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

 

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.

 

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

 

Messaging you!

 

@jrmiata42069 Do you have any updates on how this transmission has held up (or not) over the past couple years?

 

I have been restoring and renewing the car for 2 years, but until the last day the transmission has worked perfectly.

 

So the transmission was in use for 2 years with this mod then? Is that about right? And that was running 500 nm with mixed street and track use?

 

Correct, more use on the track than on the street

 

I guess more people aren't doing this simply because it's difficult to find a shop to do it and if your box goes then you're having another built instead of grabbing a junkyard box (in the case of the ZF swaps)? I suppose it also doesn't increase the power handling by a ton (considering the gears will still strip teeth), so anyone who wants to push past 400 WHP is probably just going to grab a stronger box.

I wish there were more people who had experience/feedback running a box with this mod. Assuming it does work it seems like a great way to bulletproof the drivetrain for people wanting to stay around/under 400 WHP.

ETA - I did reach out to TRE to see if they're still doing this in the states.

 

I'd love to have the mod done to my 6 speed, but getting it done is really intimidating for those of us who don't rebuild transmissions, even if I could get the modded parts.