Fork repair procedures are well covered in BMW repair manuals. The 00-09 models are Showa forks & 10-15 year models are Sachs forks. See the modifications Section for upgrades. Fitting emulators to separate compression & rebound circuits plus enable reduction of spring preload is strongly recommended. The piston rod retaining bolts in the lower fork leg are 10mm on the G Series. (8mm F Series)
The Showa fork length on 00-09 model 650GS & Dakar is set by a different length damper tube, see parts list.
Facory lowering on all year models is done by a different length rear shock & different fork damper tube.
2000 to 2015 Fork Part No List GS Fork Parts.pdf
2000 to 2015 Fork Seal Info Fork Seal pdf
The fork brace is known to crack, during maintenance it is worth checking.
A cracked fork brace will give a less precise feel on the front suspension and increase twisting loads on the axle lugs.
Dual Spark axle lugs are stronger but a little excessive force can crack them. After a fall or during maintenance it is worth inspecting the axle lugs.
The GS and Dakar have different length shock absorbers rather than different linkages.
The lengths (in mm) are: GS 315 - Stroke 47.5, Dakar 326 - Stroke 59.5, Linkage Ratio 3:50
F650GS & G650GS rear shocks are the same Part No 33 53 7 728 374, the 2010+ shock is Sachs not Showa
Dakar & Sertao rear shocks are the same Part No 33 53 7 728 377, the 2010+ shock is Sachs not Showa
The swingarm axle bearings are unsealed & require maintenance or they wear prematurely & can seize. The axle can be difficult to remove if it is left for too long. The pdf outlines how to add seals to prevent problems without swingarm modification. Swingarm Bearing Mod & Linkage Part Info
The suspension linkages require maintenance, the bolts are known to bend & in some cases break. At least some bolts are fully threaded & weaker than they should be. The bolts should be checked & replaced. Part info is in pdf
The bolts are M10x51, M10x65, M12x110 & worthy spares to carry.
The Showa shock absorber on the Dakar is DIY rebuildable, the GS with no remote reservoir requires a suspension specialist to dismantle. A write up on rebuilding the the Dakar shock has been done by PeteHK There is a link in the pdf to the thread at f650 for discussion. Dakar Shock Rebuild pdf
The shock bushes can perish & the steel inner wear. The top bush is a press fit & could be replaced but
no replacement has been found.
Top bush dimensions are 10x20x30mm, Outer steel ring width is 27mm.
Lower bush dimensions, not measured as yet.
Not all F650GS frames have the preload adjuster mount as per the Dakar. Where upgrading a rear shock
a mount may need to be added.
The adjuster is Showa Type B0292 and is rebuildable.
The chain adjuster bolts do not allow the full range of adjustment, the threads can be extended by to allow further adjustment. It is normally only needed with 114 link chains & different sprocket sizes. Adjuster pdf
Remove the wheel bearings & sprocket carrier bearings using blind hole pullers not the bash method. A little heat on the hub or sprocket carrier is also advisable. These steps minimise damage to the hubs.
Blind hole bearing puller sets like the kits above are low cost & fit most motorcycle wheel bearings. When fitting bearings use bearing pullers & a little heat to fit the bearings. Pullers are easy to make without major expense. Thirty percent of bearing failures are due to poor installation.
When replacing the rear sprocket carrier bearings dont forget to remove the circlip behind the inner bearing before removing the outer bearing. The use of a hydraulic press for bearing removal is not recommended.