oil leak from rear drive

Hi all as the title says I have oil leaking from the rear drive I realise I must take off the back wheel but can anyone tell me what oil seal or gasket I will need to replace as I will need to order it from the uk and would sooner have to hand before I remove the wheel its on a 94 cali 1100i thanks

This is the ‘normal’ big block style of FD isn’t it? First, where’s it coming from exactly? Could be a number of things, depending. This may help, my web page from when I rebuilt mine, based on the workshop manual instructions and pix. http://livinginthepast-audioweb.co.uk/index.php?p=finaldrive HTH

A leak or a weep.
If the latter the secret is to run the bike till it is warm, undo the fill bolt then redo it up.
you create a very partial vacuum which stops it weeping when hot and therefore expanded.
Small blocks and latter spine frame models have breathers.

What he ses, run it get it hot and “Burp” it. If you get a weep of oil after that on a run by all means change the seal, not too difficult follow the Haynes manual …

Thanks for the advice lads I was talking to a fellow member (mo biker)yesterday and he told me about burping the fd after a run , the fact that it didn’t leak before I changed the oil sounds like it could be the answer so i’ll try it at the weekend and see if it works cheers

There are two oil seals on the big block final drive. The large output oil seal is 90407085 but there is a smaller internal oil seal which can only be replaced by dismantling the rear drive. It is 90403850.

Out of interest what oil and what quantity did you put in there?You never know, it just might have some bearing on why it started to weep.

Keep forgetting about burping …

It was halfords own EP80W/90 gear oil and I filled it til it came out of the level plug

YOU DID put Molyslip in as well I hope …it needs it… , get it hot and take the plug out you will hear a wee pop as the hot air is expelled, do it up job done. IF the seal HAS blown it is 9/10 times the big one fairly easy to get at and take off and replace…

Each to their own but I’ve never used that method to refill the 'box. I drain out overnight and then fill with the correct measured volume, (including the moly) then ‘burp’ it after a run.

Go with GJ on this.
Always put a measured amount in in all 3.
Guzzis are fairly agricultural.

I concur, rarely disturb the level plugs

I believe, in Guzziology, that the advice is also to ignore the level plug on some models (I forget which) and measure the correct amount.

Well Dave Richardson is very clever and quite often agrees with me.
And I would say all models.

Well, as they say; ‘Great minds drink alike’.

I’ll have a Laphroaig on that.

Meee too Something I DO agree with Ian on

I don’t have my Guzziology at the moment, lent it out, but I seem to recall DR saying that the drive box has to be horizontal if you’re going to use the level plug as your guide.
As this means either removing the suspension or getting a 25 stone mate to sit on the pillion, it seems a far better option to measure the oil in…

Another reason to measure the oil is if you buy a measuring jug , Wilko’s or similar pop the moly in FIRST then the oil to get it correct. BUT I do know of a few filler plugs that cross threaded and stripped the threads NOT somewhere you really want to be.

I measure the Bevel box, Gearbox and engine oil levels. THEN measure it on the dipstick for the engine oil THEN marked the dipstick so I know what the “real” full level is. YOU may be a bit surprised if you do this as I was. the proper “fill” level was a wee bit below the top mark on the stick…which means by filling to the dipstick put a bit too much oil in causing oil to pass thro the breathers.