Bad cable or bad speedo?

[Wunjee]

88 Blazer. I was driving home a few days ago and suddenly I started hearing a loud grinding sound coming from behind the dash. The speedo pegged to the right and started bouncing. The grinding is speed-sensitive and starts doing it at about 35mph. Odometer and trip are still working fine.

Is this a bad speedo cable or a bad gauge?

 

[dyeager535]

Had exact same issue, was the speedometer.

 

[Wunjee]

Alright, thanks! At least replacement gauges are available.

If I wanted to take the opportunity to add a tach and relocate the fuel age, is that possible in the stock dash?

 

[obijuank5]

Yea there are factory looking replacement tach setups out there.

 

[Jimmy85]

I had the same grinding noise. I used graphite lube at the joint and it worked temporarily. Replaced the cable and has been quiet since.

 

[badmix]

I'd replace cable first, easiest solution. I had that sound too was cable

 

[Wunjee]

Alright, I'll try the cable first.

At LMC, is 36-2026 the correct cable? It says it's for a TH400 and I believe the 88s have a 700r4? There is a cable for the 700r4 but it's listed under 2wd trucks.

 

[Blue85]

I've had a cable messed up by the T-case and the noise could be heard from the speedo, but it was not very loud. I think the big clue here is that the speedo is reading really high. That almost has to be an issue in the speedometer itself. If you don't know, the speed reading is a balancing act between a spring that returns the needle to zero and the pull of magnets spinning around it. The faster the spinning, the more force created.

I would disassemble the cluster and look for a foreign object stuck to a magnet, something bent, or some issue like that. Could be an easy fix.