Chi
10-15-03, 02:45 PM
How much oil is needed for servicing? The manual calls for 5w light weight oil but doesn't specify how much. Anyone know?
Bicycle Mechanics - Rock Shox Mag 21
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BAC5.2
10-15-03, 03:35 PM
Same amount you take out of the fork.
Rev.Chuck
10-15-03, 03:53 PM
<140lbs, 40-45mm 38-42psi 5wt
140-180lbs, 35-40mm 40-45psi 5wt
>180lbs, 30-35mm 42-50psi 8wt
The oil is measured from the top of the leg with the slider fully compressed. Cycle it a couple of times and recheck to make sure there is no air below the damping valve. Use a little more oil to make the fork ramp up faster.
140-180lbs, 35-40mm 40-45psi 5wt
>180lbs, 30-35mm 42-50psi 8wt
The oil is measured from the top of the leg with the slider fully compressed. Cycle it a couple of times and recheck to make sure there is no air below the damping valve. Use a little more oil to make the fork ramp up faster.
Stubacca
10-15-03, 03:57 PM
Chi, this link (http://www.math.chalmers.se/~olahe/Bike/Front/rsmag.html) should provide you with some decent servicing tips, including oil level adjustment for the fork.
Chi
10-15-03, 07:17 PM
Thanks Rev and booyah for your help. My friend is trying to fix his Mag21 that's too stiff. He thinks he may have installed a valve the wrong way the first time he changed the oil (long time ago) but he isn't sure.
Rev.Chuck
10-15-03, 08:43 PM
Sometimes to get good action on mags I had to add a "valve" to the damping piston with a drill. Booyahs link may help with this.
If your friend is a big guy using a lot of psi run the oil at 30mm and use 8 or 10wt. This will let you run a lower psi. These forks were known for seal stiction esp. at higher pressures.
If your friend is a big guy using a lot of psi run the oil at 30mm and use 8 or 10wt. This will let you run a lower psi. These forks were known for seal stiction esp. at higher pressures.
Chi
10-15-03, 08:51 PM
He's a lightweight ... around 140 lbs. I think he might need to change some bushings too. Dunno.
Rev.Chuck
10-15-03, 09:16 PM
He should be careful with that fork, the museum may want it back :D
It sounds like he need to increase the fluid flow thru the damping plate. There is a 2.5wt oil this might quicken his fork without having to make any permanent changes.
It sounds like he need to increase the fluid flow thru the damping plate. There is a 2.5wt oil this might quicken his fork without having to make any permanent changes.
Chi
10-15-03, 09:22 PM
....... I'm hoping he'll register and start blurting out comments anytime now .....