1990 manual difficulty shifting
Oil Producer
Joined: Apr 2014
Posts: 9,374
Likes: 2,736
i honestly cannot help in terms of 'cold weather' zf6 operation but i do know that amsoil syncromesh manual transmission fluid is the ultimate that i have found for these trannies. perhaps you have an oldschool fluid that is too thick in the cold. try full synthetic?
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
Problem that suddenly happened? Guess if the hydraulics are good must be as the others said..thick and cold
my T56 is sensitve to this also.
Id call Bill at ZFDoc if anyone knows he will. Id be afraid most local tranny shops are going to want you to bring it to them....and sell you something.
my T56 is sensitve to this also.
Id call Bill at ZFDoc if anyone knows he will. Id be afraid most local tranny shops are going to want you to bring it to them....and sell you something.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
Two things could have happened:
1. Your slave could be leaking slowly. Car sat....you lost some fluid, now it's too low.
2. fluid was low, got cold....contracted and now it's too low.
Melting Slicks
Joined: Jul 1999
Posts: 3,214
Likes: 101
From: Decatur, Alabama
90% of all ZF6 transmission failures are the result of weak hydraulics..... replace your clutch master and slave and cable now if you haven't already and save $4500 for a transmission rebuild. Also be sure to use the correct fluid. Also change your transmission fluid... see zfdoc.com website,
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Drifting
Joined: Jul 2014
Posts: 1,426
Likes: 46
From: Lynchburg, VA
90% of all ZF6 transmission failures are the result of weak hydraulics..... replace your clutch master and slave and cable now if you haven't already and save $4500 for a transmission rebuild. Also be sure to use the correct fluid. Also change your transmission fluid... see zfdoc.com website,
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Had similar issue with my "new" '89 ZF6.
The master would gradually drop in level with hard shifting eventually resulting.
Since the master was not leaking, a new slave solved the problem.
The master would gradually drop in level with hard shifting eventually resulting.
Since the master was not leaking, a new slave solved the problem.
Drifting
Joined: Jul 2014
Posts: 1,426
Likes: 46
From: Lynchburg, VA
Yeah, I was counting on it being about $3k including shipping both ways. For $4500 I'd definitely either buy a used one with reasonable mileage or swap a T56. I like the ZF6 and the idea of keeping my car somewhat stock, but you can buy a brand new T56 Magnum for about $3k (of course a trans swap has other associated costs, but still). I think I'll call ZFDoc tomorrow to get a quote.
Last edited by C4ProjectCar; Jan 24, 2021 at 06:25 PM.