Follow the Bouncing Speedo

1985 Chevy Caprice Estate.

Been driving it full time for the past 3 weeks, trying to roll the odometer over to 00000 again and on a road trip during the weekend the speedometer gets the bouncies. its between 40 and 50 mph, and is accompanied by a chirp or squeak and it smooths out above 50 and below 40.

The kicker is after sitting over night, it doesnt bounce.

Are there parts inside the cluster that may need to be serviced, cleaned or lubed? Or can there be something my cable is doing funny somewhere between the trans and the cluster? have any GM guys had this problem and corrected it?

(side note: my buick riviera speedo bounced and chirped for several miles before a pop and stopped working. i dont want that to happen on my chevy if i can prevent it. Im hoping my buick just has a bad cable end, i just havent checked it)

 

Generally the bouncing is due to the cable. After many years the lube gets dry. If you disconnect the cable at the back of the "head" unit usually you can pull the cable up and out then you can clean it an relube. A dry lube tends to work best but the gunk in the cable hosing needs to be cleaned out. Not a simple task.

 

Pull the cable off at the transmission, and pull the inner cable out completely. Then run the inner cable between your fingers using a cloth to wipe the cable. If the cable snags the cloth, then there is a broken wire that is causing the problem. This very small broken wire is grabbing on the inner cable sheath. Replace the inner cable with a new one. If there are no broken wires, then lubricate the lower 2/3 of the cable with a very light coating of white lithium grease, and reinstall. You shouldn't have any more problems with the cable. If the speedometer continues to have problems, then it is in the head, and it will need to come out to be serviced. Better to fix it before it stops, because parts are very scarce for the older cars, and many times they can fix a problem, but can't fix it when it becomes junk..

 

thanks Tbird and Junk. ill have to get out there and check into it. i need to drive the car the next day or two while i get brakes on something else.

while i have your attention, what do you think about the Buick. it should be the exact same set up as the chevy, they are the same year and almost have the same speedo, but it doesnt turn at all. someone told me that it could just be the cable slipped out of one end or the other..

im hoping on the chevy, its just dry because it doesnt do it on my regular short trips around town, but after about 100 miles of 40-45mph thru the mountains, she started complainin'

 

If it stopped, it could have a broken cable, or the speedometer head might have gone bad. Only way to tell is to pull the inner cable from the housing by unscrewing it at the transmission. If you are lucky, it will be broken, and you will need to remove the cable at the speedometer head to get the other piece out. Sometimes you need the new one to push the old one through the casing. You just don't know until you get into them.

 

I'm really glad your post referred to a speedometer. I had some concerns about opening this up to find a bouncing Speedo.

 

Not a good mental picture.... you know usually old fat men wear them.... Thanks for that

 

LOL Cyber!!

 

Is there a year that this will not work for? My 62 is doing the same thing at lower speeds. below 30-35. Can I remove the inner cable and replace?

Something that old might break if tugged on too hard.

Thanks,
Dave

 

Yup...no problem, temp.

 

I agree - I have "fixed " this problem with several old cars. Most of the time all that is needed is a good cleaning and re-lubing. I prefer the graphite lube, but to each their own.....

 

Where are you getting just the inside part of the cable?

 

I don't understand the question, temp. You unsrew the connection at the tranny and slide the actual cable out of the flex tube. I don't know if new ones are available from Auto Zone or Car Quest or such but I would try. Otherwise check it for broken spots and if there are none...lube it up and try it again.

 

Bouncing in Speedo

As I sit here in sunny Florida, bouncing up and down in my speedo, I think this is all good advice. Or go to your nearest discount auto store and buy, order, a new speedometer cable........

 

I am familiar with the cable, but have never replaced just the "inside", or wire part of the cable. Have not seen one available thats all. When I got a new one, it came with both ends with the cable already installed.

Thanks
Dave