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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: jimmyd on February 28, 2012, 12:07:54 AM

Title: Starter Clutch
Post by: jimmyd on February 28, 2012, 12:07:54 AM: I bought a 1994 K 1100 RS about 3 years ago, Previous owner told me the there was a starter clutch problem. I put in a new battery and never had any problems until last fall.
I have asked around and found a couple of former BMW dealer mechanics. The going quote is 10 hours of labor to diagnosis/fix the problem.
Anyone have any experience with this problem?
The starter turns and occasionally catches. Sometimes it starts but most of the time I crank until the battery starts to get low or give up because it obvious the starter is not going to engage.
I have read that the starter armature/shaft gets gummed up and the spring that engages the starter gear is likely the problem.
The quote from the former owner was $1,500 to get this issue fixed at the dealer. Sounds expensive but this bike is pristine otherwise with about 45,000 miles on the clock. If I were sure I had all the tools I need I would tackle this myself, but it sounds really complex. I do not have a garage to work in and probably do not have all the right tools.
Can anyone offer any assistance with this issue?
Title: Re: Starter Clutch
Post by: Scott_ on February 28, 2012, 12:46:16 AM: I can't recall where I have read it but, I have read about some others using some cleansing additive prior to an oil change. Like an extra detergent to help clean up the gum/crud from inside the sprags. Seafoam comes to my mind.
It may take more than one treatment to get it all, but it's easier/cheaper than a teardown.
Title: Re: Starter Clutch
Post by: frankenduck on February 28, 2012, 11:10:28 AM: Paul Glaves (top BMW mech guru) recommends Rislone for cleaning starter sprags.

(http://ecx.images-amazon.com/images/I/31zEZ7niROL._SL500_AA300_.jpg)
Title: Re: Starter Clutch
Post by: Rick G on February 28, 2012, 06:19:13 PM: Use an oil that is meant for diesel engines it will clean and keep clean the sprag clutch mechanism and the rest of the engine.
Works a treat.
Title: Re: Starter Clutch
Post by: jimmyd on February 28, 2012, 10:36:16 PM: Great suggestions here, but I can't get the bike started. I use to bump start all my old bikes some times just for the thrill of it.
I have not tried to bump start this bike, but this hefer is heavy compared to my Honda and Suzuki bikes.
Anyone have suggstions for bump starting this baby? It is going to be a motha when this thing is cold trying to bump start it.

I guess I might have to find a decent hill someplace :biggrin:
Title: Re: Starter Clutch
Post by: jimmyd on February 28, 2012, 10:51:58 PM: Any thoughts on synthetic versus conventional oil?
I read someplace that the K engines did not like synthetic so I always stayed with conventional oil.
Title: Re: Starter Clutch
Post by: Scott_ on February 29, 2012, 07:57:12 AM: I haven't done it, but have read something about rolling the bike backwards to help engage the starter clutch sprags, then hit the button to start it.
Maybe in a higher gear(like 4 or 5) so the intermediate housing gears can rotate easier.

My experience with Synthetic was a few more leaks and just as much or more consumption. For the more expensive $ of syn over dino, I went back with the dino. YMMV
Title: Re: Starter Clutch
Post by: DRxBMW on February 29, 2012, 09:27:29 AM: Quote from: Scott_ on February 29, 2012, 07:57:12 AM
I haven't done it, but have read something about rolling the bike backwards to help engage the starter clutch sprags, then hit the button to start it.
Maybe in a higher gear(like 4 or 5) so the intermediate housing gears can rotate easier.

My experience with Synthetic was a few more leaks and just as much or more consumption. For the more expensive $ of syn over dino, I went back with the dino. YMMV

Under the impression that rocking the bike only worked for clearing loaded up carbon deposits on the starter commutator shaft.

The brushes shed over time, hence the deposits.

The deposits create a weird grounding path. When you turn the key, there's NOTHING, zero,zilch, almost like someone stole your battery while you were buying a pack of smokes in the store. WTF Rocking causes the carbon dust to dislodge and the grounding path restores itself magically.

Ha, first time above happened to me, freaked me out, as I was in the middle of nowhere and clueless. At least you novice bricKheads now have a heads up of the snafu.

If you did happen to un-goo the sprag rocking the bike back & forth just plain luck in my opine. It WILL happen again, try the detergent method fix and pray to the BMW God's it is successful. Royal pain in the ass tearing into a sprag for R&R. Think clutch spline but deeper in.

Synthetic oil Vs dino ? I ONLY run on Mobil 1 15/50, 8 to 10 K drain intervals,truly all season viscosity.

After 250K of motobricK miles using synthetic, I'm biased. Recent oil analysis from Blackstone labs turned out wunderbar last time around. 8,700 miles, winter,spring,summer seasons. Plus, I run HOT & HARD, read I do NOT baby my bricK.

http://www.blackstone-labs.com/report-explanation.php (http://www.blackstone-labs.com/report-explanation.php)

YES, you might experience some oil "misting effect", especially on the crankcase side if you like to flog the bitch. NO BIG deal, wipe it off with a paper towel or park your bricK within the Hardley Ablesome gaggle.

If oil piss dribbling bothers you, R&R the valve cover & crankcase seals with new and it will cease. Be aware, there's very little torque on the shoulder bolts that affix the covers. Inside rubber pieces perform most the retention duties. EASY to strip ! GO slow, you have been warned !

Oh the joy of removing the CC cover rad hose and reinsertion. Tip: use Silicone as a lubricant. Hose R&R is NOT necessary for seal RR but one of my customers had road trashed his CC cover and desired a new replacement. Twisting,pulling,swearing about that damn rad hose,real bastard to deal with.

Snow here in the Mid Atlantic this morning.
Title: Re: Starter Clutch
Post by: DRxBMW on February 29, 2012, 11:21:58 AM: Quote from: jimmyd on February 28, 2012, 10:51:58 PM
Any thoughts on synthetic versus conventional oil?
I read someplace that the K engines did not like synthetic so I always stayed with conventional oil.

Using dino oil can exacerbate the sprag clutch issue !!

read snobum's verbose comments below for a detailed explanation.

Part 1; Noticeable mechanical damage; you have done the large amount of labor and have the sprag clutch on your workbench:
Sprags not spragging? Look at them carefully. You may see a "polished" flat where it runs on the inner cylinder lightly pressed there by the springs. When the springs get gunked, they end up exerting less force and so less friction for it to "lift itself" over the high point to start wedging.

Part 2: You have the sprag clutch on the workbench and there is NO noticeable mechanical damage nor gunking-up:
The starter clutch is a constantly running device that is designed to transmit force in one direction, and it is not supposed to have any appreciable grabbing engagement until the starter rotates, which is supposed to cause the sprags to move, and that movement is to LOCK the clutch up, so the starter rotates the engine. When the starter is NOT powered, the starter sprag clutch is free-wheeling, with no appreciable friction in its innards. This clutch is a ONE-WAY device. One direction, it locks up, other direction, it rotates freely, with no coupling between the two main parts other than quite minor friction except in the oil film contact involved. I have seen TWO of these sprag clutches (of the later types too!...not the earliest K bike ones that were heavily modified by the factory for later versions) that have failed, withOUT any apparent real wear on any part. I have ONE of these in the shop. I was so curious about it, that I paid the owner to send it to me. I have compared it to a brand-new one, with no good conclusions, beyond the fact that dimensions have not changed enough to mention. My suspicions are STILL that it failed due to unseen-by-the-eyeball microscopic surface glaze, or other type of surface change... on the inner friction 'drum' part (and likely also the sprag parts that contact it). I have not proven this....might be able to at some point. The owner told me he had tried both Seafoam and CD40 additives. Even if I could prove what happened, it likely would not help us all very much (??).

Anecdotally, no one that has used Mobil 1 a TRUE full synthetic, has had a problem...that has been reported to me. It is entirely possible that OIL is THE > major factor.....or not. I do NOT want to imply that wear is not a concern. I HAVE seen worn starter sprag clutches; and the springs, if gunked-up enough, could cause reduced tension. My suspicion is that it was also the OIL that enabled excessive wear, when that is seen, but I cannot be 100% sure about it. The only way I can get a handle on that, is maybe to actually be present at some teardowns, and MEASURE side-play, and so on. I am a bit hesitant to state that it could be a problem, because there is no indication of sideplay wear on the needle bearings in the starter sprag clutch here....that I can see...nor on the ones I have looked at in that particular regard (two of them). Keep in mind that a starter sprag clutch works by friction, and it is not supposed to be friction of metal to metal, but oil film to oil film. Most do not understand how oil films work. There is an in-depth article on my website for anyone who wants details. My guess is that there is more than just one thing at work with the starter clutch problems. I suspect basic failure modes; OIL film failure (the result is mechanical damage as in part 1 above, or failure due to a glaze or gunked springs). I am beginning to think that all the other failures, which manifest themselves as WEAR failures, are due to a combination of oil, perhaps side forces, and maybe there is some sort of production tolerance...and maybe contaminant/protectant problem at work too. I am only too well-aware that MANY have NEVER had a problem with the later starter sprag clutches, and have used fairly conventional oils. My mind jumps to the same situation with camshaft and followers, in the Airheads. Many got HUGE mileages without problems; others, even running the same oils, had problems. I have personally witnessed these engines apart. WHAT was the answer? Seems to be heat treatment variations. For the Classic K bikes, I think we have a combination of effects, and anecdotal evidence TENDS to point towards using a REAL synthetic oil (Castrol Syntec is NOT!), like the Mobil 1 I have been recommending. It may well be that the higher amounts of ZDDP in Mobil 1 is helping with the WEAR failure modes. In addition, in what APPEARS to be the case, Mobil 1's formula does not leave the surfaces such that the sprags do not properly grab. Until someone does a serious laboratory analysis, right down to the surface's molecular analysis, I doubt we will know much more.

Because of the huge amount of labor involved ,...not to mention the $$$$$ parts cost...I personally use ONLY Mobil 1 in my K bike, from WalMart, in 15W50, it comes in 5 quart jugs. I am simply using the oil that the majority of information I have points towards it being much less of any problem. I have nothing against someone using the particular Mobil 1 20W50 oil that has even higher amounts of certain additives (V-Twin version) but I think that the K bikes do not require the thicker oil. Maybe the 20W50 is a bit better if someone rides a lot in the hot Southwest, where temperatures can exceed 100°F relatively often. I don't think the Mobil 1 20W50 is warranted otherwise. I leave my Mobil 1 in my K11 for the entire year; unless I have put more than 8,000 miles on the bike. It really does not need to be changed often, particularly if one does not do a lot of very short commutes; even more particularly in cold weather. I also note that analysis of my oil at changes has shown no wear to speak of, so I quit paying for analysis. My K11 also works hard; so is hard on oil...it hauls a big sidecar. I do change the filter at the same time, but I well understand that I could, without the slightest harm, go for an extra oil change between filters. The in-depth analysis by a lab showed that the additives in Mobil 1 hold up quite well over time and mileage. You get, sometimes, what you pay for. I also use nothing but BMW filters. I have no problem with folks using aftermarket filters, but find them highly variable internally, so I don't use them. NOTE!....K bikes seem to use less oil, if the oil is a quality one, and if the oil level is NOT maintained all the way to the top of the sight glass. I like the middle.

Part 3; fixing an original late model starter sprag clutch (of course, you have to remove it first, not a simple job!):

It has been reported to me by a trusted source that after removing a starter sprag clutch that has failed or gotten intermittent, but exhibits no signs of bad mechanical wear, that it can be repaired by a very thorough cleaning in strong solvents. I have, myself, done this to one, and I also used about a 2000 grit paper in 'polishing' the contacting surfaces; with no further problems from the starter operation; so it was nice to hear that someone had used JUST solvents to effect cures. I would recommend the polishing by super-fine grit paper, as I did, plus VERY thorough solvent cleaning (and scrubbing by turkish toweling with the solvents). I used a 50-50 mixture of MEK and Acetone.
Title: Re: Starter Clutch
Post by: jimmyd on March 09, 2012, 04:04:16 PM: Anyone have success attempting to bump start there K Bike?
I tried it once or twice after the starter probelm got real bad last fall. I had no success getting enough speed/force and popping the clutch. I am sure it would be a mutha trying this with the bike cold from winter storage. I obviously need to get it started to add the cleaning solution and warm it up enough to drop the oil and hopefully get the spring to release.
Title: Re: Starter Clutch
Post by: frankenduck on March 09, 2012, 04:31:09 PM: Pulling the air intake snorkel off and spraying some starter fluid in the bottom of the air box might help it get started.

Bump starting on a long hill might work. I wouldn't recommend towing it behind a car.

Never tow a Motorcycle (http://www.youtube.com/watch?v=btRGJt-zOE0#)
Title: Re: Starter Clutch
Post by: Rick G on March 09, 2012, 06:55:34 PM: One guy in Australia I recommended trying diesel oil had to bump start twice and go for a 20k run and the third time the sprag caught on the second try and eversince all starts have worked properly. The seafoam would probably work as well but I have had no experience with it as it isnt available in Oz. Probably thanks to some greenie goose.
Title: Re: Starter Clutch
Post by: Chaos on March 09, 2012, 07:09:05 PM: Regular oil changes are key to sprague clutch health. Never had a problem, but I used Rinsoline a couple years ago just for insurance. I use dino nowadays, it's cheaper and the bike has lasted 200K so far. I remember reading somewhere the sprague clutch is barely accessible when the starter is pulled, just enough so that lubricant could be sprayed in the general area and loosen it up. Or maybe it was the alternator of crankcase cover you had to remove. #5 is what causes all the grief.....
Title: Re: Starter Clutch
Post by: WayneDW on March 09, 2012, 08:37:20 PM: ".I personally use ONLY Mobil 1 in my K bike, from WalMart, in 15W50, it comes in 5 quart jugs."

I was in our local MalWart yesterday and the weights they offered didn't go up that high. Is everyone else finding that weight there? (It was a good price, BTW).
Title: Re: Starter Clutch
Post by: johnny on March 09, 2012, 09:30:22 PM: there are only 2 places i can find mobil 1 in 15w50 in socal and thats napa and oreilly... not at walmart...

in wisconsin they had it at farm n fleet and napa... not at oreilly or walmart...

j o
Title: Re: Starter Clutch
Post by: DRxBMW on March 09, 2012, 11:22:56 PM: Quote from: WayneDW on March 09, 2012, 08:37:20 PM
".I personally use ONLY Mobil 1 in my K bike, from WalMart, in 15W50, it comes in 5 quart jugs."

I was in our local MalWart yesterday and the weights they offered didn't go up that high. Is everyone else finding that weight there? (It was a good price, BTW).

Ha, only game in my city for Mobil 1 15/50 full synth anymore is Advance Auto and pricey to boot.

In 2011, K Mart had it sale for $3.99 a quart. Walked out the door with the last 3 cases.

Mobil only makes that 15/50 on selected runs anymore. If you happen to see in stock,BUY it !

5 gallon jugs are a rarity in any state.

dunno do Marine engines use a 15/50 weight ? I'm a landlubber. LOL
Title: Re: Starter Clutch
Post by: frankenduck on March 09, 2012, 11:31:22 PM: Another good synthetic that is Shell Rotella Synthetic that comes in 5/40. Generally easier to find and less $$$.
Title: Re: Starter Clutch
Post by: Chaos on March 09, 2012, 11:45:30 PM: A thought on bump starting a K, I believe you have to push the starter button when you drop the clutch to activate the fuel pump.
Title: Re: Starter Clutch
Post by: frankenduck on March 10, 2012, 12:02:57 AM: Quote from: Chaos on March 09, 2012, 11:45:30 PM
A thought on bump starting a K, I believe you have to push the starter button when you drop the clutch to activate the fuel pump.

Not 100% positive on this but I think that what activates the fuel pump is not the starter switch but the signal from the Hall Effect sensor when the engine spins.

Also, on the 4V K bikes, just turning the key runs the fuel pump for a second or two to pre-pressurize the fuel system.
Title: Re: Starter Clutch
Post by: Inge K. on March 10, 2012, 12:39:14 AM: Quote from: frankenduck on March 10, 2012, 12:02:57 AM
Not 100% positive on this but I think that what activates the fuel pump is not the starter switch but the signal from the Hall Effect sensor when the engine spins.

Both the starter switch and the HES affecting the fuel pump.
Starter switch has the same effect as turning on the ignition on a 4V, a quick touch is enough to start
the fuel pump for a couple of seconds without the engine turning.
When the the signal from the HES is received, the pump starts to run continuously.

Inge K.
Title: Re: Starter Clutch
Post by: frankenduck on March 10, 2012, 12:50:27 AM: That makes sense from what I know of K bike wiring.

I talked on the phone the other night with some guy who was an EE (Electrical Engineer) who had taken apart an L-Jetronic, analyzed the circuitry and understood exactly how everything worked. Man, would I love to pick his brain.... just out of curiosity....
Title: Re: Starter Clutch
Post by: Rick G on March 10, 2012, 01:41:35 AM: I have bump started my K75 without having to touch the starte button. As soon as the engine turned past a hall sensor the pump started to run.
Title: Re: Starter Clutch
Post by: jimmyd on March 14, 2012, 03:52:18 PM: Quote from: jimmyd on February 28, 2012, 12:07:54 AM
I bought a 1994 K 1100 RS about 3 years ago, Previous owner told me the there was a starter clutch problem. I put in a new battery and never had any problems until last fall.
I have asked around and found a couple of former BMW dealer mechanics. The going quote is 10 hours of labor to diagnosis/fix the problem.
Anyone have any experience with this problem?
The starter turns and occasionally catches. Sometimes it starts but most of the time I crank until the battery starts to get low or give up because it obvious the starter is not going to engage.
I have read that the starter armature/shaft gets gummed up and the spring that engages the starter gear is likely the problem.
The quote from the former owner was $1,500 to get this issue fixed at the dealer. Sounds expensive but this bike is pristine otherwise with about 45,000 miles on the clock. If I were sure I had all the tools I need I would tackle this myself, but it sounds really complex. I do not have a garage to work in and probably do not have all the right tools.
Can anyone offer any assistance with this issue?
Has anyone been brave enough to tackle this at home? Anybody have a Utube video on how to DIY :dunno
:biggrin:
Title: Re: Starter Clutch
Post by: frankenduck on March 14, 2012, 04:03:21 PM: Quote from: jimmyd on March 14, 2012, 03:52:18 PM
Has anyone been brave enough to tackle this at home?

I have. About 8 or 9 years ago my K75RT stripped it's splines at 35k. Since I had to replace the transmission anyhow I replaced the bellhousing as well suspecting that the old one might have been out of alignment and the cause of my spline failure at such low miles. Part of this involved moving the starter sprag from the old bellhousing to the "new" (used actually) bellhousing.

It's not really that hard but is a fair amount of labor.

Somewhere I've got a checklist that I made at the time.
Title: Re: Starter Clutch
Post by: jimmyd on March 15, 2012, 12:14:13 AM: Quote from: frankenduck on March 14, 2012, 04:03:21 PM
Quote from: jimmyd on March 14, 2012, 03:52:18 PM
Has anyone been brave enough to tackle this at home?

I have. About 8 or 9 years ago my K75RT stripped it's splines at 35k. Since I had to replace the transmission anyhow I replaced the bellhousing as well suspecting that the old one might have been out of alignment and the cause of my spline failure at such low miles. Part of this involved moving the starter sprag from the old bellhousing to the "new" (used actually) bellhousing.

It's not really that hard but is a fair amount of labor.
Pm Sent
Somewhere I've got a checklist that I made at the time.
Title: Re: Starter Clutch
Post by: frankenduck on March 15, 2012, 05:07:40 PM: Here you go. I just added this to The Lieberry: Getting the bellhousing off/accessing the starter sprag (http://www.motobrick.com/index.php/topic,1967.0.html)