MOTOBRICK.COM
TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: saints on March 08, 2024, 07:28:13 AM
-
Hello,
Question, i got all the other valve clearances in check, but the exhaust valves for 4th cylinder are both too tight, even with the 2.50mm cam follower which is the smallest you can get. Barely 0.05mm feeler goes under.. What is the next step? If i need to remove cylinder head, then i am afraid it is a job for a real mechanic.. Pray
-
Sounds like the valve seat (where it seals in the head) is worn down, stretched valve stem is highly unlikely. Means you'd have to pull the head and take to a shop...
Probably have to pull the head in any case just to figure out what's up...
If I'm not mistaken the seat is a ring that's inserted into the aluminum head. 177381
11 12 1 461 301 VALVE SEAT RING EXHAUST 0.02 8 $66.76 From MAX BMW parts fiche... I believe that's for a set of 8
-
11 12 1 461 301 VALVE SEAT RING EXHAUST 0.02 8 $66.76 From MAX BMW parts fiche... I believe that's for a set of 8
Means there are eight of them and they are $66.76 each. I am pretty sure if you take the head to a machine shop they can get generic seats a lot cheaper.
If you do decide to pull the head, make sure you use the correct Torx bit. You need the T50 1/2" impact bit. It is a lot heavier and will fit better than the standard Torx bit. The head bolts are a bitch. High torque, and the ones back by cylinder #4 usually have corrosion as an added bonus. I broke one off in the block when I pulled the head on my '92 RS.
https://www.ebay.com/itm/404590465510?
-
^ Agree with Gryphon, 66+ a PIECE is heavy, but what else do we expect?! Machine shop can likely source cheaper.
And : Head bolts are BRUTAL. Just to get them to brake loose, once there the rest is fine. As above stated, make sure to have the best tool possible for this.
-
I would advise using an impact wrench to loosen up the head bolts before going after them with a big breaker bar. You don't want to break one off in the block. It will definitely ruin way more than one of your days.
-
I just remembered: I turned my craftsman torx socket into a corkscrew on the head bolts, had to buy a set of impact rated sockets from HF...
But at least the new head gasket is made of stainless steel, I feel it's much improved over the old style that left a lot of hardened material on the aluminum of head and cylinder block and was hard to remove without hurting the surfaces. 112350 At any rate, this is likely to be a somewhat bigger job...
-
Ok, so valve seats might be the problem. I doubt i can change them with my tools, so i will give this assignment to the local shop. Thanks for rapid answers!
-
The head bolts are "Torque To Yield" type and are one time use. When installed they are torqued to a spec and then angle torqued another 90 deg. if I remember correctly. You can feel them stretch during the angle torque- an uneasy feeling. Your problem is probably a combination of valve seat wear and valve head wear. I know of a couple of valve failures on K1100's.
Frank
-
YIKES!!! :johnny I reused them on my '92 RS!!! :johnny The head is going to fall off!!! :johnny
Boy, am I glad I don't own that bike anymore.
-
The head bolts are "Torque To Yield" type and are one time use.
Consider also that torque-to-yield bolts don't always have an angle spec in tightening. Another prominent use of them by BMW is in attaching the clutch pack assembly to the clutch housing.
-
I dunno know, I think I reused also ( would likely recall "how friggin expensive..."), ooops. Been a while so it's prolly ok.
As far as valve: yes, it's entirely possible that the affected exhaust valve is fried from gases blowing by... There's another 100 or 200 gone...
Depending on mechanical inclination and tools available I'd suggest to work the bike and just turn the head into a machine shop. Of course would have to go and buy gaskets and stuff, still a lot cheaper than having a BMW shop remove all the plastic and dismantle the engine top then put all that stuff back together.
In any case: good luck with this, and remember: the only stupid question is the one that wasn't asked...
-
I dunno know, I think I reused also ( would likely recall "how friggin expensive..."), ooops. Been a while so it's prolly ok.
As far as valve: yes, it's entirely possible that the affected exhaust valve is fried from gases blowing by...
Probably many of us reuse those clutch bolts; I haven't found much negative feedback about that. Maybe the Bricks are sold on when owners encounter problems generated by that. :laughing4-giggles: Did you do a compression test and a leak-down test yet? The results could be interesting.
-
I put a good 20,000 miles on those reused head bolts. They even went through a somewhat major fender bender and bike rebuild with another 2,000 miles.
[ Invalid Attachment ]
Hey, who knows, maybe the head did fall off and I didn't notice.
-
Head must still be on, otherwise she'd lay lower, flatter!
Still sucks!
-
Hey guys, a little bit of an apology here. I was slightly mistaken about the torque to yield head bolts. After consulting a couple of maintenance books I have (Clymer/Haynes) the angle torque method is used on K1200 engines. K100/K1100 use a simple two step torque sequence with no mention of single use bolts. The last engine I had the head off of was a 1200 so that's what I remembered. Foremost in my mind was the feeling of the head bolts stretching. If you've been a mechanic for a while you may know this feeling. The bolt is turning but the feeling is that it is NOT getting tighter. Earlier 1200's use an initial 20nm torque followed by a followed by a 76 deg. angle and then ANOTHER 76 deg. angle! Later 1200's use an initial 20nm followed by 90 deg. angle. Maybe the change was issued after some bolts snapped during the second angle torque.
It seems that re-use of the head bolts on K100/1100's is fine.
Frank
-
OK, we all can breathe easy now, no heads are coming off! icon_cheers
-
Changing the valve seat is not an easy job. I've seen plenty of engines with new valve seats, supposed to be needed because of use of unleaded fuel, release the newly fitted seats into the combustion chamber.
The installation requires real machining skills, Nitrogen freeze, negative tolerances... The kind of skills you could acquire when it was common to change the valve seats on engines, that is to say the kind of skills that you can today almost only find on retired mechanics.
Considering the price of a used head, and the chances of fail, I'd consider buying another head.
Maybe you could find shops specialised in overhauling K heads at Mini specialists, who love to adapt these heads on Mini engines.
-
Maybe you could find shops specialised in overhauling K heads at Mini specialists, who love to adapt these heads on Mini engines.
That's the old 997 or 1275cc mini, not the new BMW/mini? I remember reading about that conversion.
-
It wast easy to disassemble, with right tools, impact torx head and one meter steel pipe leverage. 103123
With amateurs eyes it looks like it has been running +131000..have to take head to shop and be prepeared to pay many moneys..
-
Seems that there's signs of seat recess on cylinder 4 and 2 also...
-
Good man, well done!
Now: I'd go and turn over the head with sparkplugs still in there. Put some motoroil into the combustion chamber and see how fast it runs out. This tells you how bad or good the valves seal. At 131K (miles or kilometers) it's probably pretty bad. Sometimes it's just the "rim" of the valve and a replacement valve and good lapping in does the trick...
-
Estimated cost for head maintenance would have been at least 700€ ..got 52 000km driven spare motor for 600€ including shipping. I’ll take the head off that one and hope that is in good condition.
-
Is it mandatory, or highly recommended to resurface Cylinder head, before installing it back? Because removal was not caused by gasket failure or so, i would like to assume that the mating surfaces are good. Have people just installed heads back with new gasket?
-
It is highly recommanded NOT to surface cylinder heads of K100/1100!
.
-
When I pulled mine to do the valve guide seals I just reinstalled it with a new head gasket.
-
^ same here...😃
-
So, i have have gotten to a point where i should tighten the head bolts. I have the BMW repair manual K1100LT/RS. I have tightened all bolts to 20Nm per manual, but the next step is unclear. In my understanding the manual kind of gives two variations, tighten 90 dergrees or 1st 75 degrees and second 75 degrees. Which one is it? Bike is 1996 RS and it has long thread bolts. [ Invalid Attachment ] [ Invalid Attachment ] [ Invalid Attachment ]
-
In my travels today, saints, I came across this service bulletin from BMW. Unfortunately, updating the manual only took place in the text and not in the charts but I doubt using the two-step method will result in problems.
(https://www.motobrick.com/gallery/4/1601-220424091509.png)
-
Thanks Laitch, I went with the two step method. Even with that the bolts didn’t seem brutally tight
-
Another prominent use of them by BMW is in attaching the clutch pack assembly to the clutch housing.
Yeah f that stretch bolt noise on the clutch assembly. I used regular hex head m5(iirc) bolts with medium strength locktite on mine when I changed my clutch plate out. Works fine, and you dont need to worry about replacing bolts every time you tighten them down, which can be a few times just trying to do a clutch for the first time. The only reason for stretch bolts is so they dont loosen up, but locktite does the same thing.
-
. . . and you dont need to worry about replacing bolts every time you tighten them down, which can be a few times just trying to do a clutch for the first time.
Whoever might worry about that stuff needs more patience, understanding and confidence instead. Perhaps wearing a Tripuṇḍra, also composed of Loctite, would help.
-
We are literally in a forum of amateur wrenchers. Expecting everyone to have high experience and knowledge levels is a bit much. Those stretch bolts are a pain since they have to be replaced after they been tightened, and they arent readily available. If one has trouble with with alignment of the clutch plate because one doesnt have the $$$ purpose built BMW tools to ensure it, then one goes through a lot of those bolts trying to get it right...and a lot of time waiting for replacements to be shipped. They're also not difficult to sheer.
Standard bolts and locktite do the trick just fine, and eliminate all the potential drama
-
We are literally in a forum of amateur wrenchers. Expecting everyone to have high experience and knowledge levels is a bit much.
You shouldn't expect that, sooprvylin. I don't. I attempt to keep my expectations out of my interactions with other folks. Controlling my astonishment is a little more difficult sometimes.
:laughing4-giggles:
I do hope folks who are new owners of Bricks develop their understanding of how to work on them based on reading the depth of success and failure displayed in the posts here by all of us, and by reading the many clear Jetronic, Motronic, and Brick workshop training manuals on the site before, or while, the undertake maintenance. I doubt many here stock up on BMW tools—I don't—because, in the USA at least, many specialized tools are loaned on a no-cost basis by large retail automotive parts franchises, NAPA and AutoZone to mention a couple. There are also links to plans for making tools, links to makers of substitute tools sold at a fraction of the OEM cost—like the main seal arbor, for one—and links to effective alternative methods to tasks beyond glopping on the Loctite to prevent worry when obstacles arise.
Understanding how the Bricks' systems function and understanding why certain approaches in repair and maintenance are taken by the makers of these motos helps us develop skills and approaches to tasks without worrying about them. The Internet makes that easy, but discernment of which is sound advice and which is sketchy advice usually grows from observation, understanding and experience. That seems to be a foreign concept to some folks but it's time-tested and seems to work well in the end.
-
The only manual that recommends replacing any clutch hardware is Clymer which recommends replacing the clutch nut. The BMW manual makes no mention of replacing that or the six clutch bolts.
I've never taken numerous clutches apart for decades and always reuse ALL of the hardware. It has never caused any issues.
The notion that you need to replace any clutch hardware is wives tale nonsense.
-
The only hardware I look at as one time use in the clutch area(outside of the main shaft lock nut) would be the star washers. I've reused the bolts with no issues.
-
The only hardware I look at as one time use in the clutch area(outside of the main shaft lock nut) would be the star washers. I've reused the bolts with no issues.
+1
I think I replaced the clutch nut once.
-
The BMW manual makes no mention of replacing that or the six clutch bolts.
The notion that you need to replace any clutch hardware is wives tale nonsense.
The only hardware I look at as one time use in the clutch area(outside of the main shaft lock nut) would be the star washers. I've reused the bolts with no issues.
+1 I think I replaced the clutch nut once.
Duly noted. :laughing4-giggles:
frankenduck's observation about what's not in most manuals he's scanned is accurate; however, BMW's, Clymer's, and Haynes don't caution against reusing head bolts, rod bolts or crank bolts during repair either yet it is often considered best practice during repair on used equipment with unknown histories. I understand why BMW's abridged manual online might leave that out because the original manual was used by techs in training with supplemental instruction, and by professional mechanics. I'm okay with wrenchers reusing those items because it adds excitement to hum-drum modern life. It's the same reason I travel with only a tire patching kit, an air pump, and the stock tool kit.
As far as duck's reference to wives tales and clutch bolts goes, wives really didn't seem to start participating in automotive mechanics to a large extent until the 1990s, but if the US Census has compiled figures declaring how many wives are actually in the trade, I haven't run across them yet. It's fair to say that they aren't old wives, the marital category commonly considered the greatest source of questionable information. At least I wouldn't call them old to their faces. The accuracy of considering wives tales—from old or young wives—as being inaccurate is also questionable. There just isn't enough quantifiable data being compiled on that subject because grant money for research these days is being redirected to AI, the ultimate outcome of which is likely to be bot tales or old bot tales.
I'm in the enviable position of only having one Brick to ride and maintain so a $13 expenditure once every ±80,000 miles on clutch bolts is small potatoes. The only written source I have that recommends replacing clutch bolts or the clutch nut is Max BMW, the source of most of my replacement parts and the only source of free M&Ms I know of outside of Halloween, so I'm all in. Happily, I'm not plague by rumination that villainous plots are afoot in business and everywhere else to control me, dominate my health, and my hold my spending hostage because I accepted those notions long ago and work around them. After all, many of us are engaged in the desire to influence others for advantage, profit, esteem, or just plain fun—every now and then. It just makes sense to me to replace parts that lead a hard life when the occasion seems appropriate and affordable: however in my case, peace of mind doesn't come from replacing parts; it comes from learning to be peaceful.
A used Brick isn't a used Toyota Corolla. It's likely to have lived a life of neglect in maintenance and purpose while its guts have been exposed to ravages from weather and humidity, at least that's how it seems to me and from what I've gathered here and elsewhere online. The Brick was built within a culture where precision is revered but some of us seem to believe it can be maintained like a bicycle with whatever tool is laying around. Free will allows that strategy. Free will is a gift but delusion and ignorance often extract large fees. If you invested in Bitcoin early, you'll probably be okay regardless.
-
The notion that you need to replace any clutch hardware is wives tale nonsense.
My sheared clutch stretch bolts when torqued to spec suggest otherwise. You may be able to get away with it, but you are literally deforming the bolt further than it is intended to be. Personally I'd rather KNOW that my bolts arent going to shear or have the heads pop off under load or come lose in the bell housing spinning at 2000+ RMP at 80mph. Thats just me tho
On another note, I have a bag of pre-stretched clutch assembly bolts if anyone is interested.
-
You could be forgiven for thinking - wouldn't a torque to yield bolt stretch rather than shear? Which would be enough to make you think - are they actually torque to yield bolts? And do they look like torque to yield bolts?
-
My sheared clutch stretch bolts when torqued to spec suggest otherwise. . . . On another note, I have a bag of pre-stretched clutch assembly bolts if anyone is interested.
I'll take them if you'll include your defective torque wrench postpaid. Maybe I can fix it. :laughing4-giggles:
-
I'll take them if you'll include your defective torque wrench postpaid. Maybe I can fix it. :laughing4-giggles:
haha, k
-
You could be forgiven for thinking - wouldn't a torque to yield bolt stretch rather than shear? Which would be enough to make you think - are they actually torque to yield bolts? And do they look like torque to yield bolts?
I purchased them from an oem supplier and they were identical to the original bolts I removed. I had to undo them after initial tightening since the alignment of the splines wasnt quite close enough to allow me to reinstall the gearbox. The head twisted off when I torqued them to spec the 2nd time, rather than sheering I suppose...and i even torqued them to the low end of the spec both times just in case. After that I had to remove them all 2nd time to get that broken bolt body out of the clutch housing. I wasnt about to try to reuse them a 3rd time after that.
its metal, it only stretches so much before failing.
This was also my 2nd batch of clutch bolts since I did my rear main seal late at night and wasnt confident I had reinstalled everything correctly. I redid it with new stretch bolts just in case...which meant ordering new bolts a 2nd time.
-
That should be unheard of, unless they're no-name bolts from who knows where. I have heard of no-name torque to yield bolts from who knows where that stretched beyond yield on first use (making them loose and two mm longer) But do they look like torque to yield bolts?
-
Yes, they are the OEM bolts. They were identical to the manufacturer installed bolts I removed.
I was super pissed when it happened because it was literally the last bolt I was torqueing after having already redone it like 2 other times(this was a 2nd set of bolts now). I had been super careful to not fully tighten them so that i could make sure the gearbox as sliding in properly before torqueing since they had already been torqued once. It was a lot of work and I was finally going to be done with it...then the head twisted off necessitating having to redo the whole thing just to get that broken bolt body out of the housing. After that I switched to standard m5(iirc) hex head bolts(i dont recall the strength atm) and locktite, after finding that advice on a couple of forums/tutorials.
I get it that Ks have a rabid OEM/stock/dont-mod-em fanbase, so it doesnt surprise me that Im getting a lot of pushback on this. I stand by my statement that stretch bolts arent needed, and that re-using them introduces potential failure that can be completely avoided with standard bolts and locktite.
-
There's no push back from me, I'm agreeing with you, I don't think stretch bolts are needed, and I know the feeling you had when that last bolt broke. It's that bloke with a beard in the sky who sometimes stretches our patients to just before yield, to test us out.
I'm not familiar with K1100 bricks, but I'm thinking maybe they're just bolts. They could look identical to the original bolts, but do they look like torque to yield bolts? Maybe they're not, including the original's.
-
Just checked the parts fiche for K1100 and K75. They have the same OEM part number. From my research before performing service they are stretch bolts....and when I ordered them from whichever parts supplier(ive used a few) they came with the part number on the bag and looked identical to the factory installed ones.
Perhaps I just had one bolt that was defective, since only one of them twisted off out of the 12 total replacement bolts I purchased. Perhaps I could have re-used one of the others, but the fact that they are stretch bolts, the fact that I work in materials enough professionally to know about stress failure in metals, and the fact that one of them twisted off led me to say f that idea.
Btw...the text from the parts fiche also suggests replacing them ... I assume because they are stretch bolts
"Clutch "allen" screw, K75 - K1200LT, R850R - R1100R. This part should always be replaced when doing any clutch work or inspection of the clutch."
-
Looking at the application, it appears to me that the tension load on these bolts is the clutch spring pressure and the result of the torque they are tightened to. To me, the primary load appears to be shear resulting mainly from engine torque. I will admit that I am not a mechanical engineer, so I am not familiar with the reasons for using a stretch bolt in a situation where shear is the main load on the fastener. If I was designing the clutch, I would have specified a high strength fastener with a high shear strength and let it be reusable with Loctite.
P.S. Has anyone ever heard of a documented case where the clutch assembly has come apart due to the failure of these nearly $7ea($42 a set) fasteners? Or is this another example of BMW's quirky and occasionally bizarre engineering and maintenance procedures?
-
Yeah, nah, yeah.
A couple of things. Prob just a bit of bad luck, they're small bolts, if you make a million, you just might get a bad egg in there. Maybe the single use suggestion is because of the wave type washers that come with them. Or if the only person telling you that you need to buy new ones is the person trying to sell them, that could be the reason.
Soop I spose the single use suggestion is why you guess they're stretch bolts, and I was guessing they're not cause it sheared instead of stretched. So if these are the same bolts from K75 through to K1200, I'll say they're not stretch bolts cause the bolts on my K100 spare engine don't look like stretch bolts, they're just bolts.
I bet ya that bloke with the beard in the sky is looking down on us laughing, and saying I'm reeling them in again.
-
I will admit that I am not a mechanical engineer, . . .
NEXT!
:laughing4-giggles:
BMW is by no means the only company using and recommending one-time stretch bolts in clutch assembly application. A likely reason to use them in production-line facilities is to be certain workers with differing skill levels, commitment, and weekend hangover recovery rate create an effectively tight assembly in the simplest way at one go. If one or more of those bolts loosen, shear force could break them.
No matter whether a stretch bolt is used once or reused, a non-stretch bolt is used and reused, or Loctite is being sprinkled like christening holy water on an assembly with the blessing of the local shaman, I think the main thing is to have an understanding of what is being done and be able to explain exactly why a personal choice is being made to do it a certain way beyond that guy (post, message from the mothership via dentalwork) told me it should be done.
After that, move on. Also, consider subscribing to AAA's rec vehicle/motorcycle long-distance towing policy.
-
The bloke with a beard in the sky, If your'e wondering what he looks like (and turn up the volume) since we're not even worthy of casting an optical nerve in the general direction of his supreme perfectness, this is what he looks like:
https://youtu.be/z-iWe4qXUD8
-
I would suspect that part of the reasoning for replacement is that the manufacturer has no control over how the machine is operated. Are shifts being done without benefit of clutch disengagement, or is the operator riding like an old fart?
I can see the shock loads when bang shifting being pretty tough on clutch bolts(as well as splines and transmission bits), as opposed to smoothly disengaging and re-engaging the clutch when shifting. Shifting gently makes it possible for me to save a bunch of cash when I service my clutch.