The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: DgM on May 18, 2009, 11:05:08 AM
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My 1983 R65 has developed an instability over 45mph - as if the bike is in a strong crosswind - on grooved and smooth asphalt and concrete. Grooved surfaces make the instability worse. During acceleration up to 65mph bike tracks well, when speed is constant wagging occurs. Tire conditions and pressures good - even wear. Anyone else experience same symptoms and fix? Steering head bearings, swingarm bushings, wheel bearings, all of the above, what? Help.
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Have you done any maintenance to the bike recently ?
Have you started using a new or different tire pressure gauge ?
I would have a good look at all of the bolts and nuts on the front end, and rear end, check for looseness, even though the R65 isn't known for causing fasteners to loosen up.
Check the steering head bearings, with the bike on the center stand, move the front wheel fore and aft, to see if you have any play, if so, then they need to be tightened up, and maybe a bit of grease as well.
Check the swing arm bearings for proper adjustment. and see if the lock nut may have loosened up, a few pumps of grease from a grease gun here wouldn't hurt either.
How old are the rear shock absorbers ?
May not be one major problem, but a combination of smaller issues coming together and acting like a large one.
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The Lazertecs on my 82 tend to get squirrely when the tire pressure is low and on grooved pavement even when everything else is OK.
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That's the reason I brought up a new tire pressure gauge, I broke the one I had been using for years, started using a new one, and started having handling issues, I had ME33/ME99 tires.
The new indicator was reading 9 psi high, I was still using the tire pressure in the owners manual, which I believe are 26 front, 28 rear.
The tires acted quite unlike tires should !!!
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when I switched from ME33/ME88 tires to the new Lasertecs I got the same experience, especially on grooved surfaces.
>:(
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I increased tire pressures to 38-40 psi, and don't have any issues with the Lazertec tires.
But at lower pressure, they do 'act up' on rain grooved road surfaces .
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When I bought my '81 R65, the rear wheel bearings were so bad the bike would actually steer itself. And badly, too!
Can't shim the tapered roller bearings. Far easier to replace them. Plus, the bearings are available at most all bearing supply shops. Not pricey at all.
Put the bike on the centerstand. Use a few wood blocks under the engine to get the rear wheel off the ground. Grab the rear tire at top and bottom and try to 'wiggle' it port to starboard.
Any wiggles, pull the rear wheel and do a visual inspection of the bearings and races; the bearings will lift right out while the race can be looked over "in place". There's this whole BMW rear wheel bearing preload angst thing...
Monte
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Thanks for the replies. The bike is really squirrelly - not the usual yaw over grooves - front and rear almost seem like they are breaking loose into a slide ALL THE TIME over 45-50mph. All nuts and bolts are secure, no play in forks. Metzlers in good condition, even wear, higher or lower tire pressure had no change in bad behavior, higher pressures before this stuff resulted in better tracking. Checking wheel bearings, steering head bearings, swingarm bushings tomorrow - wheel bearings take a mighty good slam over construction expansion joints.
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While checking your bearings at both wheels, swingarm, steering head, also check your pinch bolts at both axles - possibly a sharp impact may have caused a crack?
I also had a strangely oscillating front end on my LS between 45 - 50 MPH- discovered that the air pressure in the front tire (BT45) was down around 24 PSI instead of the usually 34 PSI that I run - topping it up again restored the good natured R65 handling again.
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My tire pressures are 34 front, 36 rear, pinch bolts tight. Symptoms occur after riding for a while - 50 - 70 miles - not when bike is cold, always a dream up to 45/50 mph, then wobble begins, which makes me think bearings but without taking apart is only speculation. Conundrum!
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I'm really fuzzy about what you are trying to describe, here. You say it's like you are "breaking loose" and then come back and say it's wobbling. These are two different symptoms. If you do indeed have a wobble I would suspect steering head bearing adjustment, front tire (whether it looks good or not), and/or front wheel bearings. I have had "wobbles" at 45-50 mph on three bikes that turned out to be the front tire.
When was the last time steering head, wheel, and swingarm bearings were serviced/adjusted? If you can't remember then it's probably past due! ;)
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I'll clarify my descriptions - breaking loose is my term to describe a twitch when bike is leaned over in a turn - left or right - over 55mph, producing that sinking feeling in the stomach that the front tire is going to wash out or rear tire is going to lose traction and come around. Wobbling is my term for a lateral oscillation at constant 65mph so intense I must struggle with handlebars to avoid tank slapping greater oscillation. Both of these symptoms occur only after 150 to 200 miles of riding. When bike is cold - like at start of long trip - handling is solid. Pulling front wheel to check bearings this afternoon. Have not yet pulled forks to check steering head bearings but steering head has no play vertically or horizontally, action smooth.
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How old are the tires ?
There's a date of manufacture molded (moulded) into the sidewall of the tire, it's a 4 digit number, like 0108, which would be the first week of 2008.
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I had that when I first got my '82LS. Felt like you were riding a greased noodle. It had ancient ME33/ME99 tires. Fresh rubber cured it in my case. El Cheap O Cheng Shin Hi-Max C906 & C907 Tires made a big difference and the addition of a steering stabilizer erased rain grooves . Next time around I'm going to spend a bit more. Not to turn this into a tire thread. I've also done a swing arm and wheel bearing service along the way. pick yourself up a set of (4) 30203 bearings and do 'em all if there is any doubt. Theyre cheap enough, go ahed and google 'em.
rich
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Hi DgM,
Yes Check all those things.
1) Wheel bearings should be smooth and tight. If you can feel anything other than smooth then replace them. These must be perfect. I have mine cleaned and greased everytime I change tires on a wheel. I also replace the outside dust seals. Use a torque wrench to set the axel nut on the outside LH fork.
2) Ditto the steering head bearing. If you have never done this and the bike has more than 20,000 miles then clean and grease thses bearings. These bearings are the return circuit (ground) for electrical items on the front of the bike and the current will crystallize (harden) the grease.
3) Swing arm Pivot Pins. While the torque setting for these pivot pins is quite small, this is the mostl likley spot for a handling problem. Clean and grease these and then set to torque to the highest setting of the range available. If they are notchy -- replace. This will greatly improve your handling (assuming everything else has been taken care of...)
4) At the risk of starting a tire thread... Stick to the stock size on the rear tire. That size is 4.00 X 18. I see no advantages in an oversize tire -- only problems. Typical oversize is 120/90 X 18. Resist the urge to go bigger is better here.
5) Oversized front tires however do have a benifit. 90/90 X 18 is too small (my humble opinion). Handling on the R65 has been desribed as "quick" when compared to other Longer wheel-based BMW Airheads. I think you can sacrifice a tiny portion of this quickness for more stability by going with an oversize here...
6) Michelin Macadam tires last the longest in terms of mileage, that I have found. And the 50E front tires are not as affected by rain groves as other brands. Ya gotta try it to believe it.
7) Lastly look for cracks in the frame and other damage or eveidence that the bike has been crashed and is possibly bent.
This crappy advise worth 2 cents.
Good Luck,
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I found my front bearing had wornout when in stop and go traffic it was difficult to keep the bike pointed in one direction. I then on a hunch pulled my earplugs out and could "hear" the front bearing "roaring".
Yikes.
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Oh, OK, so there are multiple symptoms, that makes more sense. I have nothing to add that hasn't been mentioned yet...
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Woaw. I took the R65 to Rick Monahan at Black Kat, explained issues, he checked steering head, wheel bearings, swing arm bushings, took bike out for test ride, of course no problems. I picked up bike, took it out over a variety of surfaces, tracked and rode fine up to 70mph. The spooky handling symptoms I have described only occur after many miles on road. Metzler front tire is six years old, tread rubber still soft, sidewalls blemish free, Metzler rear tire same age, same condition. Could the electrical ground, after a couple of hours riding, actually change property of grease? And would the grease return to pliable state afterwards? Do older tires give up the ghost after a couple hundred miles and then return to decent form after prolonged cooling? Puzzle.
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I know that the metzlers that were on my LS when I first bought it passed inspection - no cracks on the sidewalls, plenty of tread, but they were old, and really the rubbers wasn't as pliable as it is supposed to be. Those tires were very slippery and not confidence inspiring if leaned over very far, and were promptly replaced - I now have no worries about leaning the bike over as far as I dare, and it runs straight and true, no wobbles, and sticks like glue. Maybe it is worth just changing your tires anyways. I know that I never have tires last that long on any vehicle I own, so I don't generally have that problem.
Oh, and no, the grease would not revert from a hard, dry state (if it was) back to a soft, pliable state unless you managed to do something to raise the temperature of the steering head up to about the max temperature of your kitchen oven - and even then, it wouldn't be consistent. Pay close attention to road surfaces, temperature, and weather conditions and note when the bike handles well or handles terribly. I am betting it is the tires
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Have you checked the balance of the tires ?
I had balance weights on the front tire of my R65 come off at 80 mph, I thought it was the end of the road for me !!
After I pulled off the road and found out what happened, I continued on home, I eased the speed up from 65 mph, and at abut 71 mph the vibration and wobble came back like someone turned on a switch.
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I don't think I've ever heard of these symptoms only occurring after a good warm-up ride. All of my issues seemed to be worse when cold... How long do you have to let the bike "cool off" before the symptoms go away?
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Bike cooled off from Sunday at 6pm until Tuesday at 8am. After morning ride Wednesday with no symptoms, rode Wednesday afternoon, stable, tracked straight, one hand only on throttle. Symptoms heat/time related? Usual when I parked bike two people approached, walking past Yamaha R1, with "nice Beemer".
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So, you have made no comparo as to whether handling returns to "normal" after one hour, two hours, etc.? I have no idea what could be going on but the only thing I can think of that might affect handling by warming caused by riding would be tires and wheel bearings. I suppose in an extreme case a frame maybe could twist/warp (depending on internal stresses) if subjected to high temps but I would imagine the engine would go up in smoke, along with your feet, before that happened...
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If you ride the bike, until this problem develops again, stop the bike and look at the tires, and see if you can see any differences in the tires., like the tread isn't straight, slight bulge in the tire etc., kind of sounds like a tire problem, but I have to admit this is the first time that I've heard of a problem like this .
How does the front brake feel when the problem starts ?
I'm going waaay out on a limb here, unlikely problem, but is the front brake(s) starting to drag or bind when this occurs ?
I'm thinking possibility of water in the caliper(s) area .
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Braking is consistent. As soon as possible I'll ride bike until symptoms return and take note of tires, brake drag, etc.
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You're describing a problem associated with the rolling chasis.
Tyres and inner tubes. They are the only components fitted to the chasis which are 'elastic' and can return, on cooling, to something like their previous state, as you describe. They will affect handling when they are sub-optimal (wrong pressure, size, worn, splashed with oil from crankcase breather, etc, etc)
If you were on a race track or motocrossing we could include shocks n forks but it doesn't sound like you're riding that hard.
The chances of having a faulty tyre are very small, BUT it could happen! Yours might be that one in a million ! Faulty tyre walls can cause a blow out! As described, this seems like a serious safety issue worthy of investment in new rubber.
Take care.
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Torqued the engine mount lately? Just a WAG.
rich