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Old 04-08-2008, 04:30 AM   #1
Cois OP
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R1200 Rear main seal or gearbox seal replacement

Bought my dream bike (late 2004 R1200GS with low mileage – ±7500 miles) and loving it. However I’ve been looking around the forum for potential problems to watch out for and upon inspection I realized I’ve got a rear main seal OR gearbox input shaft seal leaking. My clutch still feels solid en I smell no oil. The oil coming out the seam also smells like engine oil – not gearbox oil. Unfortunately my bike is out of warranty. I would like to see if I can negotiate with my local BMW dealer for fixing under warranty due to my low mileage but I think it will be wishful thinking. I also don’t want to take the chance and let them split the bike only to tell me that they can’t help me with a warranty type deal and then I have to pay the high labour cost. So I think I’ll be splitting the bike myself, but now comes the questions.
I have the new Hayes manual and I’ve been studying it carefully, and it doesn’t look difficult at all. At this stage I need help with the following:
In order to get to the gearbox the whole half of the frame needs to come off. Now the stiff break line going from the ABS unit to the position as shown on the photo needs to be disconnected – or does it? Otherwise the sub frame can’t be disconnected from the gearbox and engine?! Is there any way to do this without having to disconnect any break lines?
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Cois screwed with this post 04-14-2008 at 10:42 PM
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Old 04-08-2008, 05:25 AM   #2
GB
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You're not going to get any responses with your black font on black background.. too hard to read, I fixed it for you.

The main seal is a known issue on virtually all model 04/05 and some early model 06's, so asking BMW for a good will fix is not unreasonable. It's a huge job so it's best left to them to do it, since you have to cut the bike in half. Before you do anything yourself, first determine which seal you want to replace. The gearbox and the rear swingarm and rear subframe all come off together to expose the clutch and main seal.
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Old 04-24-2008, 12:43 AM   #3
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So I did it...

So after thinking long and hard I decided to jump in. Also have a look at the following thread http://www.advrider.com/forums/showthread.php?t=143392&highlight=R1200+main+seal Here is my pictorial of how thing turned out: I use the Haynes manual as a guide. I also took my camera and took a lot of pictures of how the wires run along the frame before I removed it. I also used tape to make labels on some of the wires to distinguish the correct position.
First disconnect the battery cables. Starting at the back of the bike loosen all the panels so you can get to the rear light wiring harness. There are quite a bit of paneling to remove. With the wiring harness exposed, you would need to temporarily remove the seat locking mechanism in order to get the diagnostic plug out. All the wiring must be cut loose from the rear sub frame.




Next you need to loosen the clutch slave cylinder. At this stage I haven’t removed the rear shock but will have to do that in order to get it fitted back again and torque to the correct setting. Free the clutch hydraulic cable from any cable ties and secure it to something. I secured it to my head protectors, any from where I work.

On the right side of the bike, the stiff break line going from the ABS unit to the rear brake caliper needs to be removed. This brake line runs in-between two pipes that make part of the rear subframe and thus making it impossible to pull the subframe off the bike. Therefore the fuel tank first needs to be removed. To do this, first pull the two overflow pipes through the route they take to the back of the starter motor. Note this route. Next you need to disconnect the fuel hose on the right side of the tank at the coupling. Lay a cloth to catch any fuel that may be in the pipe. Tie a plastic bag over the two pieces of the couplings to ensure no dust entering.



Now move over to the left side of the tank at the fuel level sensor. Remove the plastic cover and disconnect all the wiring and the main fuel supply pipe. Also tie a plastic bag over these couplings to keep dust out.



Now the tank is ready to come off. Remove the four bolts holding the tank in place (2 on the side, 2 in the front) Take note of the position of the brackets on the two side bolts. These are the brackets for the side panels.



Back to the ABS and brake line. Disconnect the rear brake line mentioned earlier at the two ends. Note the way it runs and completely remove the pipe. Make sure to always catch any brake fluid spillage and wipe it off the paint with a wet cloth. Also disconnect the brake line running from the ABS rear brake reservoir to the rear brake lever. This pipe only needs to be disconnected from the ABS unit and will come off with the subframe. Note the plastic clips holding the brake lines together.



While working in this area also remove the throttle box from its position at the front of the air intake box.



On my bike the muffler clamps at the back of the throttle bodies could not be loosened so I had to loosen the muffler clams on the air intake box. Next the throttle bodies on both sides also need to be removed. On the left side of the engine the location of the throttle body obstructs the way to loosen the top bolt of the rear subframe and therefore the throttle body needs to be removed. Note the path of the wires connecting to the left injector in respect to the subframe and the clutch hydraulic pipe. Loosen the front camp on the throttle body and pull it out. Take care to move the whole system (left, right and the centre throttle box) as one unit. Tie it off with a wire to keep it out of the way.



Remove the gear shift lever and then loosen and remove the gearshift from the gearbox use your Torx E8 spanner. It’s not necessary to remove the linkage from the frame, just make sure it’s not in the way of the CAT as you put the frame back.

Next we move over to the propshaft. Cut the cable tie of the front rubber boot. Remove the rear wheel. Remove the plastic brake line and ABS sensor cover from the Paralever linkage. Remove the ABS sensor. Loosen the Paralever linkage rear bolt and tilt the final drive down. Pull out the propshaft in the prescribed way using a screwdriver from the front. And I got the feeling the previous owner did not think about spline lube.



I also removed the rear shock at this stage. This would give more room for up and down movement when pulling the frame apart. Put the rear wheel back on. Support the engine with your bike lift or just use wooden blocks like me. Make sure you also brace the front of the bike against sideway movement.

Now we’re ready to split the bike. Loosen all 6 frame-to-engine bolts and don’t forget about the one bolt fixed to the back of the gearbox. Ask for help and pull the bike apart slowly taking care to move the wiring harness out of the way. Make sure the rear brake pipe doesn’t get damaged by the right throttle cable going to the right throttle and disconnect the non-return valve for the fuel overflow pipes from the back of the air box. Disconnect the air sensor on top of the air box.



Next you will see the gearbox in front of you. Remove the plastic top cover over the clutch. Disconnect all the wires from the starter motor. Disconnect the gear indicator wire at the back of the gearbox. Loosen the 2 starter motor bolts and remove the starter motor. Loosen the 3 bolts holding the gearbox to the engine (note the positions of the bolts cause they differ in length) and carefully pull out the box using a rubber hammer to help it along.

My oil leak is due to the balancer shaft seal not doing its job. I also smell gearbox oil and therefore will replace both these seals. To get to the balancer shaft seal you need to remove the clutch. Mark the position of the clutch with respect to the clutch backing plate before you remove it so you’ll find your way back to how it was. Lock the engine in TDC and start to remove the 6 hex bolts holding the clutch to the back plate. (These 6 bolts need to be replaced by new bolts) I removed the whole clutch as a unit and kept it that way.

Now the balancer can be removed by loosening the bolt and pulling out the counter balance.



The way of the Germans helps a lot due to the one oversize spline inside the counter balance. This makes it fit only one way onto the balancer shaft.



If you bought the new seals, have a good look at the dimensions and how it looks. This will aid you when drilling a small hole in the old seal (±2mm to 3mm) and using a self tapping screw and pliers to remove the seal. Take care not to drill to deep or to damage the seal seat surface. Clean the inside of the seal seat with a clean cloth. Use a correct size drift (27mm socket works well) to install the new seal. I installed the seal dry but lubricated the inner surface that will mate with the counter balance with a small amount of grease, just to ease the introduction of the counter balance into the seal. Do it slowly not to damage the seal.

Now replace the bolt and torque to 10Nm and 90°



Over to the gearbox. Measure the depth of the gearbox seal before you remove the old one. Use the same method to remove the old seal. When installing the new one first cover the input shaft spline with tape and lubricate with gearbox oil to ease the seal over the shaft. Install the new seal to the correct depth.



The job is done and you can start to put everything back together again. After you fit the clutch and gearbox, fit the propshaft first before you mate the subframe to the bike. Make sure the front u-joint clips into place on the gearbox output shaft. Use the photos you’ve taken to help you remember the correct position of all the wiring as you mate the subframe to the bike again. Especially the wiring on the left side running to the left throttle. And the position of the clutch hydraulic line and the side stand cutoff switch wire.
After I installed all the wiring as it was and connected all the pipes, I took the bike to my local dealer to do a brake bleed (still need to build my own funnel) and throttle balance and a quick diagnostic to check the all the connections were done correctly.

Hel of a job but quit fun.
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Old 04-24-2008, 07:10 AM   #4
JimVonBaden
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Nice work! It is a little different than the 1100/1150.

Anyhow, this is a perfect example of why you need to lower your FD and lube it on occasion. The PO did a lot of water crossings, right?



That spline and seal wont last too long looking like that!

Nice work!

Jim
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Old 04-24-2008, 11:10 PM   #5
Cois OP
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Water crossing

I don't know the PO personally but thats in the past now. It looks like mud but it's actually fine dist sticking to a thin layer of oil/grease. I cleaned it up nicely and will be monitoring this.

When driving offroad the rubber boot covering this part sometimes opens up/pulls of the front of the paralever and lets in dust. What can one do about this?
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Old 04-25-2008, 08:08 AM   #6
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Quote:
Originally Posted by Cois
I don't know the PO personally but thats in the past now. It looks like mud but it's actually fine dist sticking to a thin layer of oil/grease. I cleaned it up nicely and will be monitoring this.

When driving offroad the rubber boot covering this part sometimes opens up/pulls of the front of the paralever and lets in dust. What can one do about this?
The boot usually has a coating of lithium grease on the mounting front and rear. This helps to seal out dust and some water. Clean it up well, and put a nice coating on it.

Jim
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Old 04-27-2008, 04:14 PM   #7
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You Rock, Cois. Nice Pictorial, Too!!
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Old 01-18-2009, 08:28 PM   #8
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Inspiration

Well thanks for the pics and diving in with this project because you inspired me to jump in too. I had the same tell-tale oil seepage at the engine-tranny joint as well as a stinky smell every time I'd stop at a light. I had already replaced the slave cylinder seal which helped a lot with the smell - but not totally. So last weekend I pulled the bike apart to get in there and see what was going on. Turns out that I have the same exact issue as you: leaky balance shaft seal. And as a bonus my input shaft seal is leaking and there's a bit of oil at the base of the output shaft seal. (jingoist epithet and un-PC remark about the heritage of this machine deleted). I do love how it rides though and even with these "qualities" the bike took me across the continent and back so I think I'll keep it. In any case, I think a 74 harley and 72 Triumph combined would have fewer leaks. OK we've heard all that before so let's forget it; I just had to get it out of my system. So now I'm ordering up a new clutch (mine's at 5.5mm so may as well) and all the seals and will be putting them all in after they arrive. Any tips you may have about removing/installing the balance shaft seal are appreciated. It looks like there's a felt ring or something before the seal (or is that the seal itself?) that needs to be removed before you get to the seal. Am I correct?
PS all the splines look terrific.
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