A body rear frame rail help

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bricud

bricud

Cuda's Cuda
Joined
Jun 22, 2022
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Location
Black River Falls, WI 54615
I have a 1969 Barracuda Convertible that has rotted rear frame rails on both sides that I am going to tackle replacing. There are sections in front of both rear wheels that are rotted through for about 10 inches or so. The back by the bumper and shock support are not any better. So I was going to replace them both. I have searched and found lots of info on replacing sections and repairing it with caps, but I was going to do the whole thing. Is there a place or link that has more information on the best way to support the body when removing and specific do's and don'ts to consider in the process? I wanted to make sure I know the best way to brace things to avoid any twist, etc., issues. Wanted to get any and all information before the fun begins. Motor and tranny are out, about to remove rear axle.

Thanks

Bricud
 
Here are a few pics. BTW, I meant to say leaf spring mount by the back bumper, not shock. Here are a few pics.

Rear Frame Rail 1.jpg


Rear Rail 2.jpg


Rear Rail 3.jpg
 
There is another thread talking about this same thing, though he other end of the car.

www.forabodiesonly.com

A-Body Frame/Body Jig

I was wondering if anyone knew of an A-body body/frame jig that anyone has made or any plans that anyone is aware of. I have a '68 project Dart that I'm getting in kind of deep on. I found a rotted front frame rail on mine and started trying to figure out how to replace it. I bought a set of...
www.forabodiesonly.com www.forabodiesonly.com

Your frame rails look as bad as mine and I'm replacing everything in the back half. Before you start, take a good honest look at EVERYTHING around them and understand that rust like that isn't localized. It's already creeped in to the rest of the car inside and out. Can you save it, HELL YES, but the assumption should be there is way more rust you can't see than what you can. You're in WI and clearly no stranger to rust. My car was from MN. It was stored inside a one car garage for 38 years. Problem is, those old concrete jobs didn't include a vapor barrier so the car sat in a sweat box since concrete sweats, (humid summers as you know) that whole time.

I'm getting ready to finally start my project after owning it for 12 years, building a jig, collecting parts, tools etc. I'll be paying attention to this project.
 
Mine sat in a barnyard for 20 years and the rear end must have been too close to the soil. Ironically, the front rails are good. But the project will include new rear rails, torque boxes, spring mounts, torsion bar crossmember, and at least the rear seat pan.
 
bricud said:
Mine sat in a barnyard for 20 years and the rear end must have been too close to the soil. Ironically, the front rails are good. But the project will include new rear rails, torque boxes, spring mounts, torsion bar crossmember, and at least the rear seat pan.
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Yeah I almost wish mine had sat outside. At least it would have been able to breath. lol.
 
You will need a fixed non adjustable 108 wheel base fixture that is the easiest way to do it correct.
 
Oldmanmopar said:
You will need a fixed non adjustable 108 wheel base fixture that is the easiest way to do it correct.
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I'm gonna go ahead and disagree. People have been "doing it correctly" for years before everyone started making jigs. Of course it helps, especially if you're doing a ton of them like you do but to say it's "required" is incorrect.
 
bricud said:
Any idea where I would find the fixture?
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If you can weld at all, they are not hard to make. Mine is way overengineered but it's for me only and I didn't want to build any more so I built it adjustable.

A static config is dead easy. There are chassis drawings for all the mopars so you can easily get the measurements needed. As I recall, "The Installation Center" AMD folks, make theres from 1/4 sq tune. Mine is 3/16 and I've seen them made from 1/8. I actually passed a basic, static design based on 1/8 sq tube, to a structural engineer friend to look at and he thought it was way overkill.

I've also seen people use "I" beams etc.

Again, before "jigs" people used "frame racks" but that keeps a rack full or they did it on a flat floor with jack stands.
 
Cuda416 said:
I'm gonna go ahead and disagree. People have been "doing it correctly" for years before everyone started making jigs. Of course it helps, especially if you're doing a ton of them like you do but to say it's "required" is incorrect.
Click to expand...
Yes you can do it on a level floor with stands to get it level. And then take many measuremets to get them square and in the correct position.

There are 8 holes in the rails to set on a fixture 2 holes on each rail that a button slips into and there are the front and rear bumper mounts to tie it down if a push or pull is needed to . For an inexperienced person to install rails it should be done on some type of fixture. Adjustable or not it should be set to the measurements of the chassis you are working on before you start the job.

Nothing is worse then after all the welding is done the doors or fenders don't line up. Or it runs down the road Doggie style. Did you ever see a car doing a burnout that won't stay straight. Many shops ruin cars with there inaccurate installations of rails.

Our fixture is a frame straightener from Mario Andretti's 3n1 race shop in NJ modified for 108 and 111 inch wheel based A-body cars. It is solid steel I beams and when not leveled it also is not correct. so we installed leveling legs. The shop we bought it from also had cross rails for pulling fixtures. The last pictures are of what we bought to make the fixture. Paid $300 well worth the money spent. Brought several truck loads of parts back.

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Those are some great pics. It looks like on the back of the car the jig is attached to the back of the frame rail. When removing the rails (one at a time) where is a good place to support the back of the car? Looks from the pics that it is supported by the torque box or close to it. Maybe what is referred to as Rocker clamps by Cuda 416. Since I am only doing the rear rails, I would think I could support/stabilize the front with a pair of jack stands under the front rails or K member and make a jig to support the back of the car only.
 
Oldmanmopar said:
Yes you can do it on a level floor with stands to get it level. And then take many measuremets to get them square and in the correct position.

There are 8 holes in the rails to set on a fixture 2 holes on each rail that a button slips into and there are the front and rear bumper mounts to tie it down if a push or pull is needed to . For an inexperienced person to install rails it should be done on some type of fixture. Adjustable or not it should be set to the measurements of the chassis you are working on before you start the job.

Nothing is worse then after all the welding is done the doors or fenders don't line up. Or it runs down the road Doggie style. Did you ever see a car doing a burnout that won't stay straight. Many shops ruin cars with there inaccurate installations of rails.

Our fixture is a frame straightener from Mario Andretti's 3n1 race shop in NJ modified for 108 and 111 inch wheel based A-body cars. It is solid steel I beams and when not leveled it also is not correct. so we installed leveling legs. The shop we bought it from also had cross rails for pulling fixtures. The last pictures are of what we bought to make the fixture. Paid $300 well worth the money spent. Brought several truck loads of parts back.

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Yep, I totally agree. Way too many "pro" shops ruining cars in the name of restorations and the frenzy that fueled them.

A jig is best, and one made from a frame rack, even better. It was an option I entertained when I was planning mine but I don't have the room to leave one in place. Mine is not only adjustable, it comes apart and is rock solid when tightened up. There are things the rack can't do though and need to be take into account and that's the inherent tension in the car that is seen when you start taking parts off.

It's very easy to forget about and just "rack build" to straight, but the reality is that the doors on my cuda for instance, require 53 lbs of weight added to each one when gutted of parts, to put the correct stress on the car as it's on it's wheels to cause the right amount of "sag". If you don't account for it, then the doors won't close on a vert. Hardtop is a different story, but these things need to be accounted for. If you look at the pics of mine, the "stand offs" have holes (might not be able to see them) for a 1 inch bolt to set into the locator holes you're talking about. Those bolts were made into toggles (like a wall toggle) to not only "locate" bur pull the car down onto the stand off.

So yes, if he can weld, he can make one, even a half jig would be better than no jig.
 
bricud said:
Those are some great pics. It looks like on the back of the car the jig is attached to the back of the frame rail. When removing the rails (one at a time) where is a good place to support the back of the car? Looks from the pics that it is supported by the torque box or close to it. Maybe what is referred to as Rocker clamps by Cuda 416. Since I am only doing the rear rails, I would think I could support/stabilize the front with a pair of jack stands under the front rails or K member and make a jig to support the back of the car only.
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Rocker clamps literally clamp onto the bottom of the rockers by grabbing hold of the pinch weld at the bottom. They are used when you don't have other options for support. On a frame rack it's the way a car is mounted for straightening pulls etc. When you gut the rear of your car, you'll need to support it by the rockers most likely.

Here is a close up or a commercial unit.
1688564687031.png
 
bricud said:
Great. The rocker clamps seem to be the best way to support the rear end before I start removing the rails. Thanks for all the detail.
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If you end up removing the floor, the other thing you'll want to consider is getting some 1" square tube , .120 wall, and build up a bracing structure inside the car. Even something simple like an x between the door jams across the inside of the car. You don't want your rockers to "spread".

Honestly, if you brace the car this way, you really should not need "clamps" but still, overkill aint bad all the time.

Anyway, I look forward to seeing your progress/success. One more MoPar kept on the road.

:thumbsup:
 
Cuda416 said:
I like the rocker clamps. I'm planning on making some for my jig.
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Thankfully I have worked in a body shop for 25 years... we had these old clamps laying around so I made them fit my jig/cart. All of the uprights I made are technically a physical "measuring system".. the clamps hold the body, the uprights are just fixed reference points. I do have additional bracing on the back and will on the front when I get there. I took some large bolts and cut the heads down with my drill press to make them into a button that fits the holes in the rails. I plan on making some tubes that support the clamp plates in between the two plates so the bolts don't bend the plates... I just haven't gotten around to it yet.

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So I've been looking for some rocker support clamps. Mostly what I see is rocker clamps for pulling. They have rings attached for that. I was looking for something I can use for more of a support. Is there anything ready made or should I be looking to buy the pulling clamp and weld a support base to it?

Thanks,

Brian
 
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