G5 layshaft thin washer

[JayDee24ca]

Good day. I have my G5 gearbox apart on the bench at the moment, trying to seal it up, as it is evident that this new-to-me bike has been dribbling gear oil out the back end for quite a while. One of the things I am struggling with is the absence of any backing washer under the oring beneath the speedo worm gear. My G5 parts book does not show a washer there, but an online tutorial does show that there should be a washer there to back up the oring, and I see that MG Cycle sells such a washer https://www.mgcycle.com/index.php?main_page=product_info&products_id=1010 . MGC seems to suggest that only later models had such a washer.
My bike is a 79, so the absence of the washer seems to suggest that mine is an older bike.
Can anyone tell me if adding this the washer is okay, or if later bikes that had the washer also had a different layshaft to accommodate this washer?  Here is a photo of the layshaft and the oring I am talking about. You can see that there is nothing to support the oring.


Thanks
John D.

[pete roper]

The sole purpose of the washer is to sit on the splines and provide a more even surface for the o-ring to crush down on therefore reducing the risk of oil leaking up the shaft.

Is it 'Necessary'? No, not at all. In fact very early five speeds didn't even use the o-ring! Is it a good idea? Certainly, as it will assist in preventing oil escaping from the gearbox into the swingarm. Whether you install one is entirely up to you. On a G5 it won't make a lot of difference. Where it is vital is on machines like 1100 Sports, Daytona's and Centauros where any leakage from the output shaft has the potential to contaminate the rear tyre.

Pete

[JayDee24ca]

Thanks Pete, that is the info I was looking for. I found a fair bit of oil in the drive shaft housing, and that is on of the suspect sources. If the washer will help seal the area by providing support for the oring, then it is worth installing; I will order one.
John D.