ZF transmission leak

Where is it leaking from?

it is a seal for one of the side plates, for the lack of a proper term, which hold the output shafts.

That seal can be replaced without pulling the transaxle. You will need to remove the half shaft on that side. Then remove the half shaft adapter by taking out its single bolt. At that point the seal is readily accessible and can be pulled. I know that Wilkinson has those seals and the other vendors likely have them as well.

is the leak around the axle (seal #917)?

Steve, I think you called this one wrong. Removal of the spline to access the seal will require separating the side plate from the ZF which requires the ZF extracted to access the lower cross bolts. My memory is less than perfect these days.

the leak is between the large plate #913 and the case, but to be honest, I also see a slight amount of moisture on the shaft # 918. The long cross bolts do engage the plate. Its probably time to do the right thing and pull the transmission again after about twenty years since the last time unless a sealer can work.

Tom

Got it. I was thinking seal 917 was leaking. But it looks like the thin paper gasket between carrier 913 and the ZF housing is leaking. The long bolts on the bottom may preclude pulling carrier 913 when the ZF is in the car. It's not very difficult to replace that gasket when the ZF is out of the car.

I will see if the bolts can be tightened further, good advice regarding the castle nuts.
I am using the Motul 80w90 gear oil. I don't believe that's Synthetic.

Thank you

Be careful on the side plate bolts...

I believe those are studs, and they seat into the aluminum case. If those pull out, or yield, you will be pulling the tranny out anyway...

Good luck with the project...

Rocky

Hi guys... Tom, I'm in agreement that I see in unlikely to get the Looong cross bolts out while still installed. I haven't tried this...but can't imagine it possible. You "could" in theory.. take mounts loose and jack up to change relative positions to try and find a sweet spot that those long bolts could be slid out... feasible, but have never tried. The side plates come off with the stub shafts attached. To properly change the paper gasket or the shaft seal, the plates need to come off.

There are a couple of guys here who are much more SME (subject matter expert) than I..such as Ron McCall for example...so maybe one of these other guys will see this thread and chime in with other remarks.

Last remark, I've experienced more leaks with synthetic than traditional oil.

Rob, you're right about the long crossbolts. It is NOT a shortcut! As an experiment a few years ago, I removed my crossbolts with the ZF in place..... sort of. When I got them out, the the bay brace was out, the ZF was loose on both ends. Since the long bolts came out thru the factory hole in the left inner fender, the wheel and left exhaust were also removed.

My final solution for "next time" I need to remove the lower cover, was to replace the 2 long crossbolts with 4 short 12-point bolts threaded into threaded 7075 slugs set in the ZF cover bosses. This changes the lower case reinforcement from in-compression (all the way across the cases) to in-tension from the 4 short safety-wired bolts threaded into the lower cover. Since early SBF GT-40s did not use crossbolts in their ZFs, I figured sort-of replacing them would be safe. So far, so good....