Speedometer not always registering 1975
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Le Mans Master
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Speedometer not always registering 1975
The speedo doesn't register until the car exceeds 40 or so, and sometimes not even then. If it does, then as the speed drops to below 30, the needle dives to zero. I changed transmissions from auto to manual, and the dash did come out for the 4-speed conversion. Cable connections to the speedometer and to the trans are good. Any ideas on what to look at? Thank you.
Le Mans Master
Joined: Oct 2006
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From: Palmdale CA
The speedo doesn't register until the car exceeds 40 or so, and sometimes not even then. If it does, then as the speed drops to below 30, the needle dives to zero. I changed transmissions from auto to manual, and the dash did come out for the 4-speed conversion. Cable connections to the speedometer and to the trans are good. Any ideas on what to look at? Thank you.
Just replaced mine.
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Le Mans Master
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I'd say it's likely to be a worn out internal speedo gear. I've got the same thing going, replaced the cable, replaced the external speedo gear and when I put my snake camera inside the hole on the trans, you could see where the center section of the speedo gear on the tail shaft, was worn down, like a flattened curve.
Just replaced mine.
Just replaced mine.
Le Mans Master
Joined: Oct 2006
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From: Palmdale CA
Thanks, F22. I figured the prob lies with the tranny since the tranny was bought as part of a "conversion pkg" and I've had more problems with that purchase than I want to admit. But that's beside the point. What's involved in replacing that internal gear in the trans? Thanks.
I haven't had a speedo since I got the car, three years ago! So if you have to wait until the next clutch change, I can't blame you.
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Le Mans Master
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We replaced it, when we had the Borg Warner T10 out. The tail shaft had to come off. Not sure if it can be done in the car, because we're doing a clutch and pressure plate change. It wasn't easy, lining up the reverse shifter fork, while assembling it. I'm thinking, likely with it out.
I haven't had a speedo since I got the car, three years ago! So if you have to wait until the next clutch change, I can't blame you.
I haven't had a speedo since I got the car, three years ago! So if you have to wait until the next clutch change, I can't blame you.
Le Mans Master
Joined: Oct 2006
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From: Palmdale CA
You can test the speedo by getting underneath and putting the end of the cable into a drill and slowly turning it (I believe it's Counter Clock Wise) to see what the speedo does. Once you determine what direction it's supposed to go, it doesn't take much to drive it to 50-60 or even 70 mph. You can then hold it at 50 and see if it stays there or not. Somebody should sit inside and tell you what's going on. That way, you know your speedo is good.
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Le Mans Master
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You can test the speedo by getting underneath and putting the end of the cable into a drill and slowly turning it (I believe it's Counter Clock Wise) to see what the speedo does. Once you determine what direction it's supposed to go, it doesn't take much to drive it to 50-60 or even 70 mph. You can then hold it at 50 and see if it stays there or not. Somebody should sit inside and tell you what's going on. That way, you know your speedo is good.
When the speed (eventually) gets up to 50 or so, the speedo reads it, but not when going slower. Then it drops to zero when speed goes down from 50 or so, but on the rare occasion it MIGHT stay at 25 - 30.
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Joined: Oct 2015
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From: Sandy Lake, PA
Sometimes the cable slips inside the key end that goes into the speedo head making the reading erratic. At least that's the problem with mine. I dread removing the left side dash to make the needed repair.
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Thread Starter
Le Mans Master
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Le Mans Master
Joined: Oct 2006
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From: Palmdale CA
The drill test, will eliminate all doubt about the speedo and the cable end. You can easily vary the RPM and get 10, 20, 30 mph and so on, holding it at each position and seeing if it's steady.
Last edited by F22; Nov 10, 2015 at 10:28 AM.
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Le Mans Master
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