speedometer issues

[tom lovinggood]

Hello--I have an '86 CUCV Blazer. Recently, I was having some trouble with the speedometer. It would bounce around and finally settle on 0. I have purchased a new speedo from LMC Trucks along with a new speedo cable. A local shop installed these for me, but these new items did not fix the problem. The speedo needle bounces around for a while, then finally settles at 0 mph. Does anyone have any thoughts about this speedo problem? Thanks in advance

Tom Lovinggood

 

[cpf240]

Check the speedo adapter on the transfer case, and the speedo gear inside the transfer case.

 

[cucvrus]

I am going to take a guess. Check the nylon gear enclosed in the rear tail section of the transfer case. You can remove the rear driveshaft and remove the speedometer cable from the connection. Remove the 10 mm/M6 bolt that holds the cable connection/gear into the tail housing. Check that gear for damage. Now remove the 15 mm/M10 bolts from the rear housing and remove the rear hosing. The rear tail shaft has a plastic gear that is held in with a small clip. See if that gear is stripped and spinning on the tail shaft. if so it needs replaced. If so I have a few parts transfer cases to harvest parts from or you can get new ones if you look around. Clean everything up after correcting the problem and use The Right Stuff Permatex to reassemble the tail shaft. Replace the out put seal with 9449 seal and complete assembly of cable. Refill transfer case with ATF and you should be good. I am not a huge fan of unfit speedometer cables. You may be better getting an OEM used one and clen it up/lube it and install it. You would be surprised what a little lubrication/cable lubricant can do to old cables of any type push/pull/spin cables. Good Luck and have a great day.

 

[tim292stro]

The above two posters have it - there are a few plastic parts right where the rotation is put into the speedometer cable, they are a wear item and do fail.