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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: pallum on July 22, 2011, 01:18:08 AM

Title: Transmission noises
Post by: pallum on July 22, 2011, 01:18:08 AM: So last year a noise developed on my 1986 K75C. (http://www.k-bikes.com/forums/showthread.php?t=22806&highlight=tapping (http://www.k-bikes.com/forums/showthread.php?t=22806&highlight=tapping))

Over the last 20,000 miles it has gotten a bit more pronounced. Whirring/tapping coming from the bell housing area only in neutral with the clutch out. In any gear the noise is gone, and as soon as I pull in the clutch (while in neutral) it's gone.

Anyhow:
6,000 miles after I filled my transmission gear oil I discovered it empty when I decided to check the level after seeing some seepage from the weep hole. So the input seal is dead, could that be what's making all the racket? Or possibly bearing wear? Is it a good idea to refresh the bearings anyways while I'm in there for the seal?

And I guess while we're on the transmission subject, should there be any radial play in the output shaft? I'm able to turn the shaft ~5mm before the gears stop it, and back 5mm again. I can definitely feel it knock into place after coming to a stop and then engaging the clutch.

Edit: Oh yea...the first input spline lube I did lasted 8,000 miles. The previous one lasted ~11,000. Used Honda Moly60 the first time, and a 50/50 Moly60 and Wurth's mix on the second. Is this hinting at some alignment issue?
Title: Re: Transmission noises
Post by: Rick G on July 22, 2011, 06:54:52 AM: If the trans has been run dry then I would replace all the bearings as a matter of course. While you are in there just have a good look around and the source of the noise will most likely become apparent. Either there or clutch and pressure plates.I also would change the rear main seal for the cost of the seal and O ring it is a heap cheaper that doing it all again just for the sake of a few dollars.
Not knowing how mechanicly adept you are it is hard to say what path you should take.
Don't buy the bearings from a BMW shop as they are very common bearings and last time I did a trans rebuild for a friend the bearings were about $70 AUD as against $100x X for genuine.
As for the play in the output shaft that is quite normal.
Best of luck and if you get stuck we are always here somewhere in the world. :)
Title: Re: Transmission noises
Post by: chrish8846 on July 23, 2011, 07:51:00 AM: After just doing a trans rebuild I can say that lots of slop when hand turning the trans shafts is normal, more even that the last Muncie car trans I did. Very disconcerting but thats how they are. Also when the trans is in low and you the move the rear wheel back and forth 30-80mm or so of play seems to be the norm.
Title: Re: Transmission noises
Post by: pallum on July 23, 2011, 01:01:43 PM: Righto, good to hear about the free play.

Just got back from the BMW dealer. Got a quote on bearing and seal replacements just to see what my options are ($400, not happening)-- but they guy I talked to said to bring it in to look at it anyway. First thing he says is, "your splines are really worn," (which they aren't) and proceeds to start processing me for a new input shaft, once I remind him that I was only looking for bearing replacements he just said that "they look fine," and he had no comment on the noise. So helpful...

But one thing I did notice this time around was that someone else has been inside my transmission. There are all new bolts on the front cover, and some (rather sloppy) black sealer around the perimeter. Never noticed it before since I usually just wipe down the housing and put it all back together, but this time I used some degreaser and really cleaned it all up-- so now the source of the leak is appearing (will investigate further), but it doesn't explain the dry input splines after 10,000 miles (mechanic had no idea, surprise). My only solution is a new lube: Guard Dog, since I've already tried others. But if someone has any other possible solutions...

So I'll be popping into the transmission to check on that black stuff and the seals and bearings. I'm fairly mechanically inclined, but don't have access to many special tools, is there anything weird needed for changing this stuff? (@Rick G: do you have any part# or link's to suitable replacements?)
Title: Re: Transmission noises
Post by: Rick G on July 23, 2011, 08:48:39 PM: The only special I need is a knife edge bearing puller. Comes in two halves and clamps under the lip by tightening 2 studs, one each side.

The one I use is about 4ins square with 9/16 nuts and 3/8 unf threads on the bolts. I use short pieces of continuous thread rod cut to length with a piece of 1 1/2 x 3/8 steel with 2 holes drilled in the right place to pull against.

The only thing that is not straight forward is removing the circlip from the input shaft in that you need to pull the inner race back away from the circlip then remove the clip and reverse the puller to take the race off.

I have found that the bearings are usually made well enough so that the original shims on the input shaft and intermediate shaft will be right but I always check them as per the manual.

Little trick when assembling is to put the intermediate shaft and output shaft in as a unit then put the selector forks in then wriggle the input shaft in by slightly lifting the intermediate shaft.

Make sure the selector forks are straight and don't drop the little rollers on the selector forks. I use a little wire hook to hold the gears up while putting the selector forks in and then slip the shafts in.

They are very straight forward and well made just like any getrag gear box.

When I rebuilt my box in the K100LT it had done 300,000km and was in remarkable condition with just slight rounding on the leading edge of the dogs and the moly coating was missing of the drive faces of the dogs but no visible wear.
Title: Re: Transmission noises
Post by: pallum on July 26, 2011, 12:41:03 AM: Pulled clutch assembly today.

Was it a factory standard to use red Loctite on the clutch nut? I had also hoped to find some indication of the lubrication problem but there's nothing I could tell off the bat. Maybe a PO had taken the clutch apart before and not reinstalled it the same way as factory?

And bingo on the rear main seal. As soon as I cut the clutch o-ring, oil started pouring from behind the clutch housing.

Sending out orders for various parts soon so real work will begin in the next week or so.
Title: Re: Transmission noises
Post by: gfx on July 27, 2011, 02:38:14 AM: Quote from: pallum on July 26, 2011, 12:41:03 AM
Was it a factory standard to use red Loctite on the clutch nut?

Ugggh, damn BMW and their red Loctite. This is exactly why I couldn't switch my own rear rotor.

Serious props for taking care of this yourself; this really inspires an amateur like me to do more of my own work.
Title: Re: Transmission noises
Post by: frankenduck on July 27, 2011, 01:40:13 PM: I've pulled many a clutch assembly and never found any red Loctite. They are, however, torqued on there pretty well.

The secret is to put a block of wood in the bellhousing to keep the clutch assembly from turning. Here's a picture of using a block of wood to install a clutch nut. Just put it the other way to loosen the clutch nut.

(http://i82.photobucket.com/albums/j246/smithduck/k75f/k75f_035.jpg?t=1311788178)

Or rent an impact wrench from a local tool shop.

The Loctite BMW uses on the rear rotor bolts is actually white but between that and corrosion in the threads it's pretty common for the Allen heads to strip no matter how careful you are. You can just drill the bolt heads off with a 1/4" drill and then remove what's left of the bolts with some Vice-Grips:

http://www.motobrick.com/index.php?topic=658.0 (http://www.motobrick.com/index.php?topic=658.0)
Title: Re: Transmission noises
Post by: pallum on July 27, 2011, 07:39:17 PM: Quote from: gfx on July 27, 2011, 02:38:14 AM
Serious props for taking care of this yourself; this really inspires an amateur like me to do more of my own work.

Well I didn't really have much of a choice on this one :P Sent my final drive and drive shaft out to Bruno's to be rebuilt, and once I pulled off my transmission I just said what the hell and kept going. I had a friend bear down on the right handle bar as I tried to get the clutch nut off with a 3 ft breaker bar. Didn't budge. I remembered reading a package of the red loctite and it said it was "service removable with heating" or something along those lines so I got out my propane torch and gave it a quick cook and went at it again with the breaker bar with better luck.

This is the first vehicle I've ever worked on and it's intimidating, 100%-- but you just have to do it before you think too much and change your own mind. Then again, I'm 21 and still a little stupid. (Rode 10,000 miles around the country last month on these splines: http://www.k-bikes.com/forums/showthread.php?t=23812&highlight=spline+advice (http://www.k-bikes.com/forums/showthread.php?t=23812&highlight=spline+advice) , note my disregard to Dr. L Duck Hubbard's humble advice ;D)
Title: Re: Transmission noises
Post by: frankenduck on July 27, 2011, 07:45:12 PM: Just curious but what was the total damage (in USD) for the Bruno job?

There's also a firm in Oregon that does it: http://www.hansensmc.com/default.asp?page=spline (http://www.hansensmc.com/default.asp?page=spline)
Title: Re: Transmission noises
Post by: Rick G on July 27, 2011, 09:23:47 PM: I have managed to get a supply of hex head bolts, 7mm thread with 11mm hexhead that do the job of holding the clutch together and they actually come out each time and can be reused without any concern.
I have done quite a few clutches now without any problem and it sure is cheaper than replacing the things at $3 each because the head is stripped out.
Title: Re: Transmission noises
Post by: pallum on July 27, 2011, 09:48:09 PM: Bruno charges $783 USD, includes shipping back to your house. I had some flat rate USPS boxes that I got for free which fit my parts perfectly, so it only cost me $63 (customs charges) to ship them to Bruno's. But with that price you get new pinion seal, an entirely new final drive spline (will call you if bearings should be replaced), entirely new shaft splines, and a new u-joint.

They use some high strength alloy for the new splines and the pinion spline is a bit longer than stock so there's more contact area between the drive shaft and final drive. Expensive? Yes, but I'm willing to pay a bit more to get it done right (not saying Hansen wouldn't do a good job :D).
Title: Re: Transmission noises
Post by: frankenduck on July 27, 2011, 09:53:42 PM: Quote from: Rick G on July 27, 2011, 09:23:47 PM
I have managed to get a supply of hex head bolts, 7mm thread with 11mm hexhead that do the job of holding the clutch together and they actually come out each time and can be reused without any concern.
I have done quite a few clutches now without any problem and it sure is cheaper than replacing the things at $3 each because the head is stripped out.

Yep, the heads on those factory bolts to tend to strip easily, even sometimes if you heat them with a torch and are careful. Replacing them with hex head bolts is a good way to go.
Title: Re: Transmission noises
Post by: wmax351 on July 28, 2011, 12:49:57 PM: Quote from: pallum on July 27, 2011, 07:39:17 PM
Quote from: gfx on July 27, 2011, 02:38:14 AM
Serious props for taking care of this yourself; this really inspires an amateur like me to do more of my own work.

Well I didn't really have much of a choice on this one :P Sent my final drive and drive shaft out to Bruno's to be rebuilt, and once I pulled off my transmission I just said what the hell and kept going. I had a friend bear down on the right handle bar as I tried to get the clutch nut off with a 3 ft breaker bar. Didn't budge. I remembered reading a package of the red loctite and it said it was "service removable with heating" or something along those lines so I got out my propane torch and gave it a quick cook and went at it again with the breaker bar with better luck.

This is the first vehicle I've ever worked on and it's intimidating, 100%-- but you just have to do it before you think too much and change your own mind. Then again, I'm 21 and still a little stupid. (Rode 10,000 miles around the country last month on these splines: http://www.k-bikes.com/forums/showthread.php?t=23812&highlight=spline+advice (http://www.k-bikes.com/forums/showthread.php?t=23812&highlight=spline+advice) , note my disregard to Dr. L Duck Hubbard's humble advice ;D)

Good to hear about other young moto-Brickers. I'm 20, and have had mine for 2 years.

I had Bruno do my driveshaft and final drive (including the bearing). Very nice work. And it makes the driveshaft count as an accessory, not as original equipment, which bumps the value for insurance.
Title: Re: Transmission noises
Post by: pallum on August 03, 2011, 06:37:29 PM: Since the last post I have progressed my noise diagnosis to a problematic intermediate housing, bent or warped to the point that it causes a misalignment of the transmission to clutch connection. Dries out the splines quickly, and makes that obnoxious noise.

But since I'm still waiting on the housing from Duck, I'm starting to replace everything else that needs doing, starting with the rear main seal. The problem is getting that out. I've tried prying with a screwdriver, pulling with pliers and even getting a screw into it to pull on. The only kind of progress I have been getting is ripping a chunk out of the seal with the pliers and pushing it further into the recess with the screw (before the screw really got started) :P

Is it possible to use a gear puller on it? Can the output shaft be pressed on like that?
Title: Re: Transmission noises
Post by: Rick G on August 03, 2011, 09:25:56 PM: I use a slide hammer with a hook to get behind the seal but not everybody has all the tools. Using a bearing puller with a lip to get behind the seal would also do the job.
I have also used special lever which is T shaped with a hook on each side of the cross piece and a long handle for leverage.
Title: Re: Transmission noises
Post by: pallum on August 04, 2011, 02:09:46 AM: After more failed prying attempts I drilled a small hole in the seal, stuck a screw in and yanked on it. Broke a few screw heads before I put a small wooden block against the engine and pried a much bigger screw with a wrench off of the block ::) . New seal installed.

I then opened up the transmission, got scared and decided not to take anything out of it :P Just put a new seal on the input shaft and silicone sealant around the cover. All races and bearings were still tight and there wasn't any scoring or wear to speak of for the front bearings so I figured that since my problems seem to be coming from that intermediate housing... I'll just leave it alone for now (see what happens when you think too much?). Nothing else to really do until the new housing arrives so it's time for a break.
Title: Re: Transmission noises
Post by: rbm on August 05, 2011, 07:31:36 PM: I recently replaced the main rear seal on my 1988 K100, I borrowed a seal puller to remove the old seal. The operation took next to no time. I used a series of even pulls around the circumference of the seal and it popped right out. No need for fooling around with screws, slide-hammers, etc.

To put in the new seal, I used a hammer and block of wood. The operation was much longer because I was extremely careful to hammer in the new seal evenly. As the seal approached 0.5mm from the face, I used calipers to measure how far proud of the face the seal lay. When all around was 0.5mm, I stopped.
Title: Re: Transmission noises
Post by: pallum on September 01, 2011, 01:56:28 AM: Well, got it running. Replaced the intermediate housing after researching and getting second opinions but alas, something still isn't right. Noise is still there with the same symptoms as before. I'm hoping since the clutch plate and transmission are still there, and still worn, they are why the knocking is still present.

But in other news, something new has reared its head. Bike idling in neutral-- fine. Bike idling in neutral with clutch pulled in-- not fine. RPM decreases by about 200 and it sounds like there's some resistance on the engine. Definitely not what I expected ::) Any ideas on that one? Still waiting on drive shaft and final drive return next week but after that I may just take johnny's advice and

Quote from: johnny
ride it till it wont move...
Title: Re: Transmission noises
Post by: wmax351 on September 01, 2011, 12:52:45 PM: Quote from: pallum on September 01, 2011, 01:56:28 AM
Well, got it running. Replaced the intermediate housing after researching and getting second opinions but alas, something still isn't right. Noise is still there with the same symptoms as before. I'm hoping since the clutch plate and transmission are still there, and still worn, they are why the knocking is still present.

But in other news, something new has reared its head. Bike idling in neutral-- fine. Bike idling in neutral with clutch pulled in-- not fine. RPM decreases by about 200 and it sounds like there's some resistance on the engine. Definitely not what I expected ::) Any ideas on that one? Still waiting on drive shaft and final drive return next week but after that I may just take johnny's advice and

Quote from: johnny
ride it till it wont move...

Check the clutch adjustment. Might want to look at the clutch throwout bearing/pushrod setup.
Title: Re: Transmission noises
Post by: pallum on October 13, 2011, 09:24:54 PM: To close this thread:

Got all my ish back last week. Final drive and drive shaft returned from Bruno's, new rear brake switch, heated grips, that whole clutch slowing the RPM thing went away and I'm back on the road in time to enjoy the last of the good weather before the cold settles in.

I think the transmission input shaft did its damage to the clutch splines and they're worn out. The extra play that's now present makes for that obnoxious noise in neutral but from as far as I can tell, danger of them totally crapping out is many miles away. I figure that I'll live with it now and get a backup transmission and clutch ready for when they do decide to give up on me though.

Bruno results:

Before:
(http://i.imgur.com/iwEFGl.jpg)
high res (http://i.imgur.com/iwEFG.jpg)
(http://i.imgur.com/kPvpyl.jpg)
high res 2 (http://i.imgur.com/kPvpy.jpg)

After:
(http://i.imgur.com/IV9wHl.jpg)
high res 3 (http://i.imgur.com/IV9wH.jpg)
(http://i.imgur.com/Jv1IEl.jpg)
high res 4 (http://i.imgur.com/Jv1IE.jpg)

Total damage for spline rebuild: $1130
New splines, seals, u-joint and bearings.
Title: Re: Transmission noises
Post by: restinthesun on August 08, 2016, 06:01:49 PM: Not sure if anyone will still read this but thought it worth asking if my problem might be the same. I could use what worked from this post if so...

I've got a decent tapping/whirring noise when in neutral but stops when clutch pulled in. You can hear the clutch go in at :10 and :20.

Pallum, anywhere near the noise you had? (see file below)

She's a 88 k75S with about 56k on her. No idea when last spline lube happened (clutch or final drive—just bought bike last summer and have put 6k on it) but was planning to do it when changed tires at the end of the month. If it's a bigger issue (like pulling the back end off), I might wait until the season ends and get it inside for some work.

Any help would be appurciated!
Title: Re: Transmission noises
Post by: saudlin on September 07, 2016, 10:25:49 PM: I have the same noise but louder. I know it's clutch related but I'd be interested to find out too because I want to see if this is something I can try tackling myself. Any insights are appreciated
Title: Re: Transmission noises
Post by: Laitch on September 08, 2016, 12:14:01 AM: Quote from: saudlin on September 07, 2016, 10:25:49 PM
I have the same noise but louder. I know it's clutch related but I'd be interested to find out too because I want to see if this is something I can try tackling myself.
Welcome, saudlin! How about posting some photos of your bike in the Klassic K-Bike section?

Regarding your bike's engine noise:
Try making a video or sound recording of it and using the Attachments and other options feature below the Post reply box to post it in this thread. We'll be better able to identify the noise. Attach the file that's on your computer when prompted. Very often that's all there is to it. Alternatively, you could post it on YouTube and put a link to it in a post here.