bevel drive oil vent

[theschoning]

having had 'issues' with oil bubbling out of the bevel drive oil vent for a while, I had my R80ST serviced by Bob Porecha last year. Few weeks later the oil came back to drench the bevel drive and right hand tyre wall.

recently (about 6 week ago or so), I had the gearbox final drive seal replaced by Victory Motorcycles in Camden (London) - as Bob was not available. Other than Victory re-installing my Wilbers rear shock upside-down, it seemed like they know what they are doing and provided a good and fast service.

Now the oil is back, dribbling over the wheel!

help, what could it be

Many thanks,

jonathan

 

[Kenny]

First, check to see if gearbox oil level is lower than usual ( more than likely ) because it is obviously running down the shaft and filling up the bevel drive! This occurs either because of overfilling said gearbox ( or breather bolt blocked etc ) or rear gearbox seal has failed again :-(
Have a look at the pics...hollow shaft meant to have oil in it but if the bevel box oil seal has failed then this lets the oil from the gearbox into the bevel drive ( also check on the amount of oil past the level plug ).
I used a guy ( sorry, four years ago and can't remember his N & A ( but not far from Motorworks ) who had the tool to remove the internal locking collar and replace the bevel/shaft oil seal ( he also helicoiled the drain plug for me ).
Hope this helps

 

[theschoning]

Thanks Kenny!

Gearbox oil was slightly low before the gearbox seal was replaced recently - so it appeared to be the output shaft seal letting oil thru.

Currently, I have not checked the gearbox oil level again.

Assuming this has now be fixed, can the oil from the shaft itself enter the bevel leading to it being over-filled? From your post and (very helpful!) photos I gather there is a seal in the bevel also that needs replacing.

Is this the next step, replacing the bevel seal and see what happens?

Many thanks,

Jonathan

 

[Kenny]

Remove the filler plug at the rear of the shaft immediately in front of the bevel box...you should be able to put a small screwdriver in the hole until in touches the shaft and there should be about 3mm of oil on the tip of the screwdriver blade... ie the shaft oil should be almost to the top etc. If this oil level is way down then that is obviously draining into the bevel box via the seal ( middle pic above ) in the bevel box. If loads of oil comes out from the shaft filler, then the oil is probably coming from the gearbox, filling the shaft and making its way into the bevel box. Pulling back the gaitor where the gearbox is bolted to the shaft will tell you if oil is leaking from the gearbox ( bastid to get back on sometimes though !)

You can see the seal in the middle photo of the bevel box input but you need a special 4 pronged tool to remove that internal collar ( very fine thread ) so you can get at the seal. Previous owner(s) from me had obviously removed the internal collar with a chisel etc as he'd broken the delicate thread on the collar ( elongated crack along entire threaded portion )..so use/fabricate a proper tool.

I'd start from scratch and top up all the gearbox/shaft/bevel box levels and then see which is leaking past its seal