The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: flybot on April 19, 2013, 09:02:18 AM
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Hello,
Im trying to figure out if there is anything more to adjusting the wheel bearings than just proper torque of the axle bolt. I have an '83 R65, and Im not satisfied with the stability. The bike tracks just fine, but if you give the handlebar a shake while riding it it feels very wobly.
During my bikes restoration last summer, I replaced all the wheel bearings and torqued them according to the owners manual. I tried to read Snowbums info on preload. That guy has probably forgotten more airhead info than Ill ever know. But I get a headache everytime I try to read through his stuff. Way too much info. Just give me the quick facts.
So, is there some sort of shimming and preload set up I need to be doing? Or do I just torque the axle bolts down to get it right on an'83?
Ive gone through and replaced the swingarm, and head bearings. All seem good. I really suspect the rear wheel bearings.
Any ideas?
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There is a shimming/preload adjustment on the bearings .
Between the two bearings in a wheel, there is a long and short metal spacer, possibly thin shims between the two spacers .
The dimension of this assembly, gives you the proper preload on the bearings when you tighten the axle nut down .
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Are your tyres good? Is the rear squared off? What condition is the front?
How is your head set? Not notchy or any tightness?
Is the correct oil and amount in the front legs?
How are you rear shocks set? much preload? I am thinking about level ride height, if the bikes rear end is in the air then the front will be skittish/quick steering.
There are many things to check before pulling your bearings apart. I have not touched mine for years.....
The bike has shorter wheel base than the larger twins due to the shorter swing arm. This gives the bike the reputation of being a bit lively to the riders of the larger airheads, etc.
I am not trying to teach you to suck eggs, but what makes you think that it is the bearings? After all your set them up according to the manual...Just trying to get a better overall impression of the state of the machine.
Cheers
Rev. light
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The bike is "fully restored" with about 6700 total miles on it. I did the resto my self. Thread here: http://www.bmwr65.org/cgi-bin/yabb2/YaBB.pl?num=1346783584/0 All I can say is that Ive replaced all the bearings on the machine, and gone over all the usual suspects, filled and rechecked all the fluids, etc.
I suspect the rear bearings for two reasons: First, when its up on the center stand, I can grab the top and bottom of the rear wheel and try to rock the top of the wheel (not spin it, but push/pull the top of the wheel) and see the gap between the rear drive and the wheel hub change very slightly. I dont hear or feel any knocking though. Second, when cruising, if I let off and back on the gas quickly, I get a very slight fishtail weave. Doesnt feel good on turns.
I took the rear wheel off yesterday to do a quick check of the bearings and they feel fine. It just doesnt seem like they are tight enough and there is bearing slop.
When I had it apart with the bearing replacment, there was a spacer tube between the bearings, but no thin shims. Then it had the outer "hat" spacers under the seals.
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None of my R65's had any shims between the spacers .
You mentioned that you replaced the bearings, so that may require checking and adjusting .
With the axle nut tightened up and you have 'play' in the wheel, most likely you need to check the preload of the bearings .
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When I had it apart with the bearing replacement, there was a spacer tube between the bearings, but no thin shims. Then it had the outer "hat" spacers under the seals.
There is not necessarily a thin shim as that is an after factory build adjustment but there should have been a "wedding band" which is a short sleeve available in various lengths of I think 2 thou increments.
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Here's a kit that is available from Cycle Works .
It has the smaller spacer in a thinner size and shims to go between the spacers if needed .
http://www.cycleworks.net/index.php?main_page=product_info&cPath=29_41_44&products_id=204
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Is the axle nut tightened to spec? I think it should be something like 32 ft lbs.
If there's play in the bearings still, then it needs a thinner wedding band. There needs to be a slight bit of loading on the bearings for best operation and life. I've heard Harley specs zero preload and no play, and they hold up just fine. Or so I've heard.
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Yes, the nut is tightened to spec. Ive checked it several times. Seems strange because there is very little info on this preload adjustment on the web. I read through snowbums 25 page tome again and it doesnt really address the rear wheel. Although I think the jig he made up must work for both. I guess Ill have to use the "feel" method to get it right. Im not making a jig, and Ive adjusted plenty of bearings in my day. And Ill order up the kit Bob_Roller posted.
Because of the lack of information, I take it they dont need much preload adjustment once its set up right. Thats good.
Does anyone have any info from a Clymer's manual or similar? I know I need to go thinner on the wedding ring to get the bearings to go tighter into the cone. I guess to start Ill measure the current wedding ring and go tighter by a few thousandths.
Thanks for all the help guys. Ill post the progress when the kit arrives and definitely write an "abbreviated" How-to.
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I've always questioned this method that BMW has for these bearings .
I don't know how many rotors and brake drums I've removed in the last 40 years, the wheel bearings are held in by the grease seals, you install the rotor or drum, put the axle nut on torque it down to seat the bearing, back off until it's free, then tighten the nut until you feel a bit of resistance and put a cotter pin in the nut .
How many wheel bearing failures have you experienced in owning a car ????????????
I wonder if you didn't have the spacers between the bearings on a BMW bike, if you torqued the axle nut down until the was no free play, if you would have any bearing issues ???????????
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I think the forks would flex too much to tighten them that way. But there has to be a better way. I'll have to look up how my VRod bearings work. They have never been a problem.
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The way I was taught:
Remove the bearings and clean them well.
Shoot some WD-40 on the bearings. Not grease.
Assemble the bearings and spacers without seals. You'll need something to take up the space normally occupied by the fork legs or rear end. I cut up some old handlebars to different lengths.
Torque the axle nut to 32 ft/lbs.
The axle should spin with no drag and no play. Try different spacers until you are right on. If the size you need falls between two shims, thin the spacer on a lathe or carefully with a file.
Grease up the bearings and reassemble.
Hardley Dangerous used to spec a few thousands of an inch in clearance, then changed their spec to no play, no drag like BMW.
-Armen
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If you need to narrow the wedding band by a couple of thou you could just lap it down by that much or turn it down if you have access to a lathe. No need for the kit.
Before all that you have to be sure that bearing spacing is the cause of your problem. Leave out the wedding band and very cautiously tighten the axle nut probably no more than hand tight to see if the play goes away.
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The front wheel, you can install it on the front forks, without the calipers installed and perform the adjustment procedure .
The rear, I made up a fixture from two jack stands made up a 'spacer' to take up the dimension of the final drive width on the rear axle, with a piece of cast iron water pipe .
Used clamps to secure the axle to the jack stands and did the adjustment procedure off of the bike .
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Those are all great ideas. I think I can work something up with black pipe and jack stands. Sounds pretty easy.
I think as someone mentioned, I can just lap the existing spacer down. I ordered the kit anyway, since I had to get new seals as well.
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Flybot,
Sorry I'm getting to this thread so late. I most closely agree with Armen's post with some amendments. There's not a short answer to the process, I would recommend re-visiting Bum's web page, and reading Section 4 of his web site on Bearings and Preload over a few times. We've been in the process of editing/improving the instructions the past few days. He's included some graphics to help some. In Bum's defense; it's a difficult task to give a tutorial as involved and complcated to such a wide range of readers with a wide variety of experience, knowledge and skill levels in a smooth delivery without detours. Correct preload determination can be a safety issue and not taken lightly. My personal opinion.
Contact me by PM, I can try to talk you through it the best I can with a phone call maybe later this evening. There's some special tools and equipment involved. And it's important for me to know some details on where you are and where you've been in regards to the work you've already performed.
Going for a ride...
mvtv@cox.net
-Mike V. / San Diego
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Thanks for the offer! I wont be getting into it until the next weekend probably. New seals on order. If I run into any issues I know where to call.
Thanks
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How many wheel bearing failures have you experienced in owning a car ????????????
Two or three, I'm not sure which. At least one on my '58 Chevy, before the Napco conversion. And my wife's '85 Civic wagon had a front wheel bearing go out. Those suckers are expensive, and are the same kind as your CRX has. The nice thing about cars is you usually get lots of growling warning and they don't make you wreck.
I'm pretty convinced that our BMW wheel bearings would also give some advance warning before they failed in such a way as to lock up a wheel.
But I can't prove that.
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OK, here is the follow up.
As stated, I initially thought the rear bearings were loose. I didnt suspect the front. I ordered the spacer kit and a few seals, and I did the bearing adjustment last night. Not what I expected.
The front wheel needed .10 mm tighter. The rear needed .15 mm looser. The rear was pretty tight and Im glad I have only done about 150 miles since they were installed. It was suprising. Also, while going through everything I found that one of the shocks was not set the same as its opposite. One full soft, one full firm. That must have been left over from the restoration rebuild.
The lesson learned: New bearings=new bearing adjustment.
Here is how I adjusted mine. It may not be the perfectionist way, but I know what a tight or loose bearing feels like.
The bearing adjustment kit is a rather ingenious kit. Instead of having a "wedding ring" of every size, the kit includes a small and medium size ring and ten 0.05 mm shim rings. Enough to make every needed size.
The adjustment takes several trial and error tests to get the setting right.
I did my front wheel first.
-Take off the front brake caliper(s) and secure them out of the way with zip ties.
-Remove the wheel and remove the left seal. The wedding ring should be under the bearing under the left seal. I had spare seals available, but I used a automotive seal remover and my seals both came out with out any damage what so ever. Since they had less that 200 miles on them I chose to reuse them.
-Re-install wheel and torque to spec. For my '83 I used 32 ft.lbs
-Spin wheel and see how it feels. Rock back and forth and see if any looseness is present. I could feel a slight knock on mine.
-Remove wheel again. I needed to tighten my bearing, so that means a thinner wedding ring.
-Remove wedding ring and measure thickness with a micrometer. Mine was at 6.65 mm. As a starting guess, I decided to try 6.45 mm using the bearing adjustment kit.
-Re-install wheel and give it a spin. If its too tight, try a setting between current and where you started. Too loose still, take off another .10 mm (two shims).
-Re-install and repeat until you have the tightness right.
-NOTE: when it gets too tight it will be apparent. From that point go one size thicker. and check again. As you change sizes to the tighter side, check for over tightening of the bearing as you torque the nut down.
-Since I still had one more wheel to go and only one adjustment kit, I took the correct spacer size, measured it, and then took the old wedding ring and used a file to carefully reduce its thickness to the required thickness.
-Re-install with re-sized spacer and recheck tightness.
-When your sure its right, re-install seals and reassemble front end.
For the rear wheel:
You cant check the bearing of the rear wheel when its on the bike. Too much drag with the rear drive. You need to make a spacer for the drive side. Pretty easy and it cost me about $6.
I bought 3/4" galvanized electric conduit and a 3/4" washer. Cut the conduit to 3.25". When testing off the bike, assemble the axle, and on the drive side of the wheel, put on the hat, 3/4" washer, conduit spacer, and washer and axle nut. Tighten to spec. I cut the conduit with a tube cutter, like for copper pipe. That way you get a nice flat cut. Seemed to work pretty well. Just make sure your spacer is pushing against the "hat" and not reaching over the hat to the seal/bearing area.
The spacer tube needs to be a min of 17 mm to go over the axle, and a max of 22 mm to stay on the hat (or use a washer like I did).
-Remove the seals as before.
-I used the same "feel" test as the front wheel, initially using the existing wedding ring as a starting point.
-From there, the trial and error adjustment is the same as the front.
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Good write up.
There is a lot of mystery around wheel bearing adjustment but it's not rocket science and actually doing it is far easier than reading about it. When I first got my bike I checked the bearing adjustment using the feel method based on Duane Aushermans write up http://w6rec.com/duane/bmw/wheel_bearing/index.htm and concluded they were fine. I stopped short of the full 32 ftlbs as 25 ftlbs is considered adequate if all traces of play have gone by that point which was the case. I think in any case that the 2 thou increments of adjustment are too big without using some variation in torque setting to compensate. When I checked again recently to re-grease and do a wheel balance I found no detectable difference in the set up.
There is some discussion doing the rounds on other forums about measuring frictional torque using string and a spring balance or a low range torque wrench. This is considered the correct and perfectionist way to it but is probably not absolutely necessary. If I have no perceptible play and the bearing doesn't get excessively hot in use then I'm happy with that.
Good to see someone else thinks seals can be re-used when appropriate.
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Thanks for the comments. Yes, the .2 mm initial stab to tighten was too much. I made an edit in the post about checking the tightness when going to a tighter spacer. It was just a guess. I really had no idea what was appropriate since Id never adjusted a bearing in this way.
The feel method does rely on a bit of experience to determine what is right. The scale and string procedure seems good, and you probably cant go wrong. But I dont have an appropriate scale, and Im confident I adjusted mine to a safe setting.
Oh, and the bike does feel much better now. It still seems like it has a lot of flex compared to other bikes Ive riden. But that seems to just be a characteristic of these great bikes.
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I've used the Ausherman Technique from the get go and find it to be more than sufficient. I like the simplicity of both the idea and the technique.
The tapered roller bearing preload on the rear axle of my 1986 VW Cabriolet is set following the popular Bentley manual's instructions:
... fit the thick washer and tighten castellated nut until the washer can be barely moved by using a flat blade screwdriver to push on the washer. Insert cotter pin.
Not too far removed from Duane's process for the BMWs.
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Here's the process of determining proper bearing preload on 737 aircraft main wheels .
While rotating wheel, tighten axle nut to 300 ft/lbs, loosen axle nut to zero, torque to 100 ft/lbs, then tighten axle nut until next holes for safety bolts can be installed .
Not exactly a very precise method to say the least !!!!!! ;D ;D ;D
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Flybot,
They say necessity is the mother of invention. No, not the precise method of preload - I would agree. But it sounds to me that you have acquired some important knowledge of the general operation of the bearing stack. That in itself is a most important result of your efforts.
Just want to go on record saying I wouldn't recommend your procedure. Not saying you didn't find the happy and safe zone of preload. And congratulations on saving a couple of dollars on the grease seals.
-Mike V.