1978 Auto - Speedo Cable Drive Leak
Thread Starter
Burning Brakes
Joined: Jan 2001
Posts: 1,219
Likes: 448
From: Loir Valley Sarthe, France
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2024 C3 of the Year Finalist - Unmodified
2023 C3 of the Year Finalist - Unmodified
1978 Auto - Speedo Cable Drive Leak
Hi
A year or so ago I fitted a new speedo cable drive gear and sleeve assembly. Last month I had to fit a new speedo cable (as part of the reinstatement of the cruise control).
Alas, I now notice that there is a slight leak of trans fluid from the speed drive
Without going into detail, suffice to say that the entire exhaust on the driver’s side needs to come off to replace the sleeve, so at the moment I have only "investigated” the issue. It almost seems as if it could do with being a tighter fit in the casing? I managed to find a few new O-rings off assorted sizes, one being a bit thicker than the original that I retained when I swapped out the sleeve, but I suspect it may actually be too thick to fit.
So, does anyone have any suggestions for getting a nice oil-tight seal again please?
(Incidentally, I looked on the wittrans (?) site but they no longer seem to list O-rings) Bear in mind I’m in France, so popping down to the local “Autozone” isn’t an option I’m afraid!
A year or so ago I fitted a new speedo cable drive gear and sleeve assembly. Last month I had to fit a new speedo cable (as part of the reinstatement of the cruise control).
Alas, I now notice that there is a slight leak of trans fluid from the speed drive
Without going into detail, suffice to say that the entire exhaust on the driver’s side needs to come off to replace the sleeve, so at the moment I have only "investigated” the issue. It almost seems as if it could do with being a tighter fit in the casing? I managed to find a few new O-rings off assorted sizes, one being a bit thicker than the original that I retained when I swapped out the sleeve, but I suspect it may actually be too thick to fit.
So, does anyone have any suggestions for getting a nice oil-tight seal again please?
(Incidentally, I looked on the wittrans (?) site but they no longer seem to list O-rings) Bear in mind I’m in France, so popping down to the local “Autozone” isn’t an option I’m afraid!
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,754
From: Charlotte NC
If the fitting is not an original...and not writing that it is NOT CORRECT...but if for some odd reason you got one that's diameter is smaller ...then it may be "FUN" trying to find an "O" ring that will fit the groove in the fitting and also seal the housing as intended.
AND you are aware that there is a seal in the fitting where the cable gets inserted...tight???
DUB
AND you are aware that there is a seal in the fitting where the cable gets inserted...tight???
DUB
Melting Slicks
Joined: Mar 2007
Posts: 2,520
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From: Hinckley OH
Melting Slicks
Joined: Nov 2013
Posts: 3,451
Likes: 336
From: Greater Cincinnati Area.
https://www.wittrans.com/Schematic.a...0C&Schematic=4
There's an O Ring outside, and a seal inside the housing (There are several styles, metal and plastic.) Watch the gear too. The seal will cut a groove into it. Some of the aftermarket parts are off size, and will leak.
Melting Slicks
Joined: Nov 2013
Posts: 3,451
Likes: 336
From: Greater Cincinnati Area.
PS, if your housing is aftermarket and sized improperly? You can get the entire assembly used on that page I linked.. (The sleeve itself doesn't wear out.. It's the seal inside that goes bad)
Don't quote me, but it seems to me that the sleeve with the non-metal seal inside? That there's room for two.. and I fixed one leaker by backing up the first seal with a second one, to get around a wear groove in the speedo gear.
Don't quote me, but it seems to me that the sleeve with the non-metal seal inside? That there's room for two.. and I fixed one leaker by backing up the first seal with a second one, to get around a wear groove in the speedo gear.
Last edited by confab; Mar 16, 2014 at 11:20 AM.
Thread Starter
Burning Brakes
Joined: Jan 2001
Posts: 1,219
Likes: 448
From: Loir Valley Sarthe, France
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2024 C3 of the Year Finalist - Unmodified
2023 C3 of the Year Finalist - Unmodified
Hi DUB and Confab
Thanks. Yes, a TH350. Well, it is a replacement sleeve assembly, and it looks like those sold by the likes of Corvette Central etc, although it came from my usual UK supplier. It is not the EXACT same style as the one that came off, but close! :-) On the old one it was the inner seal that was leaking. From what I can see now, the inner seal is fine (I put a new gear in as well as the sleeve) but the outer O-ring seems to be the culprit. It just seemed that the sleeve assembly could be a tighter fit in the casing.
I've decided to keep an eye on it for the time being, but I guess if the leak gets too bad I'll have to take out the sleeve assembly again and then begin a search for a better fit item or O-ring in ernest.
Thanks!
Thanks. Yes, a TH350. Well, it is a replacement sleeve assembly, and it looks like those sold by the likes of Corvette Central etc, although it came from my usual UK supplier. It is not the EXACT same style as the one that came off, but close! :-) On the old one it was the inner seal that was leaking. From what I can see now, the inner seal is fine (I put a new gear in as well as the sleeve) but the outer O-ring seems to be the culprit. It just seemed that the sleeve assembly could be a tighter fit in the casing.
I've decided to keep an eye on it for the time being, but I guess if the leak gets too bad I'll have to take out the sleeve assembly again and then begin a search for a better fit item or O-ring in ernest.
Thanks!
