FF: Forks Girdraulic eccentric shimming method

[Spqreddie]

Hi!
This is the method I am thinking of using to correctly shim the lower Girdraulic link.
I am planning of shimming individually each side alone by simulating the eccendrtic assembly with a shorter nut and bolt, and then assembly the whole togeter afterwords.
Hopefully this would avoid "false readings".
What do you think?
Eddie

 

[Bill Thomas]

Hi!
This is the method I am thinking of using to correctly shim the lower Girdraulic link.
I am planning of shimming individually each side alone by simulating the eccendrtic assembly with a shorter nut and bolt, and then assembly the whole togeter afterwords.
Hopefully this would avoid "false readings".
What do you think?
Eddie View attachment 22127View attachment 22128View attachment 22129

Hello Eddie, Yes good idea, The problem is if the eyes are not true, The eyes are often out of line, In and out and up and down, If they are not right, It could go stiff.
Cheers Bill.

 

[chankly bore]

Also note that the inner faces of the FF8 adjusting stops must be dead flush against the steering column boss, and may therefore need shimming there. Otherwise, as Bill says, once you tighten the nut on the spindle it will pull your eyes out of line and create a Strabismus in the Steering Department.

 

[Spqreddie]

Thank you Bill and Chankly Bore, I will check that, and surely i will need to shim in between the steering stem and the eyes, but in this way i was hoping to get the shimming right in the eccentrics and go with trian and error just for the stering stem. The eccentic bushes are new and hoefully true and inline togheter both side.
Thanks!

 

[Bill Thomas]

Hello Eddie, It's not the bush, It's the link, If it has been damaged.
Try and find a bar that goes through the eccentric bushes and a bar to go through the the other bushes that connect to the fork legs and I hope they line up, They bend very easy !, If someone has used force to try and fit them before. Good Luck, bill.

 

[Spqreddie]

Hello all!
I believe I have find a very good compromise for the shimming of the four spindles.
all the individual components move freely with no noticeable play, and the big washers can be just rotated by hand.
All this whitout lubrication. So I am sure this will even be better when oil or grease will be applied.

Trouble is that when inserting the Steering Stem FF33 into the head clip FF1, they are not perfectly concentric! (the steering stem is slightly too on the left so need to force it a bit to the right to get it in the FF1 hole), so this make the hole assembly a bit stiff. It still falls under its on weight so it's not too bad, and probably when lubricated it will be even better, I believe than that I could leave it as it is but still not ideal.

I have shimmed the stem as much as possible to the right and is a bit better, but not sure if this is the solution. Some of the links might be bent? and this is why the stem is not pointing perfectly vertical?
Or it might be vertical but too on the left as some of the bush too thick and moving all the assembly to one side...?

as suggested above, might need to disassemble everything again and get some bars of the right diameter through the eyes and measure everything for straightness.. :-(

 

[timetraveller]

Hello Spqreddie, I am not sure that I understand what has gone wrong. The only shims in the steering parts are those for the eccentrics. There are no other shims on any of the other spindles. If you take the FF33 and insert it into the bottom of the main steering lug then it should just appear in the middle of the hole at the top of the steering lug. Prior to this the FF36 washer and all parts of the lower cup and cone type bearing will have been placed on the FF33. The upper cup bearing, FT128 should be in place. If the top of FF33 is not in the middle of the top cup bearing then that suggests that some part of the lower bearing is not fitted correctly. Lower the FF33 slightly so that the bearings are loose, but don't fall out, and then see if the top of the FF33 tube is in the middle of the top cup bearing. If it is then, to me, that suggests that at least one part of the lower cup and cone is not properly into its housing.
One other thing to be aware of is that the felt washers, to protect the lower cup and cone, are often/always supplied much too thick. Roughly double the thickness needed. Make sure that felt washer is not causing trouble.
Come back with more information after you have tried that.

 

[Albervin]

I have just spent three months of trying to get a steering head/stem working. Totally impossible when the bearing cup housings are totally shagged and shot. This has led to having the the whole system jigged, mandrel set and bored. The upper bearing cup was "floating" and the lower was loctited and off centre. It was either a matter of poor maintenance or a crash. A lot of fine engineering, a shim and sleeve plus some inventiveness were required to bring all into line. There are no short cuts here as it all has to do what it is supposed to. Amazing that I rode it at 90 mph and it felt fine. But in the slow and twisty roads it was horrible. Next will be the rear suspension ....

 

[Simon Dinsdale]

I had a similar problem with the Girdraulics on my Shadow and it was the top link FF4 which had been machined wrong. End faces of the area where the flanged bronze bush FF6 press in were not machined equally central through the axis in relation to where the link attached to the head clip FF1 thus it tried to throw the fork leg sideways at the top. The top link FF4 was not bent or distorted in any way, just machined wrong which was clear when placing another good link on top of the problem one. To correct it I ended up machining new FF6 bush with different thickness flanges which resulted in the forks all aligning up. It took days to realise what was going on and yes the bike had being run with this error for years by the previous owner and probably like that from new.

 

[Albervin]

The more you learn the more you don't know. Thanks Simon, back to the shed.