In the stuff I have read and also in the MTFCA video on rebuilding the Model-T rear end there are references to straightening a bent axle housing but I can find no information on a procedure for doing so. Anyone have any information on how to go about this?
Every bend is different so rather than type a book here how about you describe where the housing is bent. Or a picture.
It's a pretty basic process. You reverse the bend by the heat-shrink, heat-bend, shop press, pull press or big hammer methods. If a tube is collapsed, you can press a ball form through the tube or just replace it. Make sure all rivets are tight when you're finished.
Larry Blair at the Tin Shed offers this service and does an excellent job. It's not expensive, but I'm not sure about the shipping... I've driven down and he's done them while I waited. I've had 3 rear ends strightened and all came out great. His contact informatino is in the 'Parts Suppliers' section of the web page.
Pictures wouldn’t help much as it looks fine until you start measuring. I haven’t determined exactly where the bend is yet but from the quick check I did it looks to be the differential bell itself the is bent.
At this point I mostly wanted to know if there is a preferred method of applying force to the housing and if it was acceptable to use heat. I am reluctant to use heat on things like this as is anneals the metal
I've used Larry Blair at he Tin Shed too, and he does a great job. He uses heat, and knows where to apply it.
If it's for your 1919, it's probably much more cost effective to buy another rear axle, many are straight (depending on previous use & abuse). You will probably find use for some of the parts inside an extra axle, like the inner hyatt bearings.
Had it been a 1909-15), then a lot of work or cost to straighten a bad axle would make more sense.
The only place you'd might want to use heat is drawing a bent tube from the opposite side of the bow. No need to worry about annealing the metal. You'll be tempering it when you apply water on the red spot to shrink the metal.
If you've never done it before, it's probably better to just replace the housing(s). It doesn't take much to draw a bowed tube back. And if you go too far and have to bow it back, the tube will get shorter. Housings are cheap. It's the innards that can get pricey.