'72 Challenger Project

[rhamson]

As usual after talking to countless frame shops they have either put me off or lack the desire to take on straightening the frame. So as always I have to engineer something on my own. I have removed all the suspension and leveled the car on jack stands 30" in the air. I constructed a rack I can level (the floor is out of level) and will drop markings down from the frame to the rack to take elevations and pull diagonals to get a basis by which I can pull the frame back into square if needed. I know the right front frame member is up by at least a 5/8". I have a beam 16' long constructed from three 2x12's and welded together a cradle I can attach to the frame that holds a hydraulic jack. I have points along the frame I can either drill a hole to attach to or use an existing one to utilize the cradle.

[rhamson]

Here is the car up on the stands with the measuring rack below. Sometimes you just have to do everything on your own. The local frame shops are so wrapped up with the collision/insurance racket they can't find the time or expertise to work on project cars.

[usraptr]

Very ingenious.   

[Challenger in NC]

As usual after talking to countless frame shops they have either put me off or lack the desire to take on straightening the frame. So as always I have to engineer something on my own. I have removed all the suspension and leveled the car on jack stands 30" in the air. I constructed a rack I can level (the floor is out of level) and will drop markings down from the frame to the rack to take elevations and pull diagonals to get a basis by which I can pull the frame back into square if needed. I know the right front frame member is up by at least a 5/8". I have a beam 16' long constructed from three 2x12's and welded together a cradle I can attach to the frame that holds a hydraulic jack. I have points along the frame I can either drill a hole to attach to or use an existing one to utilize the cradle.

I know it must be frustrating to run into these type of roadblocks, but it appears you are doing a thorough job and know it will be correct in the end. Will be interested to see more of your frame setup.

[Chlngrcrzy]

I like what i am seeing. I had to learn and do everything myself on my car. But if i had a second car to work on, i know i would be able to save a lot of money and do it much quicker. Good luck, and i look forward to seeing your progress.

[soundcontrol]

5/8" does not sound that much, considering the way theese cars were put together. Is there any specs on how much the measurements could actually be off?

[rhamson]

You may have a point because as I understand it these cars were assembled in as little as 58 minutes on the assembly line. I have measured everything from the manual and verified my suspicions and it is that bend in the frame rail as the only thing out of spec. After 45 years all the other measurements match exactly. I don't have any information as to the tolerances but you can see a noticeable lean that direction without the torsion bars leveled up to height. When I level across the frame rails is where it proves the bend. Also the dent in the floor corresponding to the bend in the frame rail was not something factory created and is the source of my concern. Spending $3,200.00 on the Hotchkis suspension equipment is also why I am doing it to utilize their technology at it's maximum value. Talking with others they said they also dealt with bent frame rails by tightening up the offending side torsion bars. I don't agree with that solution. This car is probably my last car and hopefully my best so I want it to be right.

[dodj]

as I understand it these cars were assembled in as little as 58 minutes

Alan?

[dodj]

5/8" does not sound that much, considering the way theese cars were put together. Is there any specs on how much the measurements could actually be off?

My front frame ends are different by 3/8" with respect to the floor. I consider that fine. Don't have any idea what factory tolerances are but 5/8" was probably 'good enough'?

[rhamson]

Was the floor level to the car? It may have been worse than you know. The dimensions I took before the leveling rack were different by more than 7/8". Maybe it was okay but the car had a very visible tilt on the passenger side where the floor is bent with the frame.

[soundcontrol]

Would be a good thing to check mine while its in primer now, and I'm about the weld in inner fender braces and radiator support. Wonder if one of those rotary lasers level things would work, my floor is not in level at all.

[rhamson]

My front frame ends are different by 3/8" with respect to the floor. I consider that fine. Don't have any idea what factory tolerances are but 5/8" was probably 'good enough'?

Uneven frames cause the tracking of the front wheels to favor the lower side as it carries that much more weight. As I said since I spent so much on the Hotchkis system I don't want it to be defeated by incorrect geometry on the front end.

[rhamson]

Here is the setup of my home made frame straightener. I bolted the rear cross member to the rear shackle mount that has a torque box. This was in lieu of a pinch weld clamp. This cross member consisted of upright 1-1/2"x1-1/2"-3/16" wall square tubing bolted to a 3"x3"-1/8" wall square tubing cross member. The other side was just bolted to a piece of strapping with holes in it to bolt too. The non-bending side did not have much pressure on it. This isolated the downward force that would be coming from the front.

[rhamson]

I then bolted the jack cradle to the front bumper holes on the front of the frame where the frame was higher than the other front frame member. I put the bolted together beam of 3- 2x12x16' through the cradle sitting on top of a 20 ton bottle jack. A couple of blocks were set on the beam where I wanted to bend the frame back to its original position. As I pumped the bottle jack up it pulled down on the frame until I made it level across the two frame rails. The beam creaked and the body popped as I pulled it back into place. Luckily I had left over steel from my rotisserie build to put this together.

[rhamson]

Here is a closer view of the cradle where it applies to the beam.