Question about my Ground Control setup

I have a 1995 Miata with Ground Control coil-overs and KYB AGX shocks. I also have FM Shock mounts on the rear to increase shock travel.

My question is regarding setting ride hight. I currently have it set at 12" from the center of the wheel to the top of the fender on all four wheels. The problem is my car is so low that I can't get any better than -2.5 rear camber which leads to excessive inner tyre wear.

I would like to raise my car high enough to get my camber to a more tyre wear friendly level (-1?) while still keeping it as low as possible. Without trying trial and error, does anyone have any idea how many threads I need to set my Ground Controls at to get a reasonable camber without sacrificing too much ride hight.

I know there are other options like offset bushings, flipping tyres, etc but I'm just trying to work with what I have first.

I have read that Ground Controls are @ 1/16th inch per turn of the coil on the sleeve. The thing you need to keep in mind is that raising the height on one corner will effect the height on the other 3 to some degree due to weight transfer.

I take my car to a shop that prepares some track cars and when I get the car aligned, they will work with ride height and corner weighting to balance the changes.

One idea might be to set it for the most positive camber possible and then lower it to the desired height or camber (which ever comes first). That way you can find the height at which the camber can't be adjusted any more positive or close to what you want.

Then you can go as far negative as you want in steps, more neg camber/lower ride height. Kinda like shampoo, lather, rinse, repeat until desired effect is achieved.

As for the camber setting required for good tire life, see AJ. I'm pretty sure he can work something out for ya that will balance tire life vs handling.

My '96 with GC and AGX is at 12.25"F, 12.75"R. Rear camber is -1.75 deg. (It's basically a "Lanny") Fairly even tire wear so far. Previous alignment was -2 deg in the rear and I did see much greater wear on the inside shoulder with that setup.

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Originally Posted by black roadster

The problem is my car is so low that I can't get any better than -2.5 rear camber which leads to excessive inner tire wear.

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You also need to compensate for the Butterfly brace you are gonna add. The last thing you want to do is rip the center section off by hitting an object in the road.......such as a manhole cover.

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Originally Posted by johnwag

You also need to compensate for the Butterfly brace you are gonna add. The last thing you want to do is rip the center section off by hitting an object in the road.......such as a manhole cover.

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Does it really hang down that low???

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Originally Posted by wrxmr2eater

I have read that Ground Controls are @ 1/16th inch per turn of the coil on the sleeve. The thing you need to keep in mind is that raising the height on one corner will effect the height on the other 3 to some degree due to weight transfer.

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According to the :batman: it is actually 1/8" per turn.

I plan on raising the car evenly around so the balance should be the same.

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Originally Posted by Nexus Flux

As for the camber setting required for good tire life, see AJ. I'm pretty sure he can work something out for ya that will balance tire life vs handling.

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I got the impression from AJ he didn't want to mess with it. He told me to raise it and he'll realign it.

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Originally Posted by CraiginTX

My '96 with GC and AGX is at 12.25"F, 12.75"R. Rear camber is -1.75 deg. (It's basically a "Lanny") Fairly even tire wear so far. Previous alignment was -2 deg in the rear and I did see much greater wear on the inside shoulder with that setup.

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Thanks Craig. I think I'm going to go 12.5 all around and see how that goes.

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Originally Posted by johnwag

You also need to compensate for the Butterfly brace you are gonna add. The last thing you want to do is rip the center section off by hitting an object in the road.......such as a manhole cover.

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Good point. "How low can you go" can no longer be my motto. :(

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Originally Posted by trickyrix

Does it really hang down that low???

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I think the incident in question involved a construction area where the manhole cover was a bit above the actual road surface. I recall seeing a post about this very thing on m.net a while back, including pictures of the boogered center section.

The center section might or might not end up a bit lower than the rails. This will depend a bit on your exhaust situation and how much space you need to allow to keep from enjoying the melodies created by metal-on-metal vibrations.

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Originally Posted by trickyrix

Does it really hang down that low???

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Rick,

Let's plan a tech day in May to install our butterfly braces. I have too much homework now. Cool?

It seems we are both wrong. One full turn raised the car 1/2".

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Originally Posted by black roadster

Rick,

Let's plan a tech day in May to install our butterfly braces. I have too much homework now. Cool?

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I'm down with that - especially to get those frame rails on! Given my current work schedule, it would have to be on a Sun, Mon, Tues, so let me know what works for you. BTW, Gary mentioned a fix for the center section to ensure that it clears the exhaust - but that might apply only to my stock pipes...

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Originally Posted by trickyrix

I'm down with that - especially to get those frame rails on! Given my current work schedule, it would have to be on a Sun, Mon, Tues, so let me know what works for you. BTW, Gary mentioned a fix for the center section to ensure that it clears the exhaust - but that might apply only to my stock pipes...

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Now that I work mornings that will work. I'll be out of school by then too.

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Originally Posted by black roadster

It seems we are both wrong. One full turn raised the car 1/2".

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Yup, like I said...
The thing you need to keep in mind is that raising the height on one corner will effect the height on the other 3 to some degree due to weight transfer. The diagonal corner usually dropped a small amount as well, more of an issue when checking the corner weights.

When I adjusted drivers rear on my car, driver front and passenger rear also raised varying amounts. If you raised each corner 1 full turn, you modified height on each corner at least 3 times.

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Originally Posted by wrxmr2eater

Yup, like I said...
The thing you need to keep in mind is that raising the height on one corner will effect the height on the other 3 to some degree due to weight transfer. The diagonal corner usually dropped a small amount as well, more of an issue when checking the corner weights.

When I adjusted drivers rear on my car, driver front and passenger rear also raised varying amounts. If you raised each corner 1 full turn, you modified height on each corner at least 3 times.

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OK... I'm confused... :confused:

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Originally Posted by black roadster

It seems we are both wrong. One full turn raised the car 1/2".

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Uhh... fail. That would imply that there are only two threads per inch on a GC sleeve. I've owned GC sleeves before, and I can tell you that ain't the case.

In this case, you jacked the car up, reset the sleeves, let the car back down, and re-measured. The suspension has not resettled. Go drive it around the block (or two or three), then come back an re-measure. I'll bet the car has magically lowered itself. :wink:

Weight jacking will play a part in ride height, but unless BR has been drinking heavily this morning he should be able to eyeball "1 turn" close enough on all four corners that it will not make that drastic of a difference.

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Originally Posted by altiain

Uhh... fail. That would imply that there are only two threads per inch on a GC sleeve. I've owned GC sleeves before, and I can tell you that ain't the case.

In this case, you jacked the car up, reset the sleeves, let the car back down, and re-measured. The suspension has not resettled. Go drive it around the block (or two or three), then come back an re-measure. I'll bet the car has magically lowered itself. :wink:

Weight jacking will play a part in ride height, but unless BR has been drinking heavily this morning he should be able to eyeball "1 turn" close enough on all four corners that it will not make that drastic of a difference.

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Sure enough. I need to raise is some more. ::Rant::

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Originally Posted by altiain

Uhh... fail. That would imply that there are only two threads per inch on a GC sleeve. I've owned GC sleeves before, and I can tell you that ain't the case.

In this case, you jacked the car up, reset the sleeves, let the car back down, and re-measured. The suspension has not resettled. Go drive it around the block (or two or three), then come back an re-measure. I'll bet the car has magically lowered itself. :wink:

Weight jacking will play a part in ride height, but unless BR has been drinking heavily this morning he should be able to eyeball "1 turn" close enough on all four corners that it will not make that drastic of a difference.

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Not only what Altiain said, you may find that the car settles a little bit more over the next week!