Alignment Issues
Drifting
Joined: Mar 2015
Posts: 3,111
Likes: 23
From: Austin, TX
Shake, did you end up putting caster bushings in the rear as well? At -2.5 in the back I can see the wheel started to be pushed back in the well noticeably so. Just curious. I had to go back to -2 in any way in the rear as my 20's are rubbing at the top outside fender at -2.5 as the shims push out the wheel a few mm's too much.
I got to -3 front without issues using shims, front toe link and caster bushing. This is probably the max and going any higher camber plates are the way to go.
As to jp's comment, I have no idea at what point cup monoballs are needed. I did not need them at -3.
I got to -3 front without issues using shims, front toe link and caster bushing. This is probably the max and going any higher camber plates are the way to go.
As to jp's comment, I have no idea at what point cup monoballs are needed. I did not need them at -3.
Pro
Joined: Sep 2015
Posts: 588
Likes: 20
How much shim did you use to get to -3, and what was the position of the top mount? Orthojoe mentioned using the Cup monoballs because they incorporate a thick shim and include longer studs to allow more shim to be added without falling too low on LCA thread penetration. Porsche evidently recommends at least 1" of thread in the LCA.
Rennlist Member
Joined: Mar 2009
Posts: 5,682
Likes: 992
Shake, did you end up putting caster bushings in the rear as well? At -2.5 in the back I can see the wheel started to be pushed back in the well noticeably so. Just curious. I had to go back to -2 in any way in the rear as my 20's are rubbing at the top outside fender at -2.5 as the shims push out the wheel a few mm's too much.
I got to -3 front without issues using shims, front toe link and caster bushing. This is probably the max and going any higher camber plates are the way to go.
As to jp's comment, I have no idea at what point cup monoballs are needed. I did not need them at -3.
I got to -3 front without issues using shims, front toe link and caster bushing. This is probably the max and going any higher camber plates are the way to go.
As to jp's comment, I have no idea at what point cup monoballs are needed. I did not need them at -3.
In the front, we moved to a camber plate, which let us run fewer mm of shims, but easily get to -3.5. Trivial to get a 265 on the front now, plenty of space - could even go bigger, but I don't think it would help much.
How much shim did you use to get to -3, and what was the position of the top mount? Orthojoe mentioned using the Cup monoballs because they incorporate a thick shim and include longer studs to allow more shim to be added without falling too low on LCA thread penetration. Porsche evidently recommends at least 1" of thread in the LCA.
Racer
Joined: Mar 2012
Posts: 381
Likes: 13
From: New Mexico
Just a note on this issue of threads on the LCAs. I added 8mm shims and removed one of the (two) spacers on the LCAs that are between the nuts and the LCAs. There is still one spacer, the nut and some threads protruding. I got -3.1 with the tops all the way in. Of course the toe was amazingly wrong, and I would have needed new tie rods, I expect. I went to -2.1 with zero toe and it all snugged up just fine, with lots of slot left at the top. Just another data point.
We are working on another GT4, and he is going with 6mm shims since his top slots were not as "bad" as mine. Seems like a bit of variation from the factory on these cars...
We are working on another GT4, and he is going with 6mm shims since his top slots were not as "bad" as mine. Seems like a bit of variation from the factory on these cars...
Pro
Joined: Sep 2015
Posts: 588
Likes: 20
Thread Starter
Instructor
Joined: Aug 2012
Posts: 113
Likes: 0
From: Cape Cod
Thanks all. I have a pretty good understanding of what mods are needed to achieve most desirable settings after reading threads and posts from many of you.
My question was whether or not anyone has heard of a factory acknowledged issue with the rear subframe that is limiting suspension adjustments. Apologies if that was not clear.
I was planning on autocrossing in stock class which prohibits mods.
My question was whether or not anyone has heard of a factory acknowledged issue with the rear subframe that is limiting suspension adjustments. Apologies if that was not clear.
I was planning on autocrossing in stock class which prohibits mods.
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Drifting
Joined: Mar 2015
Posts: 3,111
Likes: 23
From: Austin, TX
Fyi, in addition to variances in the cars themselves (I only got -1.5 camber in the front bone stock whereas others got -2, for example), what's achievable before needing tie rods would depend on the toe you want along with your target camber. A track-optimized setup that has a bit of toe out in the front might not be achievable for a given amount of camber, whereas a street-optimized setup that had 0 toe or maybe a hair of toe-in might work with that same amount.
Burning Brakes
Joined: Dec 2015
Posts: 866
Likes: 180
Yes, I had to add thrust bushings in the rear (which are already solid BTW) when I increased to -3, it was too close to the liner and rubbing on full compression.
In the front, we moved to a camber plate, which let us run fewer mm of shims, but easily get to -3.5. Trivial to get a 265 on the front now, plenty of space - could even go bigger, but I don't think it would help much.
I think that's right. I don't think you could do more than -3.2F without upping to a different end-link with longer bolts (unless you combined with camber plates too)
In the front, we moved to a camber plate, which let us run fewer mm of shims, but easily get to -3.5. Trivial to get a 265 on the front now, plenty of space - could even go bigger, but I don't think it would help much.
I think that's right. I don't think you could do more than -3.2F without upping to a different end-link with longer bolts (unless you combined with camber plates too)
A 265 front would be awesome.
Rennlist Member
Joined: Oct 2010
Posts: 4,727
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From: Cyprus and USA
Neutral toe. Caster 10.5. Lots of shims, can't remember. Park Place Motorsports did my car. No lowering either.
Drifting
Joined: Mar 2015
Posts: 3,111
Likes: 23
From: Austin, TX
Impressed that you hit -3 and 0 toe with only shims, but that amount of caster will probably cause you to rub under full lock and/or high-load cornering. I'd keep an eye on your tires, since others here have rubbed with a lot less caster than that. I'm also curious how much LCA thread engagement you've got left. You must be right up against the safety margin with the top mount already maxed out.
Last edited by jphughan; Apr 18, 2016 at 07:19 PM.
Rennlist Member
Joined: Oct 2008
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Impressed that you hit -3 and 0 toe with only shims, but that amount of caster will probably cause you to rub under full lock and/or high-load cornering. I'd keep an eye on your tires, since others here have rubbed with a lot less caster than that. I'm also curious how much LCA thread engagement you've got left. You must be right up against the safety margin with the top mount already maxed out.
Drifting
Joined: Mar 2015
Posts: 3,111
Likes: 23
From: Austin, TX
Quick question I just had after looking under the rear of my car. I have the locking plate kit to remove the eccentric bolt on the toe links, but I just now realized that there's another eccentric bolt on what I think is the LCA. I assume this is used to make camber adjustments without messing with shims, but does this one tend to stay in place even at the track? If not, is there a separate locking plate kit for that one, or is that just not a feasible option because the shims don't allow sufficiently fine adjustments?