4 replies [Last post]
ahdoman
ahdoman's picture
 Offline
Santa Clarita, Ca.
Joined: 08/30/2007
Posts: 24

I did a search and couldn't find anything. How do you remove the pushrod tubes from the cylinder?

schrader7032
schrader7032's picture
 Offline
VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
Posts: 6784
How do you remove pushrod tubes?

They're driven out with a special drift. Vech at Bench Mark Works sells them. Probably Ed Korn at Cycleworks does too.

You should note the depth that they're installed so that they can go back to the same location. The drift is also used to adjust their depth, and thus how much they push on the seals on the crankcase, prior to the heads being bolted on.

Kurt in S.A.

__________________

Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

EuroIron
EuroIron's picture
 Offline
VBMWMO #7266
Joined: 04/23/2007
Posts: 414
How do you remove pushrod tubes?

is there not a proper spec for their installed height?

even a guesstimate based on the amount of "crush" of the spherical seal?

ie......... at what point the tube makes contact with a fully seated new seal....

schrader7032
schrader7032's picture
 Offline
VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
Posts: 6784
How do you remove pushrod tubes?

I've not seen a spec. When I installed my R69S cylinder with the four base bolts, I monitored how the seals were compressed. I had purposely set the tubes into the cylinders a smidge too far away from the engine block. Then with the drift, I pushed the tubes in from the head-side until I felt I had enough squeeze but not to the point that I damaged or split the seal. If I were to get a leak (which, thankfully, I have not so far), I supposed I could remove the heads and redrift another skosh and try again. I think with all the variables, there's probably not a "set tube mm from X point" type of specification...

Kurt in S.A.

__________________

Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

EuroIron
EuroIron's picture
 Offline
VBMWMO #7266
Joined: 04/23/2007
Posts: 414
How do you remove pushrod tubes?

I'd think that would be an easy one to reverse engineer and create a spec

seems straight forward to me, how much, in inches or mm, should the spherical seal be compressed

the Brits never saw fit to give a spec for their push rod tubes either...... Triumph in particular

deck one, mill a head, end up with stacked tolerances against you by mixing and matching.......... you for sure have a leak resulting from under or over compressing those seals and unlike the BMW design, you have two tubes with seals top and bottom, on angles which make them fight each other during assembly

however, thru the years some of us took notes and have excellent numbers for each and every of the three different tube/tappet block combos, along with the various type seals available with the ultimately best solution always being to go with type 3 tubes and tappet blocks, the good quad(I like the modern hex ones) quad seals at the top, compress 1/16" of an inch........ seal with RTV (one place on that engine I am not opposed to it if done carefully) Gasgacinch or even Yamabond

and then they seal up and remain dry

but you have to be quite methodical and set fore and aft, individually

and be prepared to deepen(easy with a handmade or store bought tool used in a drill press) the counterbore in the head, or add shims

the BMW setup is much easier since the variables seem only to be base gasket thickness, block deck height relative to the seal seat, and of course tube seating in the cylinder which is the only thing that would have to be adjusted to correct

but I have seen many of them crying at that point and I think it would be a safe bet that not all seep there, due to only being set up too loose, but maybe too tight as well

I'm thinking something along the lines of feeler gauge noting when you can no longer freely turn the seal.......... yada yada bleh bleh

different feeler gauge for new base gasket than if reusing

once established I think a light application of Gasgacinch, right before final assembly, wouldn't hurt a thing, and it's very easy to remove all visible traces

just rambling

it seems the Brits and Germans also seemed to think anyone tinkering with their engines would also know about rocker geometry too

maybe the Germans thought the motorcycle guys would read some of the automotive service manuals

but maybe not, seen some of both as left the factory which indicated the manufacturers didn't pay much attention to that tiny detail

Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.