I had recently made a post "Bringing a 23' Roadster Back To Life". I received a lot of good information that has helped me evaluate the extent of service necessary before driving.
During my pre-start inspections, I found some good and bad news. The good news is that the babit thrust washers seem to have been replaced. The bad news is that I see signs of heavy rivet wear to the break drum in the transmission.
My question(s) are in regard to this rivet wear to the break drum. The grove that is worn appears to be in the center of the drum about 1/16" deep. Will this require attention? Also, I was able to observe the bands in the transmission are Scandinavian, however I cannot determine if they require replacement.
How can I determine if the existing bands need replacement? If this break drum requires attention, what is the best method to go about removing it from the transmission? Finally, if attention is required to this drum, where should I send it?
If the drum groove is from the current rivets, that suggests it's time for new bands.
Some good pictures of the drum would help experienced T guys evaluate its condition.
If you have to remove it, get the MTFCA transmission book and follow the instructions. If you can get an experienced T mechanic to help, that's even better.
I believe the standard treatment for a damaged drum is to replace it with a good one.
If the drum isn't cracked then don't worry about the groove. Next time you rebuild the transmission is the time to replace that drum.For goodness sakes don't take the car apart for that reason alone.
Under no circumstances should any machining be done to the drum to try to bring the rest of the drum down to the worn area you describe. Doing that weakens the entire drum, greatly increasing the likelihood it could crack, or fail in catastrophic fashion.
You can look at the end of the band linings to see how thick the remaining material is. If it looks to be 1/8" or more it's good.
My conclusion to why drums have groves worn in them is; 1; about WW2 band manufactures started supplying steel rivets instead of brass and did so for many years after the war ended. 2; Rivets were install with the tangs bent the wrong way.
Many drums have groves worn in them and unless you see any cracks you should be ok.
If you need a replacement drum check the classifieds there are several people that sell 'em.
If you don't have a copy you should get the Model T Service Manuel also parts catalogs from the suppliers. There is a link on the Home page that list suppliers.
If the band material does not look frayed and appears to have thickness to it you should be good for more then a few trips around the proverbial block.
As far as removing the drum, that requires the engine being pulled and more or less a complete tear down. It will also require a clutch drum puller. I would suggest also getting the Transmission rebuild book. It's sold by most if not all the T parts suppliers.
To assist in determining if the band lining requires replacement is to visibly verify how much shaft thread is left for taking up the adjusting nut. If the return spring is fully compressed, it is obviously time to replace the lining.
Consider this analogy:
To add to what Royce said, my personal opinion is that the grooves in question in Model "T" transmission drums compare to the grooves we used to see in brake drums before disc brakes became prevalent. (I'm talking here about brake drums on cars of the '50's-'80's) I have argued more than once in the past against a mechanic automatically "turning the drums down" for no particular reason, or just to remove enough material to remove a groove in a brake drum. Such a groove is absolutely harmless; in fact, it actually adds a bit to the total effective surface area of the brake shoe/brake drum contact area. If a brake drum was "out of round", that's a different story, and certainly a good reason to "turn" the drum down. But a slight groove(s) in a brake drum is absolutely harmless, as long as the groove is not deep enough to compromise the strength of the drum. After all, the more material removed from a brake drum, the quicker the drum heats up and becomes less effective (brake fade). And to remove any amount of metal from a drum for no good reason is a waste in my opinion, and this compares to needless machining of a Model "T" transmission drum (which weakens the drum) just to remove a groove. For what it's worth,...harold
I TOTALLY agree with Harold S. I had a '65 Ford pickup I drove for work for 17 years. I put over a half million miles on that truck. Replaced brake shoes less than ten times (didn't count, probably about five times). NEVER ground a drum. It had the same drums on it when I sold it as when I bought it.
With a slightly scored or worse drum, I would use wood linings when I had to change them. They will wear in and conform to the score the best. Cotton linings will probably shred. I don't know what Kevlar would do, but I don't think I like it.
Drive carefully, and enjoy, W2