Chassis squareness
Thread Starter
Le Mans Master
Joined: Oct 2005
Posts: 9,429
Likes: 44
From: Macon, GA
Chassis squareness
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.
What/where do you measure and what are your personal tolerances?
Just curious and it seems like a good discussion.
Melting Slicks
Joined: Sep 2003
Posts: 3,031
Likes: 74
From: If you don't weigh in you don't wrestle Road America
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.
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.
Drifting
Joined: Dec 2005
Posts: 1,822
Likes: 1
From: Dayton, OH
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
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
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Michael S. Palmer
Race Director
Joined: Sep 1999
Posts: 12,439
Likes: 920
From: CONCORD NC
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
Melting Slicks
Joined: Dec 2004
Posts: 3,382
Likes: 250
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.
Burning Brakes
Joined: May 2010
Posts: 900
Likes: 3
From: Cary illinois
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 .
Height , width and length , down to a Mill.
Only as accurate as the guy useing it though .
Le Mans Master
Joined: Oct 2001
Posts: 5,145
Likes: 125
From: The Motor City
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.
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.
Melting Slicks
Joined: Sep 2003
Posts: 3,031
Likes: 74
From: If you don't weigh in you don't wrestle Road America
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.
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.
Drifting
Joined: Sep 2009
Posts: 1,937
Likes: 65
From: Mooresville NC
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???
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???
Burning Brakes
Joined: Aug 2005
Posts: 1,057
Likes: 11
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.
Melting Slicks
Joined: Aug 2004
Posts: 3,003
Likes: 89
From: Indy IN
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.
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.
Drifting
Joined: Sep 2002
Posts: 1,642
Likes: 0
From: Suwanee,Ga
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
Melting Slicks
Joined: Dec 2004
Posts: 3,382
Likes: 250
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.
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.
