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MG MGB Technical - Speedo and Heat

On hot days 80+ speedo quits.
when car cools restarts
any suggestions
Martin
Martin J. Mead

Quits in what way? What does the odo do?
Paul Hunt

Thread: Speedo and Heat
1977 mgb roadster non overdrive
on start up and for 1st 5 miles or so speedo and odometer work fine
then both stop working.
if i park car swith off iqn. park for a few minutes speedo starts working again for a few miles on restart [I realize speedo is mechanical]
it seems worse on hot days [do not drive in winter or rain]
could it be the old problem of oil travelling up the cable?
thank you
Martin
Martin J. Mead

Make sure both ends of the outer are properly located and fully screwed to the spedo and gearbox. If not that, when the speedo stops working take the cable out the back of the speedo and see if the inner is still turning, when pushed right in and when pulled slightly out. If not, could be a broken inner. I would expect oil to either clog up the works altogether, or only start working once it has warmed up and got thinner.
Paul Hunt

I have had similar problems with the squared off ends of the inner cable wearing and rounding off at the pinion in the gearbox (the metal shaft with a nylon cog at the end).

The cable would move in and out on the pinion, so the speedo would work on-and-off.

The most noticable thing was that if I ran the car in reverse for a few feet, the speedo work work fine in the forward gears for a few miles, then suddenly stop.

I got sick of replacing the cable every 12 months, that the last time I fitted a right-angle drive to the gearbox in the hope that it take a bit longer between replacements.

I would have replaced the pinion but I understand that they are not available.
P R Akers

This thread was discussed between 13/08/2003 and 15/08/2003

MG MGB Technical index

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