Death wobble & Bearing #

BelgiqueBasterd · Oct 16, 2006

Just got my 2002 650 supermotard, i've been having a bit of a problem with a death wobble when i'm flat out in 5th and 6th gear. This doesn't happen on smooth asphalt roads, but only on rough concrete roads.

The previous owner set the suspension on max wherever he could, but i have now reset all to the original factory supermoto settings, but to no avail, the problem is still here.

Somebody on a local supermoto forum suggested, that I tighten the bearings in the tripple clamps (don't know the english word for this), I have done that, but noticed that the handlebars don't turn smoothly anymore, they make a very faint grinding noise (i didn't overtightened the bearings) so I'm changing them out, wich leads me to my question, does anyone know the Bearing numbers? The husa numbers are 130 019-01, but i'd like the bearing numbers so that i can order them outside the husa dealer and get them cheaper directly from my SKF bearing dealer.

Why don't I open up the clamps myself and look for the numbers, well I'm just lazy

If anybody has some other suggestion to remedy this death wobble other than a steering damper, i'd be happy to hear it.

Simon · Oct 16, 2006

Hello BB,

And welcome.

Well whoever told you to tighten the bearings should have their motard taken away from them and crushed, possibly with them on the bloody bike - that is possibly the most stupid thing I have ever heard (unless the bearings were loose in the first place, of course).

When you say a death wobble do you actually mean it's slapping from side to side or weaving?

I have found that the worst times for slapping are when the suspension has too much rebound damping - either front or rear and WP had a habit of letting their units go from the factory with far far too much of it!

As I'm sure you're aware it can be caused by a multitude of things and here's a helping hand in the right direction:

1. put a cable tie around the front fork stanchion and take it for a ride along the roads you have trouble with. When you get home have a look to see where it has ended up. If it is right at the bottom of the fork you've probably got an issue with the rebound damping. If it is still high, you'r not getting enough travel. Alternatively, push down on the front and if it comes up slowly there's too much rebound damping.

2. Check the rear sag very carefully. Then lean on the bike to push it down and then let it go - it should back up readily. If not wind off the rebound damping.

3. check your tyre pressures.

Then let us know how you get on....

Simon

jzfe · Oct 16, 2006

Mine did that with too much sag out back. After proper set-up, never again.

BelgiqueBasterd · Oct 16, 2006

Thanks for the reply, could anyone explain to me what sag exactly is, I speak dutch normally and don't understand what you mean with sag. Is it the compression or rebound damping or is it something else completely?
I'll play with the settings a bit and also try your zip tie method, and keep you guys posted on how it works out.

About the bearings, the bearing retainer nut was only hand tightened and the front end could very easily be turned from side to side. I checked the husa owners manual and they state that there should be some resistance when moving the handlebars from left to right, so i tightened the nut until i got some resistance (just a litlle and that's when i felt the problem with the bearings), didn't have time for a test drive today, but we'll see tomorrow. So don't crush the guy just yet as i think he had a valid point with the bearings

.

Thanks again for the tips!

jzfe · Oct 16, 2006

It's in the "owner's doc", basically it is the pre-load on the rear spring. The suspension should travel 90-105mm from full droop with rider and gear sitting on the bike stationary.

Taffy · Oct 16, 2006

yours is the last year before they uprated the wheel spindle sizes. you DESPERATELY need to go to the larger spindles for strength. you can buy the alloy 'foot' of each leg seperate, then you needa different spindle, niut, bearings and bearing spacer as well as one if not two oil seals.

that's the front.

then on the rear - the same! you need two larger bearings and the spacer as well as sorting out the external wheel spacers (two) and also the adjuster blocks and the spindle and nut itself.

regards

Taffy

supertireguy · Oct 17, 2006

I think the Dutch word for sag is verzak.

Another comparable Dutch word for rear suspension sag or (slump) is ineenstorting.

Rear sag is distance between the rear wheel and the frame of the bike when the rear wheel is off the ground versus when the rear wheel is on the ground.

Your rear suspension has a recommend amount of sag. This can be adjusted by increasing or decreasing the amount of pre-load on the rear spring.

BelgiqueBasterd · Oct 20, 2006

Problem solved!!! Tigtened the front end bearings (retainer nut was only hand tightened) and set the suspension back to the factory settings, problem solved, she runs like a train on rails now

I never tought that those little thingies on the suspension mattered so much,

@ taffy, how can I be sure that i have the old setup? I've read somewhere on this site that the old axle bolt is 20mm and the newer versions are 26mm, mine has 26mm axles so maybe i already have the updated stuff, is there another way of checking?

Thanks.

Taffy · Oct 20, 2006

i'll check mine out sometime but there are others here that could do the stats straight off like joe. joe?

regards

taffy

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Death wobble & Bearing #

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