower polar moment of inertia than front engine/rear drive cars because their major weight sources (engine & transmission) are centered near the middle of the car, which is also typically where axis of rotation is.

The only way to noticeably improve the polar moment of inertia of the car is to remove weight from the extremities, or move that weight closer to the axis of rotation. Removing the bumper beams, the "baby teeth" (which is one of the reasons that removing them is illegal in SCCA Stock and Street Prepapred classes), or other structure at the extreme ends of the car will improve polar moment of inertia. Reducing the overall weight of the vehicle will also impropve the polar moment of inertia, although the closer the weight is to the center of rotation the less of an impact it will have.

Stiffening the driveline with an additional powerplant frame is going to have very little, if any, net positive effect on polar moment of inertia. It certainly won't reduce it, because you're adding mass to the car, and moment of inertia is the rotational analog of mass - add mass, you've increased the polar moment of inertia by definition, unless you've managed to completely concentrate that added mass along the axis of rotation.

Now, I'm not saying that adding the powerplant frame won't improve a car's lap times, which is what I think you're trying to suggest in your explanation. The stock driveline certainly does move around a bit in response to throttle inputs. It was designed to, to isolate noise, vibration, and harshness. Stiffening the driveline will have the effect of improving throttle response and linearity. But I don't believe that it will have the slightest effect on polar moment of inertia. The car won't turn in any quicker or rotate any faster with a powerplant frame, two things that you would gain with a reduction in polar moment of inertia.

[channelmaniac]

Ow... I need an asprin for my headache...