1986 Fork problem, please help

[xnr]

Hi guys, this is my first posting here.

Setup: I drive a '86 1XJ, 30000 miles. The Anti Dive Unit is removed and the port is covered and a progressive Fork Spring is installed. I did not change the Fork oil yet.

Problem: The front suspension does not work properly on fast thrusts like potholes, i.e. its way too stiff. Also I could not adjust the damping at the right fork.

What I did: I removed the Forks and recognized that there is something wrong with the right one. When I tried to compress it by hand it was very stiff and there was like a cracking noise inside.
I disassambled the Fork and everything was in its right place. For me there was no major damage at any parts. Only the Damper Adjust Rod (see attatchment Fork Assembly: Part Number 4) was bent. (See Attatchment: Damper Rod)

Anyone an idea how to deal with that? Could the Damper Rod be the reason for the disfunction? Is it enough to try to straighten the Rod?

Thanks for your Help,
Felix.

[red]

Hi guys, this is my first posting here.
Setup: I drive a '86 1XJ, 30000 miles. The Anti Dive Unit is removed and the port is covered and a progressive Fork Spring is installed. I did not change the Fork oil yet.
Problem: The front suspension does not work properly on fast thrusts like potholes, i.e. its way too stiff. Also I could not adjust the damping at the right fork.
Thanks for your Help,
Felix.

Felix,

Welcome to the FJ sandbox!  Relax and be among friends.

How did you cover the opening for the Anti-Dive units?  There must be an oil passage inside the plate connecting the top and bottom holes.  A flat plate (with no oil passage) will cause your problem.  You want something like this:

[red]

Felix,

If you do not have the right cover plates for the Anti-Dive unit holes, you can simply use the old Anti-Dive units with no hydraulic hoses connected, to provide the oil passage needed for now.  Some riders turn the A-D units upside down, to make a somewhat better appearance.  The old A-D units will not leak, with or without hoses attached.

[woodcreekpete]

Looking at the bend in the damper rod, I'd say that it wasn't in the damper but likely down the side between the damper and the spring. Straighten it out and re-install it, being careful to keep it centered inside the spring as it goes in. It should go into the damper with no force required. When you figure it's in right, try turning the damper adjuster in the cap - it should turn smoothly and the spring shouldn't move at all.

[xnr]

How did you cover the opening for the Anti-Dive units?  There must be an oil passage inside the plate connecting the top and bottom holes.  A flat plate (with no oil passage) will cause your problem.

Hi red, thanks!
My cover plates are flat and do not have a oil passage, see attachment. I bought it like this and do not have the old AD-Unit. I will take a look for the correct ones.
But anyway, the same plate is installed at the other fork which is operating fine.

Looking at the bend in the damper rod, I'd say that it wasn't in the damper but likely down the side between the damper and the spring. Straighten it out and re-install it, being careful to keep it centered inside the spring as it goes in. It should go into the damper with no force required. When you figure it's in right, try turning the damper adjuster in the cap - it should turn smoothly and the spring shouldn't move at all.

I guessed as well that this was the reason I couldnt adjust the damping by turning the rod.


I will try to find and install the correct plates and straighten the rod, thank you guys!

[Motofun]

That cover plate can be fixed with a little drill work.  Drill an axial hole down the through the body, underneath the o-rings (no need to go all the way to the bottom).  Drill through the center of the o-rings to tap into the axial hole.  Plug the entrance of the axial hole...voila.
Failing that, I happen to have 2 proper block off plates on my old FJ1100 forks that are sitting unused and can ship to a needy fellow FJ'er if required.  May need new o-rings.

[xnr]

Plug the entrance of the axial hole...voila.

How would you block the hole? Could I just cut a thread into it and put in a screw with an O-Ring?
Or is Epoxy oil-resistent?

[FJ_Hooligan]

You can bypass the A/D circuit by drilling 2 holes in the damper rod above the "step" where the tapered spindle seats.

Tapered spindle = #20 Oil Lockpiece in your parts diagram

Then you can continue to use the undrilled block off plates

[xnr]

You can bypass the A/D circuit by drilling 2 holes in the damper rod above the "step" where the tapered spindle seats.

You mean at the red circle ?

I already drilled the blocking Plates but hit the seats of the O-rings as you can see. I try to use them and will see if it leaks.

[T Legg]

I'm no expert on this at all but one of my 84 FJ's has flat block off plates and I have therefore assumed the damper rods have been drilled. I had a conversation with Robert from RPM about installing fork cartridges and if I remember correctly having the rods drilled will affect the function of the aftermarket cartridges. It would be best to ask Robert about that he knows what he is talking about and I don't .

[red]

How would you block the hole? Could I just cut a thread into it and put in a screw with an O-Ring?  Or is Epoxy oil-resistent?

xnr,

Epoxy  (when fully set) is impervious to oil.  

You could just use a small self-tapping screw, with an O-ring under the head.  Use a slightly larger drill bit at the entrance to the hole, to create some space for the O-ring.  It probably won't leak, but you can install the screw with RTV and be sure.

[RPM - Robert]

The fork valves wont work properly with the anti unit in the original capacity. But if you bypass the unit either with block off plates that flow or by drilling the rod as Dave suggested, they should work properly. (Well will work properly with the ported block off plates.)

[xnr]

Hi guys,
I reassembled the forks and used new ported blocking plates and straightened the rods. Everything works fine now!

[fj1289]

Hi guys,
I reassembled the forks and used new ported blocking plates and straightened the rods. Everything works fine now!

Excellent!  Thanks for the feedback on what got it fixed - that'll help someone in the future!

Enjoy the Kookaloo