I finally had time to remove the transmission. It's obvious that the rear main seal is leaking. However, the one on the transmission doesn't seem to be leaking.  Should I replace both?

I would be inclined to leave it be unless it is a low mileage bike that has been bought back to life where the seal could be hardened.
I haven't seen many of those seals leaking.

bmwk100rs wrote:I finally had time to remove the transmission. It's obvious that the rear main seal is leaking. 

How have you verified that it's the rear main seal leaking rather than the output shaft o-ring leaking?

RicK G wrote:I would be inclined to leave it be unless it is a low mileage bike that has been bought back to life where the seal could be hardened.
I haven't seen many of those seals leaking.

Copy that. I'll not replace the one on the transmission.  Thanks Rick G!

Laitch wrote:How have you verified that it's the rear main seal leaking rather than the output shaft o-ring leaking?

Laitch, good point. I'll remove the nut tomorrow to find out. Hopefully, the o-ring is the one leaking since it will be easier to replace beside cheaper. Cheers!

If you are in there, replace the rear main seal, the O ring, gearbox seal [no need to open the gearbox, its replaced from outside]. Clutch friction plate is cheap too, buy Sachs as they make them OEM.

Its a bit of a false economy to leave original stuff in there due to bike age. Been in on my 84 K100 RT at 78,000 miles [bought at 36,000 miles] and rear main seal failed at about 70,000 miles, replaced at 78,000 as I had some trips planned. By that stage it had just reached the clutch plates.

A lot of other little items, O ring, clutch pivot arm bearings [change them to bushes and grease nipples], drive shaft boot, clutch pushrod boot, 

Pleasantly surprised at the cost of the parts too.

I've had five bricks in the past 7 years and never needed a transmission seal so my advice is to let the sleeping dog lie.  

Clutch o-ring is a must, and the rear main seal is a judgement call depending on mileage(or kilometerage).  I would check the clutch thickness, depending on riding habits it may not need replacement.  I've yet to need a friction disc on any of my bikes.  I'll admit I'm a cheap bastard and hate spending large amounts to replace parts that still have significant life left in them.

92KK 84WW Olaf wrote:If you are in there, replace the rear main seal, the O ring, gearbox seal. Clutch friction plate is cheap too, buy Sachs as they make them OEM.
Its a bit of a false economy to leave original stuff in there due to bike age.  

That's a well-balanced strategy from Olaf to you, bmwk100rs.

I come down on the side of false economy because my personal economy is mostly false so is in line with that strategy, and because I'm unlikely to irritate people into bar fights anymore at my advanced age, don a wingsuit or attempt K2's summit. So adventure for me is down to doing maintenance only on those items showing wear then riding the moto out to where mechanical failure would make life more challenging. I get peace of mind from my mind rather than MaxBMW. That's a cheaper route for me although Max's prices are reasonable and its service is excellent. 

The point I tried and failed to make in my first post is that making assumptions without personal experience to develop them is futile hurling. Determine for certain what is going on before taking action until there comes a moment when the order of the day is Do something, even if it's wrong. 

Point-Seven-five wrote:I've had five bricks in the past 7 years and never needed a transmission seal so my advice is to let the sleeping dog lie.  

Clutch o-ring is a must, and the rear main seal is a judgement call depending on mileage(or kilometerage).  I would check the clutch thickness, depending on riding habits it may not need replacement.  I've yet to need a friction disc on any of my bikes.  I'll admit I'm a cheap bastard and hate spending large amounts to replace parts that still have significant life left in them.

I can't disagree. I did replace the gearbox seal; because of being cheap and having it to hand and the bike had 30 years on it and never been opened. Clutch original friction plate might have done maybe 2,000 miles more and got to 80,000 miles, not from oil contamination but nothing left on it. A very timely project. 

I did a load of other things at the same time, change the fan, brakes, you name it. Its currently getting a replacement gas tank due to corrosion.

Euro MotoElectrics has the Sachs for $99 vs $354.03 at MAX BMW.  The current one measures 5.15mm, so I might just clean it with brake cleaner and install it back.

I like the idea of replacing other little items (drive shaft boot, pivot arm bearings, etc.), but they look in good condition and it will cost me another extra $250. Therefore, I'm going to stay within budget and just replace the clutch boot, o-ring, and the rear main seal for now in that area.

Just curious, how many miles does your odometer show? Even though these bikes are coming up on 30 years old, there are still a lot of them with under 20,000 miles on them. Even at higher mileage, a well maintained bike will have little wear beyond things like brake pads and some of the rubber bits.

Point-Seven-five wrote:Just curious, how many miles does your odometer show?  Even though these bikes are coming up on 30 years old, there are still a lot of them with under 20,000 miles on them.  Even at higher mileage, a well maintained bike will have little wear beyond things like brake pads and some of the rubber bits.  

It has 53K miles with all service records documented from two previous owners. You are right, most of the part that I have checked are still in good working condition and others like brake pads and rubbers are just must-do replacements.

__________________________________________________
1952 BMW R51/2
1967 BMW R60/2
1987 BMW K100RS
1991 Ducati 851
1993 Ducati 916s

@92KK 84WW Olaf wrote:Did you order the O ring and other parts needed?

You have to take off the O ring to get at it. Its not reusable.

These are from Motorworks. Also the clutch bolts are single use stretch bolts and are not part of the clutch plate kit..

Output shaft to clutch carrier O-ring | ENA60456 Fits K1 (09/1988 - 08/1993), K100 (09/1983 - 08/1987), K100 (09/1987 -... Show All... Associated BMW part: 11211460467 (11 21 1 460 467)
Larger Image		£1.12 INC VAT £0.93 EX VAT UK VAT will not be charged on non UK orders

Clutch friction plate | CLA64795 Fits K1 (09/1988 - 08/1993), K100 (09/1983 - 08/1987), K100 (09/1987 -... Show All... Associated BMW part: 21211464795 (21 21 1 464 795)
Larger Image	New clutch bolts and washers are required when fitting this part - please use 6 x CLA54417  and 6 x CLA42377  . If you are interested in an equivalent used part click here	£84.00 INC VAT £70.00 EX VAT UK VAT will not be charged on non UK orders

Is the tool below needed to remove the nut? Others seem to be able to remove itwithout it.

bmwk100rs wrote:Is the tool below needed to remove the nut? Others seem to be able to remove itwithout it.

What are the others doing to it that fails to convince you that they're actually removing it without it?   
Here is additional information to confound you from the Duckian Brick Research and Development Laboratory located at an undisclosed location somewhere in the Pacific Northwest, maybe. Scroll through it.

Laitch wrote:What are the others doing to it that fails to convince you that they're actually removing it without it?

The video here: https://youtu.be/3heap0adhXM?t=35

Thanks for the link to Drake Smith's page.

bmwk100rs wrote:

Laitch wrote:What are the others doing to it that fails to convince you that they're actually removing it without it?

The video here: https://youtu.be/3heap0adhXM?t=35

That video shows its being removed. Pick one of the methods you've run across and remove it. 

I ordered several of the parts you guys suggested here. However, I just realized that I didn't order the Clutch Stop Disc (11 21 1 460 873). Is it necessary to replace it when it still looks in perfect condition (1mm without cracks or scratch marks)?

No its reusable  



I had a bugger of time with my rear main seal  

and the O ring that I got from 4 different suppliers all seemed slightly different   

Charlie, Martin, Dave ended coming to my rescue 

but I did get really good at removing the  gearbox  off the bike in under 2 hours

Matthew-Brisbane wrote:No its reusable

Great, then I'll reuse it and save the $40.  Thanks!

The seal came out easily without any fight. The new should arrive tomorrow. However, I don't have the recommended mandrel (83300401441) to drive it in. Max BMW doesn't have it in stock and it will take ~4 weeks to ship it from Germany. The wood version made by Kenneth Lively is also out of stock, but he is might make more in 2 weeks. Does anyone know where I can purchase this tool in the U.S.?

Yes  you can tap them in slowly and softly with a bit of wood and rubber hammer  

Make sure you sand the back of the clutch basket were the seal cut it new grove

This is one of the many mistakes that I made

Matthew-Brisbane wrote:Yes  you can tap them in slowly and softly with a bit of wood and rubber hammer  

Make sure you sand the back of the clutch basket were the seal cut it new grove

According to the BMW Service Bulletin below, tapping them with a bit of wood or rubber hammer might not install them correctly.

Regarding sand the back of the clutch basket were the seal cut it new grove, do you mean sand the area where the arrows below are pointing?

No 
If you have a look at the clutch basket shaft you will see some  very fine wear mark that  the previous seal  would have cut in

Matthew-Brisbane wrote:see some very fine wear mark that the previous seal would have cut in

Using your picture, is the mark pointed with the arrow?  If so, then what sandpaper grit did you use?  1000?

Matthew-Brisbane wrote:very fine wear mark that  the previous seal would have cut in

Mine just has a fine line around. I'll try to clean any residue from the preview seal instead of sand it.  Thanks for pointing this out though.

I made a seal installation tool out of a chunk of 1x4 pine and a piece of cardboard from a cereal box.

Trace the seal on the cardboard and cut a hole just a bit larger than the seal.

Glue the cardboard with the hole on to the piece of pine wood.

Start the seal into the engine and then with the block tap it gently into place. When the cardboard on the pine block touches the face of the engine the seal will be standing proud by the required amount.

bmwk100rs wrote:

Matthew-Brisbane wrote:very fine wear mark that  the previous seal would have cut in

Mine just has a fine line around. I'll try to clean any residue from the preview seal instead of sand it.  Thanks for pointing this out though.

You don't need to use sandpaper on this stuff. Use a fine Scotchbrite-style abrasive pad to polish it, if that is necessary.

You also need to determine if you'll be using a Teflon seal. Teflon seals don't get oil-soaked like earlier seals and their openings are gently widened so they fit over the shaft. They will contract once installed.

Laitch wrote:You don't need to use sandpaper on this stuff. Use a fine Scotchbrite-style abrasive pad to polish it, if that is necessary.

You also need to determine if you'll be using a Teflon seal.

Thanks for this information. I'm glad I ordered the Teflon version.

When I removed my clutch it was obvious it was just the o-ring that was leaking. I left the main seal. About 40k km down the road and it's still fine.
Couldn't see any mention above about the 6x clutch bolts and star washers but these need to be replaced along with the split nut. Cheers

Holister wrote:The 6x clutch bolts and star washers but these need to be replaced along with the split nut.

Correct and they were ordered as well. Thanks.

I'm ready to refit the new teflon output shaft seal. The Haynes book says, "apply a thin smear of great grease to the housing, the seal outer edge, and its sealing lips".

Questions:

1) What kind of grease?  Staburags NBU 30 PTM?

2) Where are the sealing lips?

3) Is the black Teflon seal better than the orignal brown version? 

TIA!

The sealing lip is the inner part that runs on the shaft, it's lighter in colour. NEVER use grease on a seal when it is going to seal oil and vise versa, grease and oil do not mix and it can very easily burn the lip of the seal and it will fail again. Put a fine smear of oil on the seal and tap it in using a block of soft wood and a small mallet making sure it is going in evenly all the way round. Haynes do not make very good mechanics I see many bits of bad advice in their books.

RicK G wrote:NEVER use grease on a seal when it is going to seal oil and vise versa, grease and oil do not mix and it can very easily burn the lip of the seal and it will fail again. Put a fine smear of oil on the seal and tap it in using a block of soft wood and a small mallet making sure it is going in evenly all the way round.

Thanks RicK G!  I used oil and the new seal is now installed.

Hi everyone,

The Clymer book suggests to check that the pilot bushing is in place. Is the bushing the inner (brass color) piece indicated with the arrow?  If so, the book also suggests to apply grease in the inner surface.  Is it okay to apply grease there?

bmwk100rs wrote:The Clymer book suggests to check that the pilot bushing is in place. Is the bushing the inner (brass color) piece indicated with the arrow?  If so, the book also suggests to apply grease in the inner surface.  Is it okay to apply grease there?

Give that book to somebody who will believe it. You don't want to be led astray.   

My answer is yes, yes, but only if you're a literalist. 

Laitch wrote:My answer is yes, yes, but only if you're a literalist.

Thanks Laitch. BTW, I'm not able to pull the pushrod out of the transmission. Does it need to be released from behind by detaching it from the thrust piston and bearing?  Both ends seem to be okay (including the rubber boot -- no dry/leaks/cracks), should I just apply a little bit of grease to it and leave everything else alone?

bmwK100rs wrote: Does it need to be released from behind by detaching it from the thrust piston and bearing?
. . . should I just apply a little bit of grease to it and leave everything else alone?

You don't detach it from the piston/bearing assembly; you detach them from it, as Haynes indicates, and draw it out rearward. It isn't a hairy and complicated process, if you want to take a look and the components.

The moto has 53K miles on it which isn't much on one these clutches, unless the previous owner neglected to keep it adjusted to spec and it was slipping without notice for thousands of miles—a distinct possibility. While you were in there, did you check the clutch disc for wear?

Which lubricant did you apply to the transmission input shaft splines?

What you should do depends upon your confidence, your tolerance of uncertainty and your deference to the doctrine of anicca. 

Laitch wrote:While you were in there, did you check the clutch disc for wear?

Which lubricant did you apply to the transmission input shaft splines?

Thanks again for the clarifications.

Although the orignal clutch is still within spec, I'm installing a brand new one that I already had.

Regarding lubricant, I'll apply Staburags NBU 30 PTM.

When I removed the clutch housing, the splines didn't have Staburags or any kind of grease on them. I guess because they are lubricated by the engine oil instead.  However, the guy in the video below recommends applying Staburags.  Is that right?

https://youtu.be/BcXbHxSj3sI?t=737

Yep the splines of the clutch housing are lubed with engine oil, but you want to use the Staburags on the splines of the gearbox input shaft to the clutch.

daveyson wrote:Yep the splines of the clutch housing are lubed with engine oil, but you want to use the Staburags on the splines of the gearbox input shaft to the clutch.

 Are you saying not to apply Staburags to the splines of the clutch housing (the video is wrong), but do apply Staburags to the splines of the gearbox?

I think that video relates to k1200 bricks and looks wrong, you can see the oil galleries, it's lubricated by oil. 

On YouTube there are at least two videos by Chris Harris about BMW K100 spline lube.

bmwk100rs wrote: However, the guy in the video below recommends applying Staburags.

What do you know about this guy? 

daveyson wrote:I think that video relates to k1200 bricks and looks wrong, you can see the oil galleries, it's lubricated by oil. 

On YouTube there are at least two videos by Chris Harris about BMW K100 spline lube.

This forum and Chris Harris are my source for instructions. It is just happened that I saw this other video and it got me confused. Anyway, as RicK G pointed out, "grease and oil do not mix and it can very easily burn the lip of the seal".  Thanks daveyson fo confirming.  Cheers!

daveyson wrote:I think that video relates to k1200 bricks and looks wrong, you can see the oil galleries, it's lubricated by oil. 

On YouTube there are at least two videos by Chris Harris about BMW K100 spline lube.

A 1200 Brick has exactly the same type of clutch but about 20mm bigger in diameter. There is no oil feed to the clutch splines as with all the flat fours and triples. There is however an oil feed to the clutch carrier splines which is where the confusion may be. That oil feed is why the oil gets onto the clutch when the big fat O-ring leaks.
Use Staburags or any other high moly content grease on the clutch splines, wire ring and where the diaphragm spring touches the pressure plate.

Yep that's what I meant. Looking back that was way too ambiguous the way I said it.

Everywhere, the initial torque recommended is 140 N·m, but is the final one 60 N·m or 90 N·m?

Or is 60 N·m plus the torque angle gauge at 60°, or 90 N·m without the torque angle gauge?

Final stage 90-114Nm (66-84lbf ft) 

You probably want to go to the higher end of the range, especially if you sometimes get a knocking noise.

Which guide are you looking at, I'm looking at Haynes and BMW manual.

daveyson wrote:Final stage 90-114Nm (66-84lbf ft) 

You probably want to go to the higher end of the range, especially if you sometimes get a knocking noise.

Hi daveyson, do you mean close to 114N·m without adding the 60 degrees with the torque angle gauge?

bmwk100rs wrote:Everywhere, the initial torque recommended is 140 N-m, but is the final one 60 N-m or 90 N-m?

Just to elaborate on daveyson's explanation—because I have expended considerable effort spacing commas correctly—sometimes submission to authority is the way to go. Stick with torque values for simplicity.

Here's the torque table from the Clutch chapter of BMW's K75/100 2V service manual onsite. What this means is after the initial tightening and release, you have a dizzying array of Newton meter choices—90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, or 114. If you have a lucky number among that array, now's the time to use it. Anything below 90—including 60—is not part of the fun.

I hope I understand what you're after; I seem to be encountering comprehension obstacles tonight.