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-   -   Getrag Transmission Shifting Issues???? (https://www.miataturbo.net/race-prep-75/getrag-transmission-shifting-issues-105616/)

fourwhls 08-02-2021 10:04 AM

Getrag Transmission Shifting Issues????
 
Is anybody else running a turbo BP and Getrag tranny having shifting issues?

I'm having issues shifting at high RPMs, especially after the car is hot. It works fine at low RPMs and seems to work better on the first run. It appears to be a clutch issue to me, but I have been unable to figure it out. This is a dedicated autocross car, so it's only seeing the 1-2 shift for the most part.

Background:
Relatively fresh rebuild on a Getrag 260. It did have a few track event on it before I bought it and worked flawlessly in the previous owner's car.
E46/E30 ACT HD clutch with Kmiata adapter

What I've done so far:
Wrapped the slave in heat wrap
Built a heat shield for slave with an air gap and reflective heat tape
ACT thought it was a pilot bearing issue, so I just installed a new pilot bearing
Sent clutch to ACT to eval and they said there were not issues found
Replaced all the driveline bushings with fresh 75-95D polly mounts, with exception of the engine mounts. I have Blackbird Fabworx drop engine mounts.

Next steps, unless you guys come up with other ideas:
Build a new downpipe with oval tubing next to the slave to get as much heat away as possible, if there is even room.
Send the tranny back to the company that rebuilt it and have them pull it apart. It may be a shift fork or syncro issue on 1-2. It worked flawless for the previous owner, but high RPM 1-2 shifts are not common on road courses.

Any other ideas?

concealer404 08-02-2021 10:05 AM

Hey Shawn, what RPM are you turning in this thing these days?

fourwhls 08-02-2021 10:33 AM


Originally Posted by concealer404 (Post 1605549)
Hey Shawn, what RPM are you turning in this thing these days?

8000 RPMs.

concealer404 08-02-2021 10:35 AM

Wonder if the transmission simply doesn't like that sort of RPM on a fast 1-2 shift. I've found every one of those transmissions i've touched to be pretty balky, and generally i find 1-2 shifts to feel nasty in most transmissions. :(


Ryan_G 08-03-2021 08:58 AM

I'm not sure if it will help with your shifting problem but why are you not putting an air gapped heat shield on the downpipe facing the transmission? It would really help the slave and the transmission temps.


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