Klr 650 clutch pressure plate - Kawasaki KLR 650 Forum
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post #1 of 45 Old 04-04-2013, 11:39 AM Thread Starter
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Unhappy Klr 650 clutch pressure plate

Hi All,

My name is Matt. I live in golden co. I am new to the forum.

My question: 2008 klr clutch- Outlaw racing kit

I am installing a new clutch kit. When I am tightening the pressure plate and springs, I got to 60 inch pounds and the pressure plate broke out the back. Spring cracked the plate. I was supposed to tighten to 84 inch pounds.
I ordered a new plate, checked the torque wench, second plate broke.

Here is the weird part, 2008 650 has 7 metal and 8 friction plates in clutch.
I removed 6 metal, and 7 friction. The case did not look to ever be cracked.
The clutch was barely working but did work.

Any help would be great!!
Thanks
Matt D
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post #2 of 45 Old 04-04-2013, 12:09 PM
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Hi Matt and welcome to the forum.

First things first. If you removed 6 metal and 7 friction plates, yes, the clutch would not have worked too well. That must have been something the Dreaded Previous Owner did.

As to the cracking, please take no offense to the following:

There is no way that 60 inch pounds will break anything in that clutch. 60 inch pounds is 5 foot pounds, which ain't a whole lot more than finger tight with a 1/4" drive ratchet.

Is it possible that you were tightening to 87 foot pounds? That would bust stuff up in a New York minute. I could see the plate breaking when you reached 60 foot pounds.

Tom

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Last edited by Tom Schmitz; 04-04-2013 at 12:14 PM.
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post #3 of 45 Old 04-04-2013, 12:17 PM
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Quote:
Originally Posted by Matt D View Post
Hi All,

My name is Matt. I live in golden co. I am new to the forum.

My question: 2008 klr clutch- Outlaw racing kit

I am installing a new clutch kit. When I am tightening the pressure plate and springs, I got to 60 inch pounds and the pressure plate broke out the back. Spring cracked the plate. I was supposed to tighten to 84 inch pounds.
I ordered a new plate, checked the torque wench, second plate broke.

Here is the weird part, 2008 650 has 7 metal and 8 friction plates in clutch.
I removed 6 metal, and 7 friction. The case did not look to ever be cracked.
The clutch was barely working but did work.

Any help would be great!!
Thanks
Matt D

1st welcome to the forum. Bummer way to start though!

Are you gradually increasing the torque evenly on all springs like on a cylinder head? You know back and forth not just going around the circle.

84" lbs. is about 7' lbs not much torque to crack a plate. Are the springs longer or alot stiffer than the OEM? That would do it maybe.

No eye has seen, no ear has heard, no mind has conceived what God has prepared for those who love him. 1 Cor 2:9
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post #4 of 45 Old 04-04-2013, 01:05 PM
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Quote:
Originally Posted by Spec View Post
...
84" lbs. is about 7' lbs not much torque to crack a plate. Are the springs longer or alot stiffer than the OEM? That would do it maybe.
Spec, I don't think so. It broke at 60, but even at 87 there would only be a wee amount of force on the plate. If the springs were of a rating that exceeded the pressure applied by 87 inch-pounds things would just not close up as they should.

87 in-pounds should provide a clamping force of ~1900 pounds. For the area of the face that the bolt acts on that would develop ~5,300 psi, which should be well below the yield strength of the material. I shouldn't think any clutch spring could exceed that, unless it was stacked (which would mean it is entirely the wrong spring).

Conversely, torquing to 60 foot pounds would yield a clamping force of 23,000 pounds and 64,000 psi. That's enough to yield the material.

I sure hope I've done my math right...

T

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“Neither of the two people in the room paid any attention to the way I came in, although only one of them was dead.” -Philip Marlowe

“'Why' and 'How' are words so important they cannot be too often used.” -Napoleon Bonaparte


Sting like a butterfly.
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post #5 of 45 Old 04-04-2013, 01:19 PM Thread Starter
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Hi guys,

Thanks for the replies. Still stumped here.
I am using inch pounds, I even checked my wrench.
10 foot = 120 inch and 5 foot was 61inch. So my torque wrench seems ok.
The first plate was the used one, but the second was factory new.

Any more ideas before I break another plate?
Thanks
Matt D

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post #6 of 45 Old 04-04-2013, 01:23 PM
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Quote:
Originally Posted by Tom Schmitz View Post
Spec, I don't think so. It broke at 60, but even at 87 there would only be a wee amount of force on the plate. If the springs were of a rating that exceeded the pressure applied by 87 inch-pounds things would just not close up as they should.

87 in-pounds should provide a clamping force of ~1900 pounds. For the area of the face that the bolt acts on that would develop ~5,300 psi, which should be well below the yield strength of the material. I shouldn't think any clutch spring could exceed that, unless it was stacked (which would mean it is entirely the wrong spring).

Conversely, torquing to 60 foot pounds would yield a clamping force of 23,000 pounds and 64,000 psi. That's enough to yield the material.

I sure hope I've done my math right...

T

Uh... I was told there wasn't going to be any math!

Matt swears he's using an inch lb. wrench so I'm going from there, trying to think why it would break.

No eye has seen, no ear has heard, no mind has conceived what God has prepared for those who love him. 1 Cor 2:9
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post #7 of 45 Old 04-04-2013, 01:27 PM
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Well, yeah, I was kind of fast and loose with the math part...

Matt -

I'm stumped. To be clear, you are using a wrench that reads in-pounds, right?

T

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“Neither of the two people in the room paid any attention to the way I came in, although only one of them was dead.” -Philip Marlowe

“'Why' and 'How' are words so important they cannot be too often used.” -Napoleon Bonaparte


Sting like a butterfly.

Last edited by Tom Schmitz; 04-04-2013 at 01:33 PM.
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post #8 of 45 Old 04-04-2013, 01:48 PM
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Matt -

Just a thought here. I have been looking at a clutch assembly to find a possible failure mode.

First, let me retract a statement. 5,000 psi could be enough to yield the plate material, according to some tables for strength of materials for die cast aluminum.

One possible failure mode I could see would be if you mis-assembled the clutch stack and had the tabs on two fiber plates in the short slots on the clutch basket rather than in the long slots. That would lock up the clutch plate and you'd be tightening against a hard surface rather than the springs.

Take a look at that.

If what I said is not clear, I can take a picture.

T

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“Neither of the two people in the room paid any attention to the way I came in, although only one of them was dead.” -Philip Marlowe

“'Why' and 'How' are words so important they cannot be too often used.” -Napoleon Bonaparte


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post #9 of 45 Old 04-04-2013, 01:56 PM
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Here's what I mean:



Note that the top two fiber plates are in the wrong slot, and note the gap between the second fiber plate and the steel plate. That indicates that the pressure plate would be tightening against the fiber plates and not the springs (and by that I mean the springs would get stacked).

T

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“Neither of the two people in the room paid any attention to the way I came in, although only one of them was dead.” -Philip Marlowe

“'Why' and 'How' are words so important they cannot be too often used.” -Napoleon Bonaparte


Sting like a butterfly.

Last edited by Tom Schmitz; 04-04-2013 at 02:02 PM.
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post #10 of 45 Old 04-04-2013, 02:15 PM
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The more I look at this, the likelier it seems.

Ready to assemble, the springs need to be compressed .5" before the bolts seat.

The springs have about .6" of compression before they stack.

Mis-assembled, the bolts need to compress the springs .65" before they seat, meaning that the springs are stacked and the bolt will not seat. If the clamping force at 60 in-pounds exceeds the strength of the material, the plate will crack.

T

Tom [email protected]

“Neither of the two people in the room paid any attention to the way I came in, although only one of them was dead.” -Philip Marlowe

“'Why' and 'How' are words so important they cannot be too often used.” -Napoleon Bonaparte


Sting like a butterfly.
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