mrr23

Had a customer bring in a 2007 z06 he bought from a guy that autocrossed it. It had the locking plates installed. How the former owner raced with it like this, I can only imagine how it drove. Of course I couldn't fix camber or caster because he didn't have any extra plates. And flipping them around would have made it worse.

hklvette

Edited again: That's a lot of front toe-in, but camber and caster aren't far off of what I would expect in an autocross setup. More camber than that is common. Any shims under the upper arms?

The rear camber and toe readings are oddly offset. Perhaps a loose or shifted cradle? It wouldn't take much to move the camber .15deg, which would make it even on both sides.

I'm sure more experienced folks will chime in, but there's my $.02

mrr23

Caster is nowhere near even. As a daily driven car, as it is being put into service now, it pulls to the right. Even still on a track it would want to drift right on the straights. The amount of negative camber is fine with the exception of the amount of difference in the rear.

The main point here is just don't put them in and not get it checked.

blkbrd69

Easy to fix the camber and caster by using shims.

Uneven cradle is normal just use shims to even it up.

mrr23

Easy to do but it would have cost the owner some money. He is going to get the orginal eccentrcs and put back in.

Bill Dearborn

Most track guys let caster fall where it will to get the camber they want. However, the front toe looks a little severe. It looks like there is around 5/16 in of total toe in. I would expect an autocross guy to have negative toe in the front to get the car to turn in quickly. I might run a 1/4 in. toe in the rear but nowhere near that much toe in up front.

Why go back to the original eccentrics? There is no need to do that. All you have to do is use regular alignment shims behind the UCAs to adjust camber/caster. Did you check to see if the car has studs or bolts holding the UCAs in place. Studs make it easy since all you have to is loosen the bolt and add or remove shims behind the UCAs. Just like aligning a C4 or a 1960s GM car.

If the front plates have Zs engraved in them they are Pfadt plates and are easily flipped over by loosening the bolts and turning the plates. When both sets of plates on a LCA are turned with the Z to the inside the LCA is pushed out for max negative camber which with no shims behind the UCAs will come in around -2.5. If you flip them over so the Z is to the outside the camber will come in around -1.3 with no shims behind the UCAs. Add shims behind the UCAs to get to a Pfadt street alignment of -.6 camber. If you want to play games leave the rear cams as they are with the Zs out and just flip the front ones. That will push the LCA ball joint forward and get you more caster then play with the shims behind the UCAs. Why limit the owner to the problems of the stock eccentrics when you don't have to?

There is an issue with the rear toe setup. There may be enough total toe but the rear wheels are pointing to the right about .25 degree. The left side is toed in about 3/32 while the right rear is toed in a little more than 1/16. The left toe in needs to be reduced and the right toe in increased until they are close to equal. That will get the thrust angle closer to where it should be rather than having the rear wheels push the rear of the car toward the right which requires turning the steering wheel to the right to go down the road straight.

Here are the GM Specs. Z06 is FE4.


Here are the Pfadt specs which pretty much fall within the GM specs.





Table for converting between Guide for converting between degrees and inches at each wheel.



Pfadt plates regular position and flipped.


Normal with curved sides upward.


Flipped.

Van Steel Plates can be flipped the same way. Not sure about Hardbar but they probably can be flipped as well. Just have to check to make sure they fit in the cradle notches when flipped. If they don't fit then you have to remove them from the bolt and flip them on their vertical axis.

Bill

mrr23

Couldn't flip them to correct caster without messing up camber. New owner didn't have any extra plates.

Former owner obviously didn't even try to check the alignment.

0.96* of toe is right at 1/2". Rear is about 1/4".

Didn't bother to try and shim top arms. New owner is basically returning back to stock. So he wants the eccentrics put back in to have full adjustability.

Edit: corrected my math.

Bill Dearborn

Caster was near dead on the GM spec so Camber wouldn't have been a big deal if both front and rear sets were flipped. I find the toe degree-inches chart pretty accurate. It comes from the people who developed the Smart Strings.


Tell him to save the plates, bolts and studs if you take them out. He can get at least $80 for the front setup if he posts them in the parts for sale section. If they are the Pfadt plates they are next to impossible to get now.

Bill

fatbillybob

For any tracking solid plates are imperative. Once you see how much a slipped rear ecentric can throw your rear toe out it will scare you. I can make a solid camber plate in about 20 minutes. It is really easy.

mrr23

caster may have been within GM specs, but what you need to look at is the difference between left and right. car pulls to the right and caster shows it. what you don't know is both plates on each arm were furthermost outward. so to correct caster would mean to flip plates on the left rear part of the arm. this would have lowered caster and raised camber. not what i was looking to do or the customer. he wants to daily drive this car and not pull and wear his expensive tires. and most likely flipping the rear plate would not have been enough or too much. so either buy more plates or put the original eccentrics back in.

current owner of the car does not track this car. does not want to. he wants to just drive the car daily. he doesn't want to put shims in the top arm to compensate for another persons error. so his best option is to put the eccentrics back in.

doing quick math in my head i was off by 1/4" my apologies. so 1/2" total toe in.

http://robrobinette.com/ConvertToeDegreesToInches.htm

we seem to be getting away from my original intention here. don't put plates in and just assume it will be fine.

mrr23

customer is returning to stock. doesn't want to shim this and that to correct errors from previous owner. not going to be tracking car.

i think they had a Z on them. after 14 years of doing alignments, i knew about shimming top. customer not interested.

thanks for the charts. the toe degree to inches is helpful. as far as GM specs, i have a complete database of specs in my hunter alignment machine. i even posted them here https://www.corvetteforum.com/forums...-corvette.html

i fixed his toe settings for now. once he gets the eccentrics, he'll be bringing it back to fix the caster issue which is causing the pull to the right. opposite of what the rear thrust angle would have done if there wasn't any other influence; IE Caster.

but again, we seem to be getting away from my original intention here. don't put plates in and just assume it will be fine.

mrr23

i agree completely. i have aligned quite a few track cars and have had one c5 with stock eccentrics move. and he SCCA races. realigned, tightened down more and hasn't moved since. but it does happen.