ADVrider

Go Back   ADVrider > Bikes > Old's Cool > Airheads
User Name
Password
Register Inmates Photos Site Rules Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
Old 06-07-2012, 03:44 AM   #1
patanga OP
BMWAirheadsDownunder
 
patanga's Avatar
 
Joined: May 2009
Location: Australia Qld
Oddometer: 160
Steering wobbles

Anyone care to comment on the most common causes of steering wobbles. i.e. the kind that develop into the nasties. I've heard opinion about tyre pressures, but personally I think that unless the pressures haven't been maintained and the treads have been affected, that incremental jigging with pressures is only going to mask other underlying issues. Eg loose steering head bearings, faulty tyres, or other causes. On the topic of tyres, are there any brands that seem more prone to developing the wobbles as they wear?... I have experienced this with the Battlax BT45's more than once.
____________________
"The only reason people get lost in thought is because it's unfamiliar territory" (Joe Garcia)

Check us out on facebook at "BMW Airheads Downunder", (The Australia and New Zealand Airhead Community). "B.A.D"
http://www.facebook.com/groups/anzairheads/

patanga screwed with this post 06-15-2012 at 07:56 PM
patanga is offline   Reply With Quote
Old 06-07-2012, 07:11 AM   #2
disston
ShadeTreeExpert
 
disston's Avatar
 
Joined: Mar 2011
Location: Silver Spring, Md
Oddometer: 8,175
I recently rebuilt my front end. I had wobbles for a week then I tightened the new bearings after they had time to seat themselves. I think this is normal. New bearings will start off making them selves a little looser for a few miles. Just keep the speed down. Tighten bearings and all is well.

Anytime I put a new tire on the front it's an improvement. I usually over extend the use of tires.

Correct tire pressure is a nice thing to have.

Tire balance. I'm trying the Dyna Beads. Not sure I like them yet. But they do work, IMHO.

You have to do it all. Probably the most dangerous thing to over look and it gets over looked too much is the bearing adjustment. The bearings themselves have to be in good condition and not caked in 3 year old hard grease.
__________________
.
Never memorize something you can look up.
---Albert Einstein

Pay your debt, piratejohn.http://www.advrider.com/forums/showthread.php?t=949341
disston is offline   Reply With Quote
Old 06-07-2012, 07:19 AM   #3
Boon Booni
Red Clay Halo
 
Boon Booni's Avatar
 
Joined: Aug 2003
Location: Richmond, Va
Oddometer: 12,970
Since the front suspension travel on my airhead is 8 inches and there's only 5 inches in the rear, I've added more sag up front to bring the steering angle down from being so chopperish.

IMHO it's quickened my steering a bit and I don't get the wobbles like I used to.
__________________
A little nonsense now and then is relished by the wisest men.

You can be Han Solo, and I can be another Han Solo...
Boon Booni is online now   Reply With Quote
Old 06-07-2012, 08:08 AM   #4
MightyManfred
Adventurer
 
MightyManfred's Avatar
 
Joined: Apr 2011
Location: the swamp known as Houston
Oddometer: 39
The only time I've had wobblies on my airhead was after I replaced the steering head bearings. Frightened me big time. My front tire has lost most of its air while my bike was parked for repairs - bent rim. An airhead with good parts and proper tire/tyre pressure should not wobble.
MightyManfred is offline   Reply With Quote
Old 06-07-2012, 08:20 AM   #5
Future ten
Gnarly Adventurer
 
Future ten's Avatar
 
Joined: Dec 2011
Location: Tampa fl
Oddometer: 206
Ultimately there are a few bikes out there that shake their heads due to aggressive geometry, I had an RC 51 that would try to eat me powering out of Turns often, Scott's stearing damper deleted the issue immediately.
My MX bikes that were problematic usually steamed from headset bearings and tires. Had a kx500 that was murder on hard packed straights. Good suspension balance front and rear with a little wieght to the front helped.
There are a lot of bikes these days coming stock with dampers due to steep stearing angles.
__________________
Semper Fi.
Future ten is offline   Reply With Quote
Old 06-07-2012, 08:56 AM   #6
mykill
odd
 
mykill's Avatar
 
Joined: Feb 2008
Location: Los Angeles
Oddometer: 1,156
Quote:
Originally Posted by Boon Booni View Post
Since the front suspension travel on my airhead is 8 inches and there's only 5 inches in the rear, I've added more sag up front to bring the steering angle down from being so chopperish.

IMHO it's quickened my steering a bit and I don't get the wobbles like I used to.
That seems bass ackwards to my experiences. Too much sag quickens the angle and would make the bike more unstable. Too little sag would make the steering slower, maybe cause a weave?

Number one culprit of these issues is steering head bearings. They need to be healthy, lubed and adjusted to perfection. Then the relationship between the front and rear suspension come into play. Both should sag by about 25% of their travel when the bike is off the stand. Less is OK but both should sag some. Front and rear should return slower than when compressed. Cupped front tires can give unnerving moments. I'm really liking a set of Michelins Pilot Activs we just put on an R80.
__________________
Never underestimate the laxative properties of motorcycling.
mykill is offline   Reply With Quote
Old 06-07-2012, 08:57 AM   #7
Boon Booni
Red Clay Halo
 
Boon Booni's Avatar
 
Joined: Aug 2003
Location: Richmond, Va
Oddometer: 12,970
Quote:
Originally Posted by mykill View Post
That seems bass ackwards to my experiences. Too much sag quickens the angle and would make the bike more unstable. Too little sag would make the steering slower, maybe cause a weave?
IMHO too much is just as unstable as too little. I think the airheads have too much to begin with. But I am talking more about a fast weave and not a tank slapper.
__________________
A little nonsense now and then is relished by the wisest men.

You can be Han Solo, and I can be another Han Solo...
Boon Booni is online now   Reply With Quote
Old 06-07-2012, 09:07 AM   #8
Future ten
Gnarly Adventurer
 
Future ten's Avatar
 
Joined: Dec 2011
Location: Tampa fl
Oddometer: 206
Theres that balance in setting up a bikes suspension that makes or breaks the way it handles. Read a book is what I tell the yougens at the track, they are all afraid to play with the settings and would rather brag that "factory joe" dialed in their bouncers, some require a bit of talent and true understanding and some just can't be remedied with what comes on the bike and are hopeless. A nice hard core "tank slapper" will make ya learn just how things work.
__________________
Semper Fi.
Future ten is offline   Reply With Quote
Old 06-07-2012, 09:40 AM   #9
supershaft
because I can
 
Joined: Sep 2010
Location: San Francisco Bay area
Oddometer: 8,170
I bet most would agree steering head bearings are the number one issue. After that it's a toss up. In my experience, fork stiction is probably second. Something I don't think anyone has mentioned. Tires, wheel bearings, swingarm bearings, sag, ride height, etc.. It can be anything or any combo of anythings.

My biggest cause of wobbles is not having your bars exactly straight when your tire comes back down. It's easier said than done a lot of times and something that can always be worked on. Of course, there is no cure for some wobbles. Not all at once anyway.

For most people the biggest cause is something that really no one should be doing: Coasting down through the 50 to 30mph speed range with no hands on the bars. It's an inherent weak point in most all motorcycles as we know them.
supershaft is offline   Reply With Quote
Old 06-07-2012, 11:29 AM   #10
ozmoses
Ride On
 
ozmoses's Avatar
 
Joined: Jul 2009
Location: USA
Oddometer: 2,416
Question

Quote:
For most people the biggest cause is something that really no one should be doing: Coasting down through the 50 to 30mph speed range with no hands on the bars. It's an inherent weak point in most all motorcycles as we know them.

Please expand upon that, meaning, what happens in that range & why?

If this is so, I can shorten my to do list by one nagging/ongoing item!
__________________
Opinions are like internet connections- everybody has one.
ozmoses is offline   Reply With Quote
Old 06-07-2012, 11:54 AM   #11
mykill
odd
 
mykill's Avatar
 
Joined: Feb 2008
Location: Los Angeles
Oddometer: 1,156
Quote:
Originally Posted by Boon Booni View Post
IMHO too much is just as unstable as too little. I think the airheads have too much to begin with. But I am talking more about a fast weave and not a tank slapper.
Rather than messing with the sag you may consider longer (+1/2") shocks. This quickens the steering without sacrificing suspension performance.
__________________
Never underestimate the laxative properties of motorcycling.
mykill is offline   Reply With Quote
Old 06-07-2012, 01:54 PM   #12
supershaft
because I can
 
Joined: Sep 2010
Location: San Francisco Bay area
Oddometer: 8,170
Quote:
Originally Posted by ozmoses View Post
Please expand upon that, meaning, what happens in that range & why?

If this is so, I can shorten my to do list by one nagging/ongoing item!
You haven't run into that phenomenon? Your lucky if you haven't. Bikes tend to go into tank slappers under those conditions. Why? From what I have read physics. I can't explain it. I have read about it. It's a bit more complicated than figuring out your tranny shimming, for instance.
supershaft is offline   Reply With Quote
Old 06-07-2012, 08:46 PM   #13
patanga OP
BMWAirheadsDownunder
 
patanga's Avatar
 
Joined: May 2009
Location: Australia Qld
Oddometer: 160
Any thoughts on tires

Thanks for all the feedback gents. You have confirmed my thoughts and added a couple more possible causes from your own experiences. Steering head bearings remain number one cause IMO, followed by any combination of the others, with tire pressures being an ongoing maintenance issue rather than a cause per se. That said, are there any thoughts on tire brands that seem more prone to developing issues with 'the wobbles' as they wear? As mentioned earlier I have found the BT45's (front) seem to 'tread block' as it wears, (even when regularly checked for pressure) which may contribute to the condition. Inmate 'Mykill' says he's having a good run with Michelin Pilot Activs (thanks) but it seems they've just been fitted and so may be too early to tell .. so what about the rest?

____________________
____________________
"The only reason people get lost in thought is because it's unfamiliar territory" (Joe Garcia)

Check us out on facebook at "BMW Airheads Downunder", (The Australia and New Zealand Airhead Community). "B.A.D"
http://www.facebook.com/groups/anzairheads/

patanga screwed with this post 06-15-2012 at 07:56 PM
patanga is offline   Reply With Quote
Old 06-07-2012, 09:23 PM   #14
supershaft
because I can
 
Joined: Sep 2010
Location: San Francisco Bay area
Oddometer: 8,170
Lots of tires tend to tank slap they get well worn. I have never noticed one type being worse than another since I usually run tires that don't cup much at all. I ran TKV11's up front until I switched to AM22's. Be thankful you don't run dual purpose tires. Most of those cup BAD.
supershaft is offline   Reply With Quote
Old 06-07-2012, 09:45 PM   #15
Hawk Medicine
Coyote's Brother
 
Joined: Jun 2008
Location: NOR CAL
Oddometer: 3,303
Quote:
Originally Posted by mykill View Post
Rather than messing with the sag you may consider longer (+1/2") shocks. This quickens the steering without sacrificing suspension performance.
Well, I guess you know your stuff and I agree completely. One of the best kept secrets to making an Airhead turn in, is to install a set of 1/2" to 5/8" over spec shocks.

I installed a set on my RS and the difference was amazing. All of a sudden the bike felt as if it had lost a lot of weight and it no longer required as much muscle to get it into a turn and to hold a line.

Later, I took the same length (longer.) shocks off of my Hot Rod and the stock shocks put the handling right to sleep. Next step will be custom length YSS shocks.
__________________
Hawkdude

Hate rots the pocket that carries it.
Hawk Medicine is offline   Reply With Quote
Reply

Share

Thread Tools Search this Thread
Search this Thread:

.
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump


Times are GMT -7.   It's 08:43 PM.


Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright ADVrider 2011-2014