ZF S6-40 Tailshaft and Driveshaft Yoke Repair | 280ZX

[@b.c4066]

its an early black tag zf s6-40 sold in 89-94 corvettes only. 94-96 used a blue tag zf s6-40

[@b.c4066]

the good news is the rear bushing and seal are the same as a th400, 4l80e. most automatic transmission rebuilders will have boxes of bushings and seals that were not used in basic rebuilds. went through this on my vette. local guy had them. charged me 50 bucks to install new bushing and seal. make sure you align the oiling hole in the bushing to the tailshaft cover housing. it does lubricate through that hole. use amsoil synchromesh, or redline heavy shockproof manual transmission oil. shim the front countershaft as tight as you can. it will help with gear rollover clash noise. they are a tough transmission. can easily handle 650-700 hp IF you keep the clutch hydraulic throwout in good shape. the number one killer of these trannys is lack of fluid changes, and lack of throwout system maintenance.

[@PracticallyStock]

Hopefully the clutch will be good. I was not able to use the factory slave cylinder for reasons shown in a future video. I built the system from alternative parts and the clutch is a little heavy, but it can exceed the upper bound of the throw listed on ZF doc. That video will likely be out 2 weeks from now if you want to take a look, I'd appreciate any input

[@b.c4066]

the yoke is the same as any gm th400 or th375. they are readily available. dont use a file it wont work, in short time the yoke will tear up the output shaft splines.

[@PracticallyStock]

I read the turbo400 yokes both ways, either they "fit worse than a worn out factory yoke" or they "are the same" so I got frustrated and gave up on that idea. I can't find anyone else who's done it, but I suspect the 4x4 yoke is the same splines as the ZF and the TH400. The yoke I used has 240K on it and has sat around for several years so I suspect it just had some crud build up in it. With how hard it was to cut, I imagine that little file cleaned rather than removed material. It currently has no detectable play side to side or rotationally (unlike the factory one that is completely thrashed) but I will keep an eye on it. If I get access to a TH400 I will do a comparison