www.boxertrix.com

Why doesn't the gearbox drain plug have a sealing crush washer ?
It seems so counter intuitive to me that tomorrow when I change the oil I'm sorely tempted to fit one.( 26 mm )
Every other plug on the bike has one, INCLUDING bizarrely the gearbox level / fill plug . WTF ?
Please someone tell me I must not fit one and why ?

kfrogzx7 wrote:Why doesn't the gearbox drain plug have a sealing crush washer ?
It seems so counter intuitive to me that tomorrow when I change the oil I'm sorely tempted to fit one.( 26 mm )
Every other plug on the bike has one, INCLUDING bizarrely the gearbox level / fill plug . WTF ?
Please someone tell me I must not fit one and why ?

I may be wrong but I seem to recall the drain plug has a taper on it that provides the required seal. Adding a washer would negate that taper I'd think?

I don't think so Steve, altho' you could be right of course I'll look later. That sound a bit crude to me too ?
It looks to me just like the other plugs and the flange ( wide enough to accommodate a crush washer btw ) definitely seats on the bottom of the box.
I'm intrigued .. I'm off to garage to look at it again with my vernier.

No , the thread is definitely straight.
On closer examination it does appear as tho' on the sealing surface of the plug flange there's an integral "o"ring, when you touch it with a screw driver tho' it seems hard ( ie metallic rather than rubber ? ), however I do wonder whether it's a bit like a dowty washer and has it's own built in ( no seperate part/ seal listed at RealOEM ) seal ?
Going to read my Clymer now to see whether examination and replacement of whole plug is recommended if in doubt about it's condition on inspection.

The microfiche shows a washer on the sump plug.

Edited to say I'm a moron. 1 bottle of red and I can't read a drawing. No washer shown on the gearbox drain plug.

Oo Er.. mystery deepens.

The manual says ( Clymer, pg 60, para 6B ):

" On R850C, R1100S and R1200C models, on the bottom surface of the transmission case, remove the drain plug and sealing washer ( Figure 27 ). Allow the oil to drain for at least 15-20 minutes "

Then ( para 7 )

"Remove and discard the sealing washer from the drain plug. Replace the sealing washer every time the drain plug is removed "

Help someone ....

Boxerscott says there's no seal in this thread :

viewtopic.php?t=18620&postdays=0&postor ... l&start=15

Anyway, mine had no seal when I removed it ?

Herb, Herb ....
One bottle of red !!
I'm only on my second glass ... and I can still type, just.

Taper plugs are very effective when mated to a taper female thread. The method is tried and tested in industry. Very!

Used to seal pneumatics, hydraulics and not least steam.

I've encountered them on car engine sumps, when the sumps were pressed steel. Also used on industrial gearboxes.

I would be surprised to find one on an aluminium sump, especially these days where there is emphasis on weight saving. The expanding force generated can be pretty significant.

If there's any kind of flange on the plug it won't be a taper plug.

Definitely a flange Corvus, so how does it seal then ?

kfrogzx7 wrote:Definitely a flange Corvus, so how does it seal then ?

I can't see it, but if there's nothing bonded on the flange or no groove where an o ring should sit, then you'd have to say a washer? Maybe it is missing or crushed on to the flange or sump so tight that it's not obvious its there? Dunno.

But taper plugs don't usually have a flange. They don't need it.

Come on, the suspense is killing me!

How's it sealing?


Edit: this is a typical taper plug with a hexagon head. Don't be misled by the "step" up to the hexagon. This isn't a flange. The taper will bite before this gets anywhere near. If it is taper it'll be a BSP thread. The Germans recognise this thread in DIN standards. I'll be gobsmacked if it's a taper plug though.

http://www.kiowa.co.uk/SupplyImages/WF0 ... HBP_hr.jpg

Is the taper, not like this:



That taper is typically for centralising either a Dowty washer or a soft metal (copper or ali) washer.

You don't tend to get tapered threads on drain plugs.

Al

Blackal wrote:Is the taper, not like this:



That taper is typically for centralising either a Dowty washer or a soft metal (copper or ali) washer.

You don't tend to get tapered threads on drain plugs.

Al

yes like that Al from what I can recall

Here's the actual plug, no taper at all and a broad flat flange.
However, in some of the pics you might be able to see sort of striations in the flat "seating" surface, these are not pronounced but maybe relevant ?







Vernier pic used to try and show no taper on thread or plug.