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Just pulled out my 190 box that was refurbed in the late 80s (and never used as yet), and I noticed a little play on the output yokes - they can be moved slightly up and down.

Given what a pain it is when the seals down there leak, am wondering how much movement is acceptable before new bushes are needed?

Any advice or thoughts out there?

Just rebuilt one of these, I would check the diff side cover bushes are within spec and that the output shafts have the correct thickness mica washers installed. It is normally one or a combination of wear on both of these that gives excessive play at the output shafts.

Just to add the bushes are machined one thou oversize verses the inner yoke diameter. You will probably get away with up to 10 thou gap between inner yoke journal and bush before oil leaks become an issue(when new seals are fitted).

Thanks for that info Jason, I can see me pulling it apart in between other jobs. Now I've noticed it, it will bug me

I like doing gear boxes and have for years. Having retired from an auto machine shop in 2000, I still get to drop in and do my own work. Cleaning up around the shop I collect 60 pot and yoke side covers. Cleaned, pressed old bushes out glass beaded pressed in new bushes and align honed. I bolt two covers to a diff cover and hone with a long king pin hone. I have to be careful to dress the hone and flip the work. I shoot for .001 to .0015. I use a lot of new pot joints and measure used yokes to insure a good fit. Why would you put a sloppy gear box together? Steve (CTR)

CooperTune wrote: ↑Sat Mar 04, 2023 1:24 pm I like doing gear boxes and have for years. Having retired from an auto machine shop in 2000, I still get to drop in and do my own work. Cleaning up around the shop I collect 60 pot and yoke side covers. Cleaned, pressed old bushes out glass beaded pressed in new bushes and align honed. I bolt two covers to a diff cover and hone with a long king pin hone. I have to be careful to dress the hone and flip the work. I shoot for .001 to .0015. I use a lot of new pot joints and measure used yokes to insure a good fit. Why would you put a sloppy gear box together? Steve (CTR)

Thanks Steve, my thoughts exactly. I thought a professional refurb would have covered this aspect. I don't have a facility to hone, so have bought new bushes in readiness.

Before retiring 23 years ago I spent 25 years working up from clean up boy to GM. My first attempts at honing side cover bushing, I did one at a time using a short hone. Once honed and checked with dial bore gauge I assembled a diff unit only to find the yokes would not turn. The size was correct and they spun on yoke freely until assembled. Honing additional clearance freed them up. It then became clear to me that the bores were not in line with each other. If just doing one set a lathe or milling machine with dial indicator and boring bar can produce a good result. I have a pair of 5 gallon buckets one for yoke/pot type and the other for HS type. I have been buying bushes for the day I decide to run a batch of HS. I also have located and gained possession of my 190 which had been out of service for the last 20 years. Good luck with your project. Steve (CTR)

Thanks Steve, that all makes good sense. Another question if I may, how do you ensure that the fibre washers / spacers are correct? I note mini spares do an oversize version to go with the standard ones.

http://www.minispares.com/product/Class ... o%20search

I began rebuilding mini trannys for pay in the early 70s. $125. plus whatever parts I demanded. I buy what ever fiber washers I can find and have a good collection of the early brass ones. I have a front mk1door glass with different grades of emery glued on both sides. It's hard to find good pre A+ diff cages and when I do I convert to tab spider thrust. A high grade diff pin and new spiders, careful attention to detail makes for a nice diff. Steve (CTR)

That is good sound practical engineers advice from Steve/Coopertune all through this thread. Including his assertion tat the output tolerances should be to within .001" and .0015"