Speedo problems

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May 20, 2010 | 06:28 PM

redvette80

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From: Emerald Coast Florida

Speedo problems

Hi guys,

I recently purchased my 1st corvette and I'm new to the forum. Its a 1980 with the L48 and I'm having an issue with the speedometer. It bounces around while accelerating (about a 20mph range) and calms down at cruise speeds but reads about 15mph fast. I'm wondering if it's possible that this could be doing any damage or if its just an inconveniece. Any inputs are greatly appreciated. Thanks!

May 20, 2010 | 06:34 PM

sniperdiver37

Burning Brakes

Joined: Dec 2004

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From: Hanging out back with the dark horses. Wa.

Quote:

Originally Posted by redvette80

it could be due to a gear change or even larger/ smaller tires. The bouncing maybe to a bad/ worn speedo cable, cruise control unit, bad tooth in the gear on the trans.
Pull the cable off the trans and hook a low speed drill to it. see if it still bounces and those speeds. start there....

May 21, 2010 | 08:21 AM

RonR80

Melting Slicks

Joined: Apr 2008

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From: Russell Ontario

St. Jude Donor '09

Right on , I had the same thing and it was the cruise servo , took it apart cleaned it , checked the routing of the cables , and it's nice and smooth now! Ron

May 21, 2010 | 03:15 PM

redvette80

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From: Emerald Coast Florida

Thanks guys. I will check that. I had figured the cable was just loose, but my cruise is inop and I didnt realize that could affect the speedo. (I'm learning as I go) Car is at a very reputable shop right now for an unrelated issue, but now I have somwhere to start when I get it back. Thanks again.

May 25, 2010 | 08:19 AM

RonR80

Melting Slicks

Joined: Apr 2008

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From: Russell Ontario

St. Jude Donor '09

let us know how you made out , and keep asking questions , you will get the help you need eventually! Ron

May 25, 2010 | 09:11 PM

Goody

Le Mans Master

Joined: Oct 2000

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From: Oak Harbor WA

I had the same issue on a '77 Camaro once and it was the speedo cable was broken internally. New cable and issue solved.

May 26, 2010 | 07:56 PM

redvette80

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From: Emerald Coast Florida

Quote:

Originally Posted by Goody

I had the same issue on a '77 Camaro once and it was the speedo cable was broken internally. New cable and issue solved.

Thanks for that response, I think that's my issue. I will take sniperdiver's advice and check cable w/ a low speed drill... I suspect it will wobble. Reading over my original post, it seems I was unclear. When I said "cruise speeds" I didn't mean using cruise control, I meant no longer acclerating.

Ok here's the dumb question. If i do not fix the cruise control, will I have to bypass it to make the speedometer work? I think I'll be needing some books :o . Any suggestions on which ones to buy/ where to look for them would be appreciated.

May 29, 2010 | 06:46 PM

redvette80

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From: Emerald Coast Florida

Well, good news! Just got my car back and on the way home, I bottomed out the speedometer and continued acceleration. I believe it has fixed itself.

No more bouncing after that so maybe that tightened the cable. Still reading about 10-15 mph fast though. Tires are 255/60/15. Im not sure what the gears are, but most of the car is original (except ugly cd player) so my question is: is calibrating the speedometer something I can do myself or should I get a professional? Thanks!