The MGA With An Attitude
Speedometer drive SPINDLE SEAL replacement -- GT-106

At 04:43 PM 9/10/04 -0400, Steve Clarke wrote:
"I need to change the rotted out seal in the speedo drive pinion housing. Is there a simple (fat chance) way to get the retainer sleeve out?"

speedometer drive disassembled
Thanks to Steve Clarke for the picture

Use a 1/2" tap. Screw it in only enough to get a very tiny bite on the sleeve, and pull. The sleeve is rolled up from flat stock with a split and a gap down one side. It is held in place only with a little spring tension from the sleeve being slightly larger diameter than the bore. Once the tap gets a light bite on the shell it should pull right out very easy.

Also use a 3/8" tap to get a BIG bite in the bore of the old seal to pull it out. Just don't drive the tap into the smaller bore of the housing (which is the bearing journal for the shaft).

Exactly the same technique also works for the mechanical tachometer drive on the engine (which incidentally can use the same seal).

On 27 February 2012,Thomas McNamara in New York, USA, wrote:
"I filled the gearbox with 20W50 and discovered that there is a leak around the speedo pinion. It appears around the outside of the housing, not the pinion shaft. Barney and Moss show no seal or washer for the housing. Is this correct? Can I just unscrew the entire assembly if necessary"?

Moss does list the seal parts for the MGA speedometer drive. The shaft seal is a small garter spring seal 461-445 (BMC 2A3254). Seal between the drive housing and gearbox housing is a copper washer, Moss #324-820 (BMC 51K3169). The washer is 1.250" OD, 1.068" ID, 0.041" thick
speedometer drive assembled
You can easily R&R the speedometer drive assembly. Drain oil from the gearbox first, because this part is below oil level. Disconnect the speedometer cable. Unscrew the drive assembly from the housing (1-1/8 inch socket size).

The spindle sits at an inclined angle with output end lower than input end. The input end of the spindle is nested in a pilot bore in the gearbox housing. In case the spindle might stick in place, be very careful and go slow pulling it out while trying not to drop the spindle with small pinion gear into the bottom of the gearbox tail housing.

When reinstalling the assembly, put the copper washer on the drive assembly first. Be careful that the washer does not slip out of place into a leading groove to be trapped in a bad spot where it might prevent mating of the assembly with the gearbox housing (again being careful not to drop the pinion gear and spindle inside).

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