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MG MGB Technical - Speedo drive pinion MGC

I Need a new speedo drive pinion for my MGC, both Moss & MGOC web sites say MGC part no longer available ! the only one listed is for the chrome bumper MGB.

The one I have taken out is the white 21 teeth (MGB ?)version, the teeth are stripped but only a small part at the top of the pinion, it doesn't seem to have been engaged into the gear very well.

does any one know if the origonal MGC version is the same as the White 21 tooth MGB version, is this the correct part to buy ?

Dave
D Ellis

Dave-
I presume that yours is a 1969 MGC. The LH-type Black Label Overdrive unit used from the 1968 through the 1974 MGB model years with an identification number of 22/61972 had a 21 tooth white speedometer pinion drive gear (BMC Part # 37H 3464) and pinion (BMC Part # 37H 3463).
Stephen Strange

I don't think that they are interchangeable. The C had a higher rear end ratio and must have used a slower turning speedometer drive gear, unless the speedometer itself was designed to turn at a slower speed. RAY
rjm RAY

The speedo is easy to check, look at the tpms on the face-plate, the MGB used 1280tpm for both OD and standard gearboxes from 67 to 74. If the MGC has the same then the speedo drive must be different to cater for the different final drive as has been mentioned. However the 72 to 76 V8, which used the same final drive as the early C, had a 960tpm speedo, and according to the Parts Catalogue had the same speedo drive as the 4-cylinder. MGB 4-cylinder non-OD gearboxes had a 10-start shaft and a 26 tooth wheel, OD gearboxes had an 8-start shaft and a 21 tooth gear, both giving close to 1:2.6 ratio. Both gears and pinions were available by Googling the last time I looked.
P Hunt

Thanks Guys, I replaced the pinion with the white one and found the reason for the previous one not being fully engaged with the gea.
The housing was not fully into the apperture, needed a bit of a clean down and it went in all the way this time, hopefully won't have to do this again, its not easy to get at !

Dave
D Ellis

Frequently if the pinion is stuffed then so is the driving worm. This can be replaced without removing the power train. If you need to know then email me.
Garth
Garth Bagnall

This thread was discussed between 28/02/2010 and 09/03/2010

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