speedo question
 

i swapped out my instrument cluster yesterday with a better looking one, the circuit board on the back was a lot better shape than mine so i switched it out, just the cluster and the only thing i kept from mine was the speedo so that way i could keep the mileage the same, now my speedo is jumping all over the place....what could be the cause of this? the circuit board was a little different than mine but from what i could tell it only affected the oil pressure gauge (the person before me rigged one in there)

Re: speedo question
 

On an 84... or 82 based on your name, if that is what your truck is, the speedo is cable driven, not electronic. (that didn't come until the later r/v series trucks)

If you speedo is bouncing I'd suspect something got messed up in a connection with your Speedometer cable when you were taking apart and putting back together.

Re: speedo question
 

Connection? It's just the cable and three wires with a screw...anything in particular? Is the cable not all the way on?

Re: speedo question
 

no ones got any input???

Re: speedo question
 

Did you just change the gauge face or the whole thing? I would say unhook the cable from speedo and put back on and make sure the cable trips the clip to hold it in.

Re: speedo question
 

i changed out the whole thing minus the speedo, i used my original speedo

Re: speedo question
 

I've seen a few post about what year the speedo went electronic.Most say 86 on up.My truck is an 87 with 700r4 and it has a cable operated speedo.What year did they actually come out with electronic speedo.Can someone post a pic of the electronic speedo connection at the tail shaft of the trans.

Re: speedo question
 

mines a 84 with the th350...also cable

Re: speedo question
 

I'd be trying this first. It's all mechanical and sounds like it's not seated properly.

Re: speedo question
 

thanks man, after dinner ill get up under there and try to reseat it

Re: speedo question
 

i have a 85 and all i did was pull it then left it out for a hour then put it back and i was good to go

Re: speedo question
 

i pulled it out and put it back in and its worse, i pulled it out and going to let it out all night and hook it up tomorrow and see what happens

Re: speedo question
 

i hope it work :chevy:

Re: speedo question
 

If the cable is plugged into the back of the speedometer properly it sounds like the Speedo is bad. It's strange but it happens. When I changed from a th350 to a 4l60 I didn't even touch my speedometer but it started bouncing the same as yours. Sure enough, I swapped with a different speedometer and the problem was resolved.

Re: speedo question
 

Things go bad by coincidence all the time like this. Before I went and changed the speedo head unit I'd try greasing the cable, that's the usual suspect in a bouncing needle for me. Just remove the entire speedo cable from within the sheath and lube it up and reinsert it and hook everything back up and give it a whirl. Takes literally minutes to do.

And speedos did not go electric until mid 89 sometime. Some 80 burbs have electronic speedos and some don't. All 90 and up models do though. In the 80's sometime they started placing a speed sensor on the speedo, which is the little thing with a couple of wires held in place with a single screw on the back.

Re: speedo question
 

yup my 89 was cable....make sure it's under the clip back there might be hard to tell

Re: speedo question
 

I have an 87 R10 700R4 and have the same problem. It was bugging the crap out of me so I replaced everything. New speedo, cable, electronic connection, new transmission (just cause not because the speedo bounced). It still bounces like no other. I just figured it was suppose to bounce. Do all of yours bounce?

Re: speedo question
 

mine dont bounce and i have the stock 85 cable :chevy:

Re: speedo question
 

My truck has a mechanical cable, I replaced it a few years back and once in a while on the highway it starts going nuts like you mentioned

Re: speedo question
 

Personally, I would check to make sure that the speedo cable is all the way on. If so, I would disconnect and lube the end of the cable. It is suppose to be pretty well lubed which thinking back to when I did mine, I forgot to lube the new cable which could explain my problem. Also, when you say jump all over the place, I assuming you mean it bounces as in your going 25MPH the needle will bounce from 15ish to 35ish? Or like random jumps from 5MPH to 85MPH to 30MPH?

Re: speedo question
 

Not an expert but my cable didn't have much slack so i really hard to put in the extra effort to get mine on. Once I did I held the cable in place and pushed in a bit on the face of the speedo. That seemed to get my cable plugged in.

Re: speedo question
 

the cables are should last a lifetime but they dont and it sucks but is better the new age style :chevy:

Re: speedo question
 

I would say it's a lube problem. you should beard a faint click as the end goes on the speedo.

Re: speedo question
 

At mpierce9 I had the same problem. I could not connect the cable to my speedo since it was too short. Then I remembered there was extra slack under the cab to allow for flex and what not. I threaded some of the slack into the firewall. The cable stuck out past my steering wheel which made it much easier to connect and here the distinct click oilman spoke of!

Re: speedo question
 

Lubricate the cable as mentioned above. It was probably a little dry and just moving it will cause a bouncing speedo sometimes. The cable binds and lets go causing the fluctuation you see. The inner cable comes out real easy. Do not over lube it.
Frank

Re: speedo question
 

it bounces and if I'm going say 25 mph it will say I'm going 75, it also bounces...really annoying

Re: speedo question
 

what should i use to lube it? wd40?

Re: speedo question
 

Take it off and pull the cable out of the housing. Then get some of that white spray grease and shirt some down the housing and while inserting the cable back in, or replace if you see any bad sections on the cable. Spray some on the cable as you re-insert then make sure it's connected right. The cable is either dry or kinked. If kinked, you can get a replacement insert from your local parts house...

Re: speedo question
 

I still think it sounds like a sticky cable. Personally I would use white lithium grease, second option would be LIQUID graphite. Not solid. If using the white lithium grease take a decent portion in between thumb and pointer finger and run the entire cable through. This way you lube the entire thing without getting too much lube which could be problematic down the road. I would also make sure to get a little extra lube on each if the ends. Careful not to make a mess and cover the speedo though!

Re: speedo question
 

I did this last week; use white lithium grease and it fixed it; at 40 the speedo would bounce up to 70 or so and make a pile of noise. I tried silicone spray first but that only sort of worked. I also read somewhere that you should not lube within 12" of the instrument cluster end or the lube will end up getting flung around.

Re: speedo question
 

so i think i may have figured out the problem, when i changed out the speedo gear i pulled it from a blazer that was a 89 or 90 maybe even 91, i changed the gear and it sordof worked, after comparing my cable with the one i pulled from the blazer the one from the blazer is about 10 inches longer or so, i believe the cable isn't catching the gear all the way, is this a good guess? or am i just a dumb a$$???

Re: speedo question
 

If you changed the speedo gear, that can also be the cause. If the cable is good-n-lubed, and the ends are not rounded off on either end of the cable, then your speedometer gear could also be partially stripped (not only the gear side, but where the cable inserts could also be partially stripped).

Using the Blazer or truck speedo cable will not cause any issues as long as the ends are the same and it reaches without binding.

Re: speedo question
 

ya i used just the gear, but I'm going to pull it tomorrow to make sure that its not rounded off in there, the cables look fine tho

Re: speedo question
 

Easy test:
put a drill on the cable underneath at the t-case and spin it up.
Have a buddy watch the speedo inside.
No bounce: gear swap is the problem
Still bouncing: cable is problem.
The gear could have only come from a '89 or down Blazer. All electronic in 90-91.
As was said, as long as there is the square cable end coming out of the sheath then it should work.
Also, remember most of the late Blazers (87-89) came with a 2.73 or 3.07 gears so the t-case gear you put in is more than likely wrong and giving you wrong speedo readings. Not sure what gears you have but pretty sure it's reading wrong.

Re: speedo question
 

thanks, ill try that tomorrow, my truck has 3.08's and 35 inch tires, so it will be off regardless, but still more accurate than what it is now....pretty anxious to try this out...thanks again

Re: speedo question
 

well i figured it out, its the speedo....the round wheel that connects to the speedo has about a 1/4 inch of play in it, i have another speedo but the mileage is way off of mine, how do i change it to match my speedo?

Re: speedo question
 

i know i can hook a drill up to it but thats going to take forever, is there a faster way?

Re: speedo question
 

well gents, just went on a test run, working like a charm, well still five mph off, but at least i know how fast I'm going....thanks for all the help....still boggles my mind how it worked one day then not the next, i didn't drop it or anything but heck its working now