Im working on a car with a new aftermarket model a style frame. It is rec tube and has a tubular k member. It has a .25" twist in the frame from the front to rear. It doesnt seem like alot, but it can be seen by the naked eye and sits cocked with the rear coilover suspension. The K member makes it so ridgid that the twist does not come out with the weight of the drivetrain and body. Is this within acceptable tolerances or should it be considered an issue? It bugs me, but Im also extremely picky. Please let me know what your opinions are.
What's the tolerance of the road that the car is going to be operated on? Heat up the k-member in strategic places to remove the twist. If that does not work, a relief cut, or two may be necessary.
Good point The frame has a 2" sweep and a 6" kick so its tough to determine just what is off. I think its the culmination of all of the weld joints adding up to the .25" discrepancy. Keep the opinions coming
if its a new frame i dont think it should be out more than an 1/8" max Trying to bolt the body to a twisted frame could start causing issues with panel alignment, or cause doors to not latch properly.
Quarter-inch is what Ford allowed on the assembly line when new. Shims were used to compensate of any discrepancy. You're just keeping up the legacy.
I don't know how old that would be. I've never seen any shims in a 30-40's Ford. Watch a video of the fords ass'y line. The bodies were slammed onto the frame and bolted down and I mean slammed. No one was checking the gaps on anything.
Im used to shimming the body for gaps, thats a non issue. I guess I mainly dont like having to modify the coilover mounting position to make up for a twisted frame. When the coilovers are attached, equally adjusted and at the same angle, the rear crossmember becomes parallel with the ground and the twist shows itself in the front.
It can be corrected, but it will take a bit of work. Know any frame guys in your area? If you can get it into a jig and throw some heat on it, it should dial right out.
Ya, there are a couple of frame shops in the the area. I worked in a collision shop for four years, so Im familiar with the frame rack procedures. I just wanted to know if I was being too anal for this era of car. I like to over analyze things
A quarter of an inch isn't horrible, but if it is a brand new frame have you talked to the builder ? That twist could be taken out with some creative jacking and binding, plus a little heat. But I bet if a lot of our frames were put under a microscope they would be out more than that. Don
I did drop a note to the builder tonight just to inquire further about his build tolerances. The frame itself is absolutely beautiful, so this really caught me off guard.
Have you moved the whole deal to a different spot on the floor? We have this argument with my boss at the shop all of the time. No floor is perfect, either.
I wouldn't live with it. I'd be measuring it every way possible. If the builder let that slide, Id be concerned.
If you have any doubts, fix it now as it is the easiest time to do so. If left it will annoy the crap out of you forever and a day. If you can't do it yourself, I am sure as others have said, it would be a fairly easy fix for folks who do this work daily.
Its actually up on jackstands right now. I didnt trust the floor either so I leveled it out with a 6 foot builders level and my digital degree finder for extra measure. Sadly it makes the twist even more obvious this way...
I'd probably put some frame gauges on it, to figure out where the problem is. You might not be happy with it, until it is a little closer.
Post some pics so we can see it and how/where you are measuring. How are you measuring it, diagonal? If so a 1/4" is nothing to worry about that is a 1/8" in the middle. A model A body is probably more than twice that.
Dont have pics on hand, but if I level the frame at the front crossmember there is a quarter inch height difference in the height of the rear rails at the rear crossmember. And vise versa if you level the rear crossmember.
This should give you 4 places across the frame and both main rails to level. That also should give 3 separate planes plus an over all- and all 4 should be square. I wouldn't use coil overs to gauge the squareness, there are too many variables, too many brackets involved, and they are adjustable. Levels can be off, and subject to the angle of sight. be sure to check again with spinning the level . You could stand the frame on its side and use the plumb sight to see whats twisted where. I'd like to see what kind of k member is so stiff that adds that much torsional rigidity.