Re ZF LEAKS

...Have You Recently Changed-Over to a Synthetic Gear Oil?? Or thinner Oil than 80W-90? Sitting for awhile... yes, the gaskets have dried and shrunk.

MJ

I haven't moved to synthetic (yet?) but the car has had the ZF fluid changed yearly for the past 4/ 5 years , I had always been apprehensive about driving it very far , mostly because I had become accustomed to how  the car was ? idk when my father had it there  was  the might get hot thing so mostly driven at night and not very far even that was no guarantee . That was Before the  world wide web, and access to,,,, well,, the world wide web and its information , my father loved that car unfortunately he didn't get to experience the doesn't get hot any more version . We had a ranch and family business in northern California and I was the mechanic ,of a wide range of equipment , machines and vehicles , but that car was not included in that list . Until his frustration of him having trouble getting it tuned like he wanted along with my sarcastic comments re my car being able to blow the doors off his , he  gave in . I tuned that car he took it for a  drive came back all i could see was teeth after that Nobody else touched that car mechanically again . I apologize for going on a little walk down memory lane , doing so gives me a smile mmmmm almost like his after I tuned his car . So  no  synthetic but regular fluid changes , And I am almost glad my truck blew, I now have complete confidence to drive that car anywhere .

Where is it leaking from? If it is from under the rear cover acorn nuts you can put o-rings under those.

That's usually the spot the ZF will leak from when you put in synthetic. I have synthetic in there and it dripped initially. Hall told me to do the o-rings and it worked. That's how long ago I did it. Gary's been gone for almost 20 years now.

I recently sealed the nuts on the rear cover with black silicon.  I like the o-ring idea because it is less of a mess.  Just do several at a time to prevent the cover from dislodging.  

left,

As you may know the ZF is installed upside down in our cars so a sealing system for the nuts on the "bottom" wasn't required. I tried using sealing crush washers awhile back with limited success. A few years ago someone purchased a large lot of acorn nuts with o-rings which worked quite well. I looked into this. Only a few companies advertise these. The one I did find (Zago) requires a minimum order of something like a 1000 and at a couple bucks apiece that 's not going to happen. I'm going to try o-rings under thin washers with acorn nuts next.

Gary passed in 2009

These will probably work too. I have not tried them.

https://www.anhosefittings.com...SEAQYBCABEgKxEPD_BwE

After a lot of miles, another source of leaks is the halfshaft seals in the side covers. They're a bit of a pain to do since they go in from the inside, so the iron cover must come out first. And if you DIY, don't cheap out- use genuine ZF side cover gaskets. Far-east 'equivalent' gaskets may be a different thickness, which will change the ring & pinion pre-load setting.

The reassembled ZF may not leak, but preload changes can make noise when under power, or more rarely when backing off the accelerator.Then you get to re-shim the side covers to reestablish the proper pre-load, which is kind of a pain. This also sometimes happens when replacing the ring & pinion gears for a different ratio.