Bill McMahon

The cast aluminum axle clamp is essentially a cup with internal threads in it to secure itself and the lower slider together. There is a bolt that goes through the bottom of it but it is only there to secure the damper assembly (the damper works like a steering damper, with one end secured to the axle clamp and the other secured to the top fork cap/preload adj. assembly).

When the thin walled lower slider flexes under braking, it becomes egg shaped. This would also stress and distort the round shape of the cast aluminum axle clamp where the two thread together. As the two parts are distorted, the threads are stressed and I can see how after many cycles of this occouring the threads would be beat to the point that the lower slider could come loose (if the stress cycles hadn't caused the lower slider to fracture first).

With the sleeve installed the lower slider can't flex (as the sleeve goes all the way down into the bottom of the axle clamp where the lower slider bottoms out) and therefore can't be distorted in shape to put stress on the axleclamp and eventually cause it to fail. The sleeve addresses both issues.

T-NECK

never got it

Bill McMahon

I think initially they would have been threaded all the way down and secured with the set screw, but as they flex they just work loose over time. Good looking out Roger, as long as we can keep them tight we can keep them safe.

Bill McMahon

Sorry, I started to send it and got tied up.

Greg Mcglynn

got all of that bill thanks for the explanation. Seems pretty full proof to me.
what a relief this is.

your gonna be rich dude. Everyone is gonna send you there forks. I know I am.

Paul

I see how that insert will reinforce the fork tube in the problem spot,but will it just move the weak point further up the slider and break above the insert,or is the problem just because of the way the fork bottoms attach and not due to a weak or brittle slider material?

Jaket

I think the smooth part of the slider cannot break, the slider breaks because it has threads which weakens the bottom.

The fork getting loose could be the first sign that the metal is starting to give. When it's just tightened, it can still go when it's tight..

I think this sleeve is good idea. It can still work loose, but it's probably lot safer for the driver.?

I think the sleeve needs to be quite thin, so it doesn't interfere with the spring. and also it's good that it has some flex so it devides the forces and doesn't create pressure point where it ends.

Also when bike is doing endo the fork is almoust completely compressed, then this sleev is inside the top part and it's solid.

Bill McMahon

The lower slider is 22" long, the upper slider is over 20" long. If you could measure from where the lower slider sits when it is bottomed out in the axle clamp you'd get almost 28". When the two pieces are assebled The two tubes overlap eachother almost entirely except for the 5" of suspension travel. The insert is 10.5" long. is extends nearly 4" into the upper tube when the fork has no load on it. the sleeve is a permanent part of the lower axle clamp and slider assembly at this point. As the lower slider moves into the upper when being compressed, the length of the insert shouded by the upper tube increases with the travel of the fork. Not only is the lower tube supported by the upper tube above the insert, but the upper tube is supported by the lower triple clamp. There is only a few inches between the top of the sleeve and the portion of the upper slider supported by the lower triple.

To make a short answer long the area of lower fork tube above the sleeve will not be a potential break point because it is too well reinforced by the upper slider which is being reinforced by the lower triple. The forks were braking in the first place because over the several inches that the lower tube was not shrouded by the upper during a stoppie they were distorting in shape under load due to a combination of a thin diameter lower tube (nearly two mm smaller than other inverted forks available) and a thin wall thickness. By reinforcing the lower tube we are stopping it from distorting in shape under load which was causing the axleclamp to distort and eventually compromising the threads or simply breaking the lower slider after enough stress cycles.






The sleeve resides underneath the damper coments. It never comes in contact with anything except the inside diameter of the lower tube, whether the fork is at rest or fully compressed. The sleeve could have actually have been made thicker but added too much unnesscessary weight and I deemed over-kill. In it's current incarnation the sleeve is still stronger than it needs to be (something I shoot for with everything Fullthrottle builds) while not adding enough weight to be significant.

fatboystuntz

im assuming that on my spare set of forks my left bottom is starting to leakin, which means the stuctural integrity is starting to break down, and wpretty worthless to get this done correct??

if so i will just look for a 05-06 set and have them done

Bill McMahon

Sorry Paul, I failed to address the last part of your question. In regards to the way the fork bottoms/axle clamps attach, they just thread in and seal the tube at the end with an o-ring. There is a redundant set screw in the side in the KYB forks, but otherwise they are the same across the board between KYB and Showa. I think the only reason you see these forks failing and not others is because as I mentioned, these forks are the longest available and they use the thinnest diameter lower slider with the thinnest wall available. Other forks (like the 929/954) have a lower tube with nearly as thin of a side wall, but the the diameter of the lower tube is larger which adds alot of strength and the length is shorter which reduces the stress that it has to handle.

Paul

Gotcha I didn't realize that the insert extends that far up that it actually rienforces the whole lower slider not just the fork bottoms.That should make for one hell of a set of forks!Definately wont have to worry about breaking that!Nice job and thank's for the response.:YEAH

Bill McMahon

Another option would be to replace the lower slider and axleclamp with one from the dealership. I called on it, retail is nearly $400 on that part. It would be a close race between which is cheapest, that part or a set of used forks.

Bill McMahon

Exactly. In the picture I'm holding the end of the tape measure where the lowertube and sleeve bottom in the axle clamp. As the sleeve is 10.5 inches long, so even when the forks are off the bike it still goes several inches into the upper slider.

fatboystuntz

yea it would be close..i think i can find a set of forks for a bit cheaper...and see what cost is on that part form my dealer...either way i am goin to be sending you a set of forks on the near future

glingglo

Are the UK and European bikes made in the same factory? as iv never heard anyone snapping them over here!?! just a thought as some of the guys have been using them in europe since 03!

Anyone know if they are all japan imports or assembled locally as your 03 has a different model name to mine!?

Stubbz

what if you were to take apart the stock forks before getting them too far into stunting and add some thread lock to the lower section versus doing this right away, i took my front wheel off just to check that set screw and mine was corroded in there and wasn't moving at all, but at the same time i have been thinking a lot about just getting a set of 07 zx6r forks cuz i dont want to take the chance, but maybe instead of doing that it'd be cheaper to do this to my stock 03 636 forks because they only have 7K miles on um and basically all street stuntin miles for past 1K or so, before that i think it was rode by a kid that couldn't get the front wheel up let alone stunt it

Big R 508

awesome , one more thing I m wondering 05 R1 will just work on 636 triples tree to just slide in and tight it up ?

of course it has to be with wheel , rotors and brake caliper.

Tomi_k

I haven't heard of broken forks yet in europe. My forks are leaking from the threads, so i quess they are weakening. And i'm going to get my forks done with this mod.

DURTY

i had my 04 forks for 2 seasons didnt snap.................

can someone post a pic of were they snap and is the problem that the threading strips loose???

old man roger

durty every thing you asked for has been covered in this thread go back and start at the beginning