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Apr 26th, 2026 | | AD Chevy Trucks  Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
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| | | | Joined: Mar 2015 Posts: 35 Wrench Fetcher | | Wrench Fetcher Joined: Mar 2015 Posts: 35 | Hi Folks-
Speedo is non-functioning. Checked, pulled, greased cable. Check. Tested speedo head w/ drill and short inner cable. So-so. Pulled speedo head, lightly lubed, bench tested w/ drill and short cable. Ran to 30 and stopped. Wouldn't come down. Needle warped against glass. Pulled needle. Disintegrated. Bugger. Replaced needle w/ handy white sweep second hand from shop clock and some clear epoxy. Check. Now we're getting somewhere. Works a treat on the bench. Hooked back up, went for a shakedown drive. No joy! Pulled cable end from head. Short drive. No spin. Bugger. Pulled driven unit from trans. Aha! Nylon gear is 1/2 great-1/2 chewed off. Bugger.
Here's my idea---
18 tooth drive from 50's powerglide. (Brown) Same shaft size as metal shaft in drive unit and only about 3/16ths shorter. Knock out metal shaft in the bullet and replace with the nylon unit. Am I crazy? Will it never work? Is this a stroke of absolute jury rigging genius? Has anyone done this before? Surely I'm not the first....
Thanks in advance for 1- reading all this drivel and 2- Any opinions/experience you might share.
Mike Burgess
Albert, KS
Three Little Words that gets a man in trouble fastest..."Ran when parked"
| | | | | Joined: Oct 2006 Posts: 289 Shop Shark | | Shop Shark Joined: Oct 2006 Posts: 289 | I'm sure I saw replacements on line somewhere. Probably worth a 1.50, but 10 from a vendor with shipping, however sure seems easier. My dad once designed and built a machine to wash those for GM, it was big and I wish I knew more, but he passed before he could explain it to me. | | | | | Joined: Mar 2015 Posts: 35 Wrench Fetcher | | Wrench Fetcher Joined: Mar 2015 Posts: 35 | Hi Eric-
I looked and looked for just the nylon gear that presses on the metal shaft in the speedo drive and had no luck. Did find some NOS drives at 50 or so per copy. That really gets my inner parts bin engineer going! Have a drive coming at 12 bucks shipped, I'll report on victory/defeat.
Thanks!
Mike Burgess
Albert, KS
Three Little Words that gets a man in trouble fastest..."Ran when parked"
| | | | | Joined: Mar 2015 Posts: 35 Wrench Fetcher | | Wrench Fetcher Joined: Mar 2015 Posts: 35 | Hi dg-
Don't want to be contrary, but when I pulled the speedo drive bullet from the trans (3-speed) it had a steel shaft through the bullet housing with a white nylon gear pressed on the end that contacts the drive gear on the tranny shaft. This is the one that's chewed up. Don't know if that's the factory one but it's awfully similar to pictures I've seen of nos units for sale. Sure would be good if the 18 tooth gear was available itself to press on to the shaft but it seems they only come as an assembly.
Three Little Words that gets a man in trouble fastest..."Ran when parked"
| | | | | Joined: Mar 2015 Posts: 35 Wrench Fetcher | | Wrench Fetcher Joined: Mar 2015 Posts: 35 | The speedo lives. Drove a few miles yesterday after installing the (brown) '57 drive. Had to take off some diameter and clean the teeth up but so far, so good!
Thanks-
Mike
Three Little Words that gets a man in trouble fastest..."Ran when parked"
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