Speedometer issues

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4spdragtop

4spdragtop

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Ok, speedo wasnt working, removed the cable at the tranny end and it was shot/frayed. Prior to finding the cable frayed, the speedo was stuck and dad got it freed up. So we ordered a new cable.....which almost every website has ATP listed and is incorrect. So we made the call to ATP and informed them. Anyway we got the correct cable and installed and now the speedo winds right around, even before dad gets outta the driveway... I checked the speedo pinion gear,(green) and we had the adapter in the right spot. I unhooked the speedo cable at tranny and spun it by hand and it moves the needle, but it doesnt return to "0" unless I spin the cable backwards.....any ideas??? We dont want to pull the dash again until wintertime but it would be nice ot have a working speedo

Thanks all!!
4spdragtop
 

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Check for cable bind, sharp bends, not straight into the back of the speedo. I had the same problem when I put a new cable in and it was right behind the cluster, it had a slight enough bend to hinder it returning to 0.
 
The problem probably is in the instrument. The 67 cable has a collector type nut at the speedo end. Loosen that nut a little might help if the cable is pushing on the instrument. Cable has a stop made on it but we cant know if the aftermarket gets that end length just right or not.
 
Badsport said:
Check for cable bind, sharp bends, not straight into the back of the speedo. I had the same problem when I put a new cable in and it was right behind the cluster, it had a slight enough bend to hinder it returning to 0.
Click to expand...

Hey Bruce, that makes sense, for not returning to "0", but why would it "peg" when he is doing like 5 mph???
 
RedFish said:
The problem probably is in the instrument. The 67 cable has a collector type nut at the speedo end. Loosen that nut a little might help if the cable is pushing on the instrument. Cable has a stop made on it but we cant know if the aftermarket gets that end length just right or not.
Click to expand...

Hey Ben, when I spun the cable by hand...not even as quick as snapping your fingers, the speedo was registering aobut 140 mph......
 
Did you try white lithian grease on the new cable before you installed it? check for bends and use moderate amout of lube,
 
The speedometer works by rotating (spinning) magnets outside a can like item that has the needle attached. You can see that here. Those spinning magnets do not touch the "can" that the needle is attached to.
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The magnetic field is what pulls the needle to its position. If the magnet is touching that can in any way, they are too close or too far away, or if the return spring is broken, it will force the needle out of position (such all the way to the right). If you said it returns when you stop, chances are the spring isn't broken, but there is some issues with how the magnets are positioned. You can't see them unless you pull the cluster and take the speedo out.
 
Ooh, I like Robs explanation, and I also have this same problem in the 67. I am reading with interest and hope you get yours sorted out Steve. I'm going back in soon anyway, so i'll take stock of the info here and watch you do your Dad's too!! Geof
 
Inside the ALT' gauge there's a magnet also. Specs of iron, tiny flakes of chrome, hair, etc. collects on both.
A lot of my customer just want to get there gauges in their driver working again, so they send the fuel gauge alone.
Others who are restoring a car send the entire instrument cluster for services.
The main difference is how many times you'll R&R the instrument panel.
Good luck with it.
 
Thanks everyone, I knew there was a magnet but unsure of zackly how it worked, thanks for the explanation RR, and for the "alt" as well Ben.

Cosgig, if you order a new cable be careful we checked several websites and also spoke on the phone to rockauto....95% of the listings are wrong! We spent $11 on the cable and $26 in shipping to get the wrong cable, they wont refund shipping...so it looks like we have one that is nfg to us. I will try to get the right # for you. The speedo doesnt return to zero on its own so I think the return spring might be pooched, but I think we will wait until winter, to R&R the dash bezel and get everything done and inspected. Wonder what the chances of finding a 67 150 speedo with trip if need be?? LOL

Again, thanks everyone for their input
 
I'll never understand the popularity of the 150 mph speedo. Nobody goes that fast anyway.
Since tire diameter and other factors make the speedometer a little wrong, a drive gear change can make it closer, just put the 150 mph decal on the 120 screen.
 
I think this weekend we will take dads speedo out and put my 69 speedo and cable in. That gives dad time to try and fix his without being in a rush....
 
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