1967 speedo cable & driven gear

[Donald O.]

The speedo is good, the gear is good, the cable is good, but since I have the cable and the o-ring retainer removed from the transmission and the driven gear is attached to the cable.
Should it come apart?
Should the o-ring retainer leak trans fluid? Not just a drop or two but more like a teaspoon.
Does the retainer have only an external o-ring, is there an internal o-ring to prevent oil migration up the speedo cable?

Where can I acquire both o-rings?
Would it be ok to spray brake cleaner down the cable (from the speedo end) down to the driven gear end? What then do I use as a cable lube, "Cable Ease" or such?

Don

[Joe L.]

Re: 1967 speedo cable & driven gear

The speedo is good, the gear is good, the cable is good, but since I have the cable and the o-ring retainer removed from the transmission and the driven gear is attached to the cable.
Should it come apart?
Should the o-ring retainer leak trans fluid? Not just a drop or two but more like a teaspoon.
Does the retainer have only an external o-ring, is there an internal o-ring to prevent oil migration up the speedo cable?

Where can I acquire both o-rings?
Would it be ok to spray brake cleaner down the cable (from the speedo end) down to the driven gear end? What then do I use as a cable lube, "Cable Ease" or such?

Don

Don-----

The FITTING is the bullet-shaped part which inserts into the transmission extension housing and is retained by the small RETAINER and 1/4-20 hex head screw. The speedometer cable has a knurled fitting which threads onto the above-referenced fitting. So, yes, these come apart by simply unscrewing the cable fitting from the bullet fitting. The speedometer driven gear can simply be pulled out of the bullet-shaped fitting.

These things are pretty notorious for leaking. The best you can do is to replace the o-ring seal that surrounds the bullet-shaped fitting and the internal seal. The internal seal is a very small lip seal with a metal frame. It can be pried out of the bullet-shaped fitting and a new one pressed in.

The o-ring is GM #10054241 and remains available.

The lip seal was GM #3869910 but it's discontinued. It may be available in the aftermarket.

You can also purchase a new fitting assembly from GM under GM #345215. This includes the fitting, external o-ring and internal lip seal.

I would be reluctant to spray brake cleaner or any other solvent down the speedometer cable. The big problem would be if any of the cleaner or cable lube you follow it with works its way back up into the speedometer. The best plan is to remove the cable from the instrument end, clean it, lube it, and re-insert it.

[Donald O.]

Re: 1967 speedo cable & driven gear

Joe,
I think the best option is to replace the fitting assembly. I'll go to my local dealer tomorrow and see what they have. I looked in the LI Corvette supply catalog and found the fitting, but no seals.

Thanks
Don

[Joe L.]

Re: 1967 speedo cable & driven gear

Joe,
I think the best option is to replace the fitting assembly. I'll go to my local dealer tomorrow and see what they have. I looked in the LI Corvette supply catalog and found the fitting, but no seals.

Thanks
Don

Don------


The fitting carries a current GM list price of $24.46.

[Joe L.]

Re: 1967 speedo cable & driven gear

Joe,
I think the best option is to replace the fitting assembly. I'll go to my local dealer tomorrow and see what they have. I looked in the LI Corvette supply catalog and found the fitting, but no seals.

Thanks
Don

Don------


If you order the GM #345215 fitting you will also have to order the GM #10054241 o-ring seal. Apparently, the fitting is no longer supplied with this. But, it does include the internal seal.

[Donald O.]

Re: 1967 speedo cable & driven gear

My local Chevy dealer said the fitting number is good, but he doesn't stock it. He did give me a list of dealers that list the part in stock, the closest being only 60 miles away.
He also said the o-ring part number is now dead. Once I get the fitting, i'm hoping china (harbor) freight has the one in the box of different sizes.

Thanks again Joe

Don

[Joe L.]

Re: 1967 speedo cable & driven gear

My local Chevy dealer said the fitting number is good, but he doesn't stock it. He did give me a list of dealers that list the part in stock, the closest being only 60 miles away.
He also said the o-ring part number is now dead. Once I get the fitting, i'm hoping china (harbor) freight has the one in the box of different sizes.

Thanks again Joe

Don

Don------

I don't think I'd use a standard o-ring. This seal might not be a standard size.

Try this:

https://www.ebay.com/itm/10054241-SEAL-General-Motors/263189244107?hash=item3d474d28cb:g:d4gAAOSwOW9Z4pch&vxp=mtr

[Phillip M.]

Re: 1967 speedo cable & driven gear

Don,
I had developed this same problem on my '67 and decided to investigate last year. What I found was that the internal lip seal that contacts the speedo. driven gear had worn a groove into the mating surface of the plastic gear shaft. Replacing with a new driven gear solved the problem. So, before you buy any seals check this area on the gear.
Phil

[Joe L.]

Re: 1967 speedo cable & driven gear

Don,
I had developed this same problem on my '67 and decided to investigate last year. What I found was that the internal lip seal that contacts the speedo. driven gear had worn a groove into the mating surface of the plastic gear shaft. Replacing with a new driven gear solved the problem. So, before you buy any seals check this area on the gear.
Phil

Phil-------


Yes, I should have mentioned that. This is a VERY common problem.

[Donald O.]

Re: 1967 speedo cable & driven gear

Don,
I had developed this same problem on my '67 and decided to investigate last year. What I found was that the internal lip seal that contacts the speedo. driven gear had worn a groove into the mating surface of the plastic gear shaft. Replacing with a new driven gear solved the problem. So, before you buy any seals check this area on the gear.
Phil

Great call on checking the driven gear for a wear groove. Its got one. Time to order a new one. I hope the new one lasts half as long as this one did.

Don

[Joe L.]

Re: 1967 speedo cable & driven gear

Great call on checking the driven gear for a wear groove. Its got one. Time to order a new one. I hope the new one lasts half as long as this one did.

Don

Don------


What color is your gear?

[Donald O.]

Re: 1967 speedo cable & driven gear

Don------


What color is your gear?

It's blue. Its a M20 WR going to a 3.361 posi
transmission brass tag reads 3870354

Joe, do you have the GM p/n for the driven gear?

[Joe L.]

Re: 1967 speedo cable & driven gear

It's blue. Its a M20 WR going to a 3.361 posi
transmission brass tag reads 3870354

Joe, do you have the GM p/n for the driven gear?

Don------


That's exactly the gear you should have with your combination. It's GM #3987920 and it's still available from GM.