Hitchcocks Forum

I am fitting sealed bearings to my 1989 350. With the bearings themselves are supplied a pair of oil seals! but do they fit inside or outside the gearbox cases, and which way round?

Hi take one side seal off each bearing sealed side faces out so lube in box gets into bearings, large bearing is fitted from inside box small one in inner cover heat cases to make it easier and put bearings in plastic bag in freezer overnight sockets and extension bar helps to fit large bearing but only drive in on outer rim dont put crap indian bearings in, best of luck.

Not sure I agree. I'd leave both seals in. The gearbox oil can lubricate the gears but leave any resultant swarf out of the bearings.

Just a bit confused by your question, if the seals are supplied separate then you do not have sealed bearings. Sealed or SFL bearings are best left sealed SFL means "sealed for life" and are supplied with the correct lubricant sealed inside, leave the seals in place.

You and me both, Dennis. This is the kit, part no 90118 and the bearings are definitely SFL. I'm wondering if the seals are for the gear selector and the kickstart/spindle, but I can't see how they fit.

Are the two "extra" oilseals upgrades to fibre washers:-

http://www.hitchcocksmotorcycles.com/pa ... 43/Gearbox

There is a separate oil seal which is fitted to the gear box counter shaft.


If you leave both of the bearing fitted seals in place, then eventually the bearings can (will) become overfilled with oil: excess churning and heat. Bad. Premature bearing failure. Remove the inner seal from both bearings.


When one is fitting sealed bearings then by inference will be running the gear-box in oil.


Depending on the gear-box and how well it is 'sealed' at the gear selector pivot pin bush, or the Oil filler plug, fitting sealed bearings can see oil passing around the kickstart shaft. And or overfilling the RH bearing and passing oil through into the Bearing cover housing, and then out of the hole that the clutch push rod passes through. In which event BOTH of that bearings' seals need to be removed to allow the gear box to 'breathe' and for the slingers to do the job that they are intended to do


Personally I have never had any issues with the oil slingers that are fitted on either side of the RH (outer) bearing, so there is no need for a sealed bearing for that application.


If one does not understand the workings of bearings or seals then I would advise NOT to fit them your self. The fit of the larger 6206 bearing into the case is critical, as special drifts and heat is involved, and so too is the tightening of the gearbox sprocket nut.

Thanks Tim, but this doesn't really answer my question; I have two sealed bearings plus two extra oil seals. It could be that I could remove one seal from each bearing and replace it with the new seal, but why do that? I am fitting the new bearings because the original LH one, which was unsealed, had failed and it seemed worthwhile to fit sealed ones as an upgrade.
In any event, I have asked Hitchcock's to explain it to me and will post their explanation in case anyone else is interested.

Our hosts replied;

"It may help to see the parts book illustration showing these items.
The one is the gearbox main bearing oil seal, the other is the gear box sprocket seal.

You will find them shown in our Parts Books On-line – 2003, 350 Bullet, page 21. They are shown as item 21, and 31.
http://www.hitchcocksmotorcycles.com/pa ... _and_Gears


An oil seal is always fitted with the open side (the side from which you can see the spring) towards the oil that you want to prevent from leaking, with the closed side facing outwards, away from the oil".

Much clearer than the '93 parts book I was looking at.

Tim,you mention tightening the sprocket nut,how tight are they supposed to be,
it seems to me that the inner bearing race has no true shoulder to press up
against,(inside the gearbox)so i presume they are only snug fitting.
cheers
colin