junkyard speedometer going crazy

[BaileySims]

Bump. I am now having the same problems with my stock cluster. The reading is off 3 mph from 0 to about 25 and it gets way off the faster I go. I cruise at 45 according to the speedo and I am actually going 35. This just went bonkers this morning when I was rushing to work. I did peg the speedo out as well before everything got messed up. If this a fixable issue without swapping clusters or did I break something internally?

[Gottolovem]

Have you looked at your cable?

[Petros]

I have seen this before, the spindle bearing on the needed is worn and sloppy so it touches the rotating magnet on the cable side and cause it to peg. not sure if there is a fix, likely much easier to just replace the whole instrument cluster.

it is actually fairly normal for a properly working speedo to be off 5-10 mph at about 60 mph, makes me crazy when I block traffic when I was just wanting ot drive at the speed limit. I use the speed readout on my GPS to know my speed. a change in tire size may correct the calibration error.

[BaileySims]

Have you looked at your cable?

I have not had the time to look at my cable as of yet, hopefully tomorrow I will have some time and report back. Would the issue be more on the cluster side or the trans side?

I have seen this before, the spindle bearing on the needed is worn and sloppy so it touches the rotating magnet on the cable side and cause it to peg. not sure if there is a fix, likely much easier to just replace the whole instrument cluster.

it is actually fairly normal for a properly working speedo to be off 5-10 mph at about 60 mph, makes me crazy when I block traffic when I was just wanting ot drive at the speed limit. I use the speed readout on my GPS to know my speed. a change in tire size may correct the calibration error.

Well dang. Not that the surgery would be the difficult part but locating one around here is near impossible. There are only 2 tercels here and both are non 4wd without the tach in the cluster. I will take it apart tomorrow and report back with what I find.

[jimcrazy]

the speedo in my 86 fwd wagon reads perfect up to 100k then at 105 it shoots to 140k, been that way for 4 years

[Petros]

mine in my '84 daily driver (with an '86 SR5 cluster) works perfectly, exactly accurate speed compared with my GPS. but occasionally on really cold days, well below freezing, at speeds above about 40 mph you can here a slight ringing noise from the speedo, and it will go to over 100 mph, and sometimes even peg. so when it is cold the clearance changes enough to cause slight contact. I mostly ignore it, if it ever gets worse I may replacement it.

[BaileySims]

Alright. I just got done taking it apart. The cable loos fine. It's not frayed or anything. The speedo gear on the trans side is not missing teeth and spins well. The only issue I think it might be is that the cable seems to bind a little in its housing.
https://youtu.be/_8KW5uALjrQ

[BaileySims]

Alright. I just got done taking it apart. The cable loos fine. It's not frayed or anything. The speedo gear on the trans side is not missing teeth and spins well. The only issue I think it might be is that the cable seems to bind a little in its housing.
https://youtu.be/_8KW5uALjrQ

I just greased the heck out of the speedo casing and just discovered a trans leak at the 4wd selector on the trans. :/

[Petros]

lots of grease will make it hold up longer, but the problem I think is in the cluster. might be possible to fix it by gluing filler in around the spindle to keep it centered. it just depends on what is causing it to allow contact with the spinning magnet within the speedo housing itself.

[BaileySims]

lots of grease will make it hold up longer, but the problem I think is in the cluster. might be possible to fix it by gluing filler in around the spindle to keep it centered. it just depends on what is causing it to allow contact with the spinning magnet within the speedo housing itself.

My first thoughts. I cleaned the grease out of it to inspect it and it looks no where near the same size as the end of the cable. I filled it back up with grease and drove it this morning and it did moderately well up until I hit a bump. It was 3 mph off from 0 to 65 then it jumped up 15mph. Looks like it's time for a new cluster.

[Petros]

did you try using light silicone lubricant within the mechanism of the speedometer itself? though making it slippery within the moving parts of the speedo might make it show higher MPH. Many of the Tercel4wd I have driven cross country were off by 3-5 mph at 65-70mph (according to GPS readings). my daily drive has larger tires than stock, and it is exactly right on. But I do get the 100-120 mph error occationally when it is well below freezing, which is unrelated to the speedo cable.

Lubricating the cable stops the bouncing speedo needle, where it oscillates 3-4 mph in rhythmic cyclic fashion. The speedo cable is winding up, and unwinding (like a torsional spring), it usually indicates the cable is wearing out and may fail soon. But I have found putting light grease on it usually stops it, and likely makes the cable lasts longer.