Help fixing a leak on a ZF

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Brian C

Hi guys, I have an inverted ZF (same config as the GT40) in my Lola, and have a leak at the joint where shown. I am pretty confident the leak is at this particular seal.

Im wondering what happens if I were to remove the two nuts holding this small housing on. Will something with critical alignment pop out and fly across the shop floor? Or does the housing come off without drama? Obviously I will drain the transaxle first.

I’m having a tough time finding this gasket so my plan was to clean the old one and coat both sides with RTV.

Advice appreciated!
 

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Brian C

The leak is at the joint right below the cast “2”, and not exactly where the red arrow is pointing, by the way.
 
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Brian C

Thanks, yup I used Right Stuff just this past weekend on my intake actually. Just looking for data on what happens when that small housing is removed. If Steve is correct in that nothing happens at all, that’s great! I might give it a shot soon.
 
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Brian Kissel

Staff member
Admin
Lifetime Supporter
You might want to reach out to Ron McCall (Pantera 1889) for further validation. I truly believe Steve is correct. I did that about 25 years ago, but can’t remember all the facts.
Regards Brian
 
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Ron McCall

Supporter
Brian,

You can remove the spring loaded detent ( 7/8" socket) and then the three M8 nuts to remove the housing. Nothing will fly out and get lost.
Use a small plastic hammer to gently tap it back and forth as it is usually a fairly tight fit into the bore in the case.
This is sometimes an issue on transaxles in the "GT40" configuration because when the trans is sitting on a bench or on the shop floor, this housing is contacting the floor and sometimes the small steel cap on the detent plug can become damaged and cause a slow leak also.
The gasket from IPSCO is correct. Use a very light coat or Right Stuff or Permatex Ultra Gray on both sides of the gasket . Install the housing without
completely tightening the nuts completely and leave it sit for a day or so. Snug up the nuts and install the detent plug . It doesn't hurt to cover the steel cap of the pug with sealer as well. Couldn't hurt to add a small amount of sealer to the detent threads as well.

Hope this helps.
Ron
 
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Brian C

You are the man Ron! Thank you. I will be sure to take a few photos of the job and let folks know how it went.

Can I impose one more question upon you? If the spring detent assembly is actually the source of the leak (or is leaking as well), is there a fix for it, or does it require a new part? I wrapped a paper towel around the detent before I order anything just to confirm (or deny) there is a leak coming from the housing gasket independent of the plug. The bottom of the detent looks wet as well now but I'm not sure which is wetting which. Does it serve a function in the upside down config or can/should that hole be capped (per your RTV comment)?
 
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Ron McCall

Supporter
Brian,
The detent needs to be installed. You can clean it thoroughly and cover the exposed portion of it with sealer . Make sure to let it fully cure before
reinstalling it . It can be replaced as well but shouldn't be necessary.

Ron
 
manta22

Neil

Supporter
One of the advantages of using Hylomar as a sealant is that it needs no cure time- it's ready to go immediately. Another is that removing an old application does not require scraping off old RTV, simply wet a rag with MEK and wipe it clean.
 
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Brian C

Interesting, never heard of it. Right Stuff apparently doesn't need much cure time either, engine builders will run an engine on the dyno immediately after sealing an intake on. Regardless, the job is done now. Just waiting on my 3 quarts to arrive then I'll fill it up (with 2.5 quarts I believe) and hopefully it'll be fixed.
 
manta22

Neil

Supporter
Brian C said:
Interesting, never heard of it. Right Stuff apparently doesn't need much cure time either, engine builders will run an engine on the dyno immediately after sealing an intake on. Regardless, the job is done now. Just waiting on my 3 quarts to arrive then I'll fill it up (with 2.5 quarts I believe) and hopefully it'll be fixed.
Click to expand...
Hylomar was developed by Rolls-Royce for sealing metal-to-metal joints on their jet engines.
 
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Brian Kissel

Staff member
Admin
Lifetime Supporter
Hylomar isn’t as popular as it once was. There’s lots of options out there and the Right Stuff is a good one.

Regards Brian
 
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Brian C

One concern before I start the car… is the drain plug supposed to bottom out on something (i.e., torque down tight)? In online diagrams it looks like the original drain plug was short and had a shoulder/washer to bottom on the exterior but mine is longer and does not. Online diagrams also show nothing behind the plug hole in the housing. Mine torqued down before the head hit the housing.

Just want to make sure I’m not up against the shifter shaft inside or something! Worst case I can drain it again and check with my finger but hoping Ron might know?

edit: getting under the car and looking again, looks like I may have simply run out of threads on the plug, explaining the “bottoming”. There is a short unthreaded portion below the head. Also it’s not on the same axis as the shifter shaft. I’m much less worried now and feel good to start the car tomorrow but I’ll leave my post up for future searchers :)
 
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