1980 MGB Back Plate Oil seal

[Ian Lomer]

After a recent engine re-build oil appeared to be coming from the split pin on the clutch housing which indicates to me that there is a problem with the back plate oil seal or the gearbox first motion shaft oil seal. The back plate oil seal was replaced during the rebuild with the improved VITON - LUF1002 seal using retainer 12H1547 as I was told the correct retainer 22G1649 was no longer available.

The parts manual lists for the 4 synchro engine a flat oil seal retainer part number 12H1547 to be used with back plate MGS20717 and for the late rubber bumper 18V engine a recessed oil seal retainer part number 22G1649 to be used with back plate CAM 1003. The recess in the retainer allows the oil seal to protrude into the clutch housing indicating to me that the back plate is thinner or the oil seal is deeper. I have also measured the back plate which is 10mm thick, the oil seal is 9.5 mm deep and the recess in the retainer is 3mm.

I have checked with a number of engine re-build specialist and they are not aware of the difference in retainers and all use the flat retainer 12H1547 irrespective of year. The correct retainer 22G1649 is now available from Moss.

Before I remove the engine to renew both seals could anyone please advise where I can find out the reason for the change in specification.

[Ian F]

Too many questions!! I think I would need to actually see the installation to make any sort of worthwhile comment. If you are doing the work yourself then a careful inspection should indicate whether it will function as intended.
Viton seals should be an improvement, but having said that, I have in the past reverted to original design seals (in a Midget engine) after trying "new improved" designs.

Ian F

[Bumpa]

I too have the same issue. I rebuilt the engine from my '71 roadster last winter and it runs beautifully, but there is that drip from the bell housing. I'm not inclined to remove the lump so soon after finishing the car, but it's ruddy annoying! It also drips from the overdrive despite very carefully fitting new gaskets when I cleaned the gauze filter. Bah! Old cars, who would have them?