Speedometer

[Blazer85]

I'm sure I'm missing something super simple but I need to ask because i cant figure it out. Pulled the motor and trans in my 68 Road Runner for a motor swap. Speedo was working fine when removed. The car has a 4 speed and all I did was unscrew the large nut on the speedo housing and pulled the cable straight off. I've verified that it works by moving it and the gauge moves. Pulled it off and re installed it 3 times now and it still wont work. Any advice?

 

[kiwigtx]

Try putting the internal drive cable in a battery drill and spin it up a bit. Have someone watch the odometer to see if it runs. If not, the internal drive may have come out of the back of the odometer. You might have to wriggle it around when putting the drive coupler back onto the transmission.

 

[Blazer85]

Ok, if that came out would that mean that the speedometer would not work either then?

 

[kiwigtx]

Maybe I misunderstood the question....

have you checked to see that the Speedometer drive unit is "clocked" correctly in the transmission - the range of gears is stamped on the outer case - should match the tooth count on your pinion drive. Once again, you have to gently wriggle the drive unit in place to seat it correctly.

 

[Blazer85]

I left the housing in the transmission, all I did was unscrew the throttle cable (big nut in the side of the trans). I left the unit with gears in the tranny. The speedometer and odometer are not working now.

 

[miller]

Might be one end of the actual cable isn't engaged, either into the squared receiver end of the speedo gear, or the speedometer. Might check that...

 

[Garys1969RR]

You need to determine which end is not working. Remove the cable from the trans end. Spin it with a drill while you have an assistant watch the speedo. You may have to try both directions. If the speedo works with the drill, then the prob is at the trans end.

 

[bigmanjbmopar]

Did you do the drill trick like suggsted? the actual cable is just in the black casing, it will come out on the speedo end if even pulled slightly, reach up under the dash and unplug the connector on the cluster and then feel for the end of the cable, it has a little sqaure end that fits just right in the speedo housing. I've gone through 3 cables now mostly due to headers and heat melting the outer casing, even had it so bad on one of them that the melted cable jamed up the cable inside and made it bind so bad the the tip of the cable on the speedo side snapped off and got stuck in the housing! took 2 hours to figure that out and get the tiny little piece out. now my cable is protected by two sleeves each rated at 600°+ and strapped tight to the frame and body as possible to avoid the heat.

 

[Blazer85]

I the speedo works then you spin the valve down by the trans. I just need to figure out why it isn't picking up the signal from the trans output.

 

[Garys1969RR]

Put a small screwdriver in the square hole at the trans, and turn the driveshaft. See if the screwdriver turns. If not, the gear in there may be bad.

 

[nuteguy]

Not to hijack this thread, but I installed a used speedometer since mine was beyond repair. It occasionally made an awful and very loud grinding noise and the needle would skyrocket to about 100 mph when I was doing 10. I replaced the cable but it still does this and even more frequently. I've been driving around without it hooked up because it is unbearable.

Also, before I put the new speedometer in, I put a drill in the back and made sure it spun good (which it did, with no noise). The needle also sat at 0 mph before I put it in the car but at some point in time it started to sit at 10 mph when not moving.

Any thoughts?

 

[bigmanjbmopar]

You used a drill to test your speedo? Well thats probably ruined it. explains why it is grinding.

 

[nuteguy]

It wasn't a drill bit. I can't remember if it was a phillips bit or something like that.

 

[bigmanjbmopar]

Well I mean spinning your speedo with some thing other than by hand will ruin it. its is just a counter balanced spring loaded calibrated assembly, desinged to be spun at a certian rpm spinning the assembly faster than the trans does will junk it fast.

 

[nuteguy]

I don't think that junked it because I've seen it done before on fully operational speedos but there's obviously a chance that this time that caused a problem. Do you think a speedometer repair place would be able to deal with it or should I just look for a new one at Carlisle this year?

 

[Garys1969RR]

You need to determine which end is not working. Remove the cable from the trans end. Spin it with a drill while you have an assistant watch the speedo. You may have to try both directions. If the speedo works with the drill, then the prob is at the trans end.

You may want to just spin it by hand so as to not damage the speedo. I spun a used one by hand and it responded immediately with just a slow turn of the screwdriver. They are quite sensitive when working properly.

 

[bigmanjbmopar]

I would get a new one. or used working one. http://www.ebay.com/itm/MOPAR-68-69...ERE-/361510336834?vxp=mtr&hash=item542bb1f942