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MG MGB Technical - Odometer problem

I recently discovered my odometer and trip meter are not working. I can reset the trip meter to zeros, but it stays there without advancing while I drive. Odometer is also frozen.
The speedometer is working fine.
It wouldn't bother me except I use the trip meter to tell when to fill up my fuel. The fuel guage doesn't work so I rely on the trip meter, filling up between 250 and 300 miles since last fill-up.

I thought the trip, odo and speedo all worked together, but obviously not.

Is there a simple way to fix these things or am I up for a whole new guage assembly?

Any help appreciated.
D O'Brien

I had a similar problem, took my gauge down to the local speedo service place and they got it all cleaned, serviced etc for about A$100. Not sure I'd have a go myself.
Grant

The odo is driven by the speedo cable through a worm gear. The speedo is obviously driven by the same cable but it has nothing to do with the worm gear. It is operated by a magnet causing a drag cup to move.

Common problem is for the gears to seize up and if it is the nylon type the gears strip whilst the cable keeps happily spinning and driving the speedo. Speedo working and odo not usually means a new gear set will be required. Not a big problem if the gears are available.

Tony
Tony Oliver

Recently had similar problem. Really easy solution in my case was to push back the white nylon collar on the inner rotating cable. This allowed deeper insertion of the inner cable into the unit - and suddenly both speedo and odometer were working again. Simple, and worth trying.
Ken B

Sorry, if your speedo is working, but not the odometer, then the inner is spinning the magnet to make the speedo work, so the contact between the inner cable and the unit mechanism must already be there, which it was not in my case. It does look like a gear problem.
Apologies, I think my suggestion was unsuitable.
Ken B

I had the same type of problem and all it was was the little circlip had come off the small nylon gear allowing it to shift. Put it back on with a dab of loctite and all was well.
Sandy
Sandy Sanders

There is a common problem where a plastic pawl falls off and the odometer stops working. Link here...

http://www.1978mgmidget.com/odometer_repair_on_a_1978_or_1979_MG_Midget.html

I had a similar problem on my Midget recently, but the spindle that runs through the middle of the drums which have the numbers on, came adrift, so the gear did not engage with the pawl. I posted on the BBS, but nobody could tell me what actually retained it.
Anyway, I pushed it back in and it is still working...at the moment!

Dave
D O'Neill

Some speedometers have a small spring that holds the white plastic pawl against the gear. It hangs from the "hook" on the pawl down to a metal tab below it. The speedos that don't have the spring do have the hook and tab.
J Brown

This thread was discussed between 26/02/2007 and 01/03/2007

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.