Speedo needle sticks at 5mph

[1987Comanche]

This is an annoying thing that's developed in the past few months. I transplanted the full gauge cluster into the '90 from my '87 2 yrs ago when I bought the '90 and sold the '87. Originally the cluster started life in a jy XJ but everything works fine. it's a mechanical speedo.

The commute to work is about 20 miles one way. I'll leave, drive to work, and everything is fine. About once a week I'll leave work, look down, and find the needle is stuck at at the bottom of the scale (5 mph) on the cluster. Tapping the lens a few times gets it moving again. I'm typically at 20-25mph and it jumps right up to that speed and works fine. What's interesting is that it doesn't do it at any other time, i.e. running errands, leaving the house, etc. Ideas?

[flint54]

Assuming you've already verified that the cable is well engaged and

not failing, I see several options:

 

1) live with it (or retire since it only happens during work commute)

2) pull cluster, pull speedo, and look for mechanical hangup (home surgery)

3) install a replacement cluster or speedo

4) send speedo to someone like this: http://www.autoinstruments.com/

5) teach it a lesson by frequently pegging the upper limit (85mph)

[TylerJY]

(or retire since it only happens during work commute)

5) teach it a lesson by frequently pegging the upper limit (85mph)

 

:rotf:

[ParadiseMJ]

Make sure the square peg is inserted solidly at the transfer case and behind the dash. I pulled my cluster and just pulled a bit on the cable and it dislodged the spinner. There is really only about 1" of play back and forth from the t/c.

[1987Comanche]

1) live with it (or retire since it only happens during work commute)

:D Would love too...unfortunately I'll probably be dead before I have enough $$ to retire.

 

5) teach it a lesson by frequently pegging the upper limit (85mph)

:) Again wish I could but she only puts out 25psi hot oil pressure cruising on the hwy. I figure following the 10psi/1000RPM rule of thumb got me 20K down the road so I might as well stick with it. It limits me to about 73mph.

 

The cable seems good though I haven't checked the transfer case end. I had a speedo cable issue on the '87 but it hissed like crazy and the needle jumped all over the place (pre full gauge cluster). This one is quiet and seems ok.

 

Would it be worthwhile to pull the needle off and reseat it? I had the speedo apart 2 yrs ago when I set the correct mileage. I was thinking about driving a bit with the needle at 5mph to see if the odometer moves. That would eliminate the cable as being the source of the problem. Would I damage the speedo by doing this?

[flint54]

What you're asking is my option #2, home surgery. I encourage

you to choose this path, ONLY if you're prepared for the possible

consequence of a ruint gauge. I really doubt that pulling and

re-seating the needle will overcome this unusual situation, but,

until you try, you never know. My JY charges $20 for instrument

clusters, and there are plenty. Pulling the speedo from the cluster

is no big deal. If you're already certain there are no cable issues,

I think just go for the swap. If you want to attempt anything

with the old gauge, you have nothing to lose if you've got the

replacement gauge ready to swap in. Who knows, you might get

lucky. Unlike engines or transmissions, I think speedometers were

really not intended to be worked on, except by specialists or by

risk takers. But, it sounds like you've done similar surgery before

with good result, so you may fare better than most of us mortals.

 

My OP on highway at 85mph is over 50psi, but, try as

I may, I cannot get this truck over (an estimated) 92mph. Probably

need one of those jap-car wings on the back, a big bleating exhaust

tip, and neon lights underneath.