I would strongly consider doing it. NB 6-speeds are only getting more expensive. I'm having mine modified since getting a new countershaft will be very challenging.

@mkrazit

Have you had the mod done? any feedback? Would you have the source for the parts needed to do the mod?

I wish I had a spare 6 speed as I've been wanting to rebuild a 6 speed, study them for anything that can be done to improve the reliability. This mod sounds interesting.

Thanks for @ mentioning to bring me back to this. I haven't formally reported back because I don't have a modified countershaft in-hand yet. The shop I'm using successfully modified a shaft, but that shaft had corrosion in the shaft gear teeth, thus I reassembled only to check clearances (no issue).

Good news is I expect another modified shaft back by December which WILL be assembled into a rebuilt box w/ new bearings and syncros. I'll share details when I have that shaft back.

Guys I just updated the post :dealwithit:

Looking forward to the follow-up. I have a set of gears and another box sitting around I want to build for a spare, but I might do this mod and make it my primary box.

Here's a pos-cat for posting the machine work information!

I just noticed something about your measurements above. Is there an issue with the curvature of the components against the flat measuring surface of the mike? I suspect so, at least if absolute precision is required of those measurements? Or is it a case of close enough for practical purposes?

For the OD it’s fine, but yes for the inside curves your absolutely right, it should be measured with a ball-anvil micrometer

Well, it's December, and still no modified countershaft. Was told they would have time mid-Nov to do the shaft, haven't been contacted for payment so I've been trying to get an email or call back since. Thrust washers are already made, shaft just needs machining and shot-peening...

What is the shop you are using for the work? I am in Indiana aswell

So I have the countershaft back from being modified but have been occupied w/ OTM maintenance -- the reason I haven't updated. (Photos below showing machined and shot-peened shaft, hardened thrust washers, Spirolox retaining ring, and 4th gear w/ clearancing for wider thrust washers.) Next is this gearbox rebuild.

Team Rip Engineering in Kalamazoo, MI. Quality and price are great. Delivery? Shaft delivered to them 21OCT, I picked it up 22DEC. It takes a few days for them to modify the shaft and set thrust washer clearance -- many other priorities shoved this to the side. If more people sent their shafts to be modified, this might become more of a priority for them. PM me if you have further questions.
https://cimg3.ibsrv.net/gimg/www.mia...5f220c7a20.jpg
https://cimg4.ibsrv.net/gimg/www.mia...2c4c83c6b7.jpg

I've got a spare 6-speed I'd like to have rebuilt