Powerglide Speedometer Cable

[Thomas R.]

The 64's powerglide transmission's, speedometer cable jacket has a hairline crack and transmission fluid is dripping from it.

My question is; should their be transmission fluid inside the cable jacket (for lubrication) or not and if no; is the transmissions speedo gear round fitting and seal leaking and should be replaced? Thanks.

[Richard G.]

Re: Powerglide Speedometer Cable

The cable isn't designed to be a seal and shouldn't have any oil in it. If it's leaking it's at the gear.
Early gears were metal, I am unsure which you have but it's likely plastic.
The seals wear a groove into the plastic gear's output shaft over time.
It is difficult to see the groove because the gear shaft has spiral wound grooves that move the oil back towards the internals.
Typically the spiral ends at the seal and the groove looks like it belongs there.
Even a new seals typically will not stop the leak on plastic gears.
I recommend replacing both the seal and the gear.
Remove the speedometer cable and pry the seal out ,with a screwdriver, while the bullet is still in the transmission.
Then remove it and replace the gear and the small "O" ring and reinstall.
You can purchase a seal kit that includes the correct gear from several vendors on Ebay.
Gears can be identified by color and typically have the gear tooth count embossed into them.
Young eyes are helpful.
Rick

[Joe L.]

Re: Powerglide Speedometer Cable

The 64's powerglide transmission's, speedometer cable jacket has a hairline crack and transmission fluid is dripping from it.

My question is; should their be transmission fluid inside the cable jacket (for lubrication) or not and if no; is the transmissions speedo gear round fitting and seal leaking and should be replaced? Thanks.

Thomas----

Do as Rick describes. The GM parts, including the fitting ("bullet), internal lip seal, and external o-ring are GM discontinued. However, they can be easily and inexpensively obtained from eBay vendors. You can use your existing fitting and just replace the lip seal and o-ring or you can purchase a complete new fitting with installed seal and o-ring.

ALWAYS replace the speedometer driven gear. Assuming your gear is original, it should be a 20 tooth blue gear. This remains available from GM under GM #3987920.

[Thomas R.]

Re: Powerglide Speedometer Cable

Appreciate the info.

[Thomas R.]

Re: Powerglide Speedometer Cable

Thanks will do.