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A Puzzlement

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Mickey Richaud

Mickey Richaud

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Yesterday, I replaced the speedometer cable in the MGB ('73 with overdrive). Took it for a drive, and it's reading faster than it was before the old one gave up the ghost. Best I can tell, it's reading close to double the speed, at least up to around 15 or 20mph (actual).

The problem with the old one was that the cable fitting had loosened from the gauge, then the drive cable had "retreated" into the jacket, and was not making contact with the bit inside the gauge.

Thoughts?
 
Test it with Janet driving alongside in another car.....or with your GPS.
 
Was going to do that later today, but it's pretty clearly off by a good bit.
 
Got an angle drive on it?

Can't figure why it'd change the reading by just swappin' cables out. :confuse:
 
No angle drive - with the old cable or the new.
 
Garmin reads 32, speedo 40; Garmin 38, speedo 50; Garmin 47, speedo 60. Looks like it's reading about 20% fast. I think it was less than 10% before.

And now the speedo's grinding...
 
Sounds like the magnet and disk inside the speedo is dragging. Tricky to fix.
 
OK - so anyone have a spare gauge? '73 B with overdrive.
 
What're the numbers on that speedo, Mick...along the bottom...something lke 1480-1200
 
S/N 5230-085 1280

And that is correct for the '73 with OD. (Original gauge)
 
That's why I needed the number....
 
Anyone...?
 
I know its a P.I.T. butt but try backing off the nut on the back of the speedometer. Maybe this cable is pushed too far in and binding something??? A free attempt at a fix is usually what i try first. Good luck , Bob
 
All my 'stuff' is for much earlier cars.
 
Pain is right, but I'll give that a shot. Thanks for the suggestion.

Mickey
 
I'm looking, Mickey
 
Thanks again, Bob - took your advice and backed off several turns. No more noise! :thumbsup:

Still reading about 25% fast, which is more than it was before, but will probably live with that.

:cheers:
Mickey
 
Stewart said:
Would the number be the same for od and non od cars?
Click to expand...

OD gauge has a 085 suffix; I think standard four-speed is 06.
 
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