nuclearfishin

Hi all, I have a question I'm hoping some of you can answer. I just had a set of H&R springs put on. The Indy shop who is doing the work (a good shop I trust) is working on the alignment now. There is a negative camber due to the springs, however the adjustment is maxed out trying to bring it in and it's still at around 2. The rear right side is fine, it's only the back left that has no more room to come in. Any ideas what's going on? The drop from the springs was very minimal, maybe a half inch, so it seems weird that it would be pushing the camber out so far. I also added a 7mm front/15mm rear spacers, but everything else is stock. This might exacerbate it a little, but shouldn't prevent the wheels from coming into alignment. Any thoughts?

L_perm

The stock adjustment mechanism is known as the eccentric, and from what I've read and been told, lowering the car can make it difficult to maintain both an appropriate camber and an appropriate level of toe in simultaneously. The two cannot be independently adjusted.

If your mechanic is dialing out the toe in that normally occurs when lowering the rear, then he may be inducing excesive camber.

I am surprised that a 1/2" drop is causing so much trouble, but I've also been told the eccentric can have different ranges of adjustment depending on how it had to be set to achieve the stock parameters.

Caveat: I could be wrong about all of this, but my sense is that you are experiencing the limited adjustability of the eccentric mechanism that leads people to lock the eccentric and replace dogbones and rear toe control arms with adjustable ones. Some don't lock the eccentric and just replace the toe control arms.

Any experts want to run with this?

LP

nuclearfishin

I think you're correct in describing what's occurring. So, will a set of rear dogbones be enough to correct it or will it also require the toe control arms? Thanks!

speed21

I have heard of some that have taken the route of drilling out/elongating the 3 holes in the top strut towers to provide enough adjustment to remove some of the neg. Not the best solution on a car like a Porsche. imo...and then there is the rear to contend with.....
To recover a good alignment requires a set of adjustable (taret) top strut mounts, combined with adjustable LFCA's (for 996/997GT3 or cup) will get it sorted. There is usually more to any lowering exercise than meets the eye than just a set of coils unfortunately. To be honest your indy shoulda known that.
Edit. Don't forget the drop links to the sways either. You don't want those all bound up.

TT Surgeon

Dog bones and adj toe links will correct the geometry, no need to lock the eccentric.

nuclearfishin

Thanks for all the help fellas! As TT suggested, I just ordered the dogbones and toe links. Out of curiousity, why doesn't the front need the correction similar to the back? Is it because the motor throws the rear geometry off much more than the front? Thanks again!

aa909

surprised to read the trouble you're having. I lowered my car on GMG springs and know of others who've lowered on H&R springs and no issues with alignment. We were able to get my rears into stock range without the need of any aftermarket parts

Are you 100% confident your tech has installed them properly? may be worth a second opinion from another shop just to be sure

good luck
Art

nuclearfishin

They're installed correctly, I think the need for dogbones or not comes down to how much adjustment room you have when it come from the factory. I also added 15mm wheel spacers in the back so that may be a contributing factor.

L_perm

Just generally speaking, the suspension geometry is different between the front and back--to allow the front to steer, among other things. You've seen suspension descriptions in car magazines, where they say multi-link this, and Macpherson that...? The front and rear don't usually have the same descriptions.

Again, an expert can give more specifics.

LP