K11 Owners Group

Alan Walker · Posted: Wed Jun 04, 2014 10:53 pm Post subject: Driveshaft slipping

Back in Feb. my K11LT had shelled out one side of the clutch disk while passing in traffic. Shortly after that event and having replaced defective clutch disk, I noticed the engine would rev up during hard acceleration much like a slipping clutch. I continued troubleshooting not believing it could possibly be the clutch yet again. I did notice the problem only existed while accelerating hard in 3rd, 4th, or 5th gear. Talked the issue over with Bentonville BMW, they said it sounded like a slipping driveshaft, so I pulled and marked the driveshaft, and sure enough found it was indeed the issue. Purchased a new old stock unit from fellow K rider in NC. Tested again with the new one in place, I could get it to slip as well. Are these driveshafts prone to failure with age, or do these engines actually produce enough horses to overpower the driveshaft? I will continue to use the newer shaft thru the summer while I find a driveline company that can possibly repair my old one.
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95 K1100LT Current ride
05 Suzuki DL650 sold
86 Honda Nighthawk 450 sold
76 Honda CB400F sold

SugarHillCTD · Posted: Thu Jun 05, 2014 5:56 am Post subject:

What did the driveshaft damage look like?

Can you post a picture of the damaged one?
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John & Cathy

'92 K100RS4V Pearl White SOLD
'04 K1200GT
IBA Several-SS1k, BBG, 50CC NYC to S.F.

Alan Walker · Posted: Thu Jun 05, 2014 6:43 am Post subject:

The inner stub shaft spins inside of the rubber sleeve. What baffled me for so long was the driveshaft never appeared to have any issues, visually it looks fine. The only telltale sign were a few very thin ribbons of rubber streaming from the rubber sleeve. It wasn't until I marked it with a Sharpie that I found it was indeed spinning inside the rubber sleeve. The only other symptom that was showing was after each slipping episode I felt more vibration at the foot pegs. I even thought for a while maybe the rear drive was failing but even after long rides the rear drive unit wasn't hot and moved freely. After the last run with the old driveshaft, it took me approx. 15 minutes to remove the rear drive unit from the yoke, and I couldn't even touch the driveshaft it was so hot. Even after an hour of letting it cool I was barely able to keep it in my hand.
_________________
95 K1100LT Current ride
05 Suzuki DL650 sold
86 Honda Nighthawk 450 sold
76 Honda CB400F sold

Flying Duck · Posted: Thu Jun 05, 2014 10:30 pm Post subject:

If your clutch was slipping and you slipped it a fair amount then it's possible that it got hot enough to glaze the metal pressure plate(s). If this occurred and you just replaced the clutch plate then that won't help. The fact that it exhibits the same behavior as before....

There's some rubber in the front half of the drive shaft but the usual failure mode for 4V drive shafts is catastrophic failure of one of the U-joints.
_________________
93 LT (x2)
94 RS
86-97 K75F(K75/100/1100 Frankenbrick)
86 K75C w/paralever, hi perf cams,TURBO!
91 & 92 K75Ss
91 K1
86 custom K100
14 WR250R
IBA #17739 (SS1K, BBG, 50CC)
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Alan Walker · Posted: Thu Jun 05, 2014 11:17 pm Post subject:

When I had replaced the clutch I deglazed both disks before reassembling. Neither one had been glazed too badly. The dealer had said they see it more with those that pull trailers, but they did acknowledge there seemed to be a weakness in the design. Most boat motor final drives use the same design the only difference is they were engineered so they could be repaired by changing out the rubber sleeve, I'm not quite sure why BMW failed to make these repairable.
_________________
95 K1100LT Current ride
05 Suzuki DL650 sold
86 Honda Nighthawk 450 sold
76 Honda CB400F sold

Flying Duck · Posted: Fri Jun 06, 2014 1:04 am Post subject:

Though I don't claim to be a clutch expert I do have an engineering degree which required me to study metals quite a bit.

I imagine that if you slip a clutch enough then the pressure plates can probably heat up enough to change the microstructure of the metal. If that's the case then it's something that can't be undone.

Not saying it's never happened but I've never heard of the rubber in the front half of the drive slipping, much less on a supposedly new one. I've heard of numerous U-joint failures but never that.

And the fact that the bike exhibits the same behavior before and after leads me to think your pressure plates are hosed.
_________________
93 LT (x2)
94 RS
86-97 K75F(K75/100/1100 Frankenbrick)
86 K75C w/paralever, hi perf cams,TURBO!
91 & 92 K75Ss
91 K1
86 custom K100
14 WR250R
IBA #17739 (SS1K, BBG, 50CC)
Buy parts HERE

Number 6 · Posted: Fri Jun 06, 2014 4:11 am Post subject:

Driveshafts don't slip, they break. It must be the clutch.
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I am not a number, I am a free man.

94 K1100LT

dave n · Posted: Fri Jun 06, 2014 5:46 pm Post subject:

Read the mans posting again - he marked the d/shaft with a sharpie and determined it had spun inside the rubber sleeve.

Stop trying to make it a clutch issue.
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Dave Norris KOG 248
1999 Cagiva Gran Canyon
1993 K1100LT w/Hannigan sidecar
2008 Suzuki DR650

Number 6 · Posted: Sat Jun 07, 2014 5:05 am Post subject:

And the replacement driveshaft also slips? No way!
_________________
I am not a number, I am a free man.

94 K1100LT

Alan Walker · Posted: Sun Jun 08, 2014 6:56 am Post subject:

Yes the replacement will slip as well. I only slipped it once, will not make another attempt, I believe this is caused more from my riding style. Coming off a Vstrom 650, I was always grabbing a lower gear prior to passing. With the K1100, I didn't feel I needed to since the engine has plenty of power. The only problem is the driveshaft can't support the power delivery in the higher gears. Remember the only time I can get one to slip is when I am doing around 35mph in 3rd, then pull full throttle, when the engine hits it's power band at around 4500rpm the driveshaft cuts loose every time. I do not recommend you do this, once a driveshaft slips it will do it easier every time and you will put it out of phase which will induce a lovely vibration directly into the foot pegs. Note the replacement I put in was not new, it had never been used before, no telling what the Date of Manufacture was. We all know what happens to rubber over time, just saying these driveshafts are not good for the lifetime of the bike if you ride them hard. I will try to get some pics posted soon, currently I have been pulling 75hr work weeks.
_________________
95 K1100LT Current ride
05 Suzuki DL650 sold
86 Honda Nighthawk 450 sold
76 Honda CB400F sold

Number 6 · Posted: Sun Jun 08, 2014 8:40 am Post subject:

Flying Duck · Posted: Sun Jun 08, 2014 9:55 am Post subject:

I've ridden the snot out of quite a few 4V Ks that I've owned (and several that I still own) and not a single one of them has had any DS or clutch slipping issues. If you've had two slipping DSs in a row then your situation is quite anomalous.
_________________
93 LT (x2)
94 RS
86-97 K75F(K75/100/1100 Frankenbrick)
86 K75C w/paralever, hi perf cams,TURBO!
91 & 92 K75Ss
91 K1
86 custom K100
14 WR250R
IBA #17739 (SS1K, BBG, 50CC)
Buy parts HERE

jpberens1994K1100RS · Posted: Mon Jun 09, 2014 6:16 am Post subject: Drive shaft slip

If you have a good speed shop, they could fix that. Build you a custom drive shaft to stop the damper from slipping maybe.
As Drake says what you are experiencing is rare for it to happen on 2 drive shafts is double rare.
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1993 K1100RS that I'd rather be riding FAST!
2014 Moto Guzzi Norge