rearend out of square...need help!

You are right, I was thinking of the top ball joints for some reason. Bottoms would be in a fixed position. Sounds like he just needs to start at the front and drop a plumb bob from as many points as he can from front to back till the 3/8" shows up.

Joe

 

Consider your distance from the wheel face of the drum to your 4 link bars/mounts. If they're in, say, 16" from where the wheel bolts on, then 1/16 to 1/8 out would be a bunch by the time you get to the wheel. It's worse on tubbed or drag cars. Sometimes "1 flat" of adjustment can move a wheel forward or back by over 1/4. Now, if you're talking about right where the bars mount on the housing, forget all of what I said here and go back to what exwestracer said.

I doubt seriously that your housing is warped unless you welded really hot willy-nilly w/out consideration of such. Even then it's hard to warp the average housing tube. Some OEM cars used thin tubes, but most 9" Fords can take more than some think.

Projecting an imaginary line down the bars, unless you have to move a bar by over 1/2", the travel/distance relationship will never be noticed in normal operation. The arc of bar travel never goes the whole distance. In the end, you'll probably end up like what 31vic said, moving the wheel's center 3/16 each. No big deal...

 

Thanks for all the response guys!! My 4 link is adjustable, and I adjusted them to place the passenger side coilover mount in the same spot as the drivers side. But when I got to measuring diagonals it showed that what I had adjusted actually threw the housing out of square in relation to the front control arm mounts.


So what Ive come to realize is that when I built this frame I must've got it out of square towards the rear, because everything up to the front 4 link cross member is only 1/16-1/8 out, at the most, I can live with that. But from the front cross member to the rear end notch and back is out....couldve been slight differences in cut dimensions when I cut the pieces and not placing them exactly the same when welding it all up. I'll admit that I wasnt as accurate with the rear notch and back , as I was with the front end. I assumed I'd just adjust to fit and the rear notch wouldn't make a huge difference in tracking as long as my rearend was squared with the front....but when the coilover mount sat further back it threw up red flags and I couldnt just let it ride without knowing where it was coming from?


So my conclusion into fixing my mistake(s) is to square my rear end diagonally off the welded upper control arm mounts on both sides and adjust the link bars accordingly and run with that? In theory it makes sense to me, but as you can tell Ive been wrong before and will openly admit it. So any input is a huge help and is greatly appreciated!! Thanks again guys!


For info: My frame is "custom" built (by me) out of 2x4 and 2x6 rectangular tubing with an art morrison front clip and a parallel adjustable 4 link. Thanks for everything guys!

 

Personally, I would still use the lower ball joint centers to square the rear off of. They pretty much locate the front spindles, so at least everything will be pointed the same direction.

 

when doin chassis measurements my trusty old trammel bar hasn't let me down yet. I usually work to round an 1/8" tolerance on older stuff (pre 1990) .
Don't know if anyone has mentioned checking the chassis for diamond...probably not likely it has ..but never hurts to check.
my .02

 

need to watch out that if a chassis is diamond (ie from a knock on a front frame horn) the wheelbase could still measure the same on each side but the vehicle could still crab along the road.

I have 2 trammels a big one and a BIG one for looong diagonals on underbodies. Heres a pic. Not getting at you at all exwestracer, just wana help the OP and any other readers.

 

Slownugly It is important that you determine the square of your vehicles axles and close enough is not a good enough answer. Exwest has given you a good start on getting your vehicle back in shape but I would suggest that you do a search on the HAMB for a post done by Brian Angus a couple years ago regarding the procedure to square your chassis. He did a pretty good job of outlining a procedure for detrmining the positoning of your axles and getting everything realigned.

 

do you have a panhard bar? if so truck needs to be level ride height or it will throw off everything.

 

being a retired big truck mechanic, we used to string the rear axle, set a jack stand infront of the front tie string on the stand, bring the string back behind the front rear axle tire, across to the tire on the other side and back to the front to another jack stand, bump the stand until the string just touches the front of the rear tire, same on the other side and measure from axle to string today i just use a level with the led light and have someone measure, it looks perty simple to just lay out a frame and weld it up, so much more to it

 

Yes, wheelbase first, then diagonal or "X". Just like #2 in post 28...

 

I think this is the thread Dick is referring to: http://www.jalopyjournal.com/forum/showthread.php?t=150434

Not sure though, Brian has been on here a long time...

 

Thanks guys! Im gonna get some measurements tonight and try to make a little more sense of my dilemma. I will try to take some pictures and post back tomorrow to give a little better description.

I'm considering taking the frame to a body shop or alignment shop to throw it on their frame machine? Any thoughts?

Again thanks for everything, you guys have a wealth of knowledge and I appreciate all the help!

 

They may need a demensioned drawing and factory points of reference to check stuff.

If you take the info exwest gave you , made a tool like fleet master showed you -
You will be able to find it.

If you can picture a Capitol "i" under your car with the top and bottom under the axles and center line in the center.

Then picture a Capitol "H" on top of the capitol "i" you should be able to cross measure everything.