C2 speedo gear-need help

[John S.]

I need help in finding a steel speedo gear that mates with the incoming worm on the speedo. See pic below. Thanks for the help!

John Seeley
67 Black/Teal 300 hp 3 speed coupe

[Sam K.]

Re: C2 speedo gear-need help

Go to an "older" tranny shop.... those old guy hang on to a lot of old parts, You may be surprized. Sam

[Joe L.]

Re: C2 speedo gear-need help

I need help in finding a steel speedo gear that mates with the incoming worm on the speedo. See pic below. Thanks for the help!

John Seeley
67 Black/Teal 300 hp 3 speed coupe

John------


The mystery to me is why you would even need such a speedometer driven gear. Your 3 speed application should have been originally fitted with speedometer DRIVE ("worm") gear GM #3708144. This is a steel gear that is a press fit on the transmission mainshaft.

The speedometer DRIVEN gear should be a 19 tooth NYLON gear, currently of GM #3987919, if you have a 3.08:1 rear gear ratio. It should be a 20 tooth NYLON gear, currently of GM #3987920, if you have a 3.36:1 rear gear ratio. If the car is original, it should have one of these rear gear ratios.

[John S.]

Re: C2 speedo gear-need help

Maybe I was not clear enough. This was taken out of the speedometer, not the transmission! It drives the odometer and eventually the trip odometer. Stoped working a couple of months back. On tear down, I found this gear to be "stripped" and the worm not engaging. By worm I mean the worm in the speedo that the speedo cable drives (right behind the magnet assy) . In all actuality I can make this at work (I run an aerospace machine shop in So. Cal. and we have gear equipment) problem is I will have to farm out the small worm as I do not have that capability. I thought it would be less expensive (and easier) to buy a steel reproduction one instead of making a "one off".

John Seeley
67 Black/Teal 300 hp 3 speed coupe

[Michael H.]

Re: C2 speedo gear-need help

I need help in finding a steel speedo gear that mates with the incoming worm on the speedo.

John,

Contact Joe Ray, a frequent poster on this board. I think he does speedo/tach repairs and stocks the gear that you need.

[John S.]

Re: C2 speedo gear-need help

Michael,
Thank you. I have emailed Joe and am looking forward to hearing from him. Gotta love the NCRS!

[Wayne M.]

Re: C2 speedo gear-need help

John------The mystery to me is why you would even need such a speedometer driven gear. ..

Joe -- John is talking about the instrument cluster speedo head. The part shown in his pic and my posting (in the link below) is the one that usually wears out.
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John -- it is known as the 2nd worm gear, or "intermediate" gear. For the Corvette (and maybe other GM C-2 era) speedos, it MAY have been located under the Delco # 868143.

I had the same problem about 4 months ago, and Ken Anderson came to the rescue. Might want to PM him.

https://www.forums.ncrs.org/showthread.php?t=72632&uid=7025

[Joe L.]

Re: C2 speedo gear-need help

Maybe I was not clear enough. This was taken out of the speedometer, not the transmission! It drives the odometer and eventually the trip odometer. Stoped working a couple of months back. On tear down, I found this gear to be "stripped" and the worm not engaging. By worm I mean the worm in the speedo that the speedo cable drives (right behind the magnet assy) . In all actuality I can make this at work (I run an aerospace machine shop in So. Cal. and we have gear equipment) problem is I will have to farm out the small worm as I do not have that capability. I thought it would be less expensive (and easier) to buy a steel reproduction one instead of making a "one off".

John Seeley
67 Black/Teal 300 hp 3 speed coupe

John------


Even if you were not completely clear, I should have figured it out by just looking at the photo you posted. It's obviously not a transmission speedo gear. I don't know what I was thinking about.

I think your best bet is to do as the others have mentioned and contact one of the speedometer instrument parts sources. WAY less trouble than trying to make these up yourself regardless of your capabilities.