I'm gathering the parts to refurbish my '24 Speedster transmission (previous thread "Lots of broken/worn transmission parts after 2,000 miles — Why?") and having trouble finding a good used low-speed drum. Lang's is quoting two months for an exchange drum and that does not suit my Labour Day weekend travel plans.
I received this drum today from a fellow in Calgary... thickness looks OK and there are no cracks but the circumference is quite pitted. I chucked it in the lathe and gave it a good sanding so there are no high points/sharpness, but I am unsure if the pitting itself will be a problem. The optimist in me would like to believe the pits will hold oil and thus help reduce band wear and heating. My pessimistic side sees me tearing this engine down yet again for another drum replacement.
FWIW, I am changing out my Kevlar bands for Guinn wood bands this time around. The photos show my drum after sandblasting and after a sandpaper polishing. So, does this drum look OK to use?
I would use it just like that. Don't remove any more metal.
OK is a relative term, unfortunately.
I would say that it could be used as is, but it might chatter and engage roughly, but it would work. It also might be hard on your bands.
My best advice is to take it to a machine shop and have them resurface it; just taking off enough metal to get rid of the pitting and make a nice, smooth surface. Taking off too much metal can certainly be a problem!
Then again, the drums in my '24 Touring are in only slightly better shape and I've had no issues with them.
I also realized that I may have sparked quite a controversy here by talking about resurfacing the drum!
We'll see what happens...
Oh, and I forgot to mention an important factor in determining whether a part is useable or not, and it's this: How much you are going to drive your car.
If you plan on doing some major cross-country touring, you would want everything to be pretty immaculate.
However, if you're like me and drive your T maybe 200 miles a year, you can get away with tired bushings, worn bearings, rough drums, etc, especially if you are like me and are extremely devoted to maintaing your car. Not to mention I plan on doing a full mechanical restoration a few years in the future, so many of these parts just have to last until then.
Pits on the drum is nothing to fix that, you should be looking at the hub, and gear, I can see some pitting! More Pictures!
I used very fine sand paper with the drums in a lathe until they felt like velvet. The pits were still there and no issues with wooden bands,
The key is a slick surface!
Mike
I think if it were mine, I would set it up in the lathe and kiss it with a flat file and then polish it with emery cloth. It looks like it has a thick rim comparatively for a low speed drum, but I agree with Royce, I wouldn't machine it pretty.
Konhke does bring up a point, what does the gear look like?
I too agree with Herm...The drum looks OK but the gear looks rough. I would look for a nicer gear and drill the rivets and re rivet it in place of the gear shown. Not a big job but will likely give you better service.JMHO
Thanks for the comments and suggestions. Here are so additional pictures. The hub faces need a bit of clean-up too — turn flat or just smooth out?
That gear might be noisy. The drum could be sanded in a lathe. I don't think you should take off much. The pits will actually hold oil, but you should get off any rough edges which would tear into the bands. I wouldn't recommend taking it smooth, because it would get thinner. Just smooth it out.
Norm
The pits are not a big deal if you are going to use wood bands. As Norman said lightly sand the drum but, do not turn the drum down in a lathe as it will weaken it. The gear shows a little wear but, it would probably be ok. Have you considered having the drums magnafluxed to make sure they are not cracked? There are forum members who have extra drums for sale.
Stephen
Pits on the drum = LOTS of tiny oil reservoirs........as long as it's smooth.......
Looking at the first two pictures you posted I now see a little more gear pitting than I would be comfortable with. That gear would probably be noisy. You may want to find a different drum.
Stephen
Let me just warn you all now that I'm WAY over thinking this!
Now I've always wondered that maybe pits on the drum are not a bad thing, as long as they are smooth. Perhaps it keeps oil on the bands when they are engaged, kind of like those aftermarket Oillite drums, or whatever they are called, that have the big oil groove in them. I've smoothed out some drums before using the lathe and file method, and it works beautifully.
I do feel that a possible problem with not turning down the drum (which I would cap at five thousandths) is that if the drum has a bit of pitting, the metal on the surface that appears fine may have microscopic pitting anyway, and the metal is still weakened, even without turning it down. Has anyone ever put the surface of pitted drum under a powerful microscope?
That's enough about drum surfaces for now!
I would also say that that gear does look a bit worn, perhaps a little too much. It would certainly work, but it would probably be noisy. I would also consider installing a new bushing. A little effort now can go a long way!
In the end, though, I'm sure that there are as many different opinions out there as there are T owners!
That gear might make a bit of noise. I build and rebuild gear boxes for conveyors in industry and I have had customers bring in gear boxes with the complaint that they are making one helluva racket.
(Industrial noise levels are monitored by OSHA.)
Upon opening and inspection, there have been times when I have found one tiny divot or chip on a pinion gear (high speed or input end) and it was that that was making all the noise.
I got suckered into using a drum like that under the theory that wooden bands can make anything shift smooth. Yes, we polished the surface of the drum until it looked smooth (except for the rust pits). My experience was that rough drums will result in grabbing/rough band operation REGARDLESS of whether you have the magic wooden bands on it.
Pitch that drum and get something that has a LOT smoother drum surface, and smoother gear teeth.
Ron Dupree
The drum will work. A drum that is smooth with nice teeth would be better. On the other hand the rim of that drum seems exceptionally thick which is good. The gear teeth show signs of past corrosion, they may or may not be noisy. Any time you mix used parts from one transmission in another, you run the risk of gear noise.
If you really want a noisy transmission combine parts from several transmissions and rebush them all.
I just reread your post,if it were mine I would stay with the kevlar bands.
You can rivet that drum to a different hub if you think the hub is better on one than the other. Use the best parts you have. After riveting the hub into a different drum of course you have to machine the rivet heads flush. Just don't machine the outside.
Those pits are minor enough to polish out with some use.
Every other consideration appears to be minor as well.
The low drum is the center meat of the drum sandwich and runs hotter from more use and abuse.
The early brake drums also get a lot of abuse.
Which drum is the most difficult to find in good condition is a toss up between the Low and Brake Drums.
The one item that gets most people in trouble when rebuilding a transmission is the clearance between the bushing and shaft. Too much is better than too little.
The new bushing material seems to expand when hot and never shrink when cold for some reason.
An old bushing with a .004 or .005 difference in diameter between the bushing and shaft might be a little noisier, but they will work much better.
This is all very helpful. Thank you. We're considering riveting the hub that came out of my transmission to the good replacement drum. This hub has good thrust surfaces and bushing clearance. Point taken about machining/countersinking the rivets to/below the surface.
If we were to use the replacement drum and worn hub (with new bushing), I can see also machining the thrust surfaces slightly to eliminate the bit of ridging. They will doubtless become a few thou shallower and my feeling is that won't be a problem later. Is this correct?
If I were going to the work of riveting the hub to another drum, I would buy a new drum. In fact, you can purchase a new drum and send your old hub to the company which will rivet it for you. That way, you will be sure to get a good job. If you are going to use the old drum, why not just go with the old gear too?
Norm
Ted Dumas on Wednesday, August 01, 2012 - 11:08 pm:
"I just reread your post,if it were mine I would stay with the kevlar bands."
Huh?
Chris Banford:
I was glad to see James Golden suggest using the original bushings. I almost never find a bushing in a trani drum that has too much wear. Even Ford stated that you could use up to five thousands clearance. I almost never find that much and I deal in many, many drums. The idea that the bushing have to be changed on all drums is not right.
I would agree with Herm, the gear is going to get most of the torque.
I likely have better ones that need to find a new home.
My opinion. That gear is well into marginal. I would change it. The drum, looks like a good one. I would spend about fifteen minutes with about three feet of 180 emery tape to take the sharpness out of the pits. But no more. I have not ever had a drum machined down and do not expect I ever will unless new material has been added to the surface.
I also agree with Dave H. Model T transmissions like to run loose. The bushings should not be replaced unless they are really loose or otherwise damaged.
Drive carefully, and enjoy, W2