'03 WR450 Rotor Damage (Again !!)


18 replies to this topic
  • Rainman_WFO

Posted September 24, 2007 - 08:01 AM

#1

OK, This is the 2nd time this has happen to me.

Apparently what is happening is that the six bolts that hold the starter clutch to the back of the rotor somehow shear off (all 6) and the allen bolt heads then chew up the stator and the rotor and pretty much kills everything in the process. I have already done the '04 starter mod when I fixed this mess the last time. The bolts were all loctited and torqued to spec on assembly last time, about 1 year ago.

So does anyone out there have any suggestions on how to keep this from happening again ?? Would grade 8 bolts help?? I was almost thinking of having the bolts welded and ground smooth on the back side of the starter clutch to keep them in place. It doesnt affect the removal of the rotor if I did that, what do you think ??

Damage Pics:
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  • Rainman_WFO

Posted September 24, 2007 - 06:08 PM

#2

BUMP.....Seriously, any suggestions ??

  • ccoates445

Posted September 24, 2007 - 09:23 PM

#3

What grade are the broken bolts. You can't go wrong with grade 8's but is there an underlying problem? What color locktite did you use? You should use red on super clean threads only. Were the surfaces squeaky clean? Did the original bolts have washers? I don't think so but I can't remember. I think you are missing a critical step in reassembly. I certainly would never recommend weldingthem in place. The heat will cause warping and it's a bandaide approach anyway. Did you notice a heavy engine vibration (other than the usual) after the last repair? The rotor or other parts of the assembly may possibly be out of balance causing fatigue to the bolts. I hope your able to sus it out as I know this has got to be a pain. Let us know if you find the problem.

  • Rainman_WFO

Posted September 26, 2007 - 06:27 PM

#4

The replacement OEM bolts from the first time this happened came from Yamaha and I have no idea what grade they were. Would Grade 8 bolts help in a situation like this ?? Are they harder and possibly more brittle in a shear load situation like this ??

The original bolts were loctited with Blue loctite. Maybe the Red or something stronger would help. I really wasn't going to weld them in, I just was frustrated with the problem again.

There are no washers in the original design. Maybe the threads still had oil residue on them when loctited last time.

Any other comments on how to stop this from happening a third time ?????

  • ccoates445

Posted September 26, 2007 - 10:00 PM

#5

The replacement OEM bolts from the first time this happened came from Yamaha and I have no idea what grade they were. Would Grade 8 bolts help in a situation like this ?? Are they harder and possibly more brittle in a shear load situation like this ??

The original bolts were loctited with Blue loctite. Maybe the Red or something stronger would help. I really wasn't going to weld them in, I just was frustrated with the problem again.

There are no washers in the original design. Maybe the threads still had oil residue on them when loctited last time.

Any other comments on how to stop this from happening a third time ?????

Grade 8 bolts can't hurt anything. I think yours sheared as they loosened and vibration and torqing took over. Red locktite is a must and get your hands on a torque wrench if you don't have one of your own. Clean, oil free surfaces are required if you want the locktite to do it's job. Take your time and it will turn out fine. Cheers

  • PBDBLUE

Posted September 27, 2007 - 05:39 AM

#6

Clean dry threads are a must. Get a can of spray brake cleaner and flush the holes and the threads on the bolts thoroughly. Then red Loctite. Torque to spec and you should be good to go. Allow plenty of time for the Loctite to set up before filling the engine with oil. Stock bolts should be fine.

  • xrmarty

Posted October 06, 2007 - 08:40 AM

#7

can't think of anything other than the bolts came loose and everything went to hell after that.

  • NW_E-rider

Posted August 27, 2008 - 09:45 PM

#8

Searching posts for stator damage and found this...mine just did the same thing. 2 of 6 bolts sheared off, other 4 hand tight.

My question is what product would everyone recommend to wash down the internal of the engine? My stator shreaded similar to these pictures. I want to make sure I wash down all the bits out of the engine before reassembling. I then plan to fill with oil, run for a few minutes, drain, refill. Then change oil again after the first ride.

Any other advice from folks that have torn engines apart before? Brake Cleaner? Engine Degreaser? Some other product?

  • roushxteam199

Posted August 28, 2008 - 05:23 AM

#9

use red locktight and make sure the bolts are to torque spec. grade 8 bolts might rips the threads out of the holes. they made those bolts the grade they are for a reason.

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  • Desracer

Posted August 28, 2008 - 04:31 PM

#10

I really feel bad for you thats a mess and pricey also. I noticed all of the bolts were broken at about the same lenght? They dont look bent or are they? I think you may have a problem with the flywheel and clutch seating together. If the two parts do not fit together tight on assembly the bolts will never torque properly. Did you use a torque wrench? I would get a new flywheel and compare it to your old one just to be safe.

  • brad the best

Posted August 28, 2008 - 07:03 PM

#11

did you torque them in steps in a star pattern ?

example hand tighten all of them down , then do them all down to 5lbs across from each other not in a circle . then 10lbs across , 20lbs across and then check . that is of coarse not the spec but a random number .

red loctight , if they do break again have fun getting the bolts out . and red loctight isn't designed for that small of fastener 3/8" or 10mm is the minimum size , and by 3/8" or 10mm i don't mean the size of the head i mean the size of the bolt .

those aren't 10mm , maybe 6mm .

there are also special surface preps for loctight , however most loctights work just as good with a slight film of oil . the permetex ones at least are made to work that way .

if you don't like blue then use green , its high strength and works with smaller stuff but you apply it differently .

since its metric , you have the option of 12.6 grade bolts . higher then grade 8 which is 10.0 .

the case will break before 12.6 bolts .

make sure that everything sits evenly , no burs or warping .

couple cans of brake cleaner , carb medic , what ever really tickles your fancy . just don't forget to lube everything after since the brake cleaner dries out everything .

good luck

  • Thumper_Bloke

Posted August 28, 2008 - 10:31 PM

#12

did you torque them in steps in a star pattern ?

example hand tighten all of them down , then do them all down to 5lbs across from each other not in a circle . then 10lbs across , 20lbs across and then check . that is of coarse not the spec but a random number .

red loctight , if they do break again have fun getting the bolts out . and red loctight isn't designed for that small of fastener 3/8" or 10mm is the minimum size , and by 3/8" or 10mm i don't mean the size of the head i mean the size of the bolt .

those aren't 10mm , maybe 6mm .

there are also special surface preps for loctight , however most loctights work just as good with a slight film of oil . the permetex ones at least are made to work that way .

if you don't like blue then use green , its high strength and works with smaller stuff but you apply it differently .

since its metric , you have the option of 12.6 grade bolts . higher then grade 8 which is 10.0 .

the case will break before 12.6 bolts .

make sure that everything sits evenly , no burs or warping .

couple cans of brake cleaner , carb medic , what ever really tickles your fancy . just don't forget to lube everything after since the brake cleaner dries out everything .

good luck




:worthy: All very good advice!

I had this happen to my KFX400, i think it was too much high rpm and no loctite from the factory. i washed the engine and replaced the parts, then sold the bike asap. :thumbsup:

The bolts backed out, that is what is happening. Can you safety wire them like this?
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  • alwho44

Posted August 28, 2008 - 10:54 PM

#13

Problem is the Yamaha engineer's pooched that design. The bolts are just scheered off. There aren't enought bolts or big enough bolts. Looks like bigger isn't an option. I'd look at doubling up the bolts. Have a machinist drill, countersink and tap an extra set off holes.

  • alwho44

Posted August 28, 2008 - 11:00 PM

#14

naw, you don't have any room for that either.
Every 6-8 months you'll need to drop by there and r&r the screws.
Oh well

  • brad the best

Posted August 29, 2008 - 09:13 AM

#15

its just odd , it only happens to your bike . it can't hurt to safety wire them if its possible .

totally forgot about safety wire . some thing just has to be wrong , try and get other people to look at it , some times they see things that you miss . it happens to me a lot .

  • ertxc

Posted September 02, 2008 - 05:05 PM

#16

I have a new in the box 04 wr450 stator coil for sale, btw, if you need....

  • matt4x4

Posted September 03, 2008 - 09:19 AM

#17

I think what happened here is that the threaded holes on the starter clutch have been ovaled due to the prior incidents. When the bolts come loose and the heads start to catch - it's a slow process, they slowly work their way out, will start to touch at the head, catch, wiggle for a time - all the while ovaling the thread holes some before shearing off.
New bolts will grab because the force was along one plane (left/right), making everything SEEM ok, but it's now weaker and you know what happens to a bolt in a slightly oversized hole, it'll shake out (even with loctite because the loctite is not designed to shake) causing the problem to reappear.

I bet if you get a new bolt, thread it in half way, you'll be able to wiggle it some side to side - that'll show you there's wear in the threads.

I'd be replacing the starter clutch and bolts - stick with Yamaha bolts - they are designed for the purpose - they may well be 8's already.
Clean with plenty of carb cleaner or brake cleaner - both cut grease and oil very well. twist a chunk of soaked paper towel into each thread hole to make sure any contaminants get rubbed off.
Use red loctite - just a drop on each bolt tip, too much loctite is as bad as not using any.

Make sure you torque it to the right specs - I find when using loctite AND torquing, I go about 5% more on the torque to achieve the actual proper torque so if the spec says 20ft lbs torque to 21.
Star pattern of course, just like a car tire.

  • sarkmych

Posted September 03, 2008 - 12:43 PM

#18

I feel for you bro'. Mine went the same way shortly after I bought it. I am just curious, did something during the ride trigger the problem like say...a high rev situation during a crash? The idler shaft casing also cracked on my bike rendering the electric starter unusable. I wish I could offer you a suggestion.

  • JimL

Posted December 03, 2008 - 09:48 AM

#19

sorry for the old post revival but here's some more info. I had the same thing happen after replacing my timing chain. I torqued the bolts but didn't clean the threads well enough before loctiting with blue. they backed out and 4 sheered off and tore up the stator and flywheel. I replaced every thing and bolted it back up. flushed the oil and I thought it would be ok. the magnet grabbed the bolts and it looked like the copper pieces had stayed in that area even though they were'nt metal and stuck to the flywheel. 1 month later and another oil change, I was on the gas hard hillclimbing and bamm!!! Locked up!! There was evidence that a copper wire piece had gotten into the crank bearing . It siezed . Snapped the rod, cracked the piston and the cylinder. the oil pump and the cases. Ruined the crank. Totally fubar. Sometimes it's worth it to split the cases and make sure you have everything flushed out.




 
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