Burping Bevel Box - or - aliterative alle

There are a few threads on here regarding burping the bevel box on older (pre-CARC) machines. When respondents have done this did anyone measure the amount of fluid loss pre burp?I have spotted oil on my back wheel and topped up. However I am going to pull the rear wheel off and check the main oil seal for tearing. Just wondered if there was any “empirical” loss that was considered normal. Just learned the lesson - if it ain’t broke dont fix it - again.

Are you sure it’s oil? I tend to get “oil” spots on my rim in hot conditions but actually it’s just little spots of grease … because I tend to be a bit generous when greasing the splines.

Shouldn’t need to “burp” a pre-CARC bevel as there is no seal on the pinion shaft allowing the box to breath into the swing-arm drive shaft tube.

Have you removed the level plug? Maybe overfull?
(Not that I use the level plug, just measure and fill)

Anyhow, if the rim is just spotted no need to rush into action, just wipe it off and monitor the situation.

Ta, but the Sporti is quite different. This is not spots either, there was a wee pool maybe 2-3 cc’s on the rim and a liberal smear over the rest of the offside rim. I dipped it and there doesn’t seem to be major losses. I topped it up but too quickly so lost some out of the level plug hole as I thought maybe it was more empty than it was before it glugged out if you know what I mean. This means I am not entirely clear how much I lost this time. I am going to dump the contents (80/90 + molyslip) into a measuring jug and then refill with 245 cc (I know!). Then run it and burb it and monitor.

Mad Farquhar2012-07-05 08:13:19

Burping my MK111 works.
The amount you otherwise lose is minimal but annoying.
I agree with lawries about spotting and grease.

Aye - with an exposed shaft I am pretty familiar with grease and centrifugal action and where it can get to!

If by loosening the top filler plug, none. I would have thought…

Mike H2012-07-05 13:21:33

Had same problem. couple cc on rim and around tyre.
Burp it no problems after.

Last bevel box change correct measure +moly, I used EP 85w 140 (Morris oils) few miles to warm up bevel box, the burp the box, very noticable hiss of air. No leaks(touch wood) Then spen next 30 mins cleaning grease of wheel, side panels, exhaust, boots and neighbours cat… wits2012-07-05 13:23:28

That is also true actually, provided the vent passage in the pinion housing is clear / aligned properly.

Ah yes… what I really meant was before the advent of “burping” did anyone measure what quantity leaked out before they took action. I should have been more accurate in my measurement before topping up. There must come a point when the pressure equalises within the bevel box and no more 80/90 or whatever leaks. It’s a long shot because if like me (and it sounds like Ian) it’s pretty frustrating having had no leak before and getting one on rebuilding with a new seal.

If deffo oil then sounds like large seal has gone. I had that.

Take the wheel out and look where it’s coming from, if only on the casing cover, outside of the seal, then probably that and the seal is easy to get at to change.

If the inside spindle tube is oily suggests the small seal has gone, which is down inside the outer side of the box, means a box strip and rebuild.

But double-check also drain plug / level plugs not leaking either, oil tends to run around the flange and drip off the bottom giving a false impression of where its coming from.


That’s assuming there’s a swing-arm drive shaft tube though - the spine frames don’t have one.

Oh you did? What the big one in the cover?

Next silly question ~ why

I mean, if it weren’t leaking

Did this involve taking the cover off?

I’m noticing a few spots on the rim on my Centauro. I’m pretty sure it’s the input seal where the driveshaft enters the 'box that’s weeping though, not the inner seal. Maybe double check that area before heading into the main seal?
guzzijack2012-07-05 13:54:24

Well that’s just silly

I have never measured the amont of oil I take out of the gear and bevel boxes on oil changes so cannot answer that question.
BTW isn’t the Haynes manual really usefull when it comes to the bevel box.

I was told about burping the bevel box on the V1000 since then I have always done it following a service and fill up, without doing it I always got oil smear on the back wheen rim, … burping does seem to help

After how many pints?

It’s just like burping a child after feeding it…

…hopefully with out a follow through?

Still awaiting more info e.g. results of having a proper butchers at your final drive box

In terms of ascertaining exactly where oil is coming from
Mike H2012-07-07 13:48:46