Hi all
A couple of days ago I put a new head set bearing kit on my 1990. This has stopped the front end chattering under hard braking, and improved handling noticeably. However I noticed today that under engine braking the handlebars start shaking if I release pressure on the hand grips. Sometimes quite violently. It also happened once under very hard acceleration.
Prior to installing the new bearings I had never experienced this before.
Anyone got any ideas??
Thanks
BB407
bb407, Feb 25 2007, 01:18 AMAnyone got any ideas??
BB407
1. Cupped front tire? [tyre!!]
2. Fork height too great, meaning the distance from the top of the fork tube to the top of the triple? Generally, you can go about 5 mm higher than OEM specs for quicker handling, but more than that can induce instability. Of course, it varies with the type of bike, it is a factor in headshake issues.
3. Not enough bearing preload....maybe needs a wee touch more?
4. All three issues at once?
I just replaced headstock bearing this week, with no unruly problems after short test rides, but I'm alert to the possibility of them happening like you've experienced. Please let us know what you find that solves the problem!!
I get that when my tires flatten out because of flat roads (cupping). I have gotten to where I run about 3 - 4 lbs of less pressure in my front tire for commuting purposes which helps the problem some. If I go out and hit some twisties and work the flat spot out it helps get rid of it for a while also. Not sure what your tire or road conditions are like there, but its a common thing for me here in the flat lands. Some tires just do it worse than others.
Thanks for the suggestions.
My front tyre is certainly "cupped". I will actually be putting a new front on in the next couple of weeks because the centre of the tread is pretty much down to the minimum wear bars. Just strange how it didn't shake with the old bearings.
Perhaps the old bearings were that far gone that they were hiding the problem (binding to the point of stopping the shake?). The steering is noticeably lighter now.
I have just been out and nipped up the pre-load slightly and will see if that makes a difference.
Will let you know how it goes.
Thanks again for the help.
BB407
bb407, Feb 25 2007, 01:18 AMHi all
A couple of days ago I put a new head set bearing kit on my 1990. This has stopped the front end chattering under hard braking, and improved handling noticeably. However I noticed today that under engine braking the handlebars start shaking if I release pressure on the hand grips. Sometimes quite violently. It also happened once under very hard acceleration.
Prior to installing the new bearings I had never experienced this before.
Anyone got any ideas??
Thanks
BB407
On both my 97 VFR 750 and 90 ST1100 I fixed headshake with:
1. Tapered roller bearings - not the Honda ball bearings - you can torque the tapereds more without hurting them
2. 15 weight fork oil - not 10 weight as Honda uses
3. New tire
This combination worked for me on both bikes - might help yours
Thanks all for your assistance.
Turns out it was a "cupped" front tyre that was causing the steering wobble. Just went for a ride with a new pilot power on the front and there wasn't even a vibration.
Thanks
bb407
I think your steering head bearing that was replaced was too tight or too badly worn to give you smooth turn in or feel.
When you replaced your bearings, the evil cupped front tyre showed it's true colors and you have head shake on decel (especially with hands free of the bars on decel).
I owuld be willing to bet that you have a Dunlop tyre as well. They are the biggest offenders of cupping in my experience.
Let us know if the new front cures it.
Keith