All BMW rear shocks and most fronts, can be rebuilt. The trick is re-charging them with nitrogen. To do this I drill and tap a 5 mm hole for a small nitrogen valve into the body of the shock.
Most but not all the front shocks can be rebuilt. The close up photo of the black spring and chrome shaft shows the cap on the body of a rebuild-able front shock. If the body is welded to the cap or if it’s bent over the cap, we are out of luck.
$290 each to rebuild.
A stronger spring with less pre-load will keep you in the upper/faster moving part of the suspensions travel more of the time. Less pre-load will mean less wiggle after turns and bumps because there is less stored energy.
Front springs are $125 + $40 for a spacer. Rear springs are $125 or $135, about half of them will need a $40 spacer.
Re-valving adds $100 to the rebuild price.
WP shocks have a strong spring but poor valving.
Sacahs shocks need a new seal head for the rebuild, about $60.
ESA Shocks
The same as normal shocks except: You must back off the pre-load and damping before un-plugging the shock from the bike. Set everything to the soft/weak setting.
Sacahs ESA shocks are not cost effective to rebuild.
If you want to or need to replace your shock a Penske E or Penske Two Way is best. Please check out my Penske page.