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Discussion in 'GS Boxers' started by bemiiten, Nov 26, 2006.
I would like to have your wrenching skills. Good luck!
Oh Man.. What an exciting post ! Can't wait to see how it all turns out. good luck.
Just a guess, input shaft bearing. Had exactly the same type of description as what you gave and that's what they found on pulling it apart. It felt just a shade unsmooth until you pushed on it at the same time as turning it, then it was downright gritty. Be interesting to hear how it turns out.
Here is a pic of the metallic fuzz on the black magnetic drain plug found at the bottom of the transmission. When I discovered the problem , first thing I did was to remove the fill plug to inspect the oil level. It was fine. Next I drained the gear oil into a clean pan to check for debris with a magnet. There was a little bit , but the small amount of fine metal particles in the hot oil would give me little concern normally. I never removed the black magnetic drain plug on the bottom of the trans before because the cat. needed to come off to gain access. I found a short 3/8 bolt that has a 9/16 hex fit's perfectly. I put on two nuts and used a wrench to remove the plug with the exhaust in place.I would soon find out that despite the service manual making no reference to remove and clean this plug for normal maintenance, not doing so was a major blunder on my part. The plug was absolutely filled with super fine metallic fuzz. I cleaned it up , refilled the trans and decided to take the bike for one last ride around the block to listen to the grinding noise one more time and to shoot the video. I should mention I drained the final drive just to make sure That the noise wasn't being transmitted somehow to the trans. Nothing at all was found on the drain plug. Here is a picture after I cleaned the trans plug once already. I rode the bike less than a mile and managed to pic up this much more debris!!! :eek1 You can bet that this will be coming out at every service from now on!
This is what was recommended by the dealer. I normally use what is called for in the manual. I already was using the 75/140 before I discovered the fact that it calls for 90w. This issue has been debated here before. Over the years , The container has been changed but what came out looked the same. BMW's latest lubricant is now red in color where the old stuff was the normal gold/brown color. Being the anal type, this set off alarm bells at my last fluid change. 5,000 miles later , bearing failure. :huh So I'm left wandering why shit happens. So what do you think?
The fuzz in the oil found it's way into the bearing and destroyed it.
The large amount of fuzz is from the bearing failure
The bearing was improperly shimmed at the factory, but took 55k to fail.
The catalytic converter's excess heat played a role in cooking the bearings.
Changing to the red oil did it!!!
The case is improperly machined , hence the reason the bearing would not come out while all the rest were falling out at a much lower temp.
Just a few of my opinions:
The fuzz isn't a concern unless it had very descernable chunks, or flakes of metal on it. Notmal wear and tear, along with break-in will create very small fuzzy particles that nicely stick to the magnetic pick-up.
The different color of your oils mean nothing. They have different colors so I wouldn't worry about that.
I would bet that it was just your time. It seems like you did all the correct maintenance, so I wouldn't blame yourself.
I'm very impressed. I wish I had the tools and knowledge to work on my own stuff.
Nothing to add other than appreciation for the time you are taking to show us your progress.
When you made the vary first post I almost spoke up to tell you what I thought it might be. Well I have been following this and I am so glad I did not say anything to show how stupid I am. You are so far advanced in your ability I don't have a chance. If I get my valves set and TB's set I think I did some thing. Well thanks for taking your time and making us all feel so small.
Thanks for a great thread
This is great stuff... It would be a fine addition to the HoW if Be-sMiiten is agreeable.
Neat post, thanks heaps for taking the time to share!!!
my cousin had his tranny go out completely on his bike and had it replaced. dealer said its a common flaw... he got it replaced and got a year warranty on the new one. he'll be getting rid of the bike with the warranty is up and getting something new. sorry
the rest of the trans looks to be in pretty good shape.....
its possible your box started out life with a problematic bearing??
shame, but always possible....
I think I will check my magnetic plug next time....dropping the exhaust system is not all that hard.....it will give me a reason to take off the center stand and give it a complete lube/rebuild.....
Thanks for the complete description....
Sounds good! But were not in the clear yet. If I screw up ,it could turn out to be the HoW NoT to do it :eek1 This is only my second transmission job and my first on a beemer , so I am no expert by any stretch. I spent some time thinking if I should take the transmission shafts to a dealer and have them swap the bearings. After careful consideration, I ordered a shop press and a bearing separator kit. Also in the works will be a way to drive the seals home properly, penny tech style. I will post a update when the parts & tools arrive.
I've been involved with several tranny rebuilds. They were all on airheads but the basics are the same. That isn't to say there won't be specific differences... One, if not the most signifigent aspect of tranny rebuilding is getting the shimming done properly. We developed a method where we dialed in a tranny and the differences are amazing. Most won't/don't want to go to the trouble/time spent to get this one aspect 'just right' but when you do the tranny shifts like a japanese gear box. Well actually like a german box with the snick-snickability of the japanese xmissions.
I can wait till the project is 'done' before we immoralize it for all posterity
You are also very modest. You are demonstrating tremendous mechanical aptitude.
This is my first BMW and I have never had the rear end off it. If it is ever necessary, I will do it. What little I know I about working on bikes I have learned by getting myself in over my head.
That's the right attitude. You've been successful in disassembly and diagnosing the problem might as well see it through to the conclusion yourself. You have already saved close to a thousand dollars in labor. Whats a couple hundred in tools. Here's to your successful conclusion.
My plan for shimming consists of carefully measuring the assembled length of the existing shafts. After the bearings are removed , I will compare them to the new ones as well. This should hopefully result in me being abel to match the same size that came out. One big assumption here is that they were shimmed properly to begin with! This is uncharted territory for me so any knowledge or suggestions would be greatly appreciated.Thanks to all for your encouragement and kind comments.
Plastic gauge is what I used on an airhead transmission. Don't forget to include the gasket thickness (or use a gasket when you measure).
I have not rebuilt any BMW transmissions but have done a few Japanese transmissions.
The main difference I see is that the bearings are pressed on the the shafts and interference fit into the cases.
When installing new bearings into the cases I always put the bearings in the freezor over night and usually they just drop into the cases.
For installing the bearings on the trasmission shaft I would put the entire assy in the freezor over night. Then find a socket that matches the inner race on the bearing and heat it red hot on the stove. put the hot socket on the inner race for a minute then pull the shaft assy out of the freezor and the bearing should slide right on.
If you need to extract any blind side bearings from the trasmission cases Snap-On makes a blind side bearing puller.