TH350 fluid leak from speedometer cable
Thread Starter
Le Mans Master
Joined: May 2002
Posts: 5,084
Likes: 786
From: Lebanon Township New Jersey
TH350 fluid leak from speedometer cable
I hadn't really looked at my 77 for a few months. I jacked it up to start a little routine maintenance and I noticed a small puddle of trans fluid. It was dripping off the trans mount. Looking up I can see fluid on the cable fitting where it threads onto the gear holder at the back of the trans. I have to remove the trans mount to get at that. I'm just wondering, is there a seal or something there that might need to be replaced?
Last edited by BKbroiler; Feb 21, 2018 at 12:52 PM.
Race Director
Joined: May 2006
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Safety Car
Joined: Apr 2006
Posts: 4,057
Likes: 421
From: BC
I just did the same with my wife's 78. You don't have to remove the cross member. Just unscrew the speedo cable then remove the 7/16" bolt holding the gear cover on and remove that. Her problem was a combination of 2 things. There is an seal inside the metal holder that was cracked and the speedo gear itself had a worn shaft. I replaced both.
Last edited by CanadaGrant; Feb 21, 2018 at 01:05 PM.
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,170
From: Hermosa
I hadn't really looked at my 77 for a few months. I jacked it up to start a little routine maintenance and I noticed a small puddle of trans fluid. It was dripping off the trans mount. Looking up I can see fluid on the cable fitting where it threads onto the gear holder at the back of the trans. I have to remove the trans mount to get at that. I'm just wondering, is there a seal or something there that might need to be replaced?
I ended up putting in a larger cross section O-ring making the "bullet" tighter in the hole where it goes into the transmission to get that to stop seeping.
A new seal also did not last very long, about a year. Seems it does not grip the speedo gear shaft very tightly even when new with a new speedo gear drive.
So on that I shoved an appropriate sized o-ring inside the cavity on the reverse side of the seal making it grip the speedo gear drive shaft tighter. That has been in there for about 5 years now.
Thread Starter
Le Mans Master
Joined: May 2002
Posts: 5,084
Likes: 786
From: Lebanon Township New Jersey
Thanks for the quick help guys.
MelWff - I checked that website and ordered a new bullet, seals, holder tab and bolt. $23, free shipping, not bad. Thanks again.
MelWff - I checked that website and ordered a new bullet, seals, holder tab and bolt. $23, free shipping, not bad. Thanks again.
Le Mans Master
Joined: Dec 2006
Posts: 8,837
Likes: 1,027
Clean the hole well, and smear some "Right stuff" silicone around it before you jamb it in. Stopped my leak .
Thread Starter
Le Mans Master
Joined: May 2002
Posts: 5,084
Likes: 786
From: Lebanon Township New Jersey
Thanks. Yeah I want to stop the leak on the first attempt. I had to remove the bracket under the trans mount since I have dual exhaust and a drive shaft loop. Couldn't reach the cable holder any other way.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,809
From: Cool Northern Michigan
I would use great caution putting any RTV in a place that could plug up the tranny filter or any of the billzillion orfices in the trans valvebody. Everything will come to a screeching halt.
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