Sorry guys, I know there's like a billion other threads out there, but none of them have seemed to help. Anyway, about half a year ago I had my clutch replaced on my 1989 f250, and when I did it, I swapped out my dmf for a proper flywheel. Of course the mechanic didn't tell me it was going to make any sort of noise, but whatever. So I drove the truck around like this for half a year (it's my daily) and nothing happened till I moved to st louis a couple weeks ago. Before I left, I changed out the fluid hoping that the noise would be lessened. Put the proper amount of fluid back in and now... it's even worse. 3rd gear was always a little shaky, but now I can only get it into third by waiting for the revs to die back down to idle speed when I'm shifting, or double clutch it. The strange this is, after I moved here, I noticed that the noise was MUCH quieter after a cold start, but after driving around for 10 or so mins, the noise comes back. The strange thing is, even though it's a lot quieter, until it warms up, 4th gear acts a lot like 3rd, where you have to be gentle with the shift or else it will grind. Now this truck has about 370000 miles on it, so I wouldn't be too surprised if I'm looking at a tranny rebuild in the future, but I really don't have the money right now to do something like that. Thanks guys.

 

What type of fluid did you put in it?

 

If you put anything else but ATF in that tranny that's your problem.

NEVER....EVER put anything thicker than ATF in a ZF5 transmission.

They have very very tight clearances and thick oil won't properly lubricate everything and will damage bearings, syncros etc and cause hard/no shifts.

 

Yup; ATF(or comparable weight oil -- I've heard of people running 30wt non-detergent engine oil) only; also, as you've got a SMF clutch, add an extra quart or two of oil to quiet the noise(fill it through the shifter hole).

 

Many of the active members when I first got my truck thought gear oil was the proper fluid to use in these things. Not everyone, but probably a majority. Someone finally found a ZF manual and posted it. ZF lists MANY acceptable oils and fluids for this transmission, from some types of lighter gear oil down to synthetic ATF.

Take it from the active members now, and go with either ATF(synthetic while you're at it) or pay about the same and get Redline MTL(Manual Transmission Lubricant. Better on synchros but otherwise just like the ATF). Its the cats pajamas and it's what I run. I had gear oil in my pickup to start with 6-7 years ago and changed it later when it was very hard to drive when cold and reading about the ATF/MTL online.
I have had great results with it, running for 4-5 years and the synchros aren't any worse than the first day I put the stuff in.
I also have the SMF, just did the conversion a few months ago. Almost zero rollover noise but I don't know if that has to do with the MTL. I did not overfill it either.

If you didn't put ATF/MTL in and you switch, let us know if it helps the gear rollover noise.
Also the issues you are having sound like you used the wrong oil in conjunction with moving to a colder environment? I don't know where you moved from but sounds like St Louis is colder than where you came from, based on noise/shifting, etc. Could just be the oil.

-Joshua

 

Not just ATF, but SYNTHETIC ATF. REQUIRED by ZF in this transmission when commissioned behind a diesel engine. So the TWO questions are, what was the old fluid, and what is the new fluid?

 

So... something I just learned today:
If you fill your ZF with 10 quarts(!) of oil, it will be very quiet, drives OK... but you will have a heck of a time getting it into gear at any speed above 0(like, hold the lever for 3 seconds before it drops in).
It will also slowly leak out of the front seal, and weep out the top.
<_<
With 4 quarts, it will work much much better.

 

im running the redline mtl in my 88 zf5. much better cold shifts but I have the rollover noise in mine. ive heard slightly overfilling it will make it go away but I just put a gallon in it when I did my clutch. I would recommend using the redline oil though. good stuff.