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Discussion Starter #1
Just purchased a used 3000 mile since rebuild diff from Bruce... Thanks Buddy !

He had his bike triked and sold me his diff... Box came in today and not only did he send the diff but with the brake rotor attached and the brake caliper and shoes !! Also sent a box of bolts and the Torque Strut....

That's what I call a deal......

I'll be carrying it in the trailer to CCR and whenever I travel far so I'll never need it....

Probably will post my cell on the CCR forum so anyone who might break down enroute can call me....

Question is::

What if any "special" tools will I need to have with me in order to change this in the field...


Thanks

John
 

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What's a "diff", John? If by "diff" you mean "differential", I don't think our LTs have one, nor any other 2-wheeled motorcycle - only need one of those when there is more than one driven wheel on the same axle and you'd like to go around a turn without scraping rubber off one of the tires.

You talkin' 'bout the rear drive, including the infamous crown wheel bearing?

- Bob
 

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Discussion Starter #3 (Edited)
Yah,,, I guess it's really not a differential is it....once again caught using a generic term.

Yes the rear drive....Complete with rotor,boot,pivot bearings...

Still need to know if I need anything special to change it in the field...

Looks like with a complete unit it would be fairly easy.....The plan is to drain and flush it so it won't be leaking any oil from the overflow and then just wrap it in plastic and box it for the duration.....I'll just throw in a half quart bottle of gearlube with it....

John
 

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Having done just this same job a week ago, I don't think I'd like to change the rear drive assembly on the road. Most of it uses basic tools found in your bike's tool kit:

T25 to remove the rear mud flap
17mm lug wrench for the rear wheel
8mm allen for the brake caliper
flat blade screwdriver to remove the clamp on the rubber boot

Here's where you'll have trouble. You also need:

16mm wrenches for the trailing arm
30mm socket to remove the rear drive pivot locknut
12mm allen to remove the two pivot bolts
gear lube and loctite
and zip ties are handy to keep the brake caliper tied up out of the way

That gets the whole rear drive assembly free from the bike.

Now installation is a bit more tricky. First, you want to align the rear u-joint with the front u-joint to minimize vibration issues, but you can't do that if you can't see the front of the drive shaft.

However, that's not as critical as the torque specs on the rear drive pivot bolts. You'll need a torque wrench plus a 12mm allen socket to torque the two pivot bolts correctly. The outside (fixed) pivot gets torqued to 160 nm, while the inside (adjustable) pivot gets torqued to only 7 nm. Then you'll need that 30mm socket with a special window cut out of it so you can hold the 12mm allen still (to maintain the 7 nm torque) while torquing the outer 30mm lock nut to 160 nm. The rest of the procedure is pretty simple though.

This is a pic of some of the special tools you'll need:


And this is a pic of how to properly torque the outer lock nut while keeping the inner pivot from moving:


Like I said, I don't think I'd like to do this on the side of the road, or in a parking lot somewhere. I suppose if you had the parts, special tools, and BMW Maintenance CD with you, you could get any motorcycle or auto shop to help you out. But the only way I'd carry all that stuff with me is if I was in the Iron Butt Rally and absolutely couldn't afford a day or so delay. I've had two rear drive failures on two different LTs, and both times I just arranged for a trailer to get me to the nearest BMW dealer and had the bike fixed within a day or two.

If you're still serious about this, I'd suggest you do the procedure at home in your own garage where you can afford to spend the time to get it right. I'd also combine that test run with a clutch slave cylinder swap. Then you'll know if you really want to bother carrying all this stuff with, or if you'd rather just pack it all up in a box ready to be shipped by a friend or relative if needed. Besides the actual chance of a failure is pretty low, unless you're on your way to CCR. :D

Hope that helps.
 

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Discussion Starter #6
Thanks Ken...
Especially for the pix...So, I know it wouldn't be the "correct" procedure.... But it looks like you could just snug up the allen and then use a crescent wrench on the lock nut.

Since it only pivots that would probably get you going long enough to get to help..

Yeah I'm talking about emergency procedures on the side of the road... That would get you running long enough to get to a dealer and have them set it up right..

Thanks for all the insight...

John
 

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Discussion Starter #7
AND !!!

I really think just having the spare and packing it around with the tools will pretty much guarantee I'll never have a failure.....Cheap insurance...and for me peace of mind... I'm certainly tech enough to change it out if I had to..

I've always found that being prepared for failure usually prevents it..

Thanks again,

John
 

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jpspen said:
I've always found that being prepared for failure usually prevents it..
John, do you wear both a belt & suspenders ? ;)

Dave
 

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grifscoots said:
Man, just thinking about getting the rear rotor off, especially if it's high mileage and say a 1999 vintage, in a parking lot with an allen key makes me all warm and fuzzy. Can you say potential cussing storm?
I've done that one as well. Ended up with a few busted knuckles and all new bolts. But fortunately John's spare drive still has the rotor attached.
 

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Your call, John. Personally, I'm short on luggage space and carrying capacity already, so I don't think I'd want to carry the extra weight around. If I did have another failure, I'd just call for a tow truck and sort it out letar. But at least you'll know what you're getting in to.
 

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Discussion Starter #11
Dave,

No, but I always wear clean underwear...

Thanks again Ken for the good info...See yall at CCR !

John
 

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"How To" WORD doc

John,

I can't remember who posted this originally...but I think you may be interested in downloading it for future reference. :)

All the best,
 

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Discussion Starter #13
Thanks Joe !!!

That get's printed and put in "The Book".

You know, I've only owned a torque wrench in the last few years.. Never EVER used one when I was young and fixed lots of things.. Never had a torque related failure.....Just gotta know when to stop pullin'.

Note to self... Buy crackpipe torch for locktite softening....."No Sir, Officer, That's not for smoking crack. That's for loosening bolts".....

John
 
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