New pushrod tubes needed?

[79beem]

Hey guys,
Been a very long time since my last post, testiment to the realiability of these old girls.
Great to see so much activity.

During clean up of left pot I discovered that the pushrod tube seal (retaining collar?) Is loose. Explains the " use pushrod tube tool to seat seals".

My seals are leaking badly and as the (collars?) are loose do I need to simply use the tool to seat the new seals and if so how is this done? Or can tubes with fixed collars be purchased?
Can the seal seating tool be used to remedy leaking seals?

I have checked the motorworks uk site and they have new tubes available, does anyone know if these collars are loose also?

[Barry]

Drawing of tool attached as a pdf.

[Tony Smith]

Pre-1980 Airheads had push rod tubes with collars that could be adjusted.

I think that the R65 has always had fixed collars. But who knows, they may have sent one down the line with "adjustable" ones on the theory that it would create a lively debate in 40 years time - Romanians are lie that...

[Barry]

Tony,

The picture I posted above is out of a July 1978 copy of a BMW workshop manual for R45/R65's. I've often wondered about the date because only a couple hundred bikes had been built at that point so it's a very early manual and things maybe did change soon after.

[79beem]

Thanks for all the responses guys.

I omitted to mention the pot was already off.....right side still on.

I have since seen your new prt installation post monte. We're your new collars fixed?

Would you guys suggest reseating the valves whilst I have the heads off? I was just going to clean up the carbon deposits but I have a very keen aircraft maintenance engineer friend who's also a seasoned bike wrench who comes complete with spring compressor, valve grinding tool and pastes.

 I feel like I'm at a crossroads with the tubes. Install new seal and hope they work with the adjustable collars or source new tubes with fixed collars. Open to suggestion with that decision.

I should also add that the seals have been leaky for a few years but have just recently gotten worse.

[Bob_Roller]

If they are loose and can move about, you could try a few spot welds to keep the collars in place .

Or possibly ' staking ' , that would require a sharp object like a center punch, or chisel like tool to move a small amount of metal on the tube at the collar to get a ridge to prevent the collar from backing off .

[Tony Smith]

Thanks for all the responses guys.


 I feel like I'm at a crossroads with the tubes. Install new seal and hope they work with the adjustable collars or source new tubes with fixed collars. Open to suggestion with that decision.

All new tubes are fixed which should tell you something.

If you decide to buy new tubes you have two choices for the R65, OEM aluminium tubes or after-market stainless steel ones.

I would go with the alloy ones as they are heaps easier to fit. That said buy 6 not 4 in case you have a "death" whilst installing the new ones.

If you are on good terms with the resident domestic goddess you may be able to gain use of the family oven to heat the cylinders to around 250 degrees (Celcius). Put the tubes in the freezer.

Before freezing the new tubes I'd wipe a thin smear of white lead onto the ends that go into the cylinder.

Getting the old tubes out is a matter between you and your Gods, try very hard not to mark up the bores, but if you do, a round file should be used to de-burr.

You front axle provides both a support mandrel and a handy lump to beat on using a reasonably heavy hammer (at least 2lb) and preferably of the "dead blow" type.

Hit firmly and as few times as possible until the tube lines up with where the removed one was.

[nhmaf]

I had tried tapping the loose collars on my 78 R100 with various devices to get leaking seals to stop leaking - to no avail.  It seemed anything I gained was undone after a a short ride or two and the leak re-appeared.

I checked with the internet gurus to learn where the bottom edge of the collar should be with respect to the cylinder base.   I took each cylinder off, cleaned up the tubes with some 000 steel wool and emery cloth and degreased them.  I put some small hose clamps around the tubes to hold the collars in position while I used a steel machinist rule to get the bottom edge of the collars to be just level with the base of the cylinder and tightened the hose clamps to hold them there.    I then used a bit of plumbing flux and silver solder and small propane torch to solder a bead about 1/2 way around each collar on the tube.   Those suckers aren't going to move now, but if I have to I can get out the torch and remove the collars again.    This way I didn't have to deal with trying to install new tubes in the head (the old ones were perfectly sound, just cosmetically stained).

So far, things have been oil tight for several hundred miles.

[79beem]

Okay, so I like your solution nhmaf. Anyone know the correct collar position for a 79? Currently sitting at 2.5mm above/uphill of cylinder base and 18mm above tube base.

[nhmaf]

I'll try to find the drawing I found - I suspect that it would be the same for the R65s, relatively speaking.  Basically have a perfectly straight edge from the cylinder base (where it contacts the side of the case) to the lowermost edge/lip of the collar - though you could probably go up a mm or so from there - seemed to make getting the cylinder back on a bit more tedious as the rubber gets really compressed with them that far in.

I'll see what I can find for pics.. here is a base starting point-

http://[URL=http://s159.photobucket.com/user/nhmaf/media/PRT_StopRing_zpsqdvlk2vb.jpg.html][IMG]http://i159.photobucket.com/albums/t138/nhmaf/PRT_StopRing_zpsqdvlk2vb.jpg[/IMG][/url]

[nhmaf]

Unfortunately we seem to have had a problem with our camera, and all my digital pics of the process may be gone - I'll continue to look, though.........

[79beem]

Thanks nhmaf hope you get your camera sorted.

[79beem]

Thanks Monte,
Going to try the Nhmaf approach first.
What type/% silver solder did you use Nhmaf ?

[Bob_Roller]

So may want to get some silver solder flux as well .

Standard silver solder used to sweat copper pipes will work .

[79beem]

After running a few test welds with silver solder my welder mate determined silver solder had a higher melting point than the thin guage oem tubes and successfully used aluminum solder rods with a propane torch on the first pot.

So the question now is, sealant on the cylinder base and head gasket or not ?  If so which product? I have hymolar but it's brush on.