Final drive taper roller bearing - how to replace?

[deftflux]

I've looked for this information around the interwebs, but I haven't been able to find it.  Basically, I am rebuilding the final drive on my 85 k100RT, because I noticed some play in the rear wheel along with some metal shavings collected by the magnetic drain plug.  I got the final drive apart, and sure enough, the crown wheel bearing has some roughness.  I think I caught it fairly early, though, which is good.  I found a video a while back of someone replacing the crown wheel bearing and oil seal, complete with measuring the shim thickness needed for proper preload, so that won't be a problem for me.

So here's what is a problem:  While inspecting the final drive innards, I discovered significant pitting of the outer race of the tapered roller bearing, which goes on the shaft end of the crown wheel.  The outer race, which is also known as the "cup" or "shell", is pressed into the final drive housing.  I'm wondering if anyone has ever replaced this outer race, and if so, how did you do it?

The only information I found about this was from a BMW shop manual:

Remove and install bearing shell for taper roller bearing.
Pull the taper roller bearing shell out with Kukko puller BMW 00 8 560.
When installing, heat the housing to 120 degrees C (thermochrome pin).

Obviously, I don't have such a tool on hand.  Is there maybe a trick to it?  Or a way to improvise such a tool?

Attached is a photo of the damaged bearing shell in the housing.  Thanks in advance for any insights!

[Bill]

I would use a suitable sized drift or pin punch from the other side, working around it tapping it out a bit each time,  Any  auto mechanic that has replaced front wheel bearings and disc rotors could show you how.  Big thing to remember is move it a little bit each time around it so it doesn't get 'cocked sideways' .  I'll look for a suitable video.

[Martin]

You don't say where you are, there are probably workshops capable of doing it for you, it might be worth it. It might be easier than buying specialist tools that you might not use again. I don't how well your workshop is equipped, but the only way I can think off is to make your own puller, or adapt another puller. There are pullers designed to do this but they are expensive. But as well as the puller you will also need a heat gun, and  if you are unsure of the temperature you are heating to a laser temperature gun would be handy. Then heat up the case, trying not to heat up the race to the correct temperature and crank it out slowly, you may have to heat up a couple of times.  To replace it you put the new race in the freezer at the coldest setting for a day or two. Heat up the housing to the required temperature and using the old race against the new one drift in the new race to the correct depth . YOU HAVE TO KEEP IT SQUARE, and do it quickly otherwise the race will heat up an the case will cool down. Unless you are REALLY CONFIDENT I would try and get somebody else to do it. If you decide to have a crack at doing it yourself let me know how much room is there behind the race.
Regards Martin

[Martin]

Bill there is no other side it's a blind hole.
Regards Martin

[Bill]

It looked accessible from the photo ,,,,, I am new to bricks so please forgive me.  Some one here must have done it  :dunno2:

[Martin]

OK Bill all is forgiven, just do 20 Hail Beemers.  :nono
Regards Martin.

[deftflux]

Thanks for the replies.  Yeah, I was considering trying to find a machine shop to do it.  I live near Minneapolis/St. Paul.  I think if a shop can get it out for me, I can probably install the new one.  I've done the freezer trick before.  Using the old race as a punch for the new one is brilliant; I'll make sure to save it.  With a great enough temperature difference, though, it may just drop in.  It will be interesting to see.

I did pick up a tool from Harbor Freight that looked exactly like the special BMW tool that I saw online for about 20 bucks.  However, the teeth that grab the edge of the race weren't nearly sharp enough.  I'd have to grind them to shape.  I'll probably try the machine shop first, though.

[F14CRAZY]

I've had to modify HF tools to suit unintended uses as well...least they're cheap so you don't feel bad about grinding on a brand new tool

[K1300S]

tool source.

http://www.cycleworks.net/index.php?main_page=product_info&products_id=57

$40

[Martin]

+ 1 Marshall  Deft go to the suggested site and Type in Kukku puller, great price. And if you have ruby red bike boots, you can just click your heels, and go get them in Kansas.  :clap:
Martin.

[Inge K.]

Deft go to the suggested site and Type in Kukku puller,

It's gonna be more succesful if you search for "Kukko".

http://kukko.com/index.php?lang=de

[Martin]

Inge it's the Ozzie accent.

[deftflux]

So I thought I would write an update as to where things are now.  I took it to a local machine shop.  The guy there was really friendly.  He doesn't have a tool that could pull out the bearing, as he said there isn't enough there to grab onto.  His idea was to heat the whole housing to 400 degrees, drop it on a piece of wood, and hope that the shell falls out.  This is probably based on the fact that the aluminum housing will expand more than whatever hard metal the shell is made out of.  However, he didn't want to do it with the pinion in place.  I looked into removing it, and it sounds like a can of worms that I'd prefer not to open.  As it is, it turns smoothly, and I can't feel any play.  Over the years, I've learned when to leave well enough alone.

Back to square one.  I was considering modifying the HF tool, but I'm worried that the 3 claws won't provide enough surface area, and if I grind them down, they won't be strong enough and will snap off.  Now that I found the real tool that you're supposed to use (more on that later), I see that the HF tool is not just like the official tool.

So I followed the links provided here (thanks guys) and was able to find more info about the official tool.  There are two pieces--an "internal extractor", which is kind of like a pipe with a lengthwise cut that flares at the end and spreads when you tighten it, and a "counterstay".  A scoured the internet trying to find these tools at a reasonable price, and the best I could find was about $65 for each at a VW tools site.  After tax and shipping, $152.  Ouch.  Still much better than $300+ at other sites, though.  Check out the internal extractor here: https://vw.snapon.com/SpecialToolsDetail.aspx?itemId=51330007

I ordered it.  Normally, I wouldn't fork out that much money for a specialty tool that I'll probably only use once.  I just don't think I have much of a choice otherwise.  It's the only sure-fire way to get that thing out.  For that price, I could get another used final drive, but with no guarantee that its race is in any better condition.  Oh well.

[Martin]

Double ouch what was wrong with the $40.00 Kukko tool Mlytle suggested??? I suppose if you keep the box it comes in, and be very careful not to damage or mark it you could sell it on??
Regards Martin

[deftflux]

That tool wasn't quite the same.  It's for BMW 00 8 551, which is different.  It doesn't say what diameters it's good for, and I couldn't find any info on the 00 8 551 tool.  Maybe it would work, but I'd be taking a chance.

[Martin]

Might of been worthwhile to contact them, because it looked different doesn't mean it wouldn't work.
Regards Martin.

[Bill]

Just a thought but if the tool is for VWs would a VW mechanic have one or could do it ?  If it is a 'one time' event what does a BMW service establishment say about it ?

[deftflux]

I guess I've gotten impatient in my old age...  (I kid, I only feel old because I'm turning 30.)  I called to see if they could cancel my order.  They might be able to, but worst-case-scenario, I can send it back for a refund if I find another solution in the meantime.

There are no BMW motorcycle dealers around here, but there are some VW dealers!  Great idea!  I gave them a call, but they said they'll have to get back to me tomorrow when one of their technicians is in.  So we'll see.  Hopefully they won't charge me $150 of shop time!

[Martin]

A bottle of Scotch, Bourbon or a slab of Beer sometime does wonders.
Regards Martin

[billday]

I know I'm late to the conversation but . . . with so many K bikes getting parted out nowadays, why not just replace the final drive?

[deftflux]

I considered that.  A brand new one is $1,000, and if I get a used one, there's no guarantee it's in any better shape than mine.  Mine worked just fine; I only opened it up to check the crown wheel bearing because I noticed a little axial play.  Any old used final drive may very well need the same attention.  Now if I could find a rebuilt final drive, that would be another story, but I haven't been able to find that.

So the tools shipped.  At least I have that as a backup in case these other ideas don't work.  One of the two VW dealers said they don't have that tool, and I'm waiting to hear back from the other one.

I got a hold of the Cycle Works guy to ask what inner diameter range that tool is good for.  He didn't know off hand, but said it pulls a 33 mm bearing and doesn't expand much beyond that, maybe 35 mm.  I don't have the tools to measure the actual inner diameter of the outer race, but using a caliper to measure the small end of the taper roller bearing, I figure it's between 40-44 mm.  So it doesn't look like that tool will work, unfortunately.  The official tool is good for 35-46, though, so that definitely covers it.

[TimTyler]

tool source.

That's ingenious!

[F14CRAZY]

I considered that.  A brand new one is $1,000, and if I get a used one, there's no guarantee it's in any better shape than mine.  Mine worked just fine; I only opened it up to check the crown wheel bearing because I noticed a little axial play.  Any old used final drive may very well need the same attention.  Now if I could find a rebuilt final drive, that would be another story, but I haven't been able to find that.

I support you trying to replace the bearing but that got me thinking...

My dealer's site says $1069.12 for a new final drive. I mean it's a lot, and it's a lot to spend on a motorcycle which may be over 30 years old, but at that point it would really last forever counting the splines are greased once in a while and the oil is changed once in a while. But what else would you spend your money on? You could buy a parts bike for that much and get another final drive that's in unknown condition (kind of like what you mentioned with getting another used drive). You could buy a whole nother ride-able bike but that's bound to have a whole nother set of problems.

So we might as well spend the money on a new final drive. I agree that it would be nice if someone was offering a rebuild service

[deftflux]

When all is said and done, assuming that I end up using and keeping the specialized tool, I've spent just under $300 between the tool and parts (bearings and seals).  That's kind of sad considering that the one tool alone was half the total cost.  But still, that's way less than a thousand.  The only thing that could still go bad are the bearings for the pinion gear, but even if I had to buy all new bearings for that, I think it would still total less than $500.

I think the only trick is preload adjustment.  If you get it wrong, the bearings could very well wear out again real soon.  Or the bevel gear will wear wrong.  So I'm taking a chance.  I plan on measuring all that, though, and if I need to, I can order different shims.

If I was Mr. Moneybags and had a grand here, a grand there laying around, I might just buy a brand new final drive.  Then again, why not a brand new bike?  :hehehe  But anyways I'd rather put that spare $700 towards a Russell Day-Long Saddle :drool:

[F14CRAZY]

well the other thing with a new drive is that you get new input splines