67 Chevelle Speedo works intermittently - Chevelle Tech
Troubleshooting Diagnosing problems done here.

 
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post #1 of 11 (permalink) Old Jun 24th, 18, 6:51 PM Thread Starter
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Charlie
 
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67 Chevelle Speedo works intermittently

I've got a 67 Chevelle with a Muncie 4 speed. Replaced the Speedo gear a few years ago because the old one broke and wasn't correct for the rear end gear ratio anyway.

Recently, while driving, the speedo starts out reading accurately but then starts swinging hi and low and then just bottoms out while I'm driving. Interestingly, when I get back to my neighborhood, it starts working again once I'm driving around 25MPH. That's why I say it's intermittent. Sometimes it works fine, other times it craps out on me.

I've checked the nylon gear going into the Muncie and it's fine - no shredded threads and the shaft looks fine there. I've unscrewed the other end from the speedo itself and that looks good too.
Has anyone ever dealt with something like this?
Am I dealing with a ganked speedo cable? Do I need to replace that or is it something in the speedo itself?

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post #2 of 11 (permalink) Old Jul 10th, 18, 10:33 PM Thread Starter
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Charlie
 
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Re: 67 Chevelle Speedo works intermittently

Update - removed the speedo cable and lubed it. Also checked to ensure that the ends were in good shape (they were) and that the nylon gear that goes into the transmission was still ok (it was). Still no improvement.
However, in test driving it after lubing the cable, I noticed a click behind the dash when the speedo starts or stops working. I'm guessing the problem is the speedo itself...

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post #3 of 11 (permalink) Old Jul 11th, 18, 5:59 AM
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Eric
 
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Re: 67 Chevelle Speedo works intermittently

I'm following this because my 66 speedo reads one thing then suddenly picks up 10 more mph for a bit and also swings up and down more than it should.
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post #4 of 11 (permalink) Old Jul 11th, 18, 6:48 AM
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Gene
 
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Re: 67 Chevelle Speedo works intermittently

I mean that cable spins, or it dont, Period. It has to be the speedo itself.

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post #5 of 11 (permalink) Old Jul 11th, 18, 7:14 AM
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Re: 67 Chevelle Speedo works intermittently

Weird things can happen to speedo readings when a cable has kinks in it.

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post #6 of 11 (permalink) Old Jul 11th, 18, 7:20 AM
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Re: 67 Chevelle Speedo works intermittently

True that. I guess I am misunderstanding the symptoms, and "bottoming out".

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post #7 of 11 (permalink) Old Jul 11th, 18, 8:49 AM
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Ed
 
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Re: 67 Chevelle Speedo works intermittently

If you have it apart, check for play in the spinning cup/magnet area.

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post #8 of 11 (permalink) Old Jul 11th, 18, 9:58 AM
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Re: 67 Chevelle Speedo works intermittently

check also the gears inside the speedometer head itself. they are easy to get to but you have to remove the unit from the dash assembly. you will see how it was so easy for used car dealers back in the day to roll back the mileage!
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post #9 of 11 (permalink) Old Jul 12th, 18, 4:41 PM
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Re: 67 Chevelle Speedo works intermittently

Chuck up a drill motor on the trans end of the cable to troubleshoot in the driveway. Sounds like a speedo problem to me too.
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post #10 of 11 (permalink) Old Jul 12th, 18, 7:23 PM
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Re: 67 Chevelle Speedo works intermittently

Option is to get an all New Speedo for around $170.00

https://www.ebay.com/itm/1966-67-Che...4383.l4275.c10

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post #11 of 11 (permalink) Old Jul 12th, 18, 8:43 PM Thread Starter
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Charlie
 
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Re: 67 Chevelle Speedo works intermittently

Thanks guys. Iím going to chuck up a drill motor on the trans end of the cable as you recommended. The cable was not kinked in any way so I donít think that will work but it can't hurt to try. Then Iíll pull the speedo. Is there a sticky or good post out there for yanking the dash? Never done that before but I guess thereís a first for everything

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