Rear wheel bearing question

m5bb

m5bb

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So as part of my rear end rebuild I replaced all the rear wheel bearings (4)

Original bearings were open style that you pack with grease.
New bearings from BMW are sealed bearings.

So there is a spacer that goes inside the hub with a shim that you can order different thicknesses of.
This spacer I feel is designed for open packable bearing like original.

So again can I leave the item #6 & 7 out and not use at all?
Bearings are pressed in to internal stops and hub is secured with a nut so no way they can move around?

What does anyone else think?

Don, have you experienced this?



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Can't seem to get list of parts to stay in format.
 
I couldn't really make heads or tails of this either when I did mine, my new bearings were open style that I packed with grease, they were the same width as previous so I just reinstalled as it was previously with the spacers and shims.
 
Stevehose said:
I couldn't really make heads or tails of this either when I did mine, my new bearings were open style that I packed with grease, they were the same width as previous so I just reinstalled as it was previously with the spacers and shims.
Click to expand...

Yes, I agree with that. I just think the spacer and shim are a tolerance device and not necessary with sealed bearings.
Did you read what the blue book says about the tolerances?
Did you buy the bearings from BMW? How long ago?

I am getting some vibration/noise that was not there before.
Does not show up till 60+ MPH and stops at 75 or so.

Tomorrow I'm going to put on lift and put in gear so I can look and listen more carefully underneath.
Makes me nervous but will get my brother to come over and sit in car to operate throttle.

BTW Steve I got the bigger output alternator put in and it's great.
No more lights flickering and now they are so much brighter.
 
Did you read what the blue book says about the tolerances?

Yes and I was more confused afterwards but all seems well back there.


Did you buy the bearings from BMW?

Hmm I don't remember but probably for something important like that.


How long ago?

About a year ago


BTW Steve I got the bigger output alternator put in and it's great.
No more lights flickering and now they are so much brighter.

Glad it worked out for you!


I am just now getting a slight vibration in 3rd gear at about 40 mph so I am going to put it up and check condition of guibo, center bearing, tranny mount and driveshaft alignment. Want this sorted before Amelia drive.
 
Nice upgrade but I think I would prefer to upgrade the bracket and alt at the same time so that you get the adjusters built in.

I have never done an e9 rear bearing, plenty of others though [e23, e28] and I have a nice kit that was custom milled for me. I don't know enough about the e9 bearing to say much of anything :[
 
I am in the process of buying new bearings to replace mine on the race car build and have had a look at this. The tolerance spacer (6) is required.

The large conical spacer (7) determines the distance between the inner case/shell of each of your bearings. The tolerance spacer makes up the remaining gap between the outer case/shell of your bearings (against the flanges in your arm) - essentially ensuring the inner and outer case/shell of your bearings are equally spaced. If the correct tolerance spacer is not used then the inner case/shell of the bearings could be 'squeezed' towards each other as you tighten the inner hub nut with the outer in a fixed position, or vice versa, inner case/shells in a fixed position and some 'float' on your outer case/shells. Either way, likely to promote wear.

The tolerance spacers are to ensure inner and outer case/shells of the two bearings are correctly spaced/aligned.

JP
 
frogisland said:
I am in the process of buying new bearings to replace mine on the race car build and have had a look at this. The tolerance spacer (6) is required.

The large conical spacer (7) determines the distance between the inner case/shell of each of your bearings. The tolerance spacer makes up the remaining gap between the outer case/shell of your bearings (against the flanges in your arm) - essentially ensuring the inner and outer case/shell of your bearings are equally spaced. If the correct tolerance spacer is not used then the inner case/shell of the bearings could be 'squeezed' towards each other as you tighten the inner hub nut with the outer in a fixed position, or vice versa, inner case/shells in a fixed position and some 'float' on your outer case/shells. Either way, likely to promote wear.

The tolerance spacers are to ensure inner and outer case/shells of the two bearings are correctly spaced/aligned.

JP
Click to expand...

Thanks JP.
I think I understand about the spacer. You are saying that without it the inner race of each bearing would be pulled in when the hub and nut are attached.
A couple of points then.
1. The new sealed bearings do not require grease which would have been in and around the spacer. Therefore the spacer is loose and just "floating" inside the hub?

2. I assembled an axle and checked the tolerance like given in the blue binders. There was a couple thousandths that the spacer would move in and out. I think the tolerance was less than that but don't have in front of me. When I took the axle apart again I noticed that the inner bearing was not very far in on the axle shaft. Some of the inner race was still over the splines. Photo. In the photo the inner is not as far down as it was assembled. Spacer on axle shaft in photo.

So my question is..... with sealed bearings that won't move around is the spacer still necessary?
 

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Potentially pulled in....if the tolerance spacer that you use is too wide, could promote wear from excessive thrust force. If it is too narrow then the bearings can float, and hence your hub.

On your photo, the inner bearing is not positioned correctly. The spacer is circa 65mm, the tolerance spacer is circa 5mm, and inside the arm flange to flange circa 60mm. It looks like your outer bearing is correct but the inner one needs pressing further down onto the hub.

Yes, just checked mine and the inner bearing does cover the start of the splines.

The tolerance spacer ensures the dimension flange to flange + tolerance spacer is the same as the conical spacer length. The toleranced spacers are at 50/1000 (mm) intervals - so quite critical.
 
frogisland said:
Potentially pulled in....if the tolerance spacer that you use is too wide, could promote wear from excessive thrust force. If it is too narrow then the bearings can float, and hence your hub.

On your photo, the inner bearing is not positioned correctly. The spacer is circa 65mm, the tolerance spacer is circa 5mm, and inside the arm flange to flange circa 60mm. It looks like your outer bearing is correct but the inner one needs pressing further down onto the hub.

Yes, just checked mine and the inner bearing does cover the start of the splines.

The tolerance spacer ensures the dimension flange to flange + tolerance spacer is the same as the conical spacer length. The toleranced spacers are at 50/1000 (mm) intervals - so quite critical.
Click to expand...

The inner bearing in the photo is just sitting on the shaft. You actually have to press it on. So I'm going to check the tolerance again and put it back together with the spacer and spacer ring installed.
 
and grease too IIRC

m5bb said:
The inner bearing in the photo is just sitting on the shaft. You actually have to press it on. So I'm going to check the tolerance again and put it back together with the spacer and spacer ring installed.
Click to expand...
 
Ed G said:
Sealed or no seals, width will be the same. Keep the original shims and you will be fine. The shims are required to compensate for the tolerance range of the wheel components. See-
http://www.e9coupe.com/forum/showthread.php?t=15815&highlight=Bearing+spacer
Click to expand...

Thanks Ed.
Frogisland explained it pretty well about the inner races being supported.
So it will go back with the spacers in place.

I searched for info and did not find anything. I must not know how to search????
 
And then I read:

It is advisable to renew the bearings after 60K miles, that means I have 2 sets to do. Well, at least I know a little more about the operation now :-(
 
Peter Coomaraswamy said:
It is advisable to renew the bearings after 60K miles, that means I have 2 sets to do. Well, at least I know a little more about the operation now :-(
Click to expand...

Wow that would be overkill.
Mine have 150K+ on them and probably would go many more miles.
They weren't making any noise but since I had it all apart it was the correct thing to do.
 
If I'm correct you are thinking about not installing the large conical spacer?
You have to install it!!

The ball bearings used in the rear axle of our cars are not designed to work with axial load (http://web.encoder.com/Portals/146177/images/radial-axial load.jpg).
So when you would be tightening the big bolt you are creating an axial force, pushing the inner rings towards each other while the outer rings are hold back by the seat they are in.
When the spacer is well installed (meaning the size of it is a little bit bigger or equal to the distance between the seats of the outer ring), the axial force between the inner and outer ring will be 0.

Hope you understand the importance of the spacer, otherwise your bearings will not last 10 miles.
 
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