Speedometer Cable Leak

[Grabinov911]

Hey All,

This may seem like an easy one, but I just replaced my speedometer cable and now it seems to have a leak at the transmission. A small drip of fluid forms on the low point of the cable about 6 inches from where it enters the trans. It is the screw on type for a 1970 727 trans (Roadrunner / 383).

Is there some type of gasket or seal in there at the trans connection that I failed to replace? It's on there pretty tight. I can't imagine trying to really torque it on there. I wouldn't bother all of you, but it's a significant leak - like a puddle in the plastic drip pan each morning...

Thoughts?

Greg

 

[IQ52]

You'll probably have to replace the o-rings in the speed-o gear housing that is held into the transmission with the, what is is it, 5/16" or 1/4" bolt.

 

[tpodwdog]

You'll probably have to replace the o-rings in the speed-o gear housing that is held into the transmission with the, what is is it, 5/16" or 1/4" bolt.

yeah,,,,what he just said!:headbang:

 

[Grabinov911]

Thanks IQ. Do I have to drain the trans to do that? I'm guessing anything that is meant to seal in trans fluid, and anything that is leaking trans fluid, is going to have trans fluid behind it!

 

[Mike Z]

You Don't have to drain the trans. don't jack the front way up though to make fluid go to the rear of the trans.
Mike Z.

 

[Grabinov911]

Solution for anyone who needs help

Just to close out this thread for anyone with the same annoying problem I had - fluid leak from speedometer cable/cable drive:

The beautious 727 breakdown on the top is from transpartsonline.com, who sells all of these parts separately. The photo on the bottom is an actual picture of parts 368 (large red O ring on which some prior mechanic apparently put black silicone) and 078, the gray speedometer drive lip seal. It is this lip seal which supports the speedometer drive shaft. Not shown here is the small steel split ring which presses into the speedometer drive housing to hold the lip seal in place.

If your speedometer cable is leaking, remove the 1/2inch bolt and retainer holding the speedometer cable drive in place, note the position of the drive (number printed at varying positions on housing - the one at the 6 o'clock position being the relevant one), remove the drive and replace these seals. Replace. 15 minute job requiring a half inch wrench and $3.00 worth of parts.

BTW: I jacked up the car to a level position. Luckily I was prepared with a catch-can because I lost about 2+ quarts of trans fluid out of the speedo drive hole when I pulled it out. Can't say I wasn't warned - see the prior post from Mike Z! Apparently the speedo drive is under the fluid level when the car is in a level position - makes sense, the drive housing has lube holes on the inside where the trans fluid lubes the turning shaft.

Jacking the back of the car WAY up MAY work to drive all the fluid forward. I was doing other work on the car so I didn't try that.

Greg