speedometer gone crazy

[justajester]

So amongst the other issues I'm ironing out in my brat, I have a new one. I hears a whining noise for a while that I kind of thought was a wheel bearing or something. All of this sudden the noise got wayyyyy louder than usual today and the speedometer shot up to 80mph even though I was doing about 20mph. And then it just kind of bounced all over the place when I slowed down. What would cause this and what should I look at replacing?

[-tombba-]

EDIT: what engine you have in it ? Thought it sounds similar to my slipping speedo cable in EA82, but since it's brat and usually has different engine I edited the first post out.

Edited December 1, 2013 by -tombba-

[TomRhere]

Most likely the speedometer has transmition lube in it.

 

The seal on the lower end of the speedometer cable fails, allowing lube to work it's way up the cable into the speedometer.

 

My White '86 BRAT would do the same thing on real cold mornings. I watched the needle peg a few times while still in 1st gear. When I parted it out, I found the back of the cluster covered in gear lube.

 

Never done it myself, but do believe you can replace that seal, clean the lube out of the cable, and clean the speedometer.

[ruparts]

hi,

 i have had the exact same thing on my wagon. first i put in a new speedometer cable, genuine oem,  did nothing. what i finally did to fix it was take the inst cluster out, turn it up so the face side is down, the back of the speedo straight up,, then put some light oil like 3-in -one or singer sewing machine oil, in the little cavity where the cable attaches.  ( this is only a few drops ) objective is to get it to go into the clearance between the cable housing and the little part that turns. with the oil in place take a small something, minature screwdriver,  and turn the little square stem,  the one the cable turns.  i'll bet it turns sorta hard at first, then as some of the oil gets in it frees up, not much oil will go in there but it's enough.  then just put it all back together . this fixed mine.   it was doing the exact same as you describe, slow speed and it would go crazy and very loud,, also it mostly did this when it's been cold outside ,, in summer it wouldn't do this.   my theory is its a chatter between  the housing and the part that turns inside it , along with the old originsal lube that has gone hard after all the years.  sounde like bunk but i swear by this after years of this same problem and now its winter and no problem this year with it.

 just to check, i took another cluster and sure enough the thing turned hard until i did this and it smoothed and went free in a few turns .

Edited December 1, 2013 by ruparts