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BMW S1000RR fork seal repair

stever

stever

Active member
Joined
May 31, 2016
Location
Vacaville
Moto(s)
2002 RC51 2007 CBR600RR sold1982 CB750F long term project?
Name
Steve
Since retirement Ive been doing a lot of fork work mostly seals with a few race tech valves and emulator kits and Ohlins cartridge swaps. So took on a S1000RR fork seal job. Customer supplied seals and BMW type 2 fork oil. Right fork have spring preload adjuster only but there is a cartridge inside. The left has the DDC electric damping control. I saw removing the DDC was going to be problematic. I downloaded a pdf manual supposed to be for the bike but doesn't address disassembly of the DDC side. So proceeding slowly I was able to remove the cap without damaging the wires. Online searches keep coming up with conflicting info as to the fork oil type and amounts. one says DDC cartridge is sealed and smaller amount of oil for internal fork lubrication. Another suggest 350ml per side which seems crazy as its a 45mm tube and even 43 Showa forks hold around 450 to 500ml per leg. Anyone have experience and accurate info on this?
 
what year
 
2022 with Marzocchi forks. I found a couple had posted that it should take 7.5wt at about 600ml. I just put 560n in the rt fork and its still a long way fro 90mm air gap if that's even correct. Also fork leg says K67.
 
Did you measure how much oil you removed from the fork tube?
 
Only drained right side and it. was the leaking side. I can check the DDC fork as I've only removed cap. Apparently that is a sealed cartridge as I got about 50ml out. of that side.
 
FRONT
  • OEM: Marzocchi 45mm Open Cartridge (26 / 14 ) -USD
  • Std Spring Rate (N): 9.9
  • Preload (mm): -
  • Unladen Sag (mm): -
  • Laden Sag (mm): -
  • Oil Viscosity (wt): 5.0
  • Air Gap / Oil Volume: Left: 120 cc / Right: 420 cc
  • Length: 755.000
  • Stroke: 120.000
  • Compression Clicker: -
  • Rebound Clicker: -

this is what i see for the 2022
 
Yep, that's the part number for BMW type 2 which is what my guy supplied. Chris your numbers make sense as the left has a very small area above the cartridge for the air gap. Also one post had an air gap of 195MM which I think would align with the 420cc of fluid. I think I'll go with these. Do you know if the cartridge in the right side has a shim valve arrangement or is it a damper rod inside the cart sleeve? I feel damping only on compression so may have a compression base valve. Thanks for the quick reply, I'm in my shop doing this as we speak so nice for timely reply. (y)(y)
 
I don’t have time to confirm but this is what came up

The 2022 BMW S1000RR uses a **closed-cartridge** fork system, not a damper rod system. It features a true valve arrangement where the damping is controlled by oil being forced through shim stacks (valves) rather than flowing around a rod.

In this setup, there is a separate damping chamber within the cartridge sleeve. The "compression base valve" you suspect is indeed present; the compression damping is typically handled by a valve located at the bottom of the cartridge (the base valve), while the rebound damping is handled by a valve at the top of the cartridge.

If you are feeling damping only on compression and very little to no resistance on the rebound, it is unlikely to be a design characteristic of the valve arrangement. Instead, it usually indicates a mechanical failure or a setup issue, such as:

* **Air in the cartridges:** If air has entered the damping chamber (cavitation), the rebound circuit may lose its prime, leading to a "bouncy" feeling with no rebound control.
* **Blown seals:** A failed internal seal can allow oil to bypass the rebound valve.
* **Incorrect oil level:** Low fork oil can lead to inconsistent damping and air ingestion.
* **Rebound adjustment:** Ensure the rebound clickers are not accidentally backed all the way out (fully open).

Because this is a closed-cartridge system, you cannot simply "bend a rod" or adjust a shim without dismantling the cartridge. If the rebound is missing, the fork likely requires a bleed to remove air or a full rebuild of the cartridge internals.
 
I notice the lack of rebound only on the right fork which is the non DDC side. It has a spring preload adjuster only. The left fork which I'm sure has both rebound and compression based on what I saw when Dave Moss was setting up DDC Beemers at the track, can't be stroked thru its travel to bleed as its sealed and inoperative unless plugged in with ignition on. The first time I tried to set sag on one of these I couldn't figure out what was going on until I turned the ignition on. It's to me, a weird system but It seems to be really effective for most riders but Dave noted the racers preferred a manual system which has finer tuning. So I expect the right side is fine but was curious if it was a shim setup. I've had a wide variety of forks apart over the last ten years or so and it's surprising what some manufacturers put in their forks. Gold Wings last I checked had a cartridge in one side and damper rod in the other. Also I had a V-Rod fork apart and same setup. Of course it was a Showa so that's likely in lots of bikes. The real challenge I faced was a Suzuki cruiser that customer had RaceTech fork springs for. Popped the cap and was looking at an upside down damper rod set up. No way to remove and replace the spring. Had to remove the axle mount from the bottom of the fork to replace the spring and take a guess a preload spacer but he came back with big smile now bike was much sharper handling.
Back to the Beemer, I think what they have here is a compression valve in the right side with a fixed setup and leave the finer tuning for the DDC side.
 
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