Front suspension hassles

[Guest Gean]

Hi All

Someone out there must have had this problem before.

I sent in my front forks for re-valve & fork seals & it's been downhill from there. It seems ( for whatever reason ) that they added 20 mm to the steel tube inside the shocks and it looks like the springs were grinded down a bit. They felt great initially ( at lower speeds ) but after reaching 180 the bike develps a small tankslapper every time you hit a dip or you jiggle the bars above 180 km/h.

I have pulled out the forks again, checked the fork oil amounts ( 480 ml & 15 WT), grinded off the added bit but the problem persists. I have always had the forks 5 mm above the triple clamp for quicker turn and apart from changing the neck bearings to tapper rollers ( which others have done I believe ) nothing was changed.

Any ideas ?? Could someone please measure the distance between the two triple clamps & let me know. Maybe the new tapper roller bearing has changed the steering angle, but this sounds far fetched ??

Unfortunatly I did all this at once so I?m not sure where I went wrong.

Regards

[Guest Gean]

Come on okes.........any idea at all ??

[Guest alburrows]

Firstly recheck the head bearing tightness, could be overtight or too much play, in case the bearing races have not been pushed fully home on fitting and after a bit of use the outer races have maybe seated further.

Also check the front tyre in case it was has been fitted with the direction of rotation going the wrong way.

fitting taper bearings and the distance between the headclamps will not change steering angle as the angle of the headstock is unchanged, rear shock spacers will, as will dropping the yokes down the forks but if the settings are the same as before they shouldn't be a fault.

[x11r 386]

Another thing to bear in mind Gean , is what are your tyre pressures and when did you last check them ?

[Guest Gean]

Hi Guys

Thanks for the input.........tyres have been on for last 1000 k's so I eliminated them......fork lenghts have also been unchanged for last two years. New screen removed old one put back in case it was this was it. Head race bearings feel nice and loose........no play or binding.

One thing that baffles me.........the people who did the shocks have put 500 ml of shock fluid in......which isnt really a major problem.......but with the shocks fully compressed & the damper rod all the way down ( please help here Eddy, no mention is made if the rod must be up or down and it makes a huge difference to the airgap )the airgap isn't near 164 mm.........even with the extra 50ml from standard the airgap should at least be close..........the airgap is approx 78 mm at the moment !!

Any.........and I mean any ideas as this is driving me crazy !!

[x11r 386]

Gean it sounds like your forks could have messed around with by someone who didn't know what they are doing I would go back to base settings , new springs 10wt oil to the correct amount and see how you go from there , I'm running 500 ml of 15wt oil on standard springs with no preload spacers and I'm not getting any adverse handling problems.

I once tried some ebaic (think that's what there called) and they were awfull caused wallowing etc because they had lowered the ride height.

[Guest Gean]

Thanks a lot.........I noticed the shocks are just over 420 mm long..........standard I believe is 415 mm........Iv'e heard of shocks getting shorter but longer.....not possible.....so I assume they changed the springs as well.

Should just have done the seals myself, hindsight is a b@tch they say......well too late now.

Thanks again !!

Regards

[Guest Gean]

Still scratching my head here.........

Tightened th head race bearings ( everybody said they might be to loose ) untill they had definite resistance and I still have the same problem.........

Have tried to reverse most of the "suspension experts" mods but no luck, its like they forgot something inside the shock !!

[fast_eddy 712]

Have they missed off the oil lock piece from the end of the damper rod?

[Guest Gean]

Hi Eddy

I havent stripped them down all the way........basically just grinded off what I could see they added on the fork tube ( stainless tube ) and drained the oil ( turned them upside down ) to check the oil quantity. I think the only way would be to strip them down and compare notes with fellow X?rs. I have a week to go before our 4000 mile trip and although we wont be traveling at 180 km/h it would be good to know everything is as it was.

I have always done my own small suspension mods on all my bikes i:e spacers, little xtra oil etc and it was the first time I actually used a "professional" for the re-valve, what a f@king disaster.

No doubt I'll be contacting you again

Rgards

[Guest Gean]

Hi Eddy

At long last I found my problem........spoke to an old biker out of desperation and he recalled a similar problem. Apparently the guy who taught him a few tricks used to be involved with racing in Britain and actually appeared as a extra in the movie Silver Dream Racer (Bill Robson)

To make a long story short he re-balanced the front wheel one one of those old stand frames and presto......the vibration & shake was gone and only re-appeared at 215km/h instead of 180. What confused us even more is that the tyres ( Michelin 2CT Roads ) were electronically balanced and nothing came up. He concluded that the tyre probably had an inherent weakness, and distorts at high speed. Why it appeared only after the shocks were done nobody knows. We had a recall on 2CT Powers from France so I'am convinced they have the same problem on the 2CT roads.

By the time you read this I'll be packing like mad and feeling better about the long trip. Thanks to all the guys who threw ideas in, you learn something new everyday even if it doesnt solve your problem.

Regards

Gean

[x11r 386]

Hi Gean , glad you found the problem . I must admit the amount of times I've had tyres balanced and thought that looks like its only doing about 25mph makes you wonder if electronic wheel balencing is worth it as your only relying on the calibration of the balencing m/c being used . A lesson for all of us I think , shame it was such hard work to find the problem

[fast_eddy 712]

Good news Gean... have a good and safe trip and let us know how you get on.