As I was
unable to fully identify the source of an oil leak somewhere around the flywheel
area of the RP engine I decided to fit proper oil seals on both the input and
output shafts of the gearbox. Some of the very late gearboxes had an oil seal
built into the rear housing which is a much larger housing than the earlier one.
If you have, or can find, one then that is a job saved, however, if you are like
me and don’t have one then this could be the answer.
A
careful examination of the front shaft revealed that by simply removing the
housing from around the input shaft a small oil seal could be used by machining
away the static scroll and opening up the front end of the housing to a suitable
bore to fit an oil seal.
I used
were metric oil seals mainly because I was able to source a seal with the inner
bore of 28mm which was a nice snug fit on the input shaft, with a 38mm outer
diameter which meant that I did not remove too much material from the housing
and that were only 7mm deep.
I set up
the housing in my lathe, turned out a new housing for the oil seal, pressed it
in and the job was done. It was as simple as that.
The rear
bearing housing was a little more tricky as there is less material in the
housing to play with. I ended up with an oil seal 35mm bore, 50mm outer
diameter and 7mm wide, this seal also incorporated a dust shield lip.
As you
can see from the pictures quite an amount of the original casing is machined
away but once the seal is pressed into place all is well. I am sure these
seals will be an improvement on the old method.
This article, written by Malcolm Watts, originally appeared in CA7C Seven Focus
in Apr 2007 pp16-17.
