Trans Rebuild: Replace brake bands & blocks?
 

Okay, I am in the middle of rebuilding my 901 transmission and have a question in which I'd like some feedback from the experienced masses.

I am replacing all bearings and the synchros on gears 1-3. 1-2 need them but 3-5 shift beautifully so adding a new synchro to 3 is more or less erring on the side of caution. I am also replacing a synchro hub and a slider that are worn.

I planned to replace the brake bands for gears 1-3 so that the new synchro would be mated to a new band.

Should I replace all synchros, all brake bands, and all stop & anchor blocks even if there is no wear evident?

I'm not really trying to cheap out on the rebuild but I also don't want to replace parts "just because".


Also, I am replacing the "Z" 5th gear with a "ZD" 5th gear to improve high speed cruising ability. Anyone have any positive or negative experience with this change?

Thanks!
David

the brake bands are an important part of the syncro mechanism, so it's a good idea to renew them. all the shift sleeves are usually pretty badly worn on 901s, especially 1st/reverse. ($$$). do you know what to look for as far as wear is concerned? how about the pressed on teeth? any of them hooked or flattened out? remember to use only one band on 1st.

I was hoping to get feedback from you! Thanks.

The pressed on teeth for 1st are hooked (getting replaced) but the slider still has good points that are only very slightly rounded. Is there an additional wear point to check?

The pressed on teeth for 2nd look good with only a very slight rounding of the sharp tip and a very slight almost undetectable concave shape to the top of them. Slider for 2/3 has a chipped tooth and will be replaced.

Teeth on 3-5 look really good.

Regarding brake bands, it sounds like I should stick with my plan to renew synchros and bands together. But, no need to replace blocks or brake bands for the 4/5 gears that are not getting new synchros?

I am getting the ZD gear and pressing out the bad synchro hubs with a gentlemen that has been through 40 of these so I hope to get a second opinion on parts from him as well.

David

For the sliders it's not necessarily the points on them that are of utmost concern. You also must look at the inside diameter or shape of the internal contact surface. This is another point of wear to inspect for possible replacement.

Good point. I did look at the shape and it "looks" good with the concave shape to "cup" the synchro ring still intact. I'm not sure about the diameter though as I did not see a dimensional tolerance in my book. Is there one?