ZF Tranny: 320Z-THCH versus 320Z-THMW

[Feffman]

Good Day All:

So it appears ZF made a small change to the 320Z transmission December 1994. As near as I can discern, it appears the only change is the dropping the Steel Breather (Part 23131204841) in favor of a different Vent Pipe (Part 23117547985). Any other changes to the ZF 320Z?

This being duly noted, is their a better choice between the 320Z-THCH or 302Z-THMW? Who do we use to rebuild the 320Z? Need to drop one in my E46 M3 racer. Thanks in advance.

Feff
www.MVPTrackTime.com

[Bimmerman535i]

Good Day All:

So it appears ZF made a small change to the 320Z transmission December 1994. As near as I can discern, it appears the only change is the dropping the Steel Breather (Part 23131204841) in favor of a different Vent Pipe (Part 23117547985). Any other changes to the ZF 320Z?

This being duly noted, is their a better choice between the 320Z-THCH or 302Z-THMW? Who do we use to rebuild the 320Z? Need to drop one in my E46 M3 racer. Thanks in advance.

Feff
www.MVPTrackTime.com

I didn't know there was any difference between ZF 320s. I think Dan at Diffsonline will build one, but since you can buy one for ~$200 used all day long, I don't personally see much reason to do so. The common issues are the 5th gear lean and detent pins replacement (which can be easily DIY'd) and aside from that they're sturdy.

For what it's worth I have been tracking an S54 with a ZF 310 with no issues.

[Feffman]

It's been suggested one of the 320Z designs (THCH vs. THMW) leaks more frequently than the other. Any insight?

Feff

[tsmith25]

It may be different out west, but they go for around $400 down here in Florida.

[testify]

It may be different out west, but they go for around $400 down here in Florida.

I am in New England and I'd agree with you.

I need one soon so I've been looking around a lot lately. To me it looks like for $200-$250 you can get one from a private party on Craigslist or a forum with high mileage, unknown condition, and no start up warranty or guarantees. For $350-$450 you can get one from a junk yard, still high mileage but theyll claim its tested and will likely return or exchange it if it doesnt work. For low mileage examples well under 100k miles, I'm seeing asking prices of about $600.

It's still probably a crapshoot no matter what you buy, though.

[Feffman]

It may be different out west, but they go for around $400 down here in Florida.

Found one (320Z-THCH) locally with 86K miles for $400 out of a 328i. Spoke to Midwest Transmission about a rebuild if I opt to have it renewed (seals, synchros, etc.) before installing. They said MAX $2,000 but likely considerably less.

[greatpumpkin]

It's been suggested one of the 320Z designs (THCH vs. THMW) leaks more frequently than the other. Any insight?

Feff

My car (10/94 build) has a ZF with the steel breather. It leaks from the breather on the track - I think that the g-loading in long right-hand corners forces trans fluid out of this orifice. My friends with '97-'99 M3s (which I assume have the vent pipe) don't have this problem.