Hi guys, I need clarification on the damping adjustment on the stock 84-85 FJ forks. I see a slotted screw on the fork caps and as I understand it this adjusts the damping. Is this compression or rebound damping? There seems to be 3 positions which are not really marked on the fork tube anywhere. How can I tell what is low, medium and high, just by riding it? Thanks a bunch!
The slotted part is rebound , has three dots for the three settings, the hex section where the slot is , is for preload, and that's what the marks are for on the upper section under the plastic cap, if fitted,, id you look closely at the upper marks they are three different sizes, that refers to the soft medium hard of the comp damping
If it is like the 86/87 then you have 2 adjustments. A slot and a hex, pre-load and damp. The slot is Damp, Hex is pre-load if I remember. After the RPM upgrade my forks are no longer stock.... Look at the dots, 1 is low, 2 is medium, 3 is max... I like my new set up, RPM valves, damp is perfect for how I ride, and pre-load is still adjustable...
OK, so I definitely see there is a 3 position spring preload adjuster with the hex, but I'm still not clear on the rebound damping adjuster. That should be with the slot screw inside the hex right? My problem is when the slot turns it has several detents but no markings to tell me what is high or low damping. If I continue to turn the screw it is obviously just cycling between several settings. Any idea on how to set it to the lowest setting?
Quote from: Heliflyer 88 on August 19, 2013, 09:13:21 PM
OK, so I definitely see there is a 3 position spring preload adjuster with the hex, but I'm still not clear on the rebound damping adjuster. That should be with the slot screw inside the hex right? My problem is when the slot turns it has several detents but no markings to tell me what is high or low damping. If I continue to turn the screw it is obviously just cycling between several settings. Any idea on how to set it to the lowest setting?
They are consistent with the dots....
There is a small center punch dot on the "dampening" adjustment of the forks. The dots should detent to the 12 o'clock, 4 o'clock and 8 o'clock position.
12 is considered the #1 softest setting
4 is the medium or #2
8 is the hard setting or #3
Now, if anyone has ever been into the forks, and they did not get assembled correctly with the damper rod on the indexing screw, the marks will not line up with the indicated settings.
I find on 98% of the forks I build they are not indexed correctly and you will have no idea which setting they are set to.
This adjustment is for dampening only and they is no adjustment for the rebound of the fork.
Randy - RPM
Ahh yes damping, , I should of ,,, just followed the post :dash1:
Rebound damping is adjustable, compression damping is fixed...... On the forks and the shock.
Damping is correct, and I do believe on the FJ it is a rebound adjustment, although the fluid passes back and forth through a small hole which does affect the compression some.
As I recall, use the oil weight to alter compression damping, the adjustment is for rebound damping.
That is correct, I wrote it down wrong...my fingers weren't following my thoughts.
The dampening adjustment is the oil control so the slider doesn't just bang open due to the increased spring pressure of the compression stroke. The spring is the only compression control of the stock FJ fork, thus the reason everyone adds heavier springs to control the movement.
Oil weight does have a lot do do with the compression rate of the forks as well as the differing viscosity ranges control the movement speed of the slider.
Until now...that is.
Remember, the RPM fork valve converts the stock forks to have a fluid control on both the compression and rebound. The addition of the RPM fork valve adds the shim stack to the fork to control the compression movement and not solely relying on the spring as the fork was originally designed.
The RPM fork valve has taken that early 80's technology and brought it current with patented technology.
Randy - RPM
The holes in the sides of the damping rod control compression, the holes at the top of the rod control rebound, neither does the job well, but they do the job... I've been wrenching on bikes since 1977, I've learned a bit about how the suspension works. 1st bike I owned with cartidge valves was my '90 YZ250WRA, all the rest are Damper Rod, I've tuned a few and rebuilt a LOT of them.