Author Topic: 93 K75 Transmission/Clutch Issue (Read 13580 times)

dwatson · « **on:** September 09, 2015, 11:55:30 AM »

New to BMW and to this forum. I am currently in the process of trying to find and correct the problem the PO had with this 93 K75 howling/gnashing of splines when engaging the clutch lever while attempting to shift. In all the bike has set for the better part of 5 years. Originally the bike was exhibiting problems with the clutch which he had repaired by a local BMW independent mechanic. Shortly afterwards he had an electrical problem which was finally traced down to a bad ground, resulting in ~3 years of sitting in his garage. Finally after the electrical repair he soon experienced the problem with the shifting and had the bike towed back to his garage where it sat for another 2yrs.

Currently I have removed the final drive and drive shaft, splines were inspected and appear to be OK with grease visible. In preparing to remove the transmission to inspect the input splines and clutch I noticed an opening at the front end of the transmission. Should this have had a bolt or is it an open weep hole?

As I said I'm new to BMW and looking for any suggestions/opinions to get this bike back on the road where it belongs.

K75RT Keith · « **Reply #1 on:** September 09, 2015, 01:29:13 PM »

The hole in the bottom of the transmission is a weep hole.

Any growling or gnashing of splines would indicate that the transmission or drive shaft are not properly installed. However, if they were not properly installed, you'd likely not be able to reassemble the drive line.

My guess is that the noise is from an improperly adjusted clutch and that the gears are grinding because the clutch is failing to fully disengage. If the clutch isn't burned or worn, I'd determine if the cable is stretched or the clutch rod isn't adjusted properly.

dwatson · « **Reply #2 on:** September 14, 2015, 03:46:44 PM »

Help - I am feeling like a real goofus so I will volunteer my suggestions for the dumbest questions for the day. After watching the Chris Harris clip on removal of the transmission and clutch on the K100 multiple times I am now attempting to do the same on this 75. Everything up to the point where you remove the boot, clamp, spring and pressure piston went great. Then #@*&! 1)How the devil do you get the circlip released from the release pushrod end?? And 2) Is it necessary to remove it when pulling the transmission off to lube and inspect the splines at the front?

Maybe I just don't have a long enough tool (distinct possibility) are maybe I am not the sharpest tool (a definite reality) but I have not been able to get the clip to spread and am hesitant to remove the transmission without knowing.

Suggestions welcome; snickers, guffaws and eye-rolls expected.

Scott_ · « **Reply #3 on:** September 14, 2015, 07:22:18 PM »

Not sure what circlip you are referring to.
Make sure that your clutch cable is disconnected from the housing, the pivot lever can stay in place, and the pushrod on a 75 stays in the transmission while you remove it.(it cannot come out the rear, you will see why after you get the trans out)

rbm · « **Reply #4 on:** September 14, 2015, 10:18:35 PM »

If you're talking about the clutch pushrod, on the K75 it comes out from the front, not the back. You have to remove the transmission completely from the bell housing to access the pushrod. Since this is a later model bike, the thrust bearing (what you call the pressure piston) is a single piece so there should not be a circlip to remove after it has been withdrawn.

Since the pushrod withdraws from the front, it is not necessary to remove it prior to removing the transmission, to inspect and lubricate the clutch splines.

Motorhobo · « **Reply #5 on:** September 15, 2015, 05:42:47 AM »

He's talking about the circlip you can see if you look into the rear end of the transmission -- dwatson, don't feel stupid for asking the question because I wondered that myself first time I looked at it -- I even tinkered with trying to get it out before someone told me to leave it the f**k alone.

That circlip belongs to the transmission and has nothing to do with the pushrod. You can be happy to learn that you will never have to deal with that circlip in your lifetime unless you want to tear the trasmission completely apart and rebuild it. So stop agonizing about that. Like rbm said -- you get the pushrod out by removing the transmission and pulling it out from the front.

So -- leave that circlip alone and pull that tranny.

dwatson · « **Reply #6 on:** September 15, 2015, 10:14:12 PM »

Thanks for the responses. Another day and I did learn something. Doesn't always happen, but it nice when it does. I hopefully will get a chance to remove the transmission and inspect and lube the splines soon.

I have been impressed so far with how straight forward the bike is to work on, except when I get in the way of the engineering that is.

dwatson · « **Reply #7 on:** October 27, 2015, 03:29:31 PM »

Well the saga continues, I was able to return to this project this weekend and removed the transmission. I found the following; the output splines on the clutch friction plate were severely worn (picture attached), the input spline on the transmission showed signs of wear, but appeared to my untrained eye to be serviceable (picture attached), and it appears the clutch release pushrod shows signs of galling where it resides within the input spline.

Questions of the day are: 1) Are the friction plate splines designed to be sacrificial??? 2) Are the transmission input splines still usable? 3) Is the galling found on the release pushrod normal or could it be an indicator or cause of the early failure of the friction plate splines?? 4) What all is recommended for replacement?

The bike has relatively few miles (<1000 miles) since the clutch was replaced by an independent BMW mechanic, so I am somewhat dismayed by what I found. All splines had signs of lubricant and no oxidation or dried grease.

Thanks in advance for all comments and suggestions.

F14CRAZY · « **Reply #8 on:** October 27, 2015, 05:03:33 PM »

I replaced my clutch disc for the same reason...trans splines were good but splines on the clutch disc hub were going bad. Was still working but I knew they weren't going to hold up much longer.

The subject of lubing splines has been covered in countless forum threads, but unfortunately the trans should be removed periodically, maybe every other season, maybe every 20k miles, something like that...to the splines can be cleaned and lubed in an effort to limit this wear. Shifting can also get difficult sometimes and lubing the splines seems to most always fix this.

A grease high in moly is prescribed by BMW. I used Honda Moly 60, though it has been recently discontinued...not sure what the direct replacement is

Laitch · « **Reply #9 on:** October 27, 2015, 05:29:31 PM »

If the friction disc was new less than 1000 miles ago and its splines have already worn out, take that up with the mechanic who installed it before you do anything else.

rbm · « **Reply #10 on:** October 27, 2015, 06:27:32 PM »

Quote from: F14CRAZY on October 27, 2015, 05:03:33 PM

I used Honda Moly 60, though it has been recently discontinued...not sure what the direct replacement is

Honda M77 Assembly Paste is the replacement.

Scott_ · « **Reply #11 on:** October 27, 2015, 08:07:55 PM »

There were splines left in that clutch disc? They looked pretty well gone to me.....

Re the previous mechanic, you have a couple of strikes against you. 1, you aren't the same owner that took the bike to them, and 2 even at only 1000 miles or less, it was over 5years ago that the work was done.........so I wouldn't hold my breath that he will offer to do anything for you.

Before you remove the bolts on the pressure plate, make sure you mark the 3 pieces so you can be sure to put them back together in the same position(relative to each other).

dwatson · « **Reply #12 on:** October 27, 2015, 10:20:52 PM »

Agree the clutch splines were nearly smooth. I was wondering if the input splines on the transmission were useable. Also trying to figure out how those clutch splines were smoothed out. I know the PO and when they sheared he was close to home and had a neighbor bring a trailer to get him home.

Agree the chance of going back on mechanic is a no go.

Laitch · « **Reply #13 on:** October 27, 2015, 10:29:50 PM »

Have you tried an alignment tool in that clutch pack? The photo makes alignment of the components look skewed.

dwatson · « **Reply #14 on:** October 27, 2015, 11:40:39 PM »

I agree, it looked out of line and wondered the same when I removed the transmission. I thought when he stuck the transmission it would have lined up. But perhaps close wasn't close enough. Hadn't thought of cking with a tool though.

Laitch · « **Reply #15 on:** October 28, 2015, 08:12:11 AM »

Misalignment would damage the friction disc splines and stress other parts, too.

rbm · « **Reply #16 on:** October 28, 2015, 05:58:26 PM »

That kind of misalignment could have resulted during the removal of the transmission. It's unlikely that alignment would have been present with the transmission in place; it would be impossible to push the transmission home like that.

Laitch · « **Reply #17 on:** October 28, 2015, 08:17:43 PM »

Brute force makes the impossible possible sometimes, just not for long—in this case maybe 1000 miles. It's hard to tell though just how misaligned it is from the photo. I agree it would be quite a feat to mate up those cases if it's as far out as it looks. Maybe it was necessary to lubricate the process with some Jim Beam, too.

rbm · « **Reply #18 on:** October 28, 2015, 08:48:44 PM »

Quote from: dwatson on October 27, 2015, 03:29:31 PM

The bike has relatively few miles (<1000 miles) since the clutch was replaced by an independent BMW mechanic, so I am somewhat dismayed by what I found.

It is known that some of the bell housing castings on the K-bies were not perfect. The surfaces forced the gearbox into non-parallel alignment with the clutch, accelerating wear of the clutch splines. This might be the case with your bike. Replacing the bell housing with a known good unit is the repair.

Paul Glaves explained the problem in the May 2011 issue of BMW Owners News:

Quote from: Paul Glaves

Clutch Splines There was a “thread” (group of posts on a single topic) about Oilhead final drives and how to check them for wear or play. The concerned poster had a bike with about 30,000 miles on it and had been told or had read that these final drives usually fail between 28,000 and 31,000 miles. After several posts that said this didn’t seem right, it became clear that what he had read or heard pertained to clutch hub spline failures in cases where there was a misalignment between the crankshaft center line and transmission input shaft centerline due to machining tolerances or errors in the engine cases and the transmission case. There have been a few such cases that I am aware of. A similar problem existed for a few classic K bikes back in the latter 1980s.

On the K bikes the problem was usually cured by replacing the auxiliary case (bell housing), which was a separate part between the transmission and the main engine block.

dwatson · « **Reply #19 on:** November 12, 2015, 04:07:52 PM »

Thanks for the response re bell housing. Is there a test to determine if its the issue??? Where do you find a replacement?? And how do you know it's not also one of the unfortunate ones?

dwatson · « **Reply #20 on:** February 28, 2016, 03:37:07 PM »

Finally the clutch us replaced, the transmission and drive shaft and final drive installed. Replaced battery, new air filter, cleaned out the gas rank and replaced fuel filter and misc deteriorated hoses.

The bike is turning over, have spark at plugs but is not firing. What is the best way to determine if the fuel pump is pumping. I do not hear it, should it be audible?

Since there was trash in the tank do I need to assume clogged injectors?

Martin · « **Reply #21 on:** February 28, 2016, 04:04:13 PM »

I am having a similar problem with a mates bike. Inge helped determine the wires to use to test the pump. Disconnect at the tank connector and connect jumper wires + to the brown wire - to the green with white tracer. If the tank is empty don't run for long, as the pump will over heat, a short burst is enough to check. One of the best fault finding guides is Bertrand Vogels ( Crazy Frog ) guide available on the K100 Forum. I am posting results of my fault finding on my mates bike in Won't Start K75RT. I have limited access to the bike, but I am going around today to try a few things.
Regards Martin.

Inge K. · « **Reply #22 on:** February 28, 2016, 04:29:20 PM »

Quote from: Martin on February 28, 2016, 04:04:13 PM

Disconnect at the tank connector and connect jumper wires + to the brown wire - to the green with white tracer.

Other way around, on a vehicle following the DIN standard for the wiring...minus is always brown.
.
.
But sometimes it can help to run the pump in reverse in short bursts to get dirt out of the intake.

Martin · « **Reply #23 on:** February 28, 2016, 04:37:06 PM »

Ooops thanks Inge.
Regards Martin.

Inge K. · « **Reply #24 on:** February 28, 2016, 04:55:56 PM »

Quote from: Inge K. on February 28, 2016, 04:29:20 PM

...minus is always brown.

It would be more correct to say that brown is always minus/negative, as black often is used on the
negative battery connection.