subframe question

So we are puting a new triangulated four link in the back of my 55 chevy pick up, and this is the first time the truck has been taken down to the frame. So when we start measuring, and find out that the chevelle subframe is 1/4" off up front, this was put on before I got the truck, so now we have to live with it, or take the subframe off and re-graph it back on. At the wheel the difference is 1/2", my question is one I think I already know the answer to, but I just want to get some other opinions that if I want this truck to track straight we have to cut it apart and straighten it out. Has anyone else delt with this?

Thanks!

 

The first time I read you comments I thought you meant the front end was canted either left or right 1/4" and therefore the centerline through the spindles was not perpendicular to the frame centerline, and I wrote the following paragraph accordingly. Then I re-read your comments and decided you likely meant the longitudinal centerline of the subframe was 1/4" to one side or the other of the centerline of the original frame. So, for that scenario...see the third paragraph.

Actually, since the misalgnment is in the front, I believe you can get the truck to track straight as long as the rear axle is perpendicular to the frame center line. What will happen, if you get a four wheel alignment, is that the front wheels with be slightly "turned" in the direction required to go straight. You have, in effect, a vehicle with a different wheelbase from side to side. All the wheels can be parallel in this scenario (not counting toe-in variations).

In the second interpretation, as see it, much the same applies except the wheel base is the same side to side....the vehicle can track straight although the centerline of the wheels will be parallel, the fronts will be offset to one side or the other to the rears

The real question is......can you live with this, since you have discovered it, even if it has no serious ill effects?

Ray

 

Grafting a frame is not a backyard operation. If you can do it properly, recut and weld it up again. Personally, I would find another frame and build the truck on that. You can have disc brakes, a simple, rugged, good handling front end for a lot less time & effort than patching frames together.

 

Re-do is the only option IMO.
All you need is a straight work floor and the right tools.

But then again, are you sure the sub-frame aint bent. If its off it should be on both sides.

Make sure to measure it right once and cut twice....no wait, the other way around .

 

Thanks guys the plasma and grinders are coming out tonight. I don't think I could live with it knowing that it dog walks... Have a good one

 

What happened then?

 

Oh crap, I did mine in the back yard...the things we do when we don't know any better.
Seriously though - it is a good point - measure measure measure!!!

 

Here is where we are at, its now cut apart. One good thing out of this situation is that we are going to Z the frame in the front too. I will post more pics as it progresses.