72 Rally dash Speedometer problem

[Pac J]

Hello,

I'm always on the way to restore my 72 Satellite Sebring Plus. The most technical work is done. The last months we have done a lot engine + transmission sealing, a new manual to power brake swap. New front brake rotors and pad, completely new KONI shocks, lot of bushings and hundreds of other small repairs electric ... I can't list them all ...
See my first step here http://www.roadrunnernest.com/forum/vie ... f=2&t=6106

Now the car is going to the body work for the rust and then for a new paint job ...

But I have always one small problem I didn't find the solution. My speedometer from my rally dash didn't work correctly and I can't find out why. When I'm driving there is from time to time a noise behind the board. And more the noise become loud more the speed needle begins to jump. It doesn't show a correct constant speed. First I was thinking it was easy to repair if I would change the speedometer cable and that the clip behind the speedometer was broken, but this isn't the case ... All seems perfect with the clip and when I made a test drive the cable turns well in each condition when I put my finger on the cable to feel how it turns slower and faster ...
So I things there could only be a problem to the speedometer himself, but all seems to be "okay" I can't see any damage ... I took a drilling machine and connect it on the cable and let it turn to test but even when you let turn the machine at a constant speed the needle jump a bit up and down ...
So I think there will be a problem to the speedometer or not ?
It's a 150 mph version ...

Did someone has any idea how to fix this or how to repair ?

Thanks a lot,

Pac

[71_bronze_gtx]

If you are certain the cable is good and correctly attached on both ends, then the possibilities are defective speedometer or problem with the speedometer drive gear in the transmission. In the A727, there is a little dial to set the correct gear mesh. If that's not right, it can damage the gear.

see here:

http://www.forbbodiesonly.com/moparforu ... ear-on-727

I suppose the situation is similar on the 4 speed, but I think the gears don't interchange.

Might be worth checking the setup and even pulling the gear to see it's condition before yanking the speedo out of the dash for replace /repair.

[Pac J]

Thank you 71_bronze_gtx !

No I'm not 100% sure, but that it makes the same up and downs when I take the cable out of the car and connect it to a drilling machine is probably a sign that it could be a speedometer problem.
Or isn't this a good way to test. One thing I forgot to say. When the speedometer is out of the car I don't have this noise ... but the speedo goes up and down anywhere . Probably I have really to search on the other end on the speedometer drive gear in the transmission ... But that would be not so easy to test I think ...

I will see what happens ...

Thanks,

Pac

[Moparlar]

I have pulled the cable out of the outer cover and greased it, some times that solves the problem

[Pac J]

@ Moparlar

Thanks,

I also pulled the cable out of the outer cover to test with the drilling machine ... I didn't pulled out the whole part of the car only the inner cable ... But when I tested with the inner cable the speedometer goes a bit up and down too ... even at a constant speed ...

What did you take for a grease ?

Thanks,

Pac

[Moparlar]

I would pull the inner cable out of the outer part in the dash and just use a small brush with white lithium grease on and hold it against the cable as I pushed it back into the outer part till a little grease was on the whole cable

[Dibbons]

My '72 SSP speedometer does the same thing, gets noisy and goes crazy, then settles down. Does it when cold and does it going over bumps sometimes. This happens with a new speedo cable. The odometer is off by about 5% but the speedo reads 80 mph when I'm only doing 60 mph. Weird, and I don't know enough about speedos to offer any solutions. After a recent 4,000 mile road trip, it seems to have stabilized, but still is inaccurate.

[dangina]

My '72 SSP speedometer does the same thing, gets noisy and goes crazy, then settles down. Does it when cold and does it going over bumps sometimes. This happens with a new speedo cable. The odometer is off by about 5% but the speedo reads 80 mph when I'm only doing 60 mph. Weird, and I don't know enough about speedos to offer any solutions. After a recent 4,000 mile road trip, it seems to have stabilized, but still is inaccurate.

do you have the correct speedo gear in the tranny for the rear diff and the size of tires your running?

[sdweatherman]

My Dodge Warlock truck did the exact same thing. It started to make noise and the needle was very erratic - jumping around and showing way too high a speed. It started to do this on a very cold morning driving to work. If the outside temperature is warm enough - or if its a cold day and the heater is on in the cab for awhile - it settles down. I sold the truck and did not have a chance to fix it. I am pretty sure that it is a problem with the gearing inside the speedometer itself.

[road chicken]

From what you've said here I would venture that either the square drive in the back of the speedo is damaged or the magnet cup is damaged inside. Easiest thing to do is get another one cause I don't think they make repair parts for these.