Cheezits954 K75 Standard Drive Train Whack Thread

[Cheezits954]

Unlatched kickstand link and readjusted bolt after making sure slack was correct and not banging on the exhaust anymore.

Also the line seems to be seated correctly unless it’s supposed to be on the bottom hole, which I thought was for getting the rubber cover out.

[The Mighty Gryphon]

That's the right hole.  But your cable looks to be sitting a couple mm higher in the hole than the cable on my bike(I just ran out to the garage to check).

Can you see a BMW part number on the cable?  I think it might be at the top end near the lever.

[Cheezits954]

So spent some more time with her and was unable to get the 2nd gear to stop rattling in low rpms by adjusting the clutch cable. Though I am grateful for not having to hear it clang against the exhaust anymore! I'm still trying to find the other thread Motorhobo started about his transmission issues after a sustained 80mph in 3rd. I really feel like the symptoms sounded close to what I'm experiencing here, high speed in low gears and all.

Well, don't do what I did -- since that day second gear has been skipping and now I have big s**t to deal with. Was there a correlation between hi-revs in third and the skipping/slipping in second? I can't prove it but one day it didn't skip and then I rode at 7000k in third and the next day it did. So...don't do it.

I'll start a new thread about this skipping in 2nd thing soon when I have some time. Basically I have one transmission that works fine except for the bad input shaft and one transmission that skips in second but has a good input shaft. I want to put the good input shaft into the good gear transmission and take apart the remaining transmission as a science project...more later.

But bottom line -- my bike has been perfectly happy averaging 5k rpms with an occasional whatever 85-90mph on the freeway gets me -- I don't know why I listened to you redline-fetishists!

This is the thread where he first mentions it before starting a new one: https://www.motobrick.com/index.php/topic,9381.0.html

Any way I know I'm vastly inexperienced with this bike compared to you folks, but I've been pouring over transmission videos and info as I was expecting that to be the problem so not sure how the clutch adjustment could fix much more. I'll start digging into "Grub Screw" conversations till I can get the bike on a lift again.

Also sadly no part number on the cable Gryphon, the whole thing is black with no markings anywhere from the lever down. My bike is registered as a regular K75 but I feel like these handle bars are for a RT/LT or something. Maybe one of the previous owners changed the cockpit or I'm to used to riding drop bar city bicycles?

[The Mighty Gryphon]

Does the shifter flop around?  There should be no free play in it's travel. 

If it is solid, that says the grub screw is okay.  That will be one less thing to be concerned about.  If you can easily flip it up and down an inch or more the screw is loose and you need to go into the transmission to tighten it. 

[Laitch]

I'm vastly inexperienced with this bike compared to you folks, but I've been pouring over transmission videos and info as I was expecting that to be the problem so not sure how the clutch adjustment could fix much more.

. . . no part number on the cable Gryphon . . .. My bike is registered as a regular K75 but I feel like these handle bars are for a RT/LT or something. Maybe one of the previous owners changed the cockpit or I'm to used to riding drop bar city bicycles?

Don't confuse your moto with a drop-bar bicycle and don't use your feelings to identify parts.  Your moto is a K75 Standard and that is the OEM bar. It's also known as high bar. I recommend you identify parts by using this fiche. It often has illustrations to differentiate among parts. Now that you know which handlebar is on your moto, you can go to the fiche, click on your model to identify the cable and its part number by the approximate measurement you take of it, but you might not need a new cable, yet.

When you expect a problem to be caused by a particular reason, you tend to quit considering other reasons that might be in play. That can send you on a snipe hunt. Because you know next to nothing about this moto, it's too early for you to be a credible diagnostician. I'd like you to take some time to record the sound again as you are shifting from first to third and back—without endangering yourself and the public—then post it here.

You wrote . . . hear some of the jittering which isn't me on the throttle but the bike slipping in the trans area. What does that mean.? Slipping—when related to forward motion of a moto—means when the engine revs increase, the ground speed doesn't. Is that what is happening in second gear—or is it just grinding and not engaging at all?

The clutch isn't adjusted by watching the motion of the rear wheel when the moto is on the center stand. Here's what I suggest you do, exactly as written without modification.

• Disengage the clutch cable from the clutch operating lever at the transmission.
• Using the clutch hand lever adjuster, adjust the free cable length to 75mm. That's the length of cable from the nipple at the end of the cable to where the cable enters its sheathing; most of it is covered by the pleated boot (grommet in the BMW instructions).
• Once the cable length is set, tighten the hand lever lock nut.
• Re-engage the cable nipple into the transmission clutch operating lever.
• Loosen the lock nut on the transmission clutch operating lever bolt.
• Loosen the lever bolt until it's a couple of millimeters distant from the clutch piston.
• Screw it in until it just touches the clutch piston but applies no pressure to it. Lock it there using the lock nut.
• At the clutch hand lever measure the free play of the lever. That's the space created between lever and its pivot assembly when the lever is squeezed but isn't applying pressure on the clutch piston. It's measurement A in the diagram.
• Adjust free play at the lever to approximately 4mm. If the lever offers no resistance when pulled with one finger until it takes up that 4mm of slack, it's adjusted correctly.

Here are BMW photos and text of the sequence.




Maybe there is a problem within the transmission as was previously indicated a possibility. If there is, I suggest you buy a replacement transmission and not get involved with disassembling it. Answer Gryph's question. If that is the problem, there are plenty of references here to consult for its repair if you insist on tackling that.

If this moto was purchased from a licensed vendor, you need to start a legal record of your problem. Email the vendor with a description of the problem and ask for a remedy.

[The Mighty Gryphon]

Well said, Laitch!

[Cheezits954]

Shifter is firm and, after adjusting, feels even better now. Flip the gear up and down with ease? Yes. If you mean the clutch lever flopping around then no. The transmission shifts from 1->2->3->2->1 without getting stuck on this small stretch of road around my apartment. I'll be able to test it better this weekend on a few less traveled roads or maybe a bit parking lot to get a better gauge.

When I wrote slipping the best description that comes to mind is: Imagine the drive shaft splines grinding against each other. As if there are still teeth but greatly worn down. It's as if the bike loses power for a brief moment and then regains it, then again and again with a loud grinding noise accompanying the feeling of slightly jerking forward. It's especially scary while turning. I did notice if I power through then it keeps grinding while losing power, but if I reduce the throttle and come back on gradually it will slip catch and slip again until I get to about 3k rpms. After that it's all smooth sailing.

Here is a video of the clutch engagement while on center stand from earlier today, I was waiting for this to upload when I saw your post Laitch not sure if it is helpful. You can at least see the clutch play here, very firm:


Here is the part # for the cable Gryphon: 32 73 2 324 960 CLUTCH CABLE - L=1625MM. I might be able to pull it and check the length before the weekend to be sure it isn't stretched or maybe I should hold off on that?. Sadly I go back to work tomorrow so this weekend I'll be able to go through the steps again from the top so I can be sure. I purchased the bike from a BMW moto dealer about 100 miles south from me. Was assured by a local/lazy? mechanic that the bike should be fine since it's a reputable dealer when I offered to pay him to go check it out ahead of time. Thanks again and Happy New Year!

[Laitch]

Shifter is firm . . .When I wrote slipping the best description that comes to mind is: Imagine the drive shaft splines grinding against each other. As if there are still teeth but greatly worn down.

I don't know what is meant by Shifter is firm. The clutch hand lever should not be firm for 2.5–4mm until it moves the clutch operating arm forward enough to apply pressure to the piston.

If worn shaft splines are loaded, they'll howl and forward motion will cease. That might be what you're describing. The location of the howl is the question. The splines in the clutch disc could be worn; the transmission input shaft splines could be failing; the rear splined socket of the drive shaft could be failing; the rear drive pinion gear splines could be failing. If the clutch disc is worn out, shifting will be difficult and speed won't increase as it normally does under engine power.

A new clutch cable is low on the list of concerns. Disassembly and inspection is the first order.

Howling splines.

[Cheezits954]

I don't know what is meant by Shifter is firm. The clutch hand lever should not be firm for 2.5–4mm until it moves the clutch operating arm forward enough to apply pressure to the piston.

In the video I posted above is that enough play in the clutch line? Based on space required, I don't have a digital caliper yet, this seemed to be enough free play.

If worn shaft splines are loaded, they'll howl and forward motion will cease. That might be what you're describing. The location of the howl is the question. The splines in the clutch disc could be worn; the transmission input shaft splines could be failing; the rear splined socket of the drive shaft could be failing; the rear drive pinion gear splines could be failing. If the clutch disc is worn out, shifting will be difficult and speed won't increase as it normally does under engine power.

A new clutch cable is low on the list of concerns. Disassembly and inspection is the first order.

After watching Chris's bad spline video the noise coming from that bike is definitely higher pitched then the sound coming from my bike. Thanks for that link btw, forgot he had a video of bad splines running. My bike vibrates and shudders forward, that bike looked to be sitting pretty still. Also my bike only makes noise and vibrates around 2-3k rpms only. Maybe the spline reference wasn't helpful. I'll grab audio asap!

The sound is definitely coming from between the drive shaft to transmission area and engine to clutch area. Included some photos of when I did the teardown of the driveshaft to check the splines. I didn't get an after photo when I cleaned the DS but there is a picture of it with whatever grease was already on it and it looked pretty good. Also I noticed a strange groove on the bottom of where the spline mounts. I was afraid I may not of securely placed the DS to the trans after using a rubber hammer on it, but after seeing that video I'm thinking it's unlikely.

[Laitch]

A digital caliper isn't needed to measure that free play space. A short, straight-edge measuring rule would do it.

Did you check the universal joint for freedom of movement and excessive play? A failing u-joint could account for vibration but wouldn't result in loss of power until it finally broke.

[The Mighty Gryphon]

It sounds like the grub screw is tight if indeed the shifter by your left foot has no slop in it.  Having a BMW part number on the cable confirm that you don't have some sort of generic cable. 

The spline photos look good, so I doubt that is the source of the problem.  I asked you to check the transmission oil level, did you do that?  It may be a very good idea to drain the transmission to see if there is any metal in it.  Put some new oil in and keep the old stuff to show the dealer where you got the bike. 

With the condition of the splines and the fact that the problem only occurs in 2nd gear makes me think the transmission is the problem.   Right now my money is on a shift drum problem, bent shift fork, or bad dogs.  None of these problems are going to be easy or cheap to fix, so I would be planning on talking to the dealer who sold me the bike.  There should be some sort of warranty on it, and the clock is running on the time you have to get back to the dealer.

At this point, if the bike has a warranty, it looks like you have three choices: return the bike for a refund, have the dealer repair it, or negotiate a partial refund to cover the cost of you doing the work to replace the transmission.  The good news for you is that there are several bike breakers in southern Cali who should have readily available used transmissions you could use.  I would make calling the dealer the next thing I do on this bike. 

[Cheezits954]

Laitch: I did check the  joint and it moved freely like mentioned in one of Chris Harris's video talking about how the joint should look/feel.

Gryhon: I was able to pull up the part number of the clutch cable but looking at the cable itself I was not able to actually find any markings whatsoever. That's why I mention measuring it to compare the length to factory spec.

I did check the oil and it almost appeared to have a "sparkle" to it. Nothing major but something that I did keep an eye out for and noticed. I was originally looking for chunks of metal but only came across about a half peas worth(for lack of better description) of metal attached to the magnet. I should've grabbed a photo but didn't think that far ahead at the time. I cleaned the magnet and then threw the oil back in topping off with about a 1/4 of the remaining trans oil I had in the bottle. Should add up to a liter total, I will check level in the morning, as well as drain and get new oil. Keeping the old as evidence as you mentioned.

Sadly no warranty, though I'm curious if Lemon Law apply's here. I specifically asked if warranty was included/available and was told that they don't offer one especially since the bike was so old.

My thinking was that gremlins were inevitable, appreciate you shedding light. Fortunately the bike has had no other issues. If you think I have a fighting chance I'm very willing to look at all my options.

[Laitch]

Fortunately the bike has had no other issues.

Was the transmission output shaft clipped into the driveshaft's front joint and the shaft needed force to separate it from the output shaft?

Did you find the various clutch cable lengths in the parts fiche and compare their length with the one on your moto? I not convinced you need one though. :-)

Have you inspected the clutch boot for tears?

Do you see that cracked plastic cover on the the rear of the transmission? That should be preventing water from affecting the gear position indicator switch beneath it. If you don't clean the switch and repair the cover, the switch is likely to malfunction if it hasn't already.


Let's have another sound file of the unidentified noise.

[Scott]

This is the proper procedure to check the gearbox oil if you don't have a manual.  The blue one that came with the bike, if it did, is quite helpful as owners manuals go.
IMG_20200103_112215734.jpg (43.08 kB . 768x432 - viewed 553 times)

[The Mighty Gryphon]

Gryhon: I was able to pull up the part number of the clutch cable but looking at the cable itself I was not able to actually find any markings whatsoever. That's why I mention measuring it to compare the length to factory spec.

The reason I asked was to confirm that you had the correct cable.  Every BMW cable I have come across has the part number printed on it.  If what you have is an aftermarket copy, there are no guarantees it is the correct length to allow proper clutch adjustment. 

I still think you have a transmission issue, probably associated with the dogs for 2nd gear, or the shift forks. 

May I ask how much you paid for this bike?  You probably need a replacement transmission.  I see a number of them on eBay for under $200 and many of them have gear position indicator switches that look to be in better condition than yours.  That switch alone in used condition could cost as much as $100 itself.

Let's hope that your clutch is still okay.

[Cheezits954]

Was the transmission output shaft clipped into the driveshaft's front joint and the shaft needed force to separate it from the output shaft?

Did you find the various clutch cable lengths in the parts fiche and compare their length with the one on your moto? I not convinced you need one though. :-)

Have you inspected the clutch boot for tears?

Do you see that cracked plastic cover on the the rear of the transmission? That should be preventing water from affecting the gear position indicator switch beneath it. If you don't clean the switch and repair the cover, the switch is likely to malfunction if it hasn't already.

Let's have another sound file of the unidentified noise.

Yes it need to be removed with force. A bit more force then I was expecting. I was glad to have removed the swing arm ahead of time so I could get a proper grip and leverage.

I didn't pull the one from my bike yet so haven't had the chance to compare. I'd like to avoid the trouble of having to re-route it under the tank, at least till the weekend.

The boot is in good shape, I used engine degreaser and tissue to clean in the bell housing as best as I could for now. I plan to take apart and give the outside a real deep toothbrush and scrub wash eventually. But for now I the boot appears leak free.

Good to know about the switch, the plastic was had to the touch and on there pretty solidly. But for sure that's gonna have to come off.

Sound file will be in on Sat.

[Cheezits954]

This is the proper procedure to check the gearbox oil if you don't have a manual.  The blue one that came with the bike, if it did, is quite helpful as owners manuals go.

I currently have a pdf of the:

BMW Motorrad GmbH + Co. Service Department
dated: 4.1988 scann: 12.2011 Order No: 01 51 9 798 791

BMW K100 & 75 Owners Workshop Manual
by Jeremy Churchill
Haynes Publishing Group
(Also printed in a binder)

Rider's Manual
US Models K75, K75S, K75RT
(Also a booklet that came with the bike)

[Cheezits954]

May I ask how much you paid for this bike?  You probably need a replacement transmission.  I see a number of them on eBay for under $200 and many of them have gear position indicator switches that look to be in better condition than yours.  That switch alone in used condition could cost as much as $100 itself.

Let's hope that your clutch is still okay.

The bike was listed for $2,300 and out the door I paid a total of $2,600. I got the bike from Escondido BMW about 100 miles south of me and rode it all the way back to LA without any issues.

I was actually planning to get a used transmission and YouTube the entire procedure of repairing whatever issue is wrong with the old one. Part learning experience part creating some HD content for others to learn from. That's why I was originally asking if I can limp along for now skipping second gear till I could get the second trans or if I should just bite the bullet and get one ASAP.

On the next tear down I was planning to check the clutch to see how much bite it had left.

[Laitch]

You can skip second gear but rev high in first before you shift into third. You don't want the engine to lug when it's shifted into third gear. I hear that in the video. Enough lugging around town and you'll break something within the engine.

[Cheezits954]

Dope, much appreciated ladies and gents for your help! I'll update you tomorrow on how she sounds!

[Cheezits954]

Thanks for your patience. Included video of me riding here:






Was riding around today for over an hour and second gear was pretty unpredictable. Sometimes it would grind in low rpms, sometimes just over 4k rpms. For sure I think the safest best would be to swap the trans. Def on the shopping list next. Gonna work on intake and timing first since I've already ordered some things to get that squared away (compression check/vacuum adjusting/valve clearance). Water pump rebuild after that since summer heat is coming soon.

[johnny]

greetings...

if it was mine... i just keep the revs above 4500...

j o

[Cheezits954]

Will do, taking some getting used to in city riding especially with 1st gear screaming from the high revs. Highway is my happy place but still adjusting to the high rev life. :)

[johnny]

greetings...

embrace it... hawt wimmins on ducatis at newcombs ranch will.take notice...

j o

[The Mighty Gryphon]

Why are you messing with the water pump?  Is it overheating?  Are you seeing water in the oil? 

If you are dead set on working on the cooling system, give it a good flush, and clean the dead bugs out of the radiator fins. Refill with 60/40 water/anti-freeze mix and spend your time and money elsewhere.