Rear Bearing Stack Pre-Load Adjustment

[Mike V]

Guys, apologize ahead of time if I'm not following protocol, this is a question in regards to my 78 R100/7 and it's rear bearing stack replacement and pre-load. Hopefully this subject (thread) will be useful for the 650. This is my first time with this procedure. The stack came out with no problems after ample application of heat to the all-aluminum hub. Original bearings were brinelled and discolored along with corosion and pitting. I have assembled the new bearings and races lightly oiled only. I've reviewed Bum's and Duane's web sites. I'm now in the process of the pre-load adjustment by feel since I have no available spacers or adequate pull scale for axle tension measurements.  I also have the shim kit with 2 wedding bands and 10 0.05mm shims.  I'm happy with what I'm "feeling" now with the addition of 2 shims and the original wedding band. The outer spacer can be shifted easily with two thumbs but not flopping and moving on it's own with 25 Ft-lbs of torque applied to the stack.  And axle rotation tension seems free with the slightest bit of resistence. My question(s) to the experienced here is; can someone describe what too "loose" and too "tight" is on the outer spacer and what is the allowable latitude of adequate pre-load?  Am I splitting hairs? Am I good to go?

Another question for re-assembly I have is; I am inclined to insert the rebuilt bearing stack without the freezer method due to condensation of the metal parts during insertion to the heated hub. I've been told with adequate heat the assembly back in the hub is easy enough to forego the freezer method.

Any opinions and advice is appreciated.

[montmil]

OK, since you've been out of pocket at the Redmon Rally, we'll cut you a little slack, Mike.

Scroll down a few threads in the Tech Section to Bob Roller's Rear Wheel Bearing Service for a few tips. There's also a DIY in there from "Monte's Ghetto Curbside Rear Wheel Bearing Preload" that's pretty simple. Way too much angst and drama from da 'bum... at least on this topic.

I, too, skip the freezer trip with the bearings for the same reason. They go right in with the hub heated to spit sizzle temperatures. I use a large socket -metric, of course - to seat the bearing's outer race. Match up something that fits the outer race diameter but does not contact the hub's shoulder. Tap it in square to the bore.

[Mike V]

Monte,

Thanks for cutting me some slack, I've been in town overwhelmed with projects in preparation for my tour. I viewed the thread between you and Bob, informative as you and Bob always are.  I won't comment on Bum's article other than I've read it several times   and have yet to draw what I'm really searching for; with all due respect obviously.  I overlooked the Wiki section as I do too often, thanks for that tip. I'll go there when I get home tonight and have a look. I guess my biggest question is the "feel" for correct bearing pre-load prior to the "wiggle test" and the reaction of the outer specer when things are right - I apologize again if the Wiki section already covers this and I take responsibilty.  But I have to vent a bit too at the enormous amount of text on the subject that's out there in abscence of graphic depiction.  I think I've been contemplating and over-thinking this subject too much and just realized ... drive the damned stack in the hot hub and access the inner spacer and wedding band from the 5-bolt retainer if the pre-load aint right by "wiggle". I'm just trying to experience the right feel of the outer spacer when pre-load is correct for myself so I can help the next poor wrench to attempt this.

Thanks for the reply and advice, I'll be going to Wiki this evening.  I'm going to try and get some photos together of the entire process in hopes it will be a useful tool in the future.

[Bob_Roller]

Mike, I've been giving this a bit of thought the last few days .

I have an idea of placing a metal pipe or other substitute on the right side of the axle, that will mate up to the bushing protruding and not cause any binding on the seal .

It needs to be long enough so you can torque the axle nut down to the proper range .

Place the wheel axle assembly on two automotive jack stands, maybe secure the axle/pipe to the jack stand with ty-wraps to steady it, then test the preload on the bearings .

Just a rough idea .

[Mike V]

Bob,
Interesting thought - are you talking about a type of jig to secure the wheel?

I've decided to pack the bearings and install the bearing stack with the two 0.05mm shims. The two shims give the bearings a good smooth feel and easy movement of the outer spacer. My guess is; I'll get some wiggle during the "wiggle test" but it should be simple to remove a shim or even two after the wheel is mounted simply by accessing the inner spacer and wedding band by removing the retainer if needed. Process of elimination, unless I get lucky and it's good as it is.  Either way it will give me an idea what the proper feel should be on the bearing stack before installation into the hub. Here's some photos.  I'll organize and add text in the near future to explain what the components are and what I'm trying to accomplish.

http://s428.photobucket.com/albums/qq8/gruntyman66/Rear%20Bearing%20Replacement%20-%2078%20R100%20Snowflake/


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[Bob_Roller]

Yes Mike, kind of a jig or fixture of sorts .

I came up with another thought about the right side of the wheel, get an extra 'hat' bushing, or as BMW calls it, a compression ring, place it on the right side with the flange part away from the wheel, then add a length of pipe to take up the remaining area, then put the axle nut on and torque it down to the correct range .  

[Mike V]

Bob,

I'm interested in your line of thought...are you trying to rig something up for the final "wiggle test" without going through the trouble of mounting the rear wheel on the bike?

[Bob_Roller]

Exactly, the '82 LS that I have, the previous owner had the wheels powder coated, upon re-assembly, the 'hat' bushing on the left side was not reinstalled, so the axle went in about half an inch or so more than it should .

My first clue to this, was the extraction hole in the axle, was now in the pinch area of the swing arm .

So I want to do this job myself, who knows what else may not be right with the bearing, shim, spacer stack up .

[Mike V]

Bob,

Are you talking about the outer top-hats or the inner wedding band? Must be the top-hats, if it was the wedding band you would have some serious issues. I don't think the large top-hat is going to affect your pre-load, it would only alter the depth of your axle in the pinch area as you stated. The outer race of the left bearing should find it's home on the inner shoulder of the hub...I would think.

[montmil]

Bob,

Are you talking about the outer top-hats or the inner wedding band? Must be the top-hats, if it was the wedding band you would have some serious issues. I don't think the large top-hat is going to affect your pre-load, it would only alter the depth of your axle in the pinch area as you stated. The outer race of the left bearing should find it's home on the inner shoulder of the hub...I would think.

You are correct in your thinking. [smiley=thumbup.gif]