So I've confirmed Shirley's frame is sagging. I am tring to plan how to straighten the frame with my limited garage tools. Lots of old threads on how to change that: http://www.mtfca.com/discus/messages/80257/86146.html
I am wondering if I have to take the body and motor off?
After bending it back with chains and a jack, would heating it so that it anneals make it resistant to re-bending? If so, what annealing method would work?
1. In my opinion most frame sagging is directly related to the engine arm blocks not being installed
2. I've seen several frames successfully straightened with the body and engine attached. No heating was done
It depends on where you are at in your life. Do you have the time, means, desire, to remove the body, and fix fifty other things you WILL find in the process?
Greatly improving the frames straightness without major disassembly is not that difficult, and does not have to be expensive. There are several ways to do this, depending upon what your resources are. Every one of those methods has its own tricks, and pitfalls. They all involve figuring out a good way for YOU to measure the frame for straightness. (There are several ways to do that, also.)
a solid cement floor with appropriate chain-down points is one of the best ways to work a frame. However, few of us have access to one.
A lot of T owners, including me, have used heavy iron beams (channel beams, I-beams, actually, even a ten foot chunk of heavy enough wooden glue-lam beam can work).
Something I have thought about, but never needed to do (and best of all, it should be cheap). Find somebody wrecking out an old pickup. Something from the '40s through the '70s would be best. Borrow or buy (scrap value?) the frame. Lay the frame on the ground (asphalt or cement would be best, preferably fairly level), and makeshift wooden ramps and rails to load the car onto the frame. You may want to block the truck frame off the ground (no more than two inches) to slip chains under the truck frame. Put the model T up on that rig and ramps.
This goes for any of the above methods.
Before doing anything to tweak the model T frame! remove the hood AND THE RADIATOR BRACE ROD!!! Depending on details of bends and the car itself, you may need to remove a few other things, or not.
If you have some really good chain (one ton minimum capacity two ton might be better), great, if not, how much you will need is not very expensive.
You either need one really long piece of chain, to wrap the car like it was a Christmas tree. Or four short pieces, about five to six feet apiece. You will need several large bolts (the biggest ones you can get that will fit through a chain link, mid chain. In place of those bolts, you could use double hooks, or any of several types of joining links available, as long as they are heavy and strong enough and again can fit into the links mid chain.
On all four corners of the T frame, wrap a full circle around both frames, bolt or hook securely. Near snug is best.
By however you have to measure frame for straight, locate the low spot of the sag. A two ton hydraulic jack may be able to do it. But I think I would prefer a three or four ton jack. Block the jack securely, and put about two feet of 2X4 between the jack ram and the frame. If the jack ram goes directly against the frame? It is likely to kink the frame slightly, and maybe give you a new problem later.
With the four corners of the frame held down, and a heavy duty jack pushing up against the bent spot, the model T frame is what will bend. You must push it a bit beyond the point of straight, because the frame WILL spring back part way. Let everything relax, measure it again. See how much you gained. Leave the chassis chained down until you think you are satisfied. If it has not gone enough, just jack it up again, maybe a bit more. Do the process several times if needed. Take it slow, be safe.
Once done with that, Put the car back together, fix a few details you have found. And hopefully, the hood and radiator all line up nicely with the body. Otherwise, we move on to the next chapter.
you might also see if a local Voc-Tech school has an autobody class that is equipted to do frame straightening ...our local school will do repairs and charge for materials only ...naturally you have to fit the work into their schedule ...always an optimist...Gene French
I'm thinking my frame may be sagging as well Ignacio, and I'm tossing some thoughts around in my head about using my engine hoist and some heavy beams.
How does this sag present itself? What is it effecting?
Unless it's really bad, I would just put body shims, (large washers), under the body mounts to shim the body into alignment to compensate for the sag and leave the frame alone. You're just beginning to enjoy your car, I wouldn't be so anxious to tear into it again.
Cold bending to straighten a frame works well if you want a straight frame but are not concerned about the structural strength of the frame. If you want a straight frame that is relaxed and structurally strong, then heat bending is the only way to go. Heat bending a frame normally does not require an external force straighten a frame, just selective heating.
Brent in 10-uh-C's post in this thread does a good job of explaining the process:
For a bunch of information on straightening structural steel do a google search for "straightening structural steel".
Or for a whole book on the subject see:
The basic process looks like:
Jim would a Mapp gas plumbers torch be sufficient to heat the frame?
Washers seem much easier but wouldn't it also remain distorted and might other things still not fit?
I wouldn't like to put all that heat into the frame with the wooden body structure so close..
The idea with shimming is to try to compensate for the distortion in the frame, so the body sits like it would on a completely straight frame. A lot of fitting needed. Would still be a fast way to get out on the road again - removing the body is a big risk that you'll find more you want to fix while you're there - and suddenly you have a total rebuild and won't get to drive for several years..
Heat bending would present more of a problem with the body still on the frame. Wood parts, paint, oil, grease, gas lines/tanks and wires nearby could be a issue.
With the problems aside, I don't know about the Mapp gas torch, I've never uses one. If it will heat bottom sections of the frame up to a medium red heat, it would be hot enough.
Agree and want to do the washers because it seems easier but the firewall mounts might still be an issue?
We used chains and bottle jacks and had to straighten in several places, the body was off so we had room.
Can the frame be straightened without taking the body off?
Ignatio, if the firewall mounts are an issue, that needs addressing first. There's no point doing a heap of work and then having still to get the body sitting in the correct place on the frame.
Allan from down under.
I changed one fire wall mount out and it closed the gap nicely. See picture of old and new mounts and the new mount installed and the gap closed. New mount on the left. However, the hood still does not fit and when I tested the sag theory by jacking on the frame behind the firewall it started to straighten out.
I am thinking if I take the motor shelf off and put a chain there, then a chain in the back with a timber then take the body bolt nuts off or loose then jack it up to about 2 inches of deflection then it should straighten out without taking the body off?