wavering speedo

MGB discussion board for Roadster and GT classic car models.
Post Reply
allanr
Posts: 4
Joined: Tue Oct 08, 2013 12:44 pm

wavering speedo

Post by allanr » Tue Oct 08, 2013 2:48 pm

I have read several accounts of speedos giving unsteady readings with many explainations.

Here is my recent experience:- speedo wavering intermittantly, sometimes noisy. Then it stopped altogether. The cause was the speedo had siezed completely.
I was able to open it enough without removing the trip reset knob to get at the rotating ( in this case not rotating part) and with a little WD40 and persuation I got the rotating magnet to move and eventually free.

On refitting it still didn't work and the cable did not rotate. I did this test with the car on axle stands and engine running in gear.

What had happened was the nylon drive gear had been stripped the drive cable OK surprisingly.

I checked the speedo on 2 other cars and they were beginning to show signs of stiffening on the internals so have all now have had a drop of light oil to keep them smooth running. All signs of wavering is eliminated. The Midget speedo suffers the same fault as well.

Hope this will be of interest. :lol:

User avatar
jonahnaylor
Posts: 47
Joined: Mon Oct 07, 2013 10:35 pm
Location: York, United Kingdom
Contact:

Re: wavering speedo

Post by jonahnaylor » Tue Oct 08, 2013 6:59 pm

Hi have you watched this John Twist video he made on the topic of wavey speedos?

http://www.youtube.com/watch?v=DpgWJ9epqwo
--
Yorkshire website design, domain registrations & hosting:
https://www.yorkshire.hosting

Jim K
Posts: 1
Joined: Sun Nov 17, 2013 10:02 pm
Location: Liberty, Kentucky

Re: wavering speedo

Post by Jim K » Tue Jan 14, 2014 5:46 pm

Yes, of interest.
Other causes can be a worn inner cable with broken strands that catch inside the sleeve. When I lived in Alaska, I used Speedograph-Richfield in Nottingham to repair my speedo from my '71 GT. Good work, and not any more than the US based shops. I had them re-zero the odometer as I wanted to know how many miles I had put on the car.

Cheers!
Jim K is a grease-stained wretch

User avatar
jonahnaylor
Posts: 47
Joined: Mon Oct 07, 2013 10:35 pm
Location: York, United Kingdom
Contact:

Re: wavering speedo

Post by jonahnaylor » Mon Feb 24, 2014 4:58 pm

Hi I'm now experiencing problems with the speedo wavering too!

So first thing was first; I wanted the easy fix and tried to replace the speedo cable.

After much fiddling I got the old cable out of the car, attached the new one to the speedo, ran it through the bulkhead and under the car - threw a clip held with a bolt to stop the cable hanging in the road and then finally tried to screw it onto the gearbox. The problem was I couldn't get it tight, it would go finger tight but nothing more before the thread slipped and the nut would be loose again. So I ended up leaving it as tight as I could by hand (but not really very snug at all...) and testing the car out. I still get the waving speedo...

So I'm not sure if the thread on the gearbox is sheared or if my problem isn't the cable at all and is that the gearbox nut at the back may need tightening like John Twist mentions in the video I posted above.

Does anyone know if there is any easy way to replace the thread on that part of gearbox or does it need to go into a garage? It's difficult for me trying to do this at the roadside with a small jack!! haha ;)
--
Yorkshire website design, domain registrations & hosting:
https://www.yorkshire.hosting

Post Reply

Return to “MGB Roadster & MGB GT Forum”

Who is online

Users browsing this forum: No registered users and 2 guests