freaky front end wobble

[Bobby]

Hi, i have just replaced my RS fairing with an S fairing and s Bars. I dropped the forks down by taking wheel and front guard off and slid each fork leg down to mount new head light ears. After putting everything back together and taking it for a test ride, It has this weird scary sway or wobble to it i never felt anything like it.
I did have trouble sliding the front axle back in when putting wheel back on.I had to loosen of all front guard bolts(i remounted the guard 1st), for it to go in, although it didnt go in easy. Could this be from the front wheel and fork lowers being out of wack and causing some off balanced gyroscopic effect thingy to the front end?
Could it be front the front guard being mounted a bit out of shape.

Any ideas???

[ME 109]

You've torqued/tightened up the front end with a twist in the forks, caused by no torque relief bar imo?

The axle must slide through by hand/fingers. The axle may have burs or other mechanical damage that must be removed before this test can be properly assessed.

A torque relief bar is needed to torque the top nuts and it should not be done with the steering head up against the stops.
Ideally.

[Bobby]

Ok, i more stupid question. Whats a torque relief bar?

[Kurt in S.A.]

About middle of the page is an idea for an anti-torque setup:

http://bmwmotorcycletech.info/frontforks.htm

You probably should also read this article to be sure the forks are setup properly:

http://w6rec.com/duane/bmw/fork/title.html

Kurt in S.A.

[SteveD]

You have a little reading to do Bobby. The torque relief bar is discussed towards the end of this first link.
http://w6rec.com/duane/bmw/forktool/index.htm
http://w6rec.com/duane/bmw/fork/title.html

[ME 109]

Bobby, my apologies for not writing.......the 'links' cavalry will be here soon. Some of these guys are encyclopedias when it comes to the internet.
If your bike handled fine before, then it's twisted during torquing the top nuts, or the fork brace has altered, or the fork leg/s are not set at the correct height in the tree. Should be 161mm from machined top of tree to top of tube, according to my bmw manual.
Read up on the effect of binding the front axle when torqueing the fork brace bolts. The brace must torque up without binding the axle.

Look closely at the top of each stanchion where it clamps in the triple tree. hopefully you will see evidence of where the fork stanchion 'was' before you pulled them out. Only thing then is which side was which, if you didn't take note? Only one other trouble is you can't see the marks with the stanchion in the tree, you'd need to drop each stanchion to see.

I've only just finished putting my RS front end back together after steering bearings and cosmetics.
I wanted to do a full fork alignment and had everything pulled apart.
The piece of 6mm laminated glass that I bought five years ago for fork alignment was warped! Flip that glass back to front and rotate it, and any twist detected should be the same whatever way the glass is. That proves flat glass.
I found variations of twist ......so my glass isn't flat........so I just smashed it back together.

But I can still spin my axle between my thumb and forefinger. Got to road test yet.

[ME 109]

Road tested this morning and found the preload was not enough. The bike was very willing to get a head shake happening at lower speeds.
Back home and increased torque on the torque nut. Torque nut is the thin one under the top plate.
After another test ride out to Airbear's, it's fixed. Front end behaving beautifully over varied situations.
Maybe you just need to increase torque?

[Bobby]

Thanks fellas for the links to read and for yr info Me 109. Today i started from the beginning with everything loosened and tightened everything back up,following the assembly steps in the fork alignment article and torquing the top nuts using some angle iron for the torque relief bar. It seems ok now i can slide the axle in and spin it with my fingers no problem

I havent ridden it yet as i have some electrical problem going now. After relocating the ignition from the rs fairing to the leftside headlight bracket the bike doesnt stop when turning the key off ( The kill switch hasnt worked since i bought it the other month). The battery has been drained over the weekend as well, i see if my electrician mate can fix it tomoz.