Speed Issues / Handling - MrRiden 11/05/06

[Justin B.]

MrRiden PostPosted: Sun Nov 05, 2006 11:00 am    Post subject: Speed Issues / handling

One thing leads to another. I had a fuel starvation problem a while back and got it all sorted out at an Airhead Tech Day. Now I can cruse along at 80 with poot to spare. Engine wise all is good. The handling is a bit quirky tho. At about 70mph (true speed) the bike begins to sway slightly making a gentle oscillation from left to right to left. Kind of snaking its way down the road. Im running new tires and shocks. I have had this bike (R65LS '82) less than a Year so haven't checked everything. There seems to be no play in the front end but maybe I'm not looking at it properly? Anyone else experience this odd behavior?
Rich       


BobRoller Posted: Sun Nov 05, 2006 12:08 pm    Post subject:

Last time I had a new front tire mounted ( Steve's Cycle in Mesa) the tire did not get seated properly on the rim. There is a line molded around the tire just above the rim, and on mine about 10 inches of that line were not visible, it was below the edge of the rim by about 1/4 inch. I had a little handling problem, but nothing too serious, until I first got the bike up to 85 mph, and a wicked vibration started. It came on like you turned on a switch, and also threw the stick-on balance weights off of the wheel to add a little more excitement to the adventure.

             
MrRiden Posted: Sun Nov 05, 2006 2:34 pm    Post subject: Handling

Bob,
I checked the rim line and it is even all 'round on both sides. I mounted these tires myself (builds characture I'm told) and it was a PITA. The problem is more of a swimming down the road until I hit 85mph and then, yes, the vibration starts like you describe. I never did feel comfortable with the balance on the front wheel and I also lack any type of balancing tools. Maybe this should be sorted first?
Rich

             
nhmaf Posted: Sun Nov 05, 2006 6:53 pm    Post subject:

I would definitely bring the wheels w/ tires mounted in where they can be dynamically
balanced (balanced while rotating), though I tend to think that your problem is not
likely due to misbalanced wheels, which have always demonstrated some sort of vibration
in my experiences.

What tires (mfg and model) do you have on the bike ? IT used to be that certain
tire combinations (particular radial and bias ply models especially) would cause
a wobble when used together. Are you certain there are no rain grooves on the highway
you tested this on ? This oscillation might also happen with slightly loose steering head bearings - best to start with the simple things (like wheel balancing) first !
 
             
msbuck Posted: Sun Nov 05, 2006 7:54 pm    Post subject:

I had this exact problem with my bike many years ago and tires was not an issue for me, rather my suspension was the culprit. Just as you say, the bike was fine until I hit 70+ mph then I would get the 'rocking' motion as you described. I was on a trip and was somewhat loaded down, but I think the real culprit was my front forks. I had my bike lowered with shorter shocks and the front forks were lowered to match. When I got back home, the front was raised back up and the problem went away.

It was odd, however because I had made other trips and this didn't show up before then.
_________________
Aïda

1984 BMW R65 Black
1998 Laverda Ghost Strike Yellow


idahotaylorman PostPosted: Tue Nov 07, 2006 8:12 am    Post subject: handeling

i have a very simular problem.
at first, i had a "pogo" effect (bouncing up and down) and a shimmy.
a friend and i replaced the seals in my forks and put in new fork oil, and that pretty well took care of the "poging".
while the front wheel was off, i took it to the local BMW shop and had it balanced.
this helped quit a bit with the shimmy, but didnt cure it completly.
i am begining to think it might have something to do with my tires.
i have metslers -the front came with the bike but seems to be in good shape- the rear was purchased last fall and has about 750 miles on it.
the bike rides and handels O.K. on blacktop up to about 65, when the shimmy begins to be noticible- at 75, it wants to pull to the right.
the freeways in my area are mostly concreat,and the handeling is much worse on this surface- speeds of over 65 are tricky.


scottyintex PostPosted: Tue Nov 07, 2006 12:22 pm    Post subject:

My R65 has a sidecar on it now but when it was solo I felt it was over sensitive on the steering. My other ride is a R27 and it has an adjustable steering damper, which is really nice. Going over to the R65 I sure missed the damper effect. The R65 does have a steering damper which came as an accessory and my bike didn’t have one. I surely would have put one on if I had not gone the sidecar route..........which has it own. Anyway if I were riding a R65 solo it would have that damper installed. Funny that the R65 was suppose to have all the best engineering ideas of all the airheads that came before it and they make the damper an accessory. Go figure.


Semper Gumby Posted: Tue Nov 07, 2006 8:30 pm    Post subject: Steering Damper

Can you still get the steering damper from BMW or one of the other locations?

[Justin B.]

scottyintex Posted: Wed Nov 08, 2006 9:54 am    Post subject:

Yes, they do, A&S BMW Motorcycles.........wwwascycles.com has them. Which means any BMW dealer should be able to get it for you. I found a old note I had written my with the part number #31-42-1-239-281. I think this is the right one but you need to double check it. Seems to me this would take out that slight oscillation. I know on the R27 I can tell when I have the damper on of off by the way the bike handles. I always leave it on.


wiemer Posted: Wed Nov 08, 2006 2:12 pm    Post subject:

No over-tightening of the steering stem?

I have wheels which are not 100% true, and one can feel that, but thad doesnt make the bike weave, as you seem to describe.
The wheel makes more shuddering movements. Rotates quite fast already at 70 mph.

wiemer.


Emiller Posted: Wed Nov 08, 2006 2:45 pm    Post subject:

wiemer wrote:
No over-tightening of the steering stem?

wiemer.


[(edit) I just noticed the author of the initial question. MrRiden, the R65's steering head bearings should feel a little more stiff than your Triumph's, at least if you still have the original ball steering head bearings on the Triumph.]

...if I understand Snowbum's article correctly, over-tightening of the stem can lead to a low speed weave. Too loose will lead to high speed wobbles, and he aims for a faint low speed weave. You can't feel the play in the steering stem even if it's a little loose. You have to judge by the way the bars will just barely fall to either side if pushed off from center, with the bike on the center stand and the front wheel suspended. If the bars just flop down (which is correct for my OTHER bike) then the stem is too loose.

What's funny is, before I read his article, I never noticed that my bikes HAD a low speed weave. They do. I think I'm not very sensative to handling issues so long as I can keep it between the lines.

Hope this helps,


wiemer Posted: Wed Nov 08, 2006 3:40 pm    Post subject:

I never did the " stem bar test". I bet it is a bit loose.
Tomorrow I will do. (now it is evening and raining)
And I will grease the bearings, with a spray can of chain lube. Better than do nothing.


Also going to check valves, ign, carb adjustment, because the left one of the brand new headers is blueing more heavy than the right one.
Also the 4500-5000 range has been better once.

AND thursday I have my weekly day off.

BTW I have no Triumph, never had.

Wiemer.


MrRiden Posted: Wed Nov 08, 2006 10:15 pm    Post subject: speed issues / handling

Welll, Yes the wheel does flop to the side rather easily, sort of a flop, not quite a gentle movement. That may turn out to be a good tip. I'll find a shop here in Feenix or just get over to the dealer and get the balance sorted as well. Meanwhile I'll reinforce my understanding of steering head adjustment with a visit to Verbose Roberts tech index.
as for the use of steering dampers, I've been cautioned that they will only hide the problem and are not really necessary on a correctly adjusted suspension. Which would bring one to the question; what are they good for?
thanks,
rich

Emiller Posted: Thu Nov 09, 2006 12:17 am    Post subject: Re: speed issues / handling

MrRiden wrote:
Welll, Yes the wheel does flop to the side rather easily, sort of a flop, not quite a gentle movement. That may turn out to be a good tip. I'll find a shop here in Feenix or just get over to the dealer and get the balance sorted as well. Meanwhile I'll reinforce my understanding of steering head adjustment with a visit to Verbose Roberts tech index.
as for the use of steering dampers, I've been cautioned that they will only hide the problem and are not really necessary on a correctly adjusted suspension. Which would bring one to the question; what are they good for?
thanks,
rich


Um, my guess is that like the TR6C, they might be more for off road? Or to mask other problems? Why does that sound familiar?

Wiermer, sorry, whilst I quoted your post, I was mostly trying to respond to MrRiden's initial question, and he does have a Triumph. That's what happens when you register the same user name for different forums! You can be recognized!

'Later,


RobValdez1979R65 Posted: Thu Nov 09, 2006 3:21 am    Post subject:

From what I have been told, the steering dampers are for sidecar use.

As Rich says, everything I have heard from those that should know, is that a properly set-up 2-wheeler should not need a damper.
Yes, extreme sport bikes have them, but that is mostly due to the steep steering angles that make the bikes change direction quickly, I think.

[Justin B.]

scottyintex Posted: Thu Nov 09, 2006 12:29 pm    Post subject: dampers are good......... really

Does a steering damper tend to mask steering problems, mute the “feel of the road”? Yes, it does. Does a steering damper smooth out and stabilize the steering? Yes, it does. Does that make it useful or not? I think that maybe a matter of personal taste. Which upon reflection maybe why BMW made it an accessory. Huuuuuuuuuuummmm could BMW engineers be smarter than I gave them credit for being. I think if you ask a dozen riders their opinions you would get at least thirteen different answers, each with valid points.
The steering damper for a R65 with a sidecar and a solo bike are very different. The sidecar damper is much, much larger and far more important. The damper simply makes the ride smoother, helps stabilize the bike, a horizontal shock absorber. I sometimes let go of the handle bars on my R27. Yes, I know this is not a good idea and please don’t flame me for it. But the R27 is so stable, so wiggle free that I feel like I could cruise forever with no hands. I could do this with the damper on, turn it off and there was no way I would ride hands free. I would never have ridden my solo R65 hands off. All I know is I like the feel and think I am safer but that is just me, know folks who agree with that and folks that don't. Try one.... you will like it.


RobValdez1979R65 Posted: Thu Nov 09, 2006 1:46 pm    Post subject:

I dare you to post that over on Boxerworks.


MrRiden Posted: Fri Nov 10, 2006 12:43 pm    Post subject: handling /damper

Ok I'll bite. Im going to sort through all the suspention / balance issues first and then give a damper a try to see what this facinating little gizmo does. I think someone posted the BMW part numbers for one eairlier on here. Are the BMW units the ones you can 'turn off and on'?
Rich


MrRiden Posted: Fri Nov 10, 2006 1:34 pm    Post subject: steering damper

Found the unit on A&S page. Price is really reasonable compaired to some aftermarket units I was browsing. The part # is 31421238221. The fiche picture leaves me to wonder what attachment points are used.
Rich


BobRoller Posted: Fri Nov 10, 2006 1:50 pm    Post subject:

Rich, look at the bottom side of the lower triple clamp, and there is a threaded hole, it looks like the threaded stud goes there. The other end looks like it mounts through a sheet metal bracket . About the only holes that I can find are below the horn, there is a vertical sheetmetal bracket with two holes in it, may have make a 90 degree bracket to bolt t one of those holes and then bolt the body of the damper to this bracket. But not too sure, don't know how long the damper is.

[Semper Gumby]

I think I'll try a tighter steering head bearing in minute increments first until I get the low speed weave.  

With the Luftmeister on the front I don't know if there is room for a steering damper.

Bill