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Speedometer Inacuracy

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darkbrg

Freshman Member
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My speedometer is reading 15% high at all speeds c
omparing it to other cars at dif speeds & according to a good quality after market tach. Has anyone else had this problem & how did you fix the problem?
 
Welcome!
Often times you'll find that the right angle gear isn't properly inserted resulting in erratic readings, however a consistent variation isn't a symbol of that problem from what I've seen so far here at the university. My guess is that you have slightly oversize tires and the speedo hasn't been adjusted to compensate. You would also see a variation in the odometer as well, I think.
Mike
 
Also make sure you have the "right" speedo.
I bought my MGC in 1985 and it wasn't until I posted pictures of it here on this forum I found out it wasn't the right one.

Welcome to the BCF!! :wink:
 
Speedo is correct for my 67 BGT.
Speedo does not match tach RPM for a given speed & tires are same diameter as the original spare (now changed to a new tire).
 
Well that pretty much leaves the cable. Check the lubrication, angle and connection at dash, 'course you probably already have. Or sit tight and Tony or Doc or Jack or Steve...... will pop in with the instant answer. But the constant variation is the real tricky part.
 
Has the differential been changed?

That would cause a constant % variation across the speed range.
 
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