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Old 11-22-2006, 09:23 AM   #16
KenR
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If the spring washer is fully compressed by the c/s bolt, how could it allow any movement. It would seem to me that the spring washer is meant to be a locking device for the bolt, (along with some Locktite 243 of course) always applying pressure against the underside of the head.

A number of years ago I attended a seminar by the fastener company Boman. Learned more than I can remember now about the importance of applying proper torque on a bolted connection. One thing that I've carried with me over the years is to use a torque wrench on critical assemblies. The engineers actually calculate how much stretch a bolt should have to stay in its hole and not shear off. I've used an impact wrench on things like this when a torque wrench wasn't available but it always made me nervous.

Good discussion!
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Old 11-22-2006, 09:43 AM   #17
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Quote:
Originally Posted by meat popsicle
Zerodog,

I recall the countershaft has some radial (?) play, if I used that wrong it slides in and out a tad. Perhaps the spring washer continues to allow it to do that while still applying load upon the seal... get it? What happens when you essentially stop the CS from moving back and forth?
It isn't the sprocket that has the radial play it is the shaft itself.

Ken, I think you are right about the spring washer. It is the locking washer for the screw. But there is for sure an issue with this design. I have read about lots of guys loosing sprockets and causing some kind of damage. There are also the 2 versions of the mounting. One, with some kind of nut and the other with the screw/ washer. KTM has changed this before because of problems. Manufacturers don't always do everything the best way. This is why the aftermarket parts companies exist. If everything was perfect from the factory why change anything at all?
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Old 11-22-2006, 10:24 AM   #18
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Quote:
Originally Posted by Zerodog

Ken, I think you are right about the spring washer. It is the locking washer for the screw. But there is for sure an issue with this design. I have read about lots of guys loosing sprockets and causing some kind of damage. There are also the 2 versions of the mounting. One, with some kind of nut and the other with the screw/ washer. KTM has changed this before because of problems. Manufacturers don't always do everything the best way. This is why the aftermarket parts companies exist. If everything was perfect from the factory why change anything at all?
That's certainly true, otherwise there'd be no product development either.

I'm not suggesting that it's a perfect design, but I wonder if the problems folks are having with the c/s sprocket bolts breaking or backing out aren't due to a) re-use of the bolt and washer when they should be replaced at each sprocket change, b) failure to clean the female threads of the countershaft before assembly, c) not using a threadlocker or using the wrong type for the application (the new bolts come with threadlock already applied), d) incorrect torque being applied to the bolt, or any of the above in combination.

I've never had the problem on any of my bikes with this design - the RFS's have the same way of mounting the c/s sprocket - but I'm probably just lucky! Glad yours didn't do more damage!!
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Old 11-22-2006, 11:25 AM   #19
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Quote:
Originally Posted by Zerodog
Ken, I think you are right about the spring washer. It is the locking washer for the screw. But there is for sure an issue with this design.
I am going to be obstinate here; I think you and wrong on this. Why use a "spring" washer at all? Sure the spring action of the washer could help lock the bolt, BUT - as you have pointed out - there are better ways to lock a fastener.

Your logic might be OK if there is no intended purpose in the radial (or is it lateral?) play of the countershaft. Maybe its important that the shaft is allowed to move back and forth I am just trying to help here based upon what I think is right: if you lock that countershaft from moving and that movement is BY DESIGN then... ?

Quote:
Originally Posted by Zerodog
I have read about lots of guys loosing sprockets and causing some kind of damage. There are also the 2 versions of the mounting. One, with some kind of nut and the other with the screw/ washer. KTM has changed this before because of problems. Manufacturers don't always do everything the best way. This is why the aftermarket parts companies exist. If everything was perfect from the factory why change anything at all?
I have not read about lots of guys losing sprockets, but when they do, yep, they can cause damage.

I wouldn't be so quick to assume it was changed because of a problem. They may have found a way to improve the design. Remember these bikes are knock-offs of race bikes that are generally intolerant of problems.

But once again: if you can come up with a better system, that does not have unintended consequences, I'd be all

Quote:
Originally Posted by KenR
...

I'm not suggesting that it's a perfect design, but I wonder if the problems folks are having with the c/s sprocket bolts breaking or backing out aren't due to

a) re-use of the bolt and washer when they should be replaced at each sprocket change,

b) failure to clean the female threads of the countershaft before assembly,

c) not using a threadlocker or using the wrong type for the application (the new bolts come with threadlock already applied),

d) incorrect torque being applied to the bolt, or any of the above in combination.

I've never had the problem on any of my bikes with this design - the RFS's have the same way of mounting the c/s sprocket - but I'm probably just lucky! Glad yours didn't do more damage!!
Good points Ken.
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Old 03-15-2007, 01:02 PM   #20
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Nord Lock Ho!

These ramped lock washers are designed specifically for this type of application. They're a bit of a save your ass part if you have high vibration bolted connections, and can't keep bolts tight. we used them on hydraulic motor sprocket retaining bolts and they work wonders. its just a matter of finding one the right size. i need one for my rotax countershaft nut too.
you can get small quantities from mcmaster.com, just search for "nord lock".
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DustMeOff screwed with this post 03-15-2007 at 01:09 PM
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Old 03-15-2007, 01:19 PM   #21
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Cool I will look in Mcmaster next time I order. Right now I am using a gnarly star washer and a ton of locktite along with my large diameter stainless support washer that I machined. It works well because I even ran little thinner CS sproket from my 2 stroke on there. I put a pocket in the back for the CS to poke through. That way you can still tighten everything up and not get leaks or have anything shaking around.
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Old 03-15-2007, 01:56 PM   #22
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Quote:
Originally Posted by Zerodog
Cool I will look in Mcmaster next time I order. Right now I am using a gnarly star washer and a ton of locktite along with my large diameter stainless support washer that I machined. It works well because I even ran little thinner CS sproket from my 2 stroke on there. I put a pocket in the back for the CS to poke through. That way you can still tighten everything up and not get leaks or have anything shaking around.

Pics?
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Old 03-15-2007, 08:34 PM   #23
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Very intersting topic here
There are some bolts that are throw aways, IMO the c-s bolt is one of them as is the bellville washer.With a good clean thread interface(ID included) properly applied blue loktite should hold that bolt no problem.If you cant heat the fastener red loktite can be a problem. I have broken the heads off of bolts and or pulled threads out in applications where red was properly applied and the use of heat(450 deg) was not an option. I agree that proper torqueing of the bolt is very important, using an impact and just hammering it on till it dont go no more is not the way to go.
The purpose of the belllville spring is to apply constant pressure to the bolt, because at proper torque that washer is not completely collapsed.
With a standard lock washer the sping tension is just enough to force the sharp edge of the split into the bolt face to resist backing off.
Maybe the original reason for the bellville spring is for constant bolt tension within a range of tempurature. If you torque that bolt while it is cold the tension will increase as the part temp increases and it expands, and the washer allows for expansion. I have seen them used in such applications, where there was a part that saw elevated temps and was prone to vibration.
my $.02's worth.
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Old 03-15-2007, 09:43 PM   #24
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My TDM had a problem with the CS bolt popping off. Red loctite didn't work so we tack welded it on. Problem solved.
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Old 03-16-2007, 08:22 AM   #25
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Eek 10 years on the same bolt!

Great info here guys. I've heard the the bolt is one time use before but still kept re-using the bolt. Been playing craps with the devil too long and I should get out while I'm still ahead. Mine is a '97 620 and I'm still using the same bolt. It's been changed many times too as I routinely swap different tooth sizes. It won't turn a another mile until it's replaced with a new one.
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Old 03-16-2007, 09:38 AM   #26
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I am sure my bolt was the original in the bike. It sheared off. It didn't back out. I will try to get some pics of the support washer set up I have this weekend. I think I took a few before I installed it.
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Old 03-14-2009, 08:19 PM   #27
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Question

Well I rode my new (2000) 640 today and I'm glad I had a 17mm socket wrench with me cause I needed to tighten the countershaft bolt several times during the ride. crazy!

so I'm thinking about flipping the spring washer around backwards or replacing it with a flat washer. why? because that would take chain torque out of the equation and let the sprocket float a bit. Many other bikes I've owned have a floating counter sprocket. My ktm300 just has a clip and the thing flops all over. It's normal.

I think this might solve the trouble. anyone tried it?
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Old 03-14-2009, 08:35 PM   #28
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Quote:
Originally Posted by bluegroove
Well I rode my new (2000) 640 today and I'm glad I had a 17mm socket wrench with me cause I needed to tighten the countershaft bolt several times during the ride. crazy!

so I'm thinking about flipping the spring washer around backwards or replacing it with a flat washer. why? because that would take chain torque out of the equation and let the sprocket float a bit. Many other bikes I've owned have a floating counter sprocket. My ktm300 just has a clip and the thing flops all over. It's normal.

I think this might solve the trouble. anyone tried it?
The LC4 countershaft requires a preload to pinch the sprocket against the sleeve that rides against the seal and in turn compresses an o-ring. If the sprocket was allowed to float the o-ring would become unloaded and create a leak...
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Old 03-14-2009, 08:39 PM   #29
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If your remove the spring washer and allow the sprocket to float the shaft seal will soon start leaking.... The way the seal works is the spring washer puts pressure on the sprocket which puts pressure on the bushing which puts pressure on the o-ring which seals the oil in.....
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Old 03-14-2009, 08:40 PM   #30
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No fair Chris, you typed with more than one finger...
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