Speedometer Problem

Well after 2900 miles on a NOS original speedometer all the sudden it started acting up. At first the speedometer would read about 10 mph fast. Next I noticed it would read very slow or nothing. So I took the cable out of the housing and inspected it. The cable was not broke and had gear oil on it from the transfer case. I cleaned up the cable and added some grease to it and put it back together making sure both ends of the housing were put in correctly. Jumped in the jeep and just crawled at an idle. The speedo gauge went all the way around past the 9. I stopped and put the jeep back in the shop and rechecked both ends to make sure they were put in correctly. I made sure there were no kinks in the speedo housing. Walcks thinks it is in the speedo and so does Novack. I could either put a new speedometer cable with housing back in it or take the gauge out and see if it has dried up inside. What would you guy's suggest? Thanks Julius

 

I took the speedo cable and housing out cleaned it and lubed it. I then took the speedometer out and took the 2 little screws off the back where the cable connects. I then took the outer ring off and the glass cover. So I looked at the mechanism that has the mileage wheel and the guts to the unit. Sprayed it off real good with a cleaner and blew it out with compressed air. Next I will lube the unit with a fine oil. I don't know what else I can do.

 

If the speedometer is broken, there are shops that can repair it. Search online, or check Hemming's Motor News. These places cater most to the classic car owners, and the service likely won't be cheap. There are also aftermarket replacement speedometers. Possible you could put the face of your speedo together with one of these repop mechanisms.

 

Did you try putting a drill on the end of the cable and trying the speedometer? That will tell if it is in the speedometer, or the drive. You can drive the Jeep and watch the cable at the dash, see if it is jumping, or smooth. Just a suggestion, I have found problems doing that on motorcycles. Good Luck.

 

The thing that gets me this was a NOS speedometer with zero miles on it when I installed it. With only 2900 miles on it I doubt it is broken.

 

With the cable disconnected, can you spin the input to the speedometer with your fingers? Does it react reasonably? Make any noise? I just spun one in the garage and it's pretty easy to get it to bump up to 20 or 30 mph, returns to 0 when I stop spinning it. Very little resistance while turning it.

 

Yes it turns easily and bounces up while I twist it with my fingers then returns to zero

 

Sounds like the speedometer may be working correctly. Very strange problem considering it acts normal when rotated by hand.

 

Sounds like your speedo may have just kicked the bucket, although it’s odd that it would happen at such low mileage. Maybe it was stored improperly for all these years causing corrosion inside?

my speedometer recently died, but was in pretty bad shape to begin with. Sun faded, likely water damage, dead moth inside and nearly 90k miles (or maybe 190 or even 590, who knows?) First it started jumping erratically anytime I was above 40mph. Then it would violently swing above 30. Then the needle snapped off. Then it started making screeching noises. All the while, the odometer continued to work flawlessly.

anyway, just yesterday I installed a new omix speedo (using the old speedo cable) and both the speedo and odometer are working perfectly again.

 

Possibly old stiff grease inside , or something like that? NOS is not the same as "new."

 

This
I have chucked the speedometer directly into the drill. Should tell you real quick if the speedo's working.

 

Stiff grease makes the most logic to me. if the grease was gumming up in the area with the magnet then getting clear it would allow the swinging and breaking of the needle. A weak spring seems like it would just read high.

Bad grease also makes sense with storage.

 

I bought an NOS speedometer off of eBay a few years ago from the guy who bought a warehouse in Vietnam with a bunch of Jeep parts (I think the seller's name was bluemoonscooter, or something like that). Anyway, when I took it apart to set the mileage correctly, I found that the original grease in the 50+/- year old speedometer had noticeably hardened up, so I cleaned it out and replaced it with white lithium grease. You might try that before sending it off to a speedometer shop, in case that's the issue.

 

You should not have gear oil running up the speedo core. That gear oil gets pretty stiff when very cold. Fix that problem and cleaning the inside of speed cup and it should be fine. Grease the worm gear only. The speed cup is mounted on a jewel so no need for lube.

 

Thanks guys for all your help.

 

I have that issue with the green B

 

Two ways to fix this problem. They make the core material with opposite twist from what you have. This will drive the gear oil down not up. You can also cut a piece of rubber (inner-tube) and make a seal to stop the lube.

 

To follow up on Walts comments, I learned about the "twist" of the inner cable back in the late '70s. My original cable broke just beyond the transfer case, so I bought a replacement inner cable from NAPA. I installed it and it worked fine for a few days, then the needle would zing all the way to the stop past the lower gauges. When I took the cable loose from the speedo, everything was soaked in gear oil. When I compared the new inner cable with the old one, the spiral ran the opposite direction. The new inner cable pulled gear oil up the cable. I went to the AMC Jeep dealer and bought the correct inner cable, and all was good after flushing all the gear oil out.
-Donny

 

Thanks Walt & Donny. Do you have any idea who makes the reverse rotation cable nowadays. I'm interested.