Fork Disassembly - Twin shock models

[Rob Valdez 79 R65]

[size=12]This is only part of the story.  More to come.[/size]



click for larger

On this one, you can see the threads that the damper rod fastens to.
The 13mm bolt face is on the "top".
The nylon washer is behind it, and the "holey" washer is lying to the right.

click for larger

[Barry]

Rob

Your damper valve body (base cylinder in your photo) looks to be original like mine and not the modified version. Was there a shim between it and the circlip ?

If not when you re-assemble and replace the circlip if there is any movement at all of the damper valve body you may want to fit a shim which I think is still available from US suppliers.  

[Rob Valdez 79 R65]

A few new pictures.

Click on this one, and go forward for the sequence.  
Thanks for watching!  (pBase is having issues, right now)


Left to right:
Bottom support for damper pipe [18]
Lock Ring [19]
Valve Housing [21] (I have no clearance shims [20])
Valve washer [22]
Flat washer 23] (holey washer)
Ring [24] (bumper ring)

And they all fit over the damper pipe, which is capped by that fitting with the 13mm head on it.  These two are listed as one in RealOEM.

Close up of bottom dismantled:


This is the bottom of the damper pipe support.  
This sits against the bottom inside of the fork slider, and the big 14mm allen head screw [17-above] goes in there, to hold them together.


This is the fitting at the top, which is intended to stay in place when you dismantle the forks.
I plan to blue Loctite this fastener.  Maybe even red! [smiley=shocked2.gif]

[Rob Valdez 79 R65]

I got the fork legs out of the triple clamps a little bit ago.  I used my heat gun on high for just a couple of minutes on each clamp, and I was able to twist the tubes out!

Bad news, the left leg (impact side) is significantly bent.  
The right one looks O.K.

MAX BMW quotes a new one at $460!

I hope I can get this one straightened to my satisfaction.

[Rob Valdez 79 R65]

I am putting my forks back together!

These are the bumpers I got from Max BMW:




These are the ones Motobins sells:




I noticed the inside diameter of my new ones is slightly larger than the old one I pulled off.  (The one in the other leg was no where to be seen)

[montmil]

The '81, didn't have them, just the black goo in the bottom of the fork, the LS, hasn't had the forks apart yet, but with 91,000 miles on it, I'd go out on a limb, and say they aren't there either .

Dang it! I was hoping to eliminate the occasional topping out of the forks. :-?   Monte

Perhaps I misread/misunderstood previous posts. RealOEM for my '81 shows the same exploded view of the front fork innards as the diagram in your post. Item #24 is the rubber/nylon "ring" above the perforated disc.

I'm going to fit the Motobins rings in the '83 as the fork legs are currently off for the steering stem bearing replacement.

Monte

[Rob Valdez 79 R65]

Yep - #24.

When I was sliding the damper rod assembly into the fork leg I knocked off two of the three thin shims that sit in a groove on the top piece:



The fact that they are brand new tubes that never had oil in them may have made it a little tougher.  I just put them back in place and tried again, pushing around on different sides as I slid it up.

Good cir-clip pliers are essential.

[Barry]

Rob

I dont know if it makes any difference but I spaced the gaps on the damper piston rings 120 Deg apart just like you would on an engine piston to get a better seal. They'll probably move around anyway. I also found it easier to put the damper rod in from the top of the stanchion so that the tapered bottom edge of the circlip groove compressed those little rings gently into the bore of the stanchion.

[montmil]

... I also found it easier to put the damper rod in from the top of the stanchion so that the tapered bottom edge of the circlip groove compressed those little rings gently into the bore of the stanchion.

This is a very good idea! I have also used two 0.002-inch feeler gauges leafs as insertion guides when refitting damper bits into the fork legs.   Monte  

[Rob Valdez 79 R65]

OK - anyone have a torque figure for tightening the damper rod and the great big allen bolt that goes up the bottom of the fork slider?


How about the same for the fork tube clamp bolts?


Thanks!  [smiley=thumbup.gif]

[Barry]

I confess I didn't use a torque wrench for the bottom Allen bolt. [smiley=embarassed.gif]

For ease of removal next time I just tightened it enough so that it didn't leak. The bolt isn't going anywhere with the wheel spindle in place and an oil leak is going to tell you if it comes loose. I've  done it this way several times and not had a problem. This suggests you could get away with using the low side of any torque values that you find.

I can get figures for the clamp bolts when I get home from work. I know I went on the low side of the reccomendation again. These bolts in alloy always scare me as they seem to keep turning more than I expect before the torque wrench clicks.

[Barry]

OK I'm home after a cold not much above freezing ride in the fog.

The fork yoke clamp bolts are 29.5 - 33 lb/ft

and the bottom allen screws 22 - 29.5 lb/ft

Can't see a figure for the damper piston itself. I Guess it should be a little higher than the bottom allen screw.

[Rob Valdez 79 R65]

Thank you!

[Landlubber]

The allen hex head bolt in the lower fork leg can be remove with an impact driver after compressing as much as possible the whole setup, just push the top of the fork down to your feet, with the legs upside down, then whack with the impact driver.

I have only done this on three bikes, but it worked three times, so I thought I would pass it on.

[montmil]

The allen hex head bolt in the lower fork leg can be remove with an impact driver ...

Just don't re-install it with the impact tool.  Danger, Will Robinson. Danger.

Monte