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Yesterday I changed the fork oil seals and oil to prepare the bike for the track. Current oil was 23.000km old.

This was my approach to rebuild the DDC forks, using only the racetech compressor without special tools:

With both forks, I had the same approach: undo the fork cap, and remove the lower allen bolt to remove the entire cartridge. This makes changing the seals very easy.

However, the service manual suggests you should measure the air chamber with only the damper part of the cartridge in the fork, so I dissassembled both cartridges. The DDC unit is easy, I could put a wrench directly between the spring to undo the cartridge cap. Then the whole cartride disassembles. Put the DDC unit back in the fork leg with the new seals, add oil, bleed and measure air chamber. Around 250cc goes in the fork leg, air chamber was 85mm according to the book, decided to follow dave moss advice and put in 90mm.

The right fork leg was terrible. With the cartridge removed, the cartridge can be disassembled in the racetech compressor. I put a PVC pipe over the spring since it now jumps in all directions while compressing. The damper from the cartridge is then placed in the fork, the air chamber is measured again, decided to go with 100mm.

Now comes the horror. When assembling the cartridge, i placed the plastic spacer in the leg, and compressed the cartridge by putting the pins of the racetech compressor on top of the plastic spacer. The holes in the spacer are very low and require a special tool from BMW which I did not had.

I had put a zip tie on the rebound rod so i could locate it (it falls very far down in the fork leg), and then I pulled the zip tie up, placed a wrench under the rebound rod nut so i could mount the cartridge cap. Very tricky. I had a friend of my pull the zip tie up, while i did the nut.

Then uncompressing the cartridge, the pins of the compressor tool were stuck by the force of the spring. Came out by very carefully undoing it while putting pressure on the spring.

After that it was done, very tricky without the special tool. It can be done without, but I could not have done it by myself, I needed an extra pair of hands.

Hope this helps other guys in the same process.
 

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To build that tool would be easy in comparison. There's industrial extrusions that can be used for the main frame, then it's just machining the small bits.

item international
Hey mate, my Father-in-law can make it but needs a few measurements if you can, on this picture:
A - distance between bracket
B - length of little arm
C - width of little arm
D - length of peg
E - diameter of peg

in mm if you can!
 

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OK, so I had some time to dig the tool out.

A 55mm
B 25 mm center to center
C 12 mm
D 4 mm
E 7.82 mm

Note that the knurled adjusters bring the pins in to mate with the holes in the part, the little arms are held by circlips on the threaded adjusters.. Also, you need BMW tool 83 30 2 350 286 ( a split collar machined to the pitch of the spring) to compress the spring.

Good luck!
 

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OK, so I had some time to dig the tool out.

A 55mm
B 25 mm center to center
C 12 mm
D 4 mm
E 7.82 mm

Note that the knurled adjusters bring the pins in to mate with the holes in the part, the little arms are held by circlips on the threaded adjusters.. Also, you need BMW tool 83 30 2 350 286 ( a split collar machined to the pitch of the spring) to compress the spring.

Good luck!
Thanks very much mate, really appreciate it.

Sent by Shoephone using Tapatoe
 

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err, thread revive, so is BMW's 11.5wt oil same as other 11.5wt oils? wasnt someone going to check and post the "cSt @ 40C" thingy?
 
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