fork stiction

Taffy · Oct 30, 2007

just seen something that reminds me of a time i went on Tt and explained how you set up the front end of a bike to stop stiction.

wheel spindle through wheel and forks.
compress forks several times and hold down while someone else tightens the pinch screws.

only very lightly tighten the triple clamp/yoke screws because the bushes inside get pinched and early failure results.

you can also shim your front brake so that the pads bind from both sides at exactly the same time. this can be done by careful study of pad wear and then with new pads watch which one contacts the disc first. shim the caliper to even up this contact. you'll find that the brake becomes instant, immediate and very firm. the bike will also free wheel very easily through the paddock!

as a last footnote: when i'm happy that my forks are right i make a note either in my head or on paper where the right fork MUST sit on the pin relative to the end as i don't want to do it everytime i strip the front end!

regards

Taffy

chilledspode · Oct 30, 2007

Taffy,

Do you find over time that the forks take a small set (deflection) ?

By example - With the left leg fixed and the axle tight and the right leg loose on the axle I find when I spin the right fork in the triple clamps you can watch the right axle pinch assembly move left and right.

I have never been able to prove if this is due to the forks taking on a slight bend due to the bike's weight or some other issue. I therefore also mark the outer tubes so I can keep them matched in the triple clamps over time. Every once and awhile I turn the tubes 180deg in the triple clamps for no reason other than it seems the right thing to do.....

Cheers

Mark

nb: Also I nearly got caught by this - with bar risers it is easy to lift the forks too high in the triple clamps and crush the tubes because you have gotten off the thickened tube zone

Taffy · Oct 31, 2007

mark

i think that the forks are very loose even when new bushes are fitted! i check them for roll-out most times it's down and they seem to be ok.....

i just did this to help folks and guage whether they want this kind of mindless unprovoked info!

wasting my time? maybe.

regards

Taffy

chilledspode · Oct 31, 2007

Taffy,

A waste of time - I don't think so. I am nowhere near the depth of experience you have but I have learned a few tricks and I try to pass them on when I think I actually know what I am talking about.....

There is need for people like you to transfer your knowledge to the next crowd - be it the simpler stuff like this one or the more complex ones.

Departing the planet with a life time's worth of knowledge only in yer head is a loss to be avoided.

Finding the time to put it all to paper - that's a big challenge. You have done better at it than most, in my opinion.

Cheers

Mark

KaBooM · Nov 1, 2007

The 2007 and newer WP forks have inconsistances in the DU bushing bore. I have changed out new bushings with good used bushings because the rider complained of fork tube slop. Well, the new bushings just fall into the bore = NOT GOOD!
Even thought the newer forks work a bit better than previous years, the quality check seems to be bypassed, because during assy, the technician would definately see this is an issue.
I add a.500" x .500" x .002" thick shim straight behind the du bushing running parallel with the bike. This does work, but you need to mark the forks on the outer tube with a dimple mark to where the shim is, and then rotate the fork tube to the backside.

Rob

steve · Nov 1, 2007

As Taffy says, make sure the forks are parallel. My method is to tighten the axle on the left, disc sde, then bounce the front end a bit. If action is smooth, tighten right side and you're away. If not, get someone else to bounce whilst you pull the fork in or out , or tap the underside of the tube with soft hammer, lump of wood, until the fork is correctly positioned and then tighten.

Also make sure that the lower triple clamps are torqured to spec, and no more, else the bush will be crushed and stiction increases. The 07s only use 12nm which can be a challenge for many torque wrenches as it is often outside their normal range.

I recall hearing about the testing and setup of the then new Oz works Yam R6s at Eastern Ck a couple of years ago. Riders complained of lack of feel in front end. No other change was made other than reducing the torque in the lower clamp from 16, progressively to 10 nm, I think, or what ever the spec on the Ohlins kit fitted said. The last 2 nm reduction resulted in lap time coming down by almost a second and riders now feeling the tyre.

Set then to spec with a calibrated torque wrench to reduce bush ware and stiction and get the flex right.

Steve

Search

Search

fork stiction

Taffy

chilledspode

Taffy

chilledspode

KaBooM

steve

Similar threads

Register CTA

Recent Discussions

Recent Discussions