41mm forks
BMW used 41mm forks on many of their models from the early '90s. As the parts breakdown shows, the first version (made by Showa) was designed for the '92 R100R and K75 models and adapted for the subsequent F650 models which were introduced up to about 2002. However, BMW sourced a different 41mm fork by Marzocchi for the F650CS. The F650GS and the first iteration of the G650GS continued to use the Showa, but everything else went to the Marzocchi one.
All part numbers start with 31 42. I omitted those from the chart for clarity.
| Showa | Marzocchi | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| K75 R100R |
F650 Funduro/ST |
F650 Dakar 00-07 |
F650GS G650GS to 2010 |
F650CS | G650 Sertao |
F650GS twin |
G650GS 2011-15 |
F700GS | |
| Complete legs | 2 312 829/10 | 2 345 005/6 | 7 676 385/6 | 7 676 381/2 low
8 520 347/8 std |
7 658 557/8 | 7 726 755/61 black |
7 708 911/2 silver |
7 726 773/4 low 7 726 757/8 std |
8 566 585/6 |
| Tube | 2 312 831 651mm |
2 345 376 | 7 660 357 | 7 661 399 | 7 666 222 | 8 521 283 | 7 721 928 | 8 521 282 | ← |
| Slider | 2 312 295/6 | 2 345 377/8 | 7 678 481/2 | ← | 7 666 231/2 | 7 726 759/60 | 7 708 913/4 | ← | 8 566 587/8 |
| Oil seal | 2 312 838 | ← | ← | ← | 7 666 225 | ← | ← | ← | ← |
| Dust seal | 2 312 836 | ← | 7 681 274 | ← | 7 666 223 | ← | ← | ← | ← |
| Bottom bushing | 2 312 847 | ← | 7 659 779* | ← | 7 666 237 | 2 310 346 | ← | ← | ← |
| Top bushing | 2 312 705 | ← | 7 659 780 | ← | 7 666 227 | ← | ← | ← | ← |
| Bottom bolt | 2 312 711
M8x18 |
← | ← | ← | 7 666 240
M10x30 |
← | ← | ← | ← |
| Damper rod | 2 312 707 | 2 345 379 | 7 660 360 | 7 658 887 low
7 655 780 std |
7 666 230 | 8 521 286 | 7 705 922 | 8 521 284 std
8 521 285 low |
← |
| Damper rod ring | 2 312 848 | 2 345 384 | 7 660 365 | ← | 7 666 228 | ← | ← | ← | ← |
| Rec. oil | Type 1 | Type 1 | Type 1 | Type 1 | Type 1 | Type 2 | Type 1 | Type 2 | Type 2 |
* Identical to the previous 847 bushing but three times the cost!
The Showa 836 dust seal is 54mm OD.
The Marzocchi design uses 52mm OD seals which are marked MARZOCCHI.
You might notice that the lower slider bushing for the G650 Sertao has a much earlier part number. This is because it was used on the Marzocchi forks of the 4V K models.
Other 41mm Showa fork tubes include CBR600F3 and VTR1000 (631mm), TDM850 (635mm), and TRX850 (646mm).
