front wheel bearings

[Bill Conquest]

Hi everyone - I'm just getting ready to replace my front wheel bearings on my '79 R65  and being my first time need some guidance. I ordered new bearings and seals from Bob's, just got them..have read some info about packing them with grease & removing the old ones with a drift or socket.. possibly heating the hub & chilling the new bearings to install..but i'm not too confident  yet on this.It's a cast snowflake rim. Any thoughts or ideas would really help!
Thanks much, Bill

[Bob_Roller]

Disregard the process that you read, thats for the larger displacement BMW bikes .

On the R65, you remove the grease seals on both sides and the bearings come right out, along with the spacers and shims if there are any .  

I think one of our members here, Mike V had a write up on bearing replacement .

If you can't find it here with a search, send him a PM or email .

[Barry]

Bill,

Are the bearings damaged ?

If not a clean and grease is often all that's needed.  
With the seals removed the inner race drops out making a clean and re-grease very easy. If the bearings are being replaced the outer race will need to be driven out  and when you press the new ones in the bearing pre-load will need to be checked so you may need a different size of wedding band spacer or alternately there are shims available in 2 thou increments.  

One debate that may come up is to heat or not to heat the hub before bearing removal. If the hubs have steel inserts (and I believe they will) nothing is accomplished by heating for outer race removal as there is no differential expansion to be had. You can still chill the bearing and or heat the hub for insertion of the new outer race.

The other debate is how to check the pre-load. Mike V's article will be excellent. He will describe measuring rotational torque and this is the puka BMW method. By some accounts BMW seemed to get the pre load set up much too tight at the factory and mine confirmed that so perhaps they didn't follow their own guidance. The other method is to shake the wheel feeling for elimination of bearing play while torquing up the axle nut. I find this method adequate and easily sensitive to 1 thou change in the pre-load spacer or shim which should be good enough given that the wedding band spacers are only available in 2 thou increments. I made my own shims and did experiment with 1 thou changes.

Leaving aside LS models and the later bikes that have ball bearing races rather than taper rollers the only significant differences between R65's and other airheads is that some of the older models have a cover over the seals and in some cases the bearing outer race is pressed directly into the alloy hub hence heating for removal does provide differential expansion and is therefore recommended.

[Mike V]

Bill,

It's all about Preload, the special tools and procedure to accomplish.

There's never a short answer to this subject.

But first; closely inspect your existing bearings and races.  Wash them well with solvent and look for discoloration and/or brinelling.  The tapered roller bearings used in our airheads theoretically should last for thousands if not hundreds of thousands of miles.  If the rollers and races look free of any damage, there's no reason you can't reuse them.

If replacement is necessary I would recommend some special tools.  You'll need a bearing puller.  I don't recommend beating them out with a drift from the opposite side of the hub, damage to the wheel hub can happen too easily.  Check some airhead friends to see if you can borrow a puller.  If not, Cycle Works (Dan Neiner) sells a great puller that is very affordable and can also be used for swingarm bearings.  Make sure your wheel hub has a steel sleeve insert. Check the hub with a magnet and visually inspect.  If no steel insert, heat is necessary and essential to remove the bearing races.  I've used heat on the steel insert hubs but it's not necessary.  If you use heat on the hubs with the steel inserts you won't need to use a temperature of 225° as with the all aluminum snowflakes for removal and replacement but much, much less.

Once the races are removed clean the internal wheel hub well along with the bearing stack parts, wedding band, inner spacer, etc.

Put your new bearings and races in the freezer for about an hour or so. Keep them mated!  Do not mix the cages and races, keep them paired as they came in the package.  Carefully tap in the new frozen race with an appropriate sized socket using a dead blow hammer until the race is seated fully home in the hub.  What does your inner spacer look like?  Is it a spacer (pipe) with plastic ring(s)?  Or is it a one piece spacer with fixed metal ings?  If it has fixed rings you will need to grind them down a millimeter or so to get then past the inside diameter of the outer races.  This makes future maintenance much easier although I believe your inner spacer will have the plastic rings. Carefully install the remaining frozen outer race into the hub.  Remember to mark the right and left side of the wheel and keep your parts, clean, labeled rt & lt, and well organized.  Pay attention to the right and left top hat spacers and don't mix them up.  Inspect the contact area of the top hat spacers where the grease seal wipers contact the top hats ... wear grooves?  replace the top hats.

We're now ready for the preload procedure I don't recommend without experience and some understanding of what 15 to 25 in-oz's of axial rotation of force feels like.  But can be accomplished.  You'll need a take-up collar at an appropriate length to make up for the fork tubes width.  Capture the wheel in a clamping device - I use a Work Mate, it works perfect for clamping the wheel.  With lightly oiled rollers and races (not grease) assemble the bearing stack, wedding band, take-up collar and axle.  No grease seals yet.  The take-up collar is very important, it needs to have perpendicular ends in order to apply equal pressure to the bearing cages.  Cycle Works also sells these collars.  I would recommend having the ends turned on a lath, but that's just me.  Some have used 1/2" pipe cut with a hacksaw.  Suit yourself - I don't recommend that but you can do as you like.  With the wheel captured and your axle nut tightened to 25 to 30 ft-lb of torque, roll the axle with your hands and use a push-pull with opposite hands feeling for lash.  If too loose, you will need to hand mill the wedding band in small increments.  If too tight, you will need a wider wedding band.  Do not exceed 35 ft-lbs of torque on the axle nut. When the feeling is right - pack your bearings with grease and install NEW grease seals.  For Crap Sake, seals are cheap.  DON'T try to reuse them!!

This is the "raw" method of preload, if done carefully it may work well.  Explaining the method of preload based on axial rotation of rolling resistance gets a bit more involved and requires a more precise focus with more special tools - but not essential and many members here have successfully performed bearing jobs without special tools or the pull method of preload.

I've developed my own feel after several bearing jobs using the string and pull scale.  I think it's important to read Snowbum's web site on the subject.  It's lengthy but informative and a lot of time has been spent making his web site on bearings more reader friendly & concise.  My advice to you is to prepare yourself with some investigation and research - get a general understanding of the parts and how they perform.  Wheel bearings are a safety issue and if done incorrectly can cause serious damage.

Feel free to contact me by phone or PM (mvtv@cox.net).  I have a library of photos and information I'm more than happy to share with you.  Happy to help in any way I can.

[Mike V]

Bill,

Here's some links of mine you may find useful.  Sorry that some of these photos need to be annotated and organized in sequence a bit better.

Tools:
http://s428.photobucket.com/user/gruntyman66/library/Wheel%20Bearing%20Tools?sort=2&page=1

Preload:
http://s428.photobucket.com/user/gruntyman66/media/Wheel%20Bearing%20Preload%20Document/BearingPreload_3a_zpsd154a49a.jpg.html?sort=3&o=0

Pictures:
http://s428.photobucket.com/user/gruntyman66/library/Front%20Bearing%20Replacement-78%20R100%20Snowflake?sort=2&page=1

http://s428.photobucket.com/user/gruntyman66/library/Rear%20Bearing%20Replacement%20-%2078%20R100%20Snowflake?sort=2&page=1

-Mike V.

[Bill Conquest]

Thanks, everyone, for the great info..and thanks Mike V for the explanation and photos. I can see i'm going to have to study and absorb all this before I go forward..The front wheel had a low speed wobble & I attempted to fix it by a home spin balance. It helped some but not much..took the wheel to a local shop for a spin balance & the wheel wobbled on the machine..the mechanic/owner checked an
d told me the bearings were bad, soo..here I am with new ones ready to fix it.(and new seals).
Bill

[georgesgiralt]

Bill,
If you tried to balance the wheel at home WITHOUT the axe and bolt present, the bearing had no preload. thus, the wheel can wobble a lot as the bearings are free.
The same apply to the pro machine as well. If the guy does not use the proper cone penetrating the hub enough to press on the bearings, the wheel will wobble.
You can check the bearings (provided the bike is not an LS) by carefully removing the lip seal and removing the inner race. Then you can check the outer race for marks, pitting or rust and ascertain the state of this.
If the bearings are fine, grease them and remount the whole lot. Double check that the wedding band does not fall when the inner race is removed from the hub.

[Barry]

Bill,

Just to keep this thing in perspective. Wheel bearings are definitely a safety related item and anal types like me will go to the nth degree to get them just right. You do have to do it right but in truth it's not quite as critical as we like to make out.  Bear in mind that there is evidence that BMW were pretty awful at setting them correctly at the factory. My bike spent it's first 28 years with too much pre-load on the front wheel bearings and grossly too much on the rear wheel.

Mike,  You'll like this. I measured the rotational torque with the rear wheel mounted and I could detect the bearing drag over and above the transmission oil drag. That's how bad it was. I had to add a 4 thou shim.  And yet still it didn't do any harm at all to the bearings that I could see and I used a low power microscope to inspect them. I've heard of similar experiences. Duane Aushermans article explains how he found that without exception they came from from the factory with too much pre-load. He suggests that most dealers were not correcting this situation and yet it didn't cause major problems.

I guess what I'm trying to say is, yes you have approach wheel bearing pre-load with a proper understanding of what's involved but it's not quite as critical as it's sometimes made out to be. The very fact that BMW only supply spacers in 2 thou increments would seem to confirm that because unless you get lucky 2 thou increments are just too big to get them spot on.

[Mike V]

Great replies by George and Barry.  Agree with both regarding the balance and amount of allowable error in the preload.  I'm curious how the shop guy surmised the bearings were bad - did he remove them, clean them and inspect them, have the correct fittings to load the bearings?

I tried not to make my post sound too anal.  And 0.05mm WILL make a huge difference in preoad if you are at the minimum-maximum extents of the preferred allowable limits.  The key is getting inside those limits like anything else.

Remember the importance of axle nut torque - that is what is loading your bearing stack.

Bill - I think the best move at this point is to closely inspect your existing bearings.  Post some pictures and let's move forward from there.

[Bill Conquest]

Thanks everyone, I'll  inspect the bearings & report back. The shop guy just felt inside the bearings with his finger & said he thought they were bad... Not too technical..not sure if he used the proper cones on his balancing machine but he works on lots of machines so..I guess it's up to me to figure this out as there are no BMW people here on Kauai..
Thanks,
Bill