The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: azcycle on August 22, 2010, 11:00:30 AM
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As you know, I just put some new rubber on the r65 and it went fairly well. However, there is a very noticeable front end shake around 25-30mph (estimated) that smooths out both below and above that speed. The wobble feels like I'm riding over washboarded road, a very "up and down" movement. I thought perhaps I needed to take another look at the balance of the front tire but it is well balanced.
However, when I was spinning the front tire to check balance again I did notice a "lump" or around a 3-4" stretch of tire that was higher than the rest. The tire seems to be mounted correctly, so why this lump? I'm sure it is what is causing the front wobble. It is not obvious just looking at the tire... but is quite so when spinning and watching the profile of the tire as it turns.
Have any of you ever experienced this? Perhaps the tire is still not mounted correctly or maybe it is a damaged tire?
Thoughts?
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Inner tube folded over on itself, or some other problem with the tube the way it is sitting inside the tire .
Less likely, a deformity in the tire itself .
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I had a similar problem on the car a rear tyre had deformed on the inner edge if the "lump" doesnt go when you deflate the tyre a replacement will be needed.
Lou
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I fiddled with it a bit today and noticed the lump corresponded with the valve stem. Upon closer inspection, the valve stem was slightly angled so I removed the valve core and straightened out the stem, and pumped it back up with my bicycle floor pump to 60psi, then back down to about 34psi. Spun the tire and while there is still a *tiny* bump/wobble, it's much better. Gotta take it for a spin to be sure.
Though while inspecting everything closely, I also noticed the wheel itself is banged out of round, too. It's got a small wobble as well, from a curb or pothole hit, maybe? I'm thinking maybe the knobby tires absorbed some of the wobble but now that I've got the street tires on there, everything is much more apparent.
We'll see... maybe I should shop around for a new front wheel. Is a small amount of wobble okay, you think?
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Frequently, R65 snowflakes show up on eBay. Keep a weather eye out.
Within the DFW MetroMess, there are quite a few outfits that straighten up automobile alloy rims; they haunt the car dealerships looking for work. Perhaps check with a dealership for service providers. They might true up your front rim. Usually far more economical than buying a new part.
Monte
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Still have a wobble/bump at the same speed, even though the physical bump in the tire seems to be lessened (though still there). I removed the wheel last night and am taking it to a local shop for them to figure out.
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What brand of tire is it ?
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What brand of tire is it ?
"Shinko 712s on sale"
http://www.bmwr65.org/cgi-bin/yabb2/YaBB.pl?num=1280883481
I've never had a Shinko brand tire.
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Just wondering, as I'm having a Metzeler Lasertec tire installed on the front wheel of my '81 today .
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I will continue to buy Bridgestone Spitfires for as long as they make them.
Providing I ever ride again, of course.
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A small update: Took it to the local neighborhood moto shop (directly across the street from Iron Horse BMW) for a look-see. At first spin on the balance rig, the mechanic said the rim was fine and the tire looked fine, but it was WAY out of balance and the bearings were rough. Guess my ghetto balancing wasn't that good, eh?
Of course, they didn't stock the correct sized bearings, so I ran across the street (literally) to Iron Horse, and bought new front wheel bearings. After picking my jaw up off the floor from paying $84 for the bearings, (they didn't even have the seals in stock) I delivered them and left the mechanic to do his thing.
I don't have any experience with other tires other than the previous Kendas (which I grew to dislike) so I can't compare the Shinkos, but I've put about 200 miles on these so far. They feel confident, good grip, comfortable, don't track all over the road's cracks, etc. We'll see how long they last but I needed tires and with my pre-wedding budget they were too hard to pass up.
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Just a thought that I should have added before now...
I found upon mounting my Spitfire on the front rim,with tube - rear runs tubeless, that removing the valve stem nut inside the rim allowed for a better valve stem install.
Monte
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AZCYCLE,
Yow! $84 for bearings. Next time you are in need of bearings hit Tucson Bearing-Belt & Chain. You can get any bearing you need there at a much better price. Yea I know it's south Tucson but you can also swing by El Guero Canelo for a tasty Sonoran Hot Dog. I'll be passing through on Wednesday on the way to Bizbee but I'll be sure to make a dog stop.
rich
http://maps.google.com/maps/place?hl=en&um=1&ie=UTF-8&q=tucson+bearing&fb=1&gl=us&hq=bearing&hnear=Tucson,+AZ&cid=17417229871034511884
http://tucsoncitizen.com/tucsontales/2009/12/10/tucsons-sonoran-hot-dog-like-a-chili-dog-on-steroids-wrecipe/
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I'm glad you were able to find the balance problem.
And I hope your mechanic is experienced in pre-loading BMW wheel bearings.
Here is Duane's page on the subject: http://w6rec.com/duane/bmw/wheel_bearing/index.htm
And Snowbum's page: http://bmwmotorcycletech.info/overview.htm
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No idea if the mechanic knows anything about BMW bearing and pre-load. My guess would be "no" so what do I do? Call the shop and explain preload? How long would these bearings and the hub last if preload was not properly set?
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Well, you would not get the smooth ride you are looking for, if the preload is not set correctly.
Too tight, and they will quickly wear out. Too loose and the bike would probably feel "not good", and again, it would ruin your $84 investment.
I'm not sure to tell you how to proceed. I have only participated in the procedure once, about 4 years ago, with several knowledgeable people around.
The best way to do this is to find a local Airhead chapter to join and host a Tech Session, advertising what you will be hoping to accomplish.
http://www.airheads.org/
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Well I called the shop and it's done. I'll ask about the preload when I get there, but I'm not expecting them to know anything about it. I suppose I'll have to drop it off at Iron Horse BMW and have them look it over and double-check. Jeez, this is becoming an expensive lesson.
:P
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Graeme,
If you're dedicated to doing this yourself I can try to help you along. I think Bob has just done his bearings also, I'm sure he can help. I just completed my /7 bearings. My initial advice would be; it's not difficult or complicated to remove and replace the grease seals and have a look at the existing condition of the tapered bearing cages yourself after cleaning. You can also do the pre-load test before reinstallation if the cages and outer races look ok. You'll need a few special tools, take a look through this thread and let me know if you want to procede on your own. I'm willing to share my limited experience. I think you'll have to join the MOA forum to view the pictures in the thread, I recommend you doing that since a picture is worth a thousand words. Your wheels won't be this difficult, I have the dreaded 78 all aluminum snowflake rear with no steel insert.
I will NEVER trust a dealer with airhead wheel bearings again. Ever.
http://www.bmwmoa.org/forum/showthread.php?t=46970
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Sorry, I guess my post is a little late.
:-[
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Ah, no worries, Mike and thanks for the offer to help. I actually WANT to learn how to do it, but don't have the tools or the time for the bike to be out of commission. My Mustang carb just started puking gas so it's in need of a sudden rebuild, which puts our usable vehicles to the Jeep, a scooter, and the r65.
Anyway, so I picked up the tire from the local shop to the tune of $30 and asked the mechanic if he knew about the preload issue and the answer was written all over his blank face before he answered: "If I had known it was a BMW wheel before, I wouldn't have worked on it. We don't do BMW stuff here."
So right across the street to Iron Horse I went. And I even got a rather blank stare from the Service Manager, too. But he shrugged and pointed at a couple old airheads around the shop and said "We have guys that know old airheads, not to worry..." and he said they'd try to squeeze it in today.
We'll see.... Now my "cheap" at-home tire change has cost $150 and counting. ;D Lesson learned for sure.
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I've been working on the rear wheel of my '82 LS, just trying to understand what really needs to be done with this pre-load .
After digesting all of the information about it , here's a real quick explanation of what's being attempted .
On a front wheel, it's a bit easier than a rear wheel .
Remove the inner and outer seals, clean all of the grease from the bearings and the outer races .
Reassemble the bearing and spacer stack-up without the seals, insert this back into the wheel .
Insert axle and the spacer that goes on the left side between the wheel and left fork tube .
Tighten the axle nut to what ever torque it calls for .
Spray a light oil onto the bearings so they have a bit of lubricant and aren't dry .
Next take a spring scale and see how much force is required to move the wheel .
If the force required is too high, add a shim between the spacers that are between the bearings .
If the force required is too light, you need to remove shims if they are installed, if you don't have any shims to remove, you need to get another small spacer, they come .5mm increment differences in length (correction, the spacers come in .05 mm increment differences) .
Measure what you have and then subtract .05 mm to get the next size shorter .
After you have this done, you need to grease the wheel bearings, re-assemble the stack-up including the inner and outer seals, then reinstall the wheel on the bike, torque to specified value, which I think is around the 35 foot pound area .
A bit of information is left out of this explanation, but this is the basic idea of what needs to be done .
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And Duane (see link, above) (http://w6rec.com/duane/bmw/wheel_bearing/index.htm) has shim kits available.
"A set of six, two of three sizes, of these shims cost $10, postage included. I sell these by the honor system. Email me with your address and I will mail them out to you with a SASE. It is up to you to insert payment and return. If you don't know how to use them, or don't like them, just return them in the SASE."
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Ed Korn, Cycle Works has a shim kit as well .
http://www.cycleworks.net/index.php?main_page=product_info&cPath=29_41_44&products_id=204&zenid=a9b13235b70ddb0b99984a623d4de566
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An update: Iron Horse had the wheel a couple days but they finished it up yesterday. They verified that the "other" moto shop had no idea what they were doing and said that the bearings were preloaded WAY too much, and the seals installed backwards. Paid my $80 (ugh) and put it on the bike today...
... only to notice the front suspension "hop" is still there, right around 35-40mph. Guess I'll have to remove the tire from the rim and inspect it for any strangeness. Have to wait until next week...
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Hi Graeme,
When all else fails you can always install the complete fron end from a 1988 K100RS.
THAT will get rid of the shakes. 8-)
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I've been doing some online research and found a couple instances exactly like mine where the REAR tire was out of balance and it caused the front to "hop/bounce" at a specific speed like mine does.
Now that the front wheel has been inspected and balance professionally by BMW, I'm starting to look at that rear tire again. Hmmm.....
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I've been doing some chatting over at the ADVrider forum, too and the collective airheads over there think the front wheel is bad. I took a bad short video of the front wheel, and there definitely is a bump or two in the wheel... it is NOT true.
[media]http://www.youtube.com/watch?v=dfCFn7Ogceo[/media]
What do you all think? Should I start shopping for a used rim? I see one on ebay from a 1979 model right now for $150 + shipping.
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I can't say from looking at that video (even on full screen), but it is possible that it got bent if FIL hit some pot holes at speed on the dirt roads (I've done it!).
You really need to have something like a dial indicator with the tire removed to know for sure. Unless you can see it, because you are there. I would accept that.
That eBay wheel is going to stress the wife-to-be, I might think. (I'm divorced :'()
And when you get it, you would have to put your new bearings in it, for another $80?
But if you can make it work, and you can get some kind of assurance (return guarantee?) that the wheel is true, I would also say go for it.
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I took the bike to a local place that repairs/straightens aluminum car wheels. Turns out the owner works on local race bike wheels and is a motorcycle rider himself. He looked at the rim and did say it had a couple small dings in the outer edge but they weren't deep enough to affect the wheel, and certainly wouldn't explain the bounce.
So I was back to the tire. I dropped the tire off the rim again last night but couldn't find anything obvious to my amateur eye. I rotated it a bit on the rim and tried to re-mount.... and promptly punctured the tube which I didn't notice until I tried to air it up.
Ugh. Waving the white flag! I'm taking it to Southwest Moto Tires today to have them examine the tire, etc. He said that if the Shinko IS bad he has a Dunlop 404 110/90-18 that he'd give me a great deal on, but I don't think the 110 will fit up front... the 100 I have up there BARELY clears the fender.
So we'll see... will update later.
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Just got back from dropping the wheel of at Southwest Moto Tires (http://www.swmototires.com/). They inspected the tire and said that there was some damage to the wire bead that could cause an out-of-round tire. Culprit? Bad installation by yours truly. Guess I muscled the tire onto the wheel without enough caressing. Live and learn, I guess.
He didn't have a tire in stock so he ordered one for me. Should come in tomorrow but with the holiday weekend, I may not get it back until next Tuesday.
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New front tire (same brand/type: Shinko 712) mounted and balance by SW Moto tires. The guy installing felt, in his opinion, that the rim was definitely bent enough that it wouldn't be round and suggested I get it straightened.
That being said, it *feels* like 95% of the hop is gone with the new tire. The remaining 5% may still be the rim, or it might be me imagining the bounce. I plan on taking it up the local twisties (safely!) this coming weekend to verify, as that is where I noticed it the most before.