Fork oil level (not the normal newbie 'how much' question)

[cay]

Conventional wisdom says that fork oil should end up 140 mm (~ 5.5 inches) from the top of compressed, spring-less forks.  Is that to be measured from the bottom of the fork cap threads or from the top of the fork tube?  It's only a 25 mm difference, but it'd be good to know for next time.

Considering how dainty the stock springs are compared to progressive springs, do we need to stop and reconsider this value?  Progressive springs (especially if you install them tightly-wound end first to reduce spring noise as discussed in the product literature) will displace more oil...  or is that 140 mm value specifically for progressive springs?

If I had a better set-up in my garage (or if googling for an equation for the volume of a coil didn't fail me) I'd settle this -- but barring any actual work on my part, what do you folks think?

One more mostly unrelated question -- when draining the oil from my right fork (rider perspective) the discarded oil was a lightweight kaluha-coloured oil (no red tint at all), while the left fork contained a heavier-seeming cranberry-coloured oil.  Do they ever use two different colours of fork oil at the factory or is it likely the previous owner broke a seal and had to replace the oil?  The bike (2002) only had 2800 miles on it when I bought it.

take care,

C

[crash]

i took "top" to mean the edge.

i used 140mm air pockets and inserted the springs tight-end down.  works ok for me, but i'm a pretty heavy guy (~200lb)

oh yeah, 140mm is for progressives (per the instructions);  for stock springs, the air pocket is 99mm.

[VersOne]

I've been wondering the same thing ever since I got my progressive springs.
140mm is also what I have been told. They displace more oil. Use this measurment as a starting point and then ride it around.

This might not sound very scientific...but if they bottom out too much bring the oil up. If your getting beat up...bring the oil level down.  Part of this is purely subjective and varies depending on your weight.

Jonah

[cay]

Thanks for the insight, folks.

Since I'm a light guy I decided to leave a little (20 mm or so) extra headroom, but it didn't seem to have much effect -- I really like how confident  the bike feels in turns, but it really isn't absorbing much in terms of bumps.  I find myself paying a lot more attention to the ground immediately in front of my bike.

Should I decrease the fork oil level a bit more or shave 5-8 mm off of my (1 inch schedule 40 end cap) spacers?  The progressive instructions said to use a 0.75 inch spacer.

C

[VersOne]

I could be totally wrong here...but I think your spacers are just for preload...which should affect rebound mostly.

Somebody please correct me...

Jonah

[BUZZIN]

I could be totally wrong here...but I think your spacers are just for preload...which should affect rebound mostly.

Somebody please correct me...

Jonah

[/size]

I think that you may be wrong.  Increasing spacer length adds pre-load which should affect compression.  The rebound spring and damper rod should affect the rebound characteristics.

[VersOne]

thanks...I wasn't even close

[werase643]

spring pre load affects sag
that is all
no effect on rate of fork travel...compression/rebound