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Discussion in 'Parallel Universe' started by tmex, Aug 24, 2009.
Thanks John. Keep me posted on your..hopefully, "progress".
DP, after installing the bearings was the spacer between the hub bearings loose or tight?
Hey, don't worry. This is ADV, and nobody should be such a tightwad as to take offense that easily!
The length of the spacer as prescribed by Woody:
here's where it gets interesting,,,there are two basic approaches to wheel-bearing set-ups.,,,i'll call them:
type A,, probably the most common,,,uses precisely machined lateral flanges on the ID of the hub to locate the bearings....an inner spacer is used to prevent crush when tightening all the components /spacers on the axle... this spacer needs to be minimally .010''+.002-.000/steel or .020'' +.003-.000/aluminum to be effective.... so the hub essentially has a little bit of lateral float buildt in... a simple elegant fairly bullet-proof technique which fails only when :
a,,,the manufacturer uses too soft axle spacer BWOE KTM several years ago on the rear dirt bikes,,too much torque would crush them resulting in many blown up rear hubs
b,,someone specs a spacer the same size or smaller than the inner lip dimension.:huh
type B,,used by Kawasaki,Honda,BmW,Triumph etc, uses some means of retaining one bearing on one side [usually the side where the disc brake is on. ie to make sure the wheel consistently is spaced /aligned properly with the disc],,Kawasaki,KTM and BMW routinely use a circlip to retain that bearing in place,,,honda and triumph usually use a nut to hold it.,,,what usually happens next is that on the other side the bore in the hub often doesn't have an inner lip or the lip is usually bored far deeper than the width of the inner spacer...VOILA you have no worries about proper inner axle spacer dimensions because the bearing should self adjust....
The clamping force of the nut is to keep the axle positioned in the swingarm (and obviously to ensure the nut doesn't back off). It is not to 'preload' the bearing assemblies. Only one bearing is held in by a circlip, so the appropriate spacer length is less of an issue than the depth the second bearing is seated to.
So maybe a little test would be to torque down the axle with the wheel off the bike. Put some spacers on the axle about the same thickness as the swing arms. Then you'll be able to turn the axle by hand and see if there's any sort of binding, which should show up if the bearings are preloaded.
After install the spacer was not tight. I could just move it or wiggle it, if you will, with my finger.
Yes, I agree that the spacer should be snug between the bearings. In fact, a spacer that is a tad long should be OK since the bearings could move in the hub to accomodate that. A spacer that is too short would spell the death of the bearing(s).
Well for record, the front wheel spacer has plenty of slack. Im feeling it right now.
It is hard to know how much slack is too much slack. In my sample of two rear wheels (mine and F8GS) the rear spacer was snug enough that you when you spun one inner race with your finger the other race would move as well. I never looked at this on a front wheel. F8GS just got his wheel back from the dealer after new bearings were installed and the spacer in the rear was quite loose (he says). I can't see how how could get the axle in if the spacer was too loose.
I suspect he meant side to side inside the hub, rather than lengthwise between the bearings??
Thats correct Bayner.
I thought so also, but you cannot have one without some of the other.
Well we have some. Not much, but some. But it's normal I think. Before I had the proper bearing tool I used to use a punch when changing bearings on bikes. I could move the spacer to one side and exposing the edge of the spacer. Then catching the edge with my punch I'd knock out the bearing. Point is, I had enough slack to move the spacer fore and aft on other bikes in the past.
When installing these bearings they defintetly seated. But the spacer was not or is not, binding.
Just curious for shadetree purposes only. Does the right side Wheel bearing have a circlip? thats the one behind the chain hub. The dvd doesn't say and no picture of that side. If it does, it doesn't seem to matter whether the axle tube supplies any pressure or not as the bearings will be supported on both sides. From the pictures of the galling I would be more interested in the left bushing and whether it is applying pressure on the inner race of the bearing when the axle is torqued down.
My money is on chinese bearings
Since I had the wheels off I decided to mount a new set of tires now for the trip.
I'm liking the way that Mitas hooks up.
Not certain but I think the circlip was on the brake rotor side. There's only the one.
source for Mitas tire in the states?
ok... i labored through this saga and think I got it:
1. Its the customer's fault...
2. I should just sell my '97, '02, and '04 Suzukis, 'cause if it can happen to a BMW, it WILL happen to my suzis..... there's no hope ....
No, I meant lengthwise between the bearings. Before replacement, spinning one bearing spun the other because of the spacer. After I got it back from the dealer with new bearings, the spacer was loose and the spinning one bearing does NOT spin the other. Which way is correct????????
spinning one bearing is more likely to spin the other bearing, but is not a gauge of correct or incorrect installation. the balance of the equation comes from the frictional drag of the four bearing seals and bearing cage drag vs the lateral friction of the assembled bearings and spacer. Now, here's where is gets interesting.... according to BMW, proper installation technique would be to heat the hub to about 100-150 degrees centigrade, and the bearing will simply drop into the hub. Having not personally performed a wheel bearing replacement, I'm not sure if the front wheel is single bearing centering (once "captured" wheel bearing, one floating) or both wheel bearings resting against a machined shoulder in the hub. I'd venture a guess that it's the latter option. If that is indeed the case, There are several possible outcomes: spacer longer, spacer same length, or spacer shorter than shouldered area. Each will produce a different "spinning" effect as you asked. I would continue to assume the tech did not take the time to heat the hub up hot enough to "drop" the bearings in. More likely, a hammer was "dropped" on a socket similar in size to the bearing, while sitting on the bearing, if yo get my drift. Fortunately, if an authorized BMW dealer did the work, you've got a 12,000 mile warranty!
I'd say "B".
I replaced the wheel bearings in my Husky not long ago and I could cock the spacer with my finger. Meaning it was not binded and had room enough I could move it. My Honda XR was the same way.
The front on the BMW is shouldered. And as I said earlier, room temp, the bearing drops half way in before needing to be pressing the rest of the way. I used a bearing tool that presses the piece in to the shoulder. Both spacers had room to slighlt wiggle them. Not binding.