chandlerbingco
Registered User
Ok everybody - I removed the ZF 542 tranny from my 1989 F250 over the winter and rebuilt it at the same time I rebuilt the engine. Engine turned out great and runs strong, but the transmission is having some problems I can't explain.
To do the rebuild, I followed the ZF factory service manual to a 't', including setting bearing preload, etc. I checked the orientation and order of parts on the main shaft as it was assembled, replaced all bearings and seals, replaced all synchro rings, and replaced reverse gear since the synchro collar teeth on the original were pretty well chewed up. Otherwise, the gears, synchro sliding collars, hubs, etc. are stock and were in good condition when I inspected at the time of rebuild. When the case was reassembled after setting bearing preload, it seemed to shift through all gears just fine on the bench and there were no engagement problems with reverse - I spun the input shaft by hand in each gear to make sure everything worked as expected. It did.
Now, the transmission is back on the truck and I'm having two noticeable problems I didn't have before the rebuild.
First, the transmission is sometimes seems difficult to get into reverse. Occasionally it will work fine and engagement is smooth and the truck immediately begins to move as soon as the clutch pedal is let out, just like you'd expect. However, about half the time the truck suddenly stops moving while backing up and requires significantly more pedal and letting the clutch pedal out even further, as if it's being forced to move in reverse. This occasionally happens when starting in reverse and also happens sometimes when the vehicle is already moving in reverse. I don't notice any unusual noises when this happens. No clunking, whining, or anything. I do, however, notice a burning smell if I have to force the vehicle in reverse more than a few seconds. I haven't found the source of the smell, but I'm guessing it could be either clutch or brakes. (The clutch was replaced with a Southbend SMF last year before the tranny rebuild and worked great.) It's possible this is a brake problem where they are occasionally engaging in reverse for some reason, but that wouldn't explain the second problem below.
Second, the transmission occasionally seems to engage when in neutral and will slowly creep forward as if it were an automatic and you took your foot off the brake. The degree of creep seems to change as well, too - sometimes it will do nothing, sometimes it will engage slightly, and once in a while it will seem to engage quite a bit and feels as if it might stall if I let the clutch pedal out in neutral with my other foot on the brakes.
I took the tranny off, stripped it down, and rebuilt it a second time with the ZF manual just to be sure I hadn't missed something. Same exact problems when reinstalled the second time.
I should also mention that I replaced the entire clutch hydraulic system at the same time. New master and slave cylinders and replaced the clutch pedal linkage with the heim joint fix. Clutch engagement seems to be working very well and shifting is smooth for gears 1-5 when moving forward. The problem is in neutral and reverse.
What the hell is going on? Anybody else have this problem?
To do the rebuild, I followed the ZF factory service manual to a 't', including setting bearing preload, etc. I checked the orientation and order of parts on the main shaft as it was assembled, replaced all bearings and seals, replaced all synchro rings, and replaced reverse gear since the synchro collar teeth on the original were pretty well chewed up. Otherwise, the gears, synchro sliding collars, hubs, etc. are stock and were in good condition when I inspected at the time of rebuild. When the case was reassembled after setting bearing preload, it seemed to shift through all gears just fine on the bench and there were no engagement problems with reverse - I spun the input shaft by hand in each gear to make sure everything worked as expected. It did.
Now, the transmission is back on the truck and I'm having two noticeable problems I didn't have before the rebuild.
First, the transmission is sometimes seems difficult to get into reverse. Occasionally it will work fine and engagement is smooth and the truck immediately begins to move as soon as the clutch pedal is let out, just like you'd expect. However, about half the time the truck suddenly stops moving while backing up and requires significantly more pedal and letting the clutch pedal out even further, as if it's being forced to move in reverse. This occasionally happens when starting in reverse and also happens sometimes when the vehicle is already moving in reverse. I don't notice any unusual noises when this happens. No clunking, whining, or anything. I do, however, notice a burning smell if I have to force the vehicle in reverse more than a few seconds. I haven't found the source of the smell, but I'm guessing it could be either clutch or brakes. (The clutch was replaced with a Southbend SMF last year before the tranny rebuild and worked great.) It's possible this is a brake problem where they are occasionally engaging in reverse for some reason, but that wouldn't explain the second problem below.
Second, the transmission occasionally seems to engage when in neutral and will slowly creep forward as if it were an automatic and you took your foot off the brake. The degree of creep seems to change as well, too - sometimes it will do nothing, sometimes it will engage slightly, and once in a while it will seem to engage quite a bit and feels as if it might stall if I let the clutch pedal out in neutral with my other foot on the brakes.
I took the tranny off, stripped it down, and rebuilt it a second time with the ZF manual just to be sure I hadn't missed something. Same exact problems when reinstalled the second time.
I should also mention that I replaced the entire clutch hydraulic system at the same time. New master and slave cylinders and replaced the clutch pedal linkage with the heim joint fix. Clutch engagement seems to be working very well and shifting is smooth for gears 1-5 when moving forward. The problem is in neutral and reverse.
What the hell is going on? Anybody else have this problem?
