Adjusting sagging frame with body on

[LHolderman]

I have run into another problems with my 29 Murray project. The doors and hood are not aligning correctly. I was not aware of the issues a sagging frame can cause with door/hood alignment. Until after I read Les Andrew's book Vol 2. He states that the frame can be straightened but you need to take the front fenders off. I have tried to align everything with shims but that is not working. I sure hate to take the fenders off since everything is painted. Has anyone corrected a frame with the fenders on? I am open to any good ideas.
Nobody close to me to learn from, so I'm learning from my mistakes.

Larry

[rotorwrench]

A person needs a straight edge and access to the frame. The top of the rail needs to be straight as a person can get it. The removal of the fenders would be minimum. It's best to do it body off so I see your dilemma. A person needs a big eye beam, some chains, and a bottle jack.

[Conaway2]

Post #2 pretty much nails it.

I think there was a short article in The Restorer or Model A News some years back, as well as a YouTube video from several years ago describing the basic procedure.

I straightened the frame on my ‘29 coupe project last fall, but was working with the bare frame, which made the process fairly easy.

You don’t mention the body type, but it sounds like a closed car. I agree with Rotorwrench that the front fenders certainly need to come off. I would also remove the running boards/splash aprons and loosen the body bolts from the cowl back to the rear of the front doors.

I used a 10’ 6X6 wood beam with a 6’ steel I-beam laid on top of it. Heavy chains at each end and a 20-ton bottle jack placed under the rear motor mounts. A smaller jack will probably not work. A taut string stretched from front to back works as an indicator.

Good luck !
Jim

[JoeCB]

I would think that a body shop that has a full size bed plate, appropriate hold-downs and hydraulic jacks could do it. Wouldn't hurt to ask...

Joe B

[nkaminar]

I will probably get some flack for this but there was an article a few years back in one of the Model A magazines about straightening a frame without taking anything off. The technique used was to chain the frame down at the front shock absorber and at the back and use a 20 ton bottle jack at the rear motor mount. The chain at the front shock was attached to an anchor in the concrete floor of the shop. I suspect the concrete was at least 6 inches thick. A bolt can be anchored to concrete using high strength epoxy. A big bolt. You drill a hole first then clean the hole with compressed air and epoxy the bolt into the hole. Google this.

The gauge to assess when the frame was straight was the hood fitting correctly. Most frames bend at the rear motor mount. Proper fitting of the doors could be another gauge to tell when the frame is straight. If the frame is damaged from an accident then that is a different story.

The rear of the car was chained down using a suction plate but a bolt epoxied into the slab would probably be easier for those who do not have the suction plate.

One side was done at a time so you could move the car over the bolts.

Some people will argue that heat should be used to bend the frame back because any bending will change the thickness of the metal in the frame. True, but the difference in thickness is minuscule.

The roads were not all that good when the Model A's were just old cars and hitting a few pot holes would be enough to bend the frame from the weight of the engine and transmission.

[History]

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I like the idea of a frame shop if you are in a position to just pay to have it done? You may have the resources to do it yourself though but if not that’s how I’d go. If reputable I’m sure they could do it quite easily.

[Oldbluoval]

You can likely “band aid” it by tying down ends of frame and jacking …usually at the rear motor mount. Judge by hood gaps and other tell-tale changes. Usually you have to jack past proper adjustment as it will relax some. The straightening will not last without heat shrinking but probably good for this lifetime!

[rotorwrench]

Where metal has been expanded, heat and pressure will shrink it back to where it was. If a good shrink job isn't done then the area will pucker when straightened. Heat the area while applying pressure will force shrink it back. Having a pucker in a frame rail will give it only partial strength to hold it's shape. I would want all that strength back if possible. A lot depends on how much deflection there was in the bent member.

[WHN]

After 90 years you will also have a bent frame!

I think to really get it done correctly, you will have to remove the body. Anything else would be half ass and most likely a waste of time.

Good luck.

[Keith True]

A shop here that does nothing but frame and body straightening will not touch something with the body still on the frame.He is an old car guy himself,and learned his lesson many years ago.He has seen it dozens of times,it's very common.Making the car pretty before making it straight.All his work is for dealers and body shops,and those wrecks come in his shop stripped as much as possible for him to work on.Deciding to do it is harder than actually doing it.If you do it yourself get the body propped up about 8 inches over the chassis,and have at it.

[LHolderman]

Thanks for everyone's input... Looks like I will be lifting the body up to get the job done correctly. One good thing is that there is no interior yet. I have started it once and it runs great with a completely rebuilt engine with insert rods..

[todd3131]

There was another thread about this issue a few years ago and Brent had a post about how he does his frames and is very good information. When I restored my roadster after a bad accident that required me to replace the frame I didn't check it and I found the issue after installing the hood and it was off. I tried to fix it half assed approach and it simply didn't work. I had a deadline so I shimmed it up and it is ok, thought I will pull the body off in the winter after the event and fix it this was in 96. I am now planning a complete tear down of the car and the frame is part of it and I think a new burtz block. My advice is you won't be happy until you take the body off and do it right, I haven't been.

[TomInCologne]

I have been thinking about this...


Over the winter i will jack my car up to prevent the tires from forming flat spots. Maybe it's a good idea to jack the frame up in the middle of the car to 'let gravity do its job' and prevent the frame from sagging further? Or maybe even straightening it out a bit? It may not help much but it also wouldn't hurt.


Where would you put a 4x4 to lift the frame?


tom

[WHN]

Tom:

I think that this would be a waste of your time. There is no telling what would come out of your efforts. You could end up doing more damage.

Over 90 years your frame has sagged, it really can’t be helped. How much and where is the question we don’t know. To check and straighten your frame, the body has to come off.

Enjoy.

[john in illinois]

I had frame sag on my Tudor and did not want to repair it. I shimmed up front of the hood and the hood mount on top of cowl. I then shimmed. The doors and body.

The hood gaps are fair and the doors open and close perfectly. I have driven it for 29,000 mi and no changes.

If you raise the hood too much,the hood latches are too short. Then you would have to straighten.

You have to do a lot of trial and error to shim the body.
Marco’s site has great info on shimming.
John