sperkins

So how many of you actually check to see if your chassis is square?
What/where do you measure and what are your personal tolerances?
Just curious and it seems like a good discussion.

Jason

Dr. Popp did mine.

96CollectorSport

Scott,

Are you talking about checking the front and rear cradles for squareness or the frame itself?
I would think you'd almost have to put the car on a frame rack for them to do the measurements accurately.

sperkins

Not the frame - mainly the cradles and/or ball joints diagonally.
I know I'm overly picky, but if mine is out by the least little bit I just have to fix it.

Jason

You need a hobby.

sperkins

Can't play golf. It's too expensive.

geerookie

Plus as you get older that little white pain in the a$$ is too hard to see. Cars are bigger!

geerookie

It would seem to me that the only real measurements that would matter are the relationship of the upper front ball joints to each other and the lower ball joints to each other as these are what position the tires on the track.
This would assume all the control arms are straight.

If you want to check verything I would think you measure all the corresponding pivot points to each other, then do the ball joints.

The measurements aren't that hard.
Put the car on blocks, level it, remove the springs and uprights, then use a plumb bob to make marks on the floor and then measure it. A fun Saturday in the garage with beer

davidfarmer

Unless it is so bad that the body is skewed ( one side high in rear, other high in front), or proper alignment can't be achieved, I dont worry too much. It's the tires doing the work, and if they are aligned and scaled to work evenly, I'm happy

fatbillybob

Very elegant statement.

I never thought of it this way but yeah this makes sense just like racing is all about managing tires.

For the sake of argument these production cars are made to such a high standard that unless wrecked a stock car should be basically perfect. In the process of just corner weighing and aligning if you achieve a 50% cross weight and notice the front adjusters left right have the same number of exposed threads and the and the rear adjuster left right have the same numbers of exposed threads you can be pretty certain that your car is dead on. That is not a requirement but don't be surprised if that is what you find. There is that much precision built into these cars.

Rob31

If you have to know , have a body shop with a Genesis , Shark or Caroliner measure it up and give you a print out .
Height , width and length , down to a Mill.
Only as accurate as the guy useing it though .

Scooter70

You give us too much credit. Production tolerances (especially system-to-system) are higher than you think.

96CollectorSport

You'll know if the car is off if you can acheive more negative camber on one side vs the other (front or rear). You could max out the camber (or put the same camber blocks on both sides) then move the cradle over until you get the same reading on both sides.
However you would still have to cross measure - say at the lower ball joints - to make sure you are strait front to rear.

Once you get it strait I would do the old DRM roll pin trick - drill a hole through the cradle on each side and into the chassis and install a 1/4" roll pin. This way whenever you pull a cradle - front or rear it will go back to the same place. The guide pins that GM install can move the roll pin holes won't.

I can just see you C5 mafia guys drilling multiple holes in each others cars just to screw with each other.

brkntrxn

I personally cannot drive straight enough that it would matter to me, LOL! As long as I cannot see more of one rear tire than the other in the side mirrors as I am driving down the, I would have no way of knowing if it were off.


Hmmm, maybe I should get David to knock my rear cradle OUT of alignment to give me more rear bite out of some of the turns at the track????

David - are you up for a little NASCAR style crabbing experiment???

kmagvette

When I went to fixed camber plates (never wrecked C5Z) the rear was so far out that I had to go back to the stock cam bolts. Front didn't matter since I did a stud kit on the uppers.

Solofast

They are all out to varying degrees, the tooling makes them consistently off. I've never seen one that could get even camber from side to side. Some are worse than others, but they all seem to be moved over to one side.

It's like the third generation Camaros, when the main chassis stamping tool cracked and they welded it back together. After that all of the cars were cocked about 1/4 of an inch to one side. I tend to think that ours are all off because of springback or twisting from the welding process. Some more than others, but they are all off. Don't let it bother you.

TJM

I have done it.

If your interested I'll email you the line diagram, now it's for a antique C4, but will give you the idea.

A Factory manual should have the points on the frame. Plum bob to a level surface. Make the marks, pop the lines, and it's real clear what's out.

I took the car to a Dealer in Cumming and he straightened it perfectly.

His comments was " they are all out a bit, most don't matter".

[ $300 later he tells me this? ]

But actually we where out more than a reasonable amount and it needed it.

I think the Nub that owned the car put it backwards into a curb and bent the rear a bit.

TJM

fatbillybob

I don't believe that at all in my experience. Modern manufacture is very precise. I come from the hand built Ferrari world and I can tell you horror stories. My last of the line z06 z16 was dead nuts perfect from the factory. I just got hit in the rear in a race and bent the frame just aft of the tanks. Frame was pulled straight then cut sleeved and welded per GM using the frame jigs and all those GM measurements in the red WSM. My car is perfect again just like factory. I scaled it to 50/50 exactly not 50.15 or 49.9%. The left and right front and rear height adjuster have exactly the same number of threads exposed and the the thread pitch is 1.5 or 1.5mm per full turn. So is that is the kind of accuracy GM can get and the kind of accuracy a good bodyshop can achieve.