449/511 Important Urgent Flywheel Inspection

[Big Timmy]

"Wow" I've seen 1/4 hexed bits like that for production and rapid assembly. But to think they make an Allen key special for bolts with a 3mm hole part way down the center of a 6mm bolt. That is going to break in the future...

I doubt they would likely be using a basic Allen Wrench key for rapid assembly inside of the flywheel but I do get the point of the Allen wrench you have presented as an example.

The hollow section of the second counter bored hole goes downward into the threaded shank area of the bolts end. That's why they stretch, come loose and eventually break. They always seem to break at the same point in its length and location too. From every picture I have seen.

I've been lucky with my 2 motors so far.

 

[NC Rick]

Are the screws in question "low head" design and is that necessary for operation?
I am thinking of ordering some in advance. Good quality socket head cap screws should actually be stronger than a grade 8 S.A.E. bolts. It used to be, the Unbreako brand was reliable. So many fasteners come from questionable sources these days, it is hard to know what you are getting. Since the metric stuff uses a different rating system I'm not sure of the euro rating for S.H.C.S I am pretty confident that many of the "Asian " ones are not so hot.

Perhaps I will do a pre-mature oil change;-)

 

[Scram503]

totally what scrambled my stator...

 

[Dangermouse449]

Never noticed the hollow in the bolts when I did mine, ( I just looked back at the photos I posted)
It's not a great design, but I don't think it's the root cause of the problem.
I reckon it's the dry type Loctite.
Mine were loose, I cleaned the threads and the holes in the flywheel with solvent and used red high strength Loctite.
I'm now at 185hrs without a failure.
Seems if they stay tight they'll survive ok.

 

[Big Timmy]

Luckily, Mine haven't sheared off or come loose either. Mine are over probably over torqued. they are probably stretched to some degree as well, but every time I see one of these broken flywheel screw disasters, after it chews up the coil windings and it looks like a copper wire rat nest. The heads of the screws in those pictures are always sheared off right at the point that the threads them selves start or rather terminate on the shanks of the screws / bolts.

I've seen several of them pictured that were ripped up on the "G450 Riders Forum and Registry" also. As I Moderate that Forum and "Husky talk" and have seen added photos sent to me. I have sent PMs to a few of those members about this issue to even ask how did the screws sever themselves and break and where along its length did they break. Its been the same thing nearly every time.

 

[Campbell]

Never noticed the hollow in the bolts when I did mine, ( I just looked back at the photos I posted)
It's not a great design, but I don't think it's the root cause of the problem.
I reckon it's the dry type Loctite.
Mine were loose, I cleaned the threads and the holes in the flywheel with solvent and used red high strength Loctite.
I'm now at 185hrs without a failure.
Seems if they stay tight they'll survive ok.

DM, the post from the G450 forum Tim has thoughtfully posted here was mine and having only just had my engine apart I have to disagree with your thoughts re the dry loctite, for the following reasons.

The manual in the section dealing with the stator gives the grade of these M6 x 1 Cap screws as 10.9 , the heads are likewise marked 10.9. The torque given in this section is 25Nm which is way too high for this grade of Cap screw, interestingly if you look in the general torque section of the manual the figure for grade 10.9 is correct.

The majority of photo's I have seen from multiple failures show the screws breaking at the point the hollow meets the thread i.e point of smallest cross section. I would also bet my lefty that a comparison of the length of those screws that have come loose without breaking with a unused screw would show elongation. Elongated screws loose their clamping load. Also a large number of instances involve screws that have broken at the point of smallest cross section leaving the threaded section still retained by the loctite. Whilst it is possible the loctite used may break down over time I don't believe their is any evidence it is the root cause of failure.

Originally Posted by Tims1572

"There have been many occasions that the stator screws or flywheel screws have come loose on the 450 BMWs and the 449/511 Husky's and it has torn up the stator like in the images posted by Doowrag above.

If you haven't already taken 20 minutes and looked inside to see the condition of the fasteners for the stator in the left case to check yours out. Please do so to make sure everything is tight. If any of the screws are loose, I would remove and replace them if you have new ones as BMW suggests. A good clean with some brake cleaner or equivalent and a blast of compressed air then use some Loctite for a hot and oily environment.

I would strongly suggest that you do this inspection as it could save you a bunch of cash and headache not to mention a possible long push or tow home out of the bush."


My post from G450 Forum;

I have just given my engine a freshen up and followed Tims advise and have dodged a bullet...thanks Tim. The head of one stator screw twisted off without any effort while checking with an allen key

I was only moments away from a costly failure. These screws have a 3mm dia hole that extends down to the first thread, which is where mine broke. A 3mm hole in a 6mm screw severely reduces the cross section, WTF was BMW thinking

I couldn't believe it when I picked up the screw head and could see straight through the allen key recess and 3mm of shank

Has anyone else noticed this on these screws? Tim could you check your spares?

If you have a close look at this photo provided by Doowrag awhile back you will notice a number of screws have broken at the junction of the shank and thread. This is because the cross section has been SEVERELY reduced at this point as a result of a 3mm hole/counter bore which extends down to this point from the base of the Hex.

Suggest(unfortunately in packs of 5 - you will need 2 packs)

ARP Kit #: 760-1016

Metric Thread Bolt Kit
ARP Stainless
M6 x 1.00
12mm UHL

8mm Hex wrenching
Torque Value*: 11 ft-lbs (14.9 Nm)

OR

ARP Kit #: 660-1016

Metric Thread Bolt Kit
8740 Chrome Moly
M6 x 1.00
12mm UHL

8mm Hex wrenching
Torque Value*: 11 ft-lbs (14.9 Nm)
*Torque value in repair manual is way too high at 25nm

Campbell

 

[Campbell]

Are the screws in question "low head" design and is that necessary for operation?
I am thinking of ordering some in advance. Good quality socket head cap screws should actually be stronger than a grade 8 S.A.E. bolts. It used to be, the Unbreako brand was reliable. So many fasteners come from questionable sources these days, it is hard to know what you are getting. Since the metric stuff uses a different rating system I'm not sure of the euro rating for S.H.C.S I am pretty confident that many of the "Asian " ones are not so hot.

Perhaps I will do a pre-mature oil change;-)

Rick, in answer to your question the low head design is not necessary. I have replaced mine and checked the head clearance prior. The head space was so large I did not write it down but was in the order of 7 - 8mm.

I chose to go up a grade to 12.9 torqued to the recommended value, see my post for ARP part#'s you could also use Unbrako Allen head cap screws which have a heavy shoulder section. (Edit - read your post properly - preaching to the converted re Unbrako....Sorry)

Given the consequences of a failure and the ease and low cost involved with replacing these screws I strongly recommend doing so.

Campbell

 

[NC Rick]

Thank you!

 

[Dangermouse449]

Thanks for your input.
I'm rapidly approaching 200hrs
on my bike now. I will likely be rebuilding the engine at that point.
The screws are something I plan to replace.
I understand your thoughts on the breakage at the step, and they are cheap to replace.
I still think they break because they come loose.
Ultimately, who knows, but they definitely need inspection if you have one of these bikes.

 

[NC Rick]

I quite agree Mr. DangerM. There seems to be plenty of screws there to hold it on. Sometimes it's fun to be obsessive. I hope I don't offend but I was having a personal giggle over the thought of the new cross drilled, loctite coated Unbrako cap screws safety wired with paper clips! I was forming a special tool today, using a good paper clip and was rather amazed by how ductile the wire actually was!

 

[Olive xm]

I checked mine Saturday after reading this and mine were all tight, also they had been loctited. 2012 TE449.

 

[Shovelhead85]

I checked my son's 2012 TE511 flywheel bolts a couple months ago by putting a tightening torque on 'em [guessing 16-18lbs] trying to detect movement. Nothing. Thank you to the Australian contingent (and everybody else) for keeping us informed.

(This was before reading about the "hollow" fasteners- I would've changed 'em out)

But I thought the Kymco motor spun "backwards". No? because if it did, wouldn't that be the major factor for bolts backing out and continuing to loosen? Maybe a misconception on my part perhaps- because I've never seen it mentioned.

I use loctite and like it, but there is a problem with it most people are unaware of: it is only effective on ferrous fasteners (it needs iron ions to react). The red, blue, green (wicking), purple (low torque) all have the same holding power on non-ferrous material: very weak. If you have any aluminum, stainless steel, plated etc fasteners.... you gotta use the activator spray or lipstick. (you might get away with touching some raw iron to the threads for a moment- but I'm not real sure about that. Any chemist out there?)

BTW, I haven't seen it in years, but 243 was the stuff I liked: oily fasteners were okay to use. I'm hyper-careful with 272 (red) 'cause sometimes the shit is permanent and impossible to get heat around it. Since Henkel bought 'em from Permatex (IIRC) 15 years ago I haven't paid much attention to Loctite (hell, I use the Habor Freight knockoff nowadays) so this info may not be current.

Here's a nugget of trivia for you: the sweet taste you get when you put a wrench in your mouth after tightening a loctite-encrusted fastener is... sorbitol. Supposedly. Man, I gotta quit holding wrenches with my teeth, I think.

 

[Huskynoobee]

It's weird that some back out and others snap the heads off. Just glad mine are fine.

 

[Dirtbikeerdad]

If only I had seen this sooner. I have had nothing but problems with my txc 511. I been a husky fan for a long time but after spending a small fortune on my 2012 txc 310 on repair after repair and I am a nut on maintenance and cleaning.
( i no longer have and took a big loss on it) and all the problems with the 511 I cant beleive i'm considering a different brand bike. It sad Husky is no longer the Husky we all knew and loved. Maybe I can find an older obe with super low hours. Check out the pics of my stator. Oh and how do you all know you dont have all the copper pieces of wire throughout the entire engine and tranny? The oil is ran through the trans and engine, is it even worth the risk? Does anyone have a failsafe way to make sue the pieces are out? Would love to here back before I make any decisions. I have heard the BMW 2010 450x has exact same stator/ flywheel combo at a cheaper price. angermouse449, post: 441708, member: 17906"]9880STS had his stator damaged by a loose screw from the flywheel. It has also damaged his flywheel itself.

I had already decided to check mine as a precaution after reading his post when we talked today & it was decided I'd loan him mine while I'm away for work.
I've just opened up the cover & was greeted by 2 loose screws!!

Do yourselves a favour, pull the Alt cover off & loctite these screws in!!


View attachment 45968

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If only i

 

[norma stitz]

Well these forums sure can trigger ocd! But hopefully also save me some money, and possibly a dangerous situation in the back country.
So I pulled the cover on my 12' smr511 and these bolts were definitely lock tited in with a blue material, and clearly labeled 10.9. I think I will replace with gr. 12.8 (12.9?) flange head hex cap screws, and re lock tite.
Any objections?

 

[norma stitz]

Pix

 

[norma stitz]

Okay well I ended up using gr 12.9 Allen screws because the flange looked too big and also only available 10.9 at my local hardware store. The cap allens were a tad taller obviously, but appear to clear fine. I torqued them to 132 in/lbs

 

[Dangermouse449]

I've just replaced my own screws with shop bought allen-head screws as well.
Anyone wanting to do this would be VERY wise to trial fit the stator assembly & check for clearance before running the engine.

 

[Trenchcoat85]

Okay well I ended up using gr 12.9 Allen screws because the flange looked too big and also only available 10.9 at my local hardware store. The cap allens were a tad taller obviously, but appear to clear fine. I torqued them to 132 in/lbs

Is that enough torque? that's 11 ft/lbs (~15Nm).

 

[Campbell]

Is that enough torque? that's 11 ft/lbs (~15Nm).

That is the correct torque for the grade and thread size, the torque listed in the repair manual (g450x at least) is incorrect at 25nm. See my posts #86 & #87 above re torque and clearance for Cap head screws.
Campbell