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Discussion Starter #1
I had a request for the old FD that failed on my '99LT at the end of last summer. The requestor never came around to actually sending out a FedEx shipping label, so it still sits in the garage.
Does anyone else want this massive amount of hardware? It also includes the brake rotor and fried Brembo. I have a picture of it all. If anyone just wants a few of the parts, let me know. I was told with all the metal shavings, the gear teeth are suspect problems for the long haul.
I really don't want to toss it in the landfill, but it all must go.

Have fun,
Jer
 

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If you are "throwing it away" I'll buy it for cost of shipping and a few bucks for your trouble. I'll rebuild it in my leisure and have it as a spare for the group. I have always thought the group should have a spare drive ready for express shipment in case someone gets stranded in the boondocks far from a BMW dealership.
I sent you a PM.


jers99lt said:
I had a request for the old FD that failed on my '99LT at the end of last summer. The requestor never came around to actually sending out a FedEx shipping label, so it still sits in the garage.
Does anyone else want this massive amount of hardware? It also includes the brake rotor and fried Brembo. I have a picture of it all. If anyone just wants a few of the parts, let me know. I was told with all the metal shavings, the gear teeth are suspect problems for the long haul.
I really don't want to toss it in the landfill, but it all must go.

Have fun,
Jer
 

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CharlieVT said:
If you are "throwing it away" I'll buy it for cost of shipping and a few bucks for your trouble. I'll rebuild it in my leisure and have it as a spare for the group. I have always thought the group should have a spare drive ready for express shipment in case someone gets stranded in the boondocks far from a BMW dealership.
I sent you a PM.
That is an excellent idea. Maybe there should be a spare rebuilt one in every country/state for emergency purposes.

I have one that I am planning to rebuild and have packed up (with all required tools for fitting) as an emergency if my new one fails.
There is no reason why someone else can not benefit from this as well.

Sounds like the start of a plan
 

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c00k1e said:
That is an excellent idea. Maybe there should be a spare rebuilt one in every country/state for emergency purposes.

I have one that I am planning to rebuild and have packed up (with all required tools for fitting) as an emergency if my new one fails.
There is no reason why someone else can not benefit from this as well.

Sounds like the start of a plan
Having the drive ready to ship with tools for change out is a great idea! I have David S's cut-out socket to put in the box. A new set of pivot bearings would be good too (they would add nothing to cost of shipping).
 

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Discussion Starter #7
yechave said:
I would be interested in seeing some pics, if you care to post. Feel free to e-mail directly if you like. Thanks!

[email protected]
Here's what I have:

There is a request pending. If they don't want it, it goes to CharlieVT.
It looks like the box weighs ~20 lbs. That's using the bath room scale with (me + box) - me.

Jer
 

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CharlieVT

Very good idea.

and as cookie said, maybe one in every country/continent and I`d also like a current list with posible contact information if one is going to be in the "neightbourhood".

This could also be good for a trailer to houl the bike on in case something happens.
 

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I had first dibs on this one. I told Jers99lt to let it go to CharlieVT if he is going to try to rebuild it. I wasn't sure what I was going to do with it,maybe wall art,maybe paperweight. I already have 2 spares. 1 is '99-01,1 is '02 on. These are available to members that need them.

dan
 

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Discussion Starter #10
DanMartin said:
I had first dibs on this one. I told Jers99lt to let it go to CharlieVT if he is going to try to rebuild it. I wasn't sure what I was going to do with it,maybe wall art,maybe paperweight. I already have 2 spares. 1 is '99-01,1 is '02 on. These are available to members that need them.

dan
You guys are quite awesome. I'm really glad I put the FD out here. The effort from you guys is much more than I ever expected.

Thanks, Dan. I'm sure you've heard that before.

I'll be PMing CharlieVT for shipping location.

What a forum! :bmw:

Jer
 

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CharlieVT said:
Having the drive ready to ship with tools for change out is a great idea! I have David S's cut-out socket to put in the box. A new set of pivot bearings would be good too (they would add nothing to cost of shipping).
Pivots yep.
So the FD 'back on the road' kits contents so far;

Rebuild FD
Torq wrench
Pivots
Cut out tool

What size wrenches for the job?

(this is giving me incentive to get on with researching rebuilding my spare now)
 

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c00k1e said:
Pivots yep.
So the FD 'back on the road' kits contents so far;

Rebuild FD
Torq wrench
Pivots
Cut out tool

What size wrenches for the job?.

(this is giving me incentive to get on with researching rebuilding my spare now)
12mm Hex/allen key
15 mil and 16 mil spanners to undo lower trailing arm
8 mm Hex/Allen key to remove brake caliper
cable tie to hang up caliper

Allen or Torx to undo the 2 screws that hold the disc on (should be heated as they have Loctite)

Loctite, tin of brake cleaner



Regards
 

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You could always clean it up and mount it on a 2x4 so you can use it (baseball bat-style) as an attention getter if you ever meet the doofus who designed it, or the BMW doofi who maintain that there is no problem with the final drives on BMW motorcycles.
 

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Final Drive arrived

Thanks Jerry, the final drive arrived today and I just finished removing the bearing and shims.
Interesting, there were two shims behind the crown wheel bearing.

It was a 19 ball bearing with severe spalling of the balls and both races.

Jerry, what do you know of the history of this final drive? Did you buy the bike new off the showroom floor, or is there a prior owner and unkown history?

The interesting thing is that the pre-load shims show signs of damage. At first I thought that the outer race of the crown wheel bearing might have spun in the housing cover, but there is no indication of a spun bearing on either the bearing itself or on the bearing seat in the housing cover.

?? I have a couple of theories as to how the shims got damaged, but I wonder what ideas you folks might have. ??

Bevel gear, taper roller bearing, etc. all look fine. Lots of metal particles, metal "mud", and obviously blown out crown wheel bearing with fractured cage, spalled bearings and races were expected. Two pre-load shims with indentations and scoring were a suprise.

Replacement bearing and seal are on their way from Chicago BMW. I have a couple of spare shims from previous rebuild, but I may need to order another depending on measurements when the new bearing gets here. I would not reuse the damaged shims from this drive; in addition to the obvious damage to them they don't "mic" as having uniform thickness.
 

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Charlie - how badly busted up was the cage? Do you think it failed first, or after the races spalled out?
THX NRP
 

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Discussion Starter #17
Re: Final Drive arrived

CharlieVT said:
Jerry, what do you know of the history of this final drive? Did you buy the bike new off the showroom floor, or is there a prior owner and unkown history?
Unfortunately, it's the later case. I am most likely the second owner. I believe it sat for at least a year before I got it. But, that's about all the history I know. First a cylindrical sound came out of the rear like the brakes were rubbing. The sound turned to loud banging that increased with speed. Then she blew out all her fluid on the road. Rode 25mi. after the banging started. Got me home.

HTH,
Jer

(Thanks for your diagnosis)
 

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niel_petersen said:
Charlie - how badly busted up was the cage? Do you think it failed first, or after the races spalled out?
THX NRP
Cage was severely broken. Spalling on balls and races was severe. I am not prepared to speculate which came first.
You can see the broken cage and unequal distribution of balls in this photo taken by Jerry before he shipped it to me:
http://www.bmwlt.com/forums/showthread.php?postid=284098#poststop
 

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Re: Final Drive arrived

jers99lt said:
Unfortunately, it's the later case. I am most likely the second owner. I believe it sat for at least a year before I got it. But, that's about all the history I know. First a cylindrical sound came out of the rear like the brakes were rubbing. The sound turned to loud banging that increased with speed. Then she blew out all her fluid on the road. Rode 25mi. after the banging started. Got me home.
HTH,
Jer
(Thanks for your diagnosis)
Thanks for the info Jer. The fact that you rode 25mi after it puked oil helps me make sense of it. That helps me explain the shim condition. I think the outer race moved in its seat and spun slowly, ground up metal parts from the failed bearing got in between the shims, and the shims spun a little like a couple of old grindstones in a gristmill, but trying to grind up material made of pulverized ball bearings. :)
 

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Rebuilding Final Drive

Crown wheel bearing arrived from Chicago BMW in just a few days, they must have had one in stock.

Credits to Dman who developed the technique I am using.

To avoid any pressure on the bearing balls and races during assembly, I heated the bearing in the oven (I used 350 degrees F) and chilled the crown wheel in the freezer. The bearing dropped onto the crown wheel without any pressure at all, gravity does it. I just made sure the bearing was fully seated on the crown wheel before the temps started to equalize. (Improper assembly technique where excess pressure is applied to the balls and races causing galling is one theory as to why these bearings are failing, so treating the bearing kindly during assembly was important to me.)

(Note: I am doing nothing to check crown wheel gear to pinion gear backlash. I inspected the gear teeth, taper roller bearing, checked the input pinion shaft for smooth rotation and decided all was okay. My procedure described here is only about installing a replacement crown wheel bearing and measuring for proper pre-load shimming.)

Another theory of final drive failure causation is improper preload, so I wanted to be very careful in measuring for preload shim thickness.

With the crown wheel/crown wheel bearing assembly placed into the drive housing, I heated the housing cover in the oven to about 170F. (BMW manual says 140F but my wife's oven doesn't set that low :)). The heated cover was quickly bolted in place on the drive housing. A dial micrometer set up. Two bolts placed into the holes in the crown wheel where the brake rotor normally bolts on. These are used to pull the crown wheel assembly up. The amount of movement is the amount of shim distance without pre-load added. NOTE: If the drive cover is too hot the crown wheel assembly moves easily and the shim distance measured will be GREATER than measured after the drive cover is cooler. POINT BEING: TEMP DIFFERENTIAL OF THE COVER DOES ALTER THE MEASURED SHIM DISTANCE. If you use a heat gun to heat the cover and have no ability to measure the temp you could make it too hot, the assembly will move up and down easily and the shim distance measured will be inaccurately large.

I experimented with a very hot cover (350F) and as the cover cooled, it became necessary to use increased force to pull the crown wheel assembly up (I used a couple of tire irons) and firm pressure was required to push the assembly back down. On this particular final drive, as the temp cooled the shim distance became a very repeatable 0.011 inch (0.28mm).

I used a heat gun to reheat the drive cover for easy removal and repeated the process several times. I removed and reinstalled the cover three times and made multiple measurements each time. As the cover cools, moving the crown wheel assembly up and down becomes increasingly difficult, but as it does, the measurements stabilize and become very consistent.

BMW Service manual states pre-load is 0.05-0.10mm. My observed shim space without preload was 0.28mm. Adding preload gives a shim range of 0.33-0.38mm.

Shims (spacer rings) are available from 0.10mm to 1.70mm thickness at 0.10 intervals, except there is one shim that is 0.15mm thick. That explains why two shims were in this drive! Rather than having twice as many shims available, BMW expects you to use a combination of shims if you want multiple of 0.05mm. So if you want a 0.35mm shim, you need to use a 0.20mm + a 0.15mm shim.

My plan is to complete the rebuild of this drive and then put it in a shipping box with tools ready to go. At some point when I am putting on a new rear tire, I'll change out my final drive and put a few thousand on this one just to "break it in". (BTW the final drive on my bike was rebuilt by me about 30K miles ago as a preemptive measure and it is going strong.)

Hope this helps someone else who is interested in rebuilding their drive.

Also: I'd like to compare this technique with that used by BMW using their special tool. I think I could make such a tool from trashed final drive cover. Anyone have a really trashed final drive cover they want to part with?
 

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