brake cam o-rings
 

I have an 82 G/S, recently oil has been leaking
on to the rear brake pads via the brake cam,I
have removed the brake cam and it only has two
o-rings on it, but six grooves on the cam.A friend told me it should have four o-rings,if so which grooves should I use for the o-rings.

Thanks.

As many as you can get in...

And grease well.

and don't forget to renew the felt on the outside as well.

I should have known to ask here first. Just posted on UkGsers about leaking rear brake cam.
So I will ask my other question here too.
What's the best way to replace leaking pushrod tube seals?
I am assuming I will have to replace the cylinder base gaskets and head gaskets also when I pull the cylinders off, or is it possible to remove the cyl without taking the head off?
There is not much info in Haynes or Clymer about this.
Any tips or tricks? Thanks, Peter

It is pretty straight forward:
you will need to take the heads off (bolts run throught the heads to the block). As such, you will need a head gasket and the three o-rings for the cylinder base seal (2 small one Large, you should be able to get this all as a kit) for each side. Check your rocker cover gasket, if they are old they often rip on removal, I like to have at least one spare on hand.

The push rod seals are pretty easy but if you are replacing the push rod tubes as well then you have to take care to seat them properly, but not too deep. It is worth measuring the depth of the stock ones before you take them out.

Don't over torque the heads when you put them back on. This will not help in sealing a leak. If you have a leak it is likely that a o-ring has gotten munched as the cylinder slid back on. Last time I did this I used some heavy grease to hole the clyinder base o-ring in it's groove and keep it from catching a lip and getting munched - seemed to work well.

good luck!

Cameron, be especially careful NOT to overtorque the heads. There is a thread on the HUBB about head torque with the correct valuse. UNDERtorquing {b}slightly[/b] - see the thread for numbers - is worthwhile, as even correct torque can strip the threads in the crankcase. Nasty.

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Grant Johnson

Seek, and ye shall find.
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One world, Two wheels.
www.HorizonsUnlimited.com

On the brake cam thing.

The groves on teh brake cam on my '81 G/S were not there for O rings - I had to have them machined out.

Later on bm placed a tube so that the brake cam shaft did not run in the bevel drive oil. On my K75C this tube measures 15.8mm OD 14.0mm ID 83.5mm length. It is a push fit into the housing - a little heat helps. This may be a better way of removing the leak. However even this has its problems - as th ehousing heats up the differential expansion can lead to leaks - a small bit of silastic is very helpfull to seal between the tube and housing.

Thanks Guys,
You answered all my Questions. For a change I was looking for info BEFORE I pulled everthing apart and mucked something up.
I did know about overtorqing the heads, as out of four overlanding bmw's in Mr Yuts Bangkok shop, mine was the only one without pulled headstuds...
Timo, I have been using silicone valve cover gaskets from Real Gaskets for years now and they work very well. With care they will last forever, they don't leak, and are easy to take off and put back on. Good stuff, but not cheap. Cheers

That's a good tip on the gaskets: I had heard about them years ago, but forgotten! To think of the many gaskets I've mangled since....

simple (but not alwys permanent) fix for leaking pushrod tubes- tap the base toward the engine block with a hammer and bit o wood to reseat em....

Tapingt th epushrod tubes to fix leaks DOES NOT WORK on newer boxers - I know it does not work on my 1980 R80 G/S for example.

Hi

Speaking as one of the four at Yut's, I heartily advocate the use of appropriate torques!

How's your project going Peter?

Sean

Hi Sean,
My project is going slow and cheap (like me).
I rode the poor old G/S all last summer, just adding gas and oil instead of fixing it first. I am such a bad BMW owner...
Just now ordering seals and carb kit for much needed winter maintenance. The front brake project is ongoing ,with new ebc rotor and pads here ,but not installed yet.
Hoping to do some "more" serious testing this summer to see if this is really a going to be a good south america bike...
How are you making out with your bike...?Siebenrock solution perhaps...let us know

Skits, sorry for hijacking your question.
How are you making out with the cam leak?
I will not be getting to mine for a few weeks yet.
Cheers, Peter

Hi Peter

Bad BMW owner? Your R80 was one of the sweetest sounding I've ever heard!

But... Have to confess my poor old girl is still in a right state. I've just bought a house so funds to fix have been scarce over the winter. Still ridable around town if you don't mind the rattles and oily feet - just wouldn't use on a longer tour.

Siebenrock kit sounds good, but what about the need for higher octane fuel? I've found another low mileage 1996 1000cc mystic and am again thinking about a transplant....

Cheers

Sean

Hey Sean, How about the other way?
Will your tank fit the mystic and that great front end should be interchangable too...
Is that mystic higher geared??? you know you like the speed.....Cheers, Peter

Cameron,

Where in YVR are you? I have an R80G/S I've rebuilt and can help you with things if needed.

Kevin

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Kevin

http://www.nohorizons.net