T20 transmission bands

[Petestuth]

How many thousandth thick are new band in a t20 transmission? And how much can they be worn down before replacing?

[thebuggyman1]

The wear material is .040-.045" thick. It has to be measured very carefully and at numerous spots, because the material is soft so calipers will sink in and it also doesn't wear evenly. It usually wears the most on the end closest to the plunger.
When you decide to replace/reline them is up to you, but it doesn't take long to ruin a drum with metal to metal contact. If they were half worn I'd condemn them.

[Mike]

If you will use the search you should be able to find the info you are looking for. Here are a couple of threads I found to get you started:

http://www.6x6world.com/forums/transmissions/25077-questions-about-my-t20-gearbox.html#post135229

http://www.6x6world.com/forums/transmissions/25485-hustler-t20-question-3.html#post138277

Really you will just want to make sure that the material isn't worn all the way through or close to the bands. Also make sure there is no badly uneven wear where one part of the band is half as thick as the other. If so, it's probably time to reline before they let go and damage a drum.

[Petestuth]

Thanks

[phabib]

I just cracked open my transmission yesterday and I saw a couple of spots where the friction material was missing. Each spot was about 3/8" long. Does that mean I should have the bands re-lined regardless of how thick they are? Also, my Max had been sitting outside in the weather for God only knows how long and I saw a couple of what I think are rust stains on the drums. One was a couple of inches long, the other maybe 4 inches. There is no pitting and the stain nearly went away with a few seconds of rubbing with 400 grit sandpaper. I'm inclined to ignore the staining. Other than that things looked good inside. The main problem I have is corrosion in the plunger holes and stuck shifters. I think a good cleaning will take care of those things.

Thanks for any advice.

[jpswift1]

As long as the drums are smooth and there's no pitting, you're fine. Clean them up well with some fine grit sandpaper and you're good to go. The bands with the missing material should be relined. Transmission Crafters in Georgia has done this for many members here on 6X6World.

[Mike]

For the missing spots of material on the bands, was there more than one spot on each band? The bands typically do have a space with no material. Look at these bands after just being relined to see what I mean:

[phabib]

Thank you JP and Mike for the replies.

I think my naked spots are larger than what's in the pictures. I called Transmission Crafters and I'm waiting for a call back. I don't see any obvious signs of wear in the transmission so I'm inclined to clean out the gunk and corrosion that's preventing the plunger holes and shifters from moving freely and then replace seals, gaskets, and O-rings and close it back up. I'd leave bearings alone unless I saw something obvious. does that make sense or is the additional costs of more parts small enough that I may as well change it all once I have it apart.

[Mike]

That seems logical to me. The only thing that would concern me is the amount of corrosion you are seeing. I would worry that the bearings may have some of the same. If the bearings were cheap, it would make this an easy decision to go ahead and change them out but since they are custom ground just for the T20 and there are no aftermarket replacement bearings available, they aren't cheap. Just check the existing ones out real good and see if you can find any flat spots, rough spots, etc. If not, you can get by without replacing them.

On the other hand, remember that if you have to go back and replace them later, the T20 has to be removed again and broken completely down to remove the output shafts and change the bearings. It's weighing the cost of the two bearings against the possibility of having to do a good bit of work down the road. Everyone approaches it differently. I used to never replace the bearings unless they were bad. Now I always replace them just so I know that I won't have to deal with it later.

[phabib]

I'm more in the camp of do it as well as I can once and then not have to think about it again so I will be looking at the bearings carefully and replacing them if there is any doubt.

On further looking at my bands, I'm leaning more towards not re-lining them. They're about .040 thick, and there are two spots per band with no material. They don't look ragged or torn so I suspect that's just how they were made. Both of the bands that I can see have the same spots with no friction material so this makes me think that they were built that way and I can just remove everything out of the case, inspect the bearings, replace seals, gaskets, and O-rings, and put it back together.

The outside of the transmission is very dirty and oxidized so I'll probably polish it up a bit when its apart. I thought of clear powder coating it, but I don't know if I want to put that much work into it.