Speedo going a little crazy

[dknight]

So just got my project on the road and the speedo is going mental for some reason, its just bouncing all over the place, cruising at say 5mph it is up at about 45 50 60

Anyone got any ideas?

thanks!

Dan

[Rissy]

Stop trying to drive it. You'll break your angle drive.

It sounds like the spindle or the mechanism is jamming and then releasing again under severe twisting pressure. Sounds like it needs cleaning up and freeing off somewhere.

[dknight]

everything was all checked before when dash was out and appeared to be functioning and working fine.

ive taken off the cable from the back of the dash to the yellow box and any movement on that the clocks dance, so i have a feeling the problem is at the dash side

just wondered if anyone has had this before

[Chris Williams]

If it's the cable you can get a one piece long cable to bypass the counter box and take away some of the resistance.
Chris

[DMCTodayMichael]

Be sure to check both cable connections at the lambda box. These should be finger tight only. Any tighter and you will have one unhappy angle drive.

[dknight]

thanks for the help guys, I did read the issues with the cables early in my project so these were checked and double checked and all appears to function fine, i suspect it is a clock issue as like i say i can remove the lambda box connection and manually turn the speedo, for example a full turn a second it is up to like 40mph, it just seems highly responsive to slight movement.

its as if the resistance or gears on the clocks are not right, i think i will strip the speedo out of the dash and look and see if i can see whats going on

[dknight]

so i did actually get to the bottom of this, my knowledge of how speedo's work is thin but the internal mech looks a bit like a gyro of sorts, and the outer part spins at speed causing the speedo to gradually raise. Mine had bits of dirt and grit so as it spins it was catching the full mechanism causing the crazy movement.

cleaned up with a can of air and a careful bit of WD40 and it now appears to move much more controlled, just need to put back on car and see what happens...

[Rissy]

Good job!

You'll be back in there if/when you find your speedo isn't reading accurately :wink:

[Rich Hanlon]

My Mum's brother once took an erratic speedo apart on his MG midget, much like you have done, only to find a tiny note in there from a previous owner which read
"Oh no, not again!" :lol:

[Rich Hanlon]

I also once had a similar issue to you when I reconnected a lower speedo cable but had somehow managed to get the inner drive arm of the cable wedged between the socket which it was meant to be in, and the outer sheath, so it would turn the socket sporadically but not evenly as intended.