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Author Topic:   Squaring car up?
dirtracer14
Member
posted February 28, 2004 12:12 PM
Man i am really getting @#@%$ in the shop today. Trying to square the front with the rear and its killing me....... I get the wheelbase set and all else goes to the birds..... My measurement from corner to corner should be the same right?? I am really having problems with this thing i have squared my cars in the past with no problems but this one is killing me...i never checked it when it was new i just used the chassis builders measurements.....what am i missing here...do i have somthing bent??


dirtracer14
Member
posted February 28, 2004 04:47 PM
Found it lf a arm mounts a tad off Much better day now LOL


Racer111
Member
posted February 28, 2004 09:43 PM
are you trying to square off of wheel base?If so remember caster changes wheel base.If its a Chevy frame you can use the lower a-frame ball joint grease certs to plum bob off of.


joeltjen
Member
posted February 28, 2004 09:53 PM
if your rear end is not centered in the car (mine is offset to the left) the rear end and front end might be square to the centerline of the car but your "X" measurements will not be equal. depends on how your chassis builder wants it or what the car needs


wissota3x
Member
posted February 28, 2004 11:12 PM
It is not wise to use the A frames on any car ,even if everything is new.The frame and A frame mounts can sometimes not be symetrical even from new.The best way is to string the absolute center line of the car from front to back.Then put a mark on the string somewhere in the middle preferably towards the back.Use a square off the mark to put a mark on both outside frame rails.These two marks will be your true and accurate perpendicular to your chassis.


dirtracer14
Member
posted February 29, 2004 01:02 AM
In the past i have allways set the front to rear square with each other....that was 3 link old style. I do have a point on the chassis that is square to measure the rearend buy then check the front end. I was just really fighting myself today in the shop trying to think to hard about it. What i do is drop off the balljoint greese zerk then on the rear hubs just inside of them i drop from there (or outside of the drive plate) then measure. Now if the car was a straight up car then the x would meet the same on both sides along with the wheelbase being same. Then after that is all square then i can adjust my car with spacers and wheel offsets....are some cars not square on the x ? I know if i set the rear from the square point on the chassis it wont match the front tires with the wheelbase.


wissota3x
Member
posted February 29, 2004 09:44 AM
The grease zerks that you measure off of are way too inconsistant.I'm going to exagerate a little bit and give you an example.If the right front suspension were 3 inchs ahead of the left on your car you would still be able to drive the car straight if the rearend were square to the chassis.If you set the rearend with the front balljoint zerks and it were 3 inchs ahead on the left the car would be so side ways you couldn't drive it.I have had quite a few cars on my jig with the A frames on the chassis and only one or two were close enough to measure off of the ball joints.A 1/4" goes a long ways when leading or trailing the rearend in a race car.
THe whole objective is to find what is the true perpendicular to the chassis.The hole in the bottom of your front cross member represents a good example of center of your chassis. Go back a little further to where the frame horns straighten out to connect to the factory side rails.Measure across and find the center. From there it gets a little more difficult because there can be too many variables.If you know the history of the chassis and are sure that the factory side rails haven't been altered or been bent,then you can measure from them and find center.Once you find an average of centers from front to back with a string then you can square off of that and it will give you the true perpendicular of the chassis. It doesn't matter if the rearend is offset to the left, it will still be square if you follow these procedures.


dirtracer14
Member
posted February 29, 2004 10:16 AM
3x i understand what you are saying ...the only problem i have is that when i try and square a car up i do this with the front and rear tires....now the spindle bolts to the ball joint wich is the center of the front wheel....so now that i have center of wheel i can center the rear wheels to the front wheels making the car straight. Now i also take my chassis point in to account so like you said the car isnt dog tracking. When i started i had 1 1/2" off on the rf lr cross but wheelbase was same.....after rechecking all things i found that the rear was to far back on the lr side measuring of the chassis points...so i measured a arms off chassis points and found the lf was back a tad.. Now by moving the lf forward 1/2 that adds .5 to the lf rr cross then to sqaure wheelbase i have to pull the lr forward .5 wich will shorten the fr and lr cross and now when i check the rear on the chassis mounts its back were the chassis builder said it would be. Im not aguing with you and have no dought that there is variance in lower a arms just tring to explain how i came up with the error i had ....if you think that i still might have a problem with it please let me know....i am no chassis builder just a guy tring to get my wheels going in the right direction


wissota3x
Member
posted February 29, 2004 08:30 PM
Dirtracer14,I understand the method that you are taking to get things right for your rearend square.I was giving you what I know to be the most accurate way to check for square.I left a few things out that would help if you decide to check it the way that we do it.When you string the car down the center like I said and make the square marks,it is best to put the marks straight ahead of your axle tubes.Probably on the under rail that runs front to back on most chassis.Use a plumb bob off of the front of the axle tubes on both sides to measure up to your marks.This probably sounds like allot of B.S. but once you have those marks and put them on permenantly it is easy to check.We weld key way stock to the under rail so it is easy to hook a tape to.Sounds like you have everything figured out and hopefully the car works for you.


dirtracer14
Member
posted February 29, 2004 09:08 PM
Thanks for the info on this 3x i had a pretty hard hit last year on the lf and kinda had a thought that it may have got moved ...i was just thinking to much out in the shop when i was tring to do it and it was getting very frustrating. I do understand what you were say about the center line and marks ..i have somthing kinda like it but its the bar behind the rear at the bottom of the cell that is square to the chassis that i use to measure...if i get in a crash i check it off the front and if its moved i write down how much then adjust the #s for it... Thanks for the info always glad to get input. I just want to make sure i have my A game this year


racinruss
Member
posted March 01, 2004 11:14 AM
An issue of Circle Track magazine had exactly what 3x is saying. They had pictures and measuring points. Good artical!
quote:
Originally posted by dirtracer14:
Thanks for the info on this 3x i had a pretty hard hit last year on the lf and kinda had a thought that it may have got moved ...i was just thinking to much out in the shop when i was tring to do it and it was getting very frustrating. I do understand what you were say about the center line and marks ..i have somthing kinda like it but its the bar behind the rear at the bottom of the cell that is square to the chassis that i use to measure...if i get in a crash i check it off the front and if its moved i write down how much then adjust the #s for it... Thanks for the info always glad to get input. I just want to make sure i have my A game this year



Chad
Member
posted March 02, 2004 09:23 AM
What issue of Circle Track has the details? I have stacks of the old magazines laying around and would like to relook at a detailed explanation.


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