The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: RandyN on April 17, 2015, 11:51:21 PM
-
My new to me 86 R65 develops a front end side to side wobble around 80 kmh. It is very noticeable but easily rectified with a firm grip on the handlebars. I have tried removing the windshield but no change. The front tire is an Avon. the PO was a bigger rider and when I got it, tire pressures front and back were low. The back tire seems to have an odd wear pattern where the tread blocks are higher on the outer leading edges. The front tire looks okay but is about 1/16 radial runout. it is also 7 years old and starting to weather check, so it will be replaced. The static balance seems okay. The front springs are aftermarket progressives and the steering head seems to have no free play but seems slightly looser toward the end of travel on both sides.
Any ideas on the causes of the wobble before I start to tackle it?
Thanks
Randy
-
Ideas as to what is causing the wobble.
Everything you mention could cause a wobble. Address them and see if it is gone.
Also check steering head bearings (while you are there check that the upper triple clamp is nice and snug) and wheel bearings.
The odd wear pattern on the rear is a bit of a worry, put someone one it and have a long careful look form front and back and make sure you aren't dealing with a bent frame or some other misalignment.
-
"...front springs are aftermarket progressives..."
Not really likely to cause wobbles but will definitely harshen your ride depending on your ATGATT weight. You did mention a 'heavy' PO.
"...steering head seems to have no free play but seems slightly looser toward the end of travel on both sides."
Time to take a look. Properly adjusted, steering head bearings should provide a gentle movement to the stops when pushed off-center with the front tire clear of the ground. Check for old, hardened grease, brinneled outer races.
"The back tire seems to have an odd wear pattern where the tread blocks are higher on the outer leading edges."
Under inflation could cause that. Front end wobbles can also be caused by loose and/or worn out swing arm pivot bearings in the rear. Check 'em.
And as already mentioned, wheel bearings should be inspected, cleaned, greased and adjusted correctly.
-
thanks for the confirmation and feedback so quickly. I will start with the front end and work my way back. Its going to take a bit but I will post back up once I am done.
Cheers
Randy
-
Not much to add to what's above, other than to check that all the engine mounts are correctly torqued, unlikely to cause a wobble, but worth a look. Another thing to have a look at is that the forks are in alignment. I'd also whip the tank off and have a good look at the frame head, for any fresh paint and/or odd looking welds just in case its had a front end prang and someone done a 'scaffold pole' frame straightening repair job. Finally and I'm not being insulting here because I've done it myself in the past, the tires are on the wheels the right way for direction of travel.
-
I might be tempted to start with the rear tire which when badly worn can cause problems even when everything on the front end is perfect.
The steering head bearings are worth checking and re-greasing. When setting them up the object is to lightly pre-load the bearings to provide a degree of drag and therefore damping. Often a clean and re-grease will be all that's needed.
BMW's spec for maximum lateral runout is 1.7mm which is just a tad over 1/16" so that's probably not the cause. I just put on a new front tire which has a similar amount of runout although I haven't yet measured it accurately. It hasn't caused any perceptible problems.
I just re-read your post and it's radial runout that you have. The spec for that is surprisingly slightly bigger at 1.8mm so you are still OK.
-
I pulled the steering head aprt today. The grease was old and very hard. This is the bottom bearing. The top was a bit better. While there was no perceptible freeplay, I was able to undo the adjuster nut with my fingers. New bearings being ordered on Monday.
I also checked the tires and they are mounted correctly for rotation. No insult taken, as I have made the same mistake also. I will be checking everything else that has been suggested
Cheers and thanks
Randy
-
I's a shame that the bearings are gone. Often with hard grease you get away with just a clean up but if there was no pre-load on the bearings you get brinelling like that and perhaps the lack of pre-load was the cause of your wobble.
-
I am surprised that the headset did not give more indication of the horrors within.
That is a pretty buggered bearing in the photo. Out of curiosity, how did you remove the outer races?
-
Randy- I recently replaced the steering stem bearings on a friend's R100/7. They were really bad but yours get the trophy. With a too loose stem nut, you likely did not have the "notchy" steering as did my buddy. Both of you will appreciate much improved control and safety.
You've found the primary source of your DUI R65's behavior but with this evidence of zero PO maintenance, suggest you continue your stem-to-stern inspection.
Keep us posted. BTW, we all love photos!
-
Improperly tightened swing arm bearings can also cause wobbles. The BMW manual gives a range for final torque for these bearing. I use the top end of the range. (It's not very much btw.)
PS what really cured my wobbles was replacing the front end with one of a 1988 K100RS. That solved all kinds of problems. ;)
-
I am surprised that the headset did not give more indication of the horrors within.
That is a pretty buggered bearing in the photo. Out of curiosity, how did you remove the outer races?
I used a small chisel and drove it in at the base of the race until the race moved enough that I could get a drift behind it. I had to modify a drift to get enough offset, but it worked well. Next time, if there is a next time, I would weld a bead around the inside of the race.
Cheers
Randy
-
I am surprised that the headset did not give more indication of the horrors within.
That is a pretty buggered bearing in the photo. Out of curiosity, how did you remove the outer races?
I used a small chisel and drove it in at the base of the race until the race moved enough that I could get a drift behind it. I had to modify a drift to get enough offset, but it worked well. Next time, if there is a next time, I would weld a bead around the inside of the race.
Cheers
Randy
I use the welded bead method, but others here believe in buying expensive tools that do not always work and which strangely enough cost about the same as a cheap stick welder. More power to you for getting them out the way you did. Rev Light drilled holes and used a drift which impressed me, I am simply surprised that you way worked at all as I didn't think there would be enough room to get a strong engough chisel in there - well done anyway.
-
I got the steering head back together today. The wobble is gone!! I still have a vibration in the front end that feel like it is coming from the tire. The wear pattern on both front and back looks suspect, so I am ordering 2 new tires. The tires were definitely run under inflated for a period of time. The front well has 1 1/4 oz of weight for a static balance and the tire has about 1/16" of run out. I am thinking of Bridgestone Battlax tires.
Cheers
Randy
-
If the bike sat long enough the tires could have developed flat spots which will cause vibration. Riding the bike will get the tires closer to round, though it sounds like you need new sneakers anyways.
Good advice here to go over the whole bike and make sure everything is up to snuff. In addition to swingarm preload, you can also make sure the swingarm is centered, and make sure that your fork fluid levels are correct.
If you can, I'd also suggest only making one change at a time so you can see how each affects the handling.
-
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.
-
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?
-
Flybot, You did not mention if your suspension has ever been updated.
-
No, its all stock, but only 7000 miles.
-
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.
-
... 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.
(https://bmwr65.org/smf/proxy.php?request=http%3A%2F%2Fi196.photobucket.com%2Falbums%2Faa1%2Fmontmil%2FBMW%2520Suspension%2FP4270002.jpg&hash=a86f6eed49600ca3c285248e56e7ca902b2295b9) (http://s196.photobucket.com/user/montmil/media/BMW%20Suspension/P4270002.jpg.html)
-
If the bike has 7,000 miles, don't know what year bike you have, but the OEM shocks were trash when new .
-
... 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.
(https://bmwr65.org/smf/proxy.php?request=http%3A%2F%2Fi196.photobucket.com%2Falbums%2Faa1%2Fmontmil%2FBMW%2520Suspension%2FP4270002.jpg&hash=a86f6eed49600ca3c285248e56e7ca902b2295b9) (http://s196.photobucket.com/user/montmil/media/BMW%20Suspension/P4270002.jpg.html)
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.
-
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
-
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.
-
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.
-
Steering head bearings might be too tight. This can cause a weave.
Don
-
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.
-
My new Bridgestone tires showed up today. I will be mounting them this week and will let you know how it feels.
Randy
-
[
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.
-
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.
I think the guys exaggerated to make a point about the Boge shocks. None of the period road tests seemed to think they were that terrible.
If the Betors are still rebuildable they might be worth a look.
-
...I think the guys exaggerated to make a point about the Boge shocks. None of the period road tests seemed to think they were that terrible.
Those well pleased road testers rode brand new bikes with brand new Boge boingers. Give it a few thousand miles and ask 'em again.
-
I put a new set of Bridgestone tires on the R65 and no more vibration or wobble or cornering issues. It is much more pleasant to ride now!!!
Randy