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Author Topic: Front end "wobble"  (Read 5893 times)

Offline montmil

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Re: Front end "wobble"
« Reply #15 on: April 26, 2015, 09:21:07 AM »
Quote
If you can, I'd also suggest only making one change at a time so you can see how each affects the handling.
[smiley=tekst-toppie.gif] Good advice.

Change two items before testing and you'll never know what the problem actually was.

Monte Miller
Denton, TEXAS
1978 BMW R100S
1981 BMW R65
1983 BMW R65
1995 Triumph Trophy
1986 VW Cabriolet

Offline flybot

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Re: Front end "wobble"
« Reply #16 on: May 10, 2015, 08:45:34 AM »
Ive often wondered how much wobble, or flex, is normal for these bikes. Ive had several motorcycles. On one end of the spectrum is my BMW HP4 that is solid as a rock all the way up past 150 mph. Harley VROD is pretty stiff, but has some flex. But on the R65 I really dont feel to safe going over about 75mph. The bike feels like there is way too much flex in the frame. Maybe this is normal for these old bikes. I dont know. But at highway speeds, if I give it a little rider induced shimmy, it feels like a wet noodle. Wheel, head, and swing arm bearings all gone through many times.

If this is normal, Im fine with it. I just dont know if I should continue to chase this issue or leave it alone. I know feel is very subjective, but what say the R65 guru's?
1983 R65

Offline montmil

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Re: Front end "wobble"
« Reply #17 on: May 10, 2015, 08:49:30 AM »
Flybot, You did not mention if your suspension has ever been updated.
Monte Miller
Denton, TEXAS
1978 BMW R100S
1981 BMW R65
1983 BMW R65
1995 Triumph Trophy
1986 VW Cabriolet

Offline flybot

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Re: Front end "wobble"
« Reply #18 on: May 10, 2015, 09:20:11 AM »
No, its all stock, but only 7000 miles.
« Last Edit: May 10, 2015, 09:21:32 AM by flybot »
1983 R65

Offline donbmw

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Re: Front end "wobble"
« Reply #19 on: May 10, 2015, 09:24:31 AM »
I went from a Honda 79CX500 to my R65. Never felt any unusual handling. Have ridden above 80 many times. Since I have have  my R90 and ride it a lot with out riding the R65. The R65 handling fills different. I think this is because of the light weight and short wheel base.
1975 R90/6, 1980 R65, 1982 R65, 2015 Ural Patrol & 1959 Triumph TR3

Offline montmil

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Re: Front end "wobble"
« Reply #20 on: May 10, 2015, 11:32:48 AM »
Quote
... its all stock, but only 7000 miles.

Couple items to consider:

1. The R65 had an OEM rubber "topping out" bushing as a component of the fork's innards. The bush soon deteriorated and dissolved. With the bushing gone, the forks are rather 'loose'. The later bushing is made of sterner stuff. Replacement requires disassembly of the forks but that no biggie. Fork oil weight and volume also control fork action... entire other discussion on that topic.

The photo shows the condition of my OEM bushings during replacement shortly after purchasing the bike.

2. The OEM Boge shocks are little more than undamped pogo sticks. Folks say that the Boge boingers were fitted simply to keep the rear fender off the back tire while the bike traveled in its shipping crate. Basically worthless.

Granted, 7K miles isn't much road time but the years can play havoc.


Monte Miller
Denton, TEXAS
1978 BMW R100S
1981 BMW R65
1983 BMW R65
1995 Triumph Trophy
1986 VW Cabriolet

Offline Bob_Roller

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Re: Front end "wobble"
« Reply #21 on: May 10, 2015, 12:54:44 PM »
If the bike has 7,000 miles, don't know what year bike you have, but the OEM shocks were trash when new .

'81 R65
'82 R65 LS
'84 R65 LS
'87 Moto Guzzi V65 Lario
'02 R1150R
Riding all year long since 1993 .
I'll give up my R65, when they pry my cold dead hands from the handlebars !!!!!

Offline flybot

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Re: Front end "wobble"
« Reply #22 on: May 10, 2015, 02:06:52 PM »
Quote
Quote
... its all stock, but only 7000 miles.

Couple items to consider:

1. The R65 had an OEM rubber "topping out" bushing as a component of the fork's innards. The bush soon deteriorated and dissolved. With the bushing gone, the forks are rather 'loose'. The later bushing is made of sterner stuff. Replacement requires disassembly of the forks but that no biggie. Fork oil weight and volume also control fork action... entire other discussion on that topic.

The photo shows the condition of my OEM bushings during replacement shortly after purchasing the bike.

2. The OEM Boge shocks are little more than undamped pogo sticks. Folks say that the Boge boingers were fitted simply to keep the rear fender off the back tire while the bike traveled in its shipping crate. Basically worthless.

Granted, 7K miles isn't much road time but the years can play havoc.




I wasnt aware of the deteriorating fork bushings. That makes sense as a possible cause.  I changed the fork oil when I rebuilt the bike, but nothing else on the forks because of the low miles. It feels like loose steering head bearings at hi-speed. But Ive replaced them and fiddled with it several times. I dont think thats the problem. But sloppy front forks may be the cause. Ill put it on the project list.
1983 R65

Offline flybot

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Re: Front end "wobble"
« Reply #23 on: May 10, 2015, 02:09:21 PM »
Quote
If the bike has 7,000 miles, don't know what year bike you have, but the OEM shocks were trash when new .


'83 R65
1983 R65

Offline Barry

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Re: Front end "wobble"
« Reply #24 on: May 10, 2015, 02:42:38 PM »
After 30 odd years the topping out bushes are an issue in that they can disintegrate and end up a sediment  at the bottom of the forks.   My experience was that at 7000 miles and 28 years the topping out bushes were still intact but they had gone hard. If still intact I doubt they are the cause of your problem as they play no role what so ever in the hydraulic damping of the forks. They are just a rubber bump stop when the forks reach full extension. They will will need replacing though.

« Last Edit: May 10, 2015, 02:49:09 PM by bhodgson »
Barry Cheshire, England 79 R45

Offline flybot

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Re: Front end "wobble"
« Reply #25 on: May 10, 2015, 04:28:34 PM »
Ok. So is the consensus that at over 75 mph the bike shouldn't feel flimsy? Mine tracks straight. Its just lines or road grooves,  and quick maneuvering at that speed do not bring a confidence feeling. It seems more like a left to right thing, and not a up and down suspension kind of thing.

Its not a problem at lower speeds. Or maybe its so slight that its not noticed.  
1983 R65

Offline donbmw

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Re: Front end "wobble"
« Reply #26 on: May 10, 2015, 07:13:51 PM »
Steering head bearings might be too tight. This can cause a weave.

Don
1975 R90/6, 1980 R65, 1982 R65, 2015 Ural Patrol & 1959 Triumph TR3

Offline Luca

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Re: Front end "wobble"
« Reply #27 on: May 12, 2015, 06:34:55 AM »
Tires will make a big change in how the bike feels over grooves in the road, "tar snakes" (sealant), etc.  I put some miles on the old hard tires my bike came with and it could get scary the way it interacted with these bits of "road character."

  Put a new set of Spitfires on and I could ride over grooves in the road without the bike making any sort of pull to the left or the right.
'82 R65LS
'01 K1200RS

RandyN

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Re: Front end "wobble"
« Reply #28 on: May 12, 2015, 04:03:29 PM »
My new Bridgestone tires showed up today. I will be mounting them this week and will let you know how it feels.
Randy

Offline Tony Smith

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Re: Front end "wobble"
« Reply #29 on: May 12, 2015, 10:36:10 PM »
Quote
[
2. The OEM Boge shocks are little more than undamped pogo sticks. Folks say that the Boge boingers were fitted simply to keep the rear fender off the back tire while the bike traveled in its shipping crate. Basically worthless.


I see that Motobins are flogging Spanish Betor shock absorbers. I remember the beggars well as they came fitted to the Bultaco Metralla I raced in production races a very, very long time ago and was stuck with under the class rules.

The saying went that Betors are better than nothing, but not by much. It is a very long time ago but my memory tells me that Boges were better than Betors.

BUT, joy OH joy, Betors are rebuildable and they use (or at least they used to use) catalog seals. So once you pulled them apart, played with the valving, fiddled with fluid quantity and weight, you could actually turn them into decent shocks.

To conclude this trip down memory lane, I created a huge bunfight when I presented my bike with the Betors fitted internally with freon bags (Yes Jennifer, once upon a time you could actually buy small plastic bags of freon gas, nasty Ozone depleting stuff that it is for the purpose of reducing "dead air space" in shocks) and mounted upside down to reduce un-sprung weight (which for some reason I thought was important in those days).

Well there were protests and I was temporarily pulled off the grid on the grounds that they were not "stock".

I then lodged a protest against all the bikes in the field not running the disc pads/brake shoes supplied by the manufacturer as OEM, and while I was at it, added handlebar grips, break/clutch levers and fork damper rods into the bargain. This created a major problem for the organizers in that two or three of the competitors had protested me and I had lodged a protest pretty much against the balance of the field.

Sensibly the race went ahead and the protests were sorted out later, my protests where dismissed and the rules quickly changed to allow aftermarket brake and clutch levers, handlebar grips and brake material.  
 
The protest against me presented a few more problems because my shocks were undeniably the ones fitted to the bike at the factory, the problem was that I had altered them in ways that had not been thought of (at the time the ranks of OEM shocks that were actually rebuildable (or for that matter could be taken apart non-destructively) probably began and ended with Ducati, MotoGuzzi, Laverda and Bultaco. Worse there were no untouched Betor shocks around to compare mine to to see if I had broken any rules (arguably I had not because there was nothign int he rules about altering shock absorber or fork internals and nearly all the Yamaha runner would have had Fox "trickit" double action conversion damper rods anyway.

Eventually the rules were changed so that you had to run OEM shock absorber bodies and stock fork bodies but internally forms and shocks were free - and shocks had to be mounted the same way up as OEM.

The joke of it was that even then I was a "big" bloke, about 6' 1" and weighing around 10~11 stone. Just how much chance did I really have in resisting the onslaught of small children on Yamaha RD250s and Suzuki Hustlers? The answer is not a prayer!


but it was fun trying.

1978 R100RS| 1981 R100RS (JPS) | 1984 R65 | 1992 KLE500 | 2002 R1150GSA |