Fork repair procedures are well covered in the BMW repair manuals. The majority of components are common between all the year models and the Dakar and Sertao. See the modifications Section for upgrades. The fitting of emulators to separate compression and rebound circuits and 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 length of the Showa forks on 00-09 model 650GS and Dakar is set by a different damper tube length not a different stanchion length as many of us believed. The Dakar and Sertao rear shock is the same part number
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
The swingarm axle bearings are unsealed and require maintenance or they wear prematurely and can seize. The axle can be difficult to remove if it is left for too long. The pdf here outlines how to add seals to prevent the problems without swingarm modification. Swingarm Bearing Mod
The suspension linkages require maintenance and the bolts are known to bend and in some cases break. At least some bolts are fully threaded and weaker than they should be. The bolts should be checked and replaced.
The bolts are M10x51, M10x65, M12x110 and 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 and the steel inner wear. The top bush is a press fit and 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 and different sprocket sizes. Adjuster pdf
Remove the wheel bearings and 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 and 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.