KTM Clutch Observation/Issue - Anyone Else???

O&GDriller
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10/5/2020 10:13am Edited Date/Time 10/9/2020 1:21pm
I recently replaced the clutch plates, steel and friction, in my 160 hour 2019 KTM 450 SX-F as it was slipping a bit due to wear. I replaced with the microfische called for OEM clutch pack KTM part number 79532010033 consisting of:

qty 8 lining disc part # 79532011000 1.95 mm
qty 7 intermediate disc part # 59032010200 1.4 mm
qty 1 intermediate disc part # 59032010100 1 mm
qty 1 intermediate disc part # 78932010000 1 mm

Problem I ran into is the newly installed clutch was not releasing/dragging when the bike was running. I was puzzled as the install went without issue.

Long story sort is the issue I discovered is the stipulated clutch pack does not provide what came with the bike from the factory. My son has an identical bike with the factory original/as delivered clutch still in it so I took his apart to have a look see. I discovered he only had one 1 mm intermediate steel disc, not the two called for in ALL documentation/parts fiches I've seen and read anywhere. I took his clutch pack out and put it in my bike and my observation was confirmed as my bike functioned flawlessly with my sons clutch installed. The clutch pack out of his bike as provided from the factory consisted of 8 - 1.4 mm steel plates and 1 - 1 mm plate. It DOES NOT have 2 - 1 mm steel plates, only one.

I'm totally baffled that I've not read of any other KTM owner having this same problem. ANYBODY changing a clutch pack in a current 450 would experience the same problem and have difficulty diagnosing if they didn't have an identical bike to use for comparative purposes. The wrong clutch pack is specified for a replacement. Only one 1 mm plate is required, not 2 as provided and stipulated in the parts catalogs.

As such my stack was 0.4 mm too short resulting in the clutch dragging. What really sucks is my "new" and incorrect $125 clutch pack was destroyed as I rode the bike with the clutch dragging while I was trying to figure out what was going on. It destroyed/burnt half the "new" friction and steel plates resulting in my having to buy another clutch pack. I'll have to reuse one of the "old" 1.4 mm steel plates in the second replacement clutch pack I'm now buying as it will also come with 2 - 1 mm steel plates.

Frustrating and puzzling. Any thoughts???
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Rickyisms
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10/5/2020 10:25am
I have two 16s and work at a Husky dealer and haven't seen this before. I would contact KTM and explain your problem, they are very easy to work with on the consumer and business side.
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sandman768
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10/5/2020 10:44am
Never had any issues replacing clutches in my ktm 450”s but I do verify what comes out must match what goes in... replace those rubber bumpers in the inner hub if you have not already, they are cheap & likely worn out.
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mxracer666
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10/5/2020 11:09am
Agreed: what goes in must match what comes out...
mx317
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10/5/2020 11:50am
The kit fits several models. Some may require the other plate. Why would you put in more plates than came out?

The Shop

O&GDriller
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10/5/2020 1:32pm
mx317 wrote:
The kit fits several models. Some may require the other plate. Why would you put in more plates than came out?
I didn't put in more than I took out. I put in a provided 1.0 mm steel plate instead of a required 1.4 mm steel plate. I didn't mic each individual steel plate upon removal. I assumed the KTM OEM replacement part/clutch pack I purchased would provide correctly sized plates... I further thought ALL KTM microfiche parts diagrams would be correct...

You might reread my post.
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Broseph
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10/5/2020 1:55pm Edited Date/Time 10/5/2020 3:32pm
Those are all the right parts in that kit. A shorter clutch pack height won’t cause drag, so something else is going on. You might check your new plates for flatness. Note: The bottom 1mm plate marked “S” is slightly wavy. It acts like a judder spring.

Edit: Finally read the entire post. You burnt up the new pack? That’s usually called slip, not drag. I see where the shorter pack could cause this, but it’s still odd because there should be room for 0.4 mm wear without slipping. Also, every KTM DDS I know of uses two 1mm plates, not one.

Are you on the OE slave cylinder? Flushed the fluid recently?
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mx317
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10/5/2020 4:30pm
mx317 wrote:
The kit fits several models. Some may require the other plate. Why would you put in more plates than came out?
O&GDriller wrote:
I didn't put in more than I took out. I put in a provided 1.0 mm steel plate instead of a required 1.4 mm steel plate...
I didn't put in more than I took out. I put in a provided 1.0 mm steel plate instead of a required 1.4 mm steel plate. I didn't mic each individual steel plate upon removal. I assumed the KTM OEM replacement part/clutch pack I purchased would provide correctly sized plates... I further thought ALL KTM microfiche parts diagrams would be correct...

You might reread my post.
My bad. I thought you put in two 1 mm plates instead of a 1.4 mm plate which might cause dragging. It sounds like it was slipping instead of dragging. Good luck.
jessdr1
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10/5/2020 5:23pm
From the 2019 KTM SX-F 450 Service Repair manual :


O&GDriller
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10/5/2020 6:43pm
Yeah, the above pictured install procedure is incorrect for a 2019 450 SX-F. My sons OEM clutch pack confirms they come from the factory with only one 1.0 mm steel. Further, installing his clutch pack in my bike resolve my issues. His clutch has never been opened since he rolled it off the showroom floor. I even mic'd all my sons steel plates to ensure the thickness of his steel plates.

My issues were the clutch was dragging when stopped in gear. With clutch lever pulled all the way to the bars there was considerate drag/lack of disengagement.

Additionally, when under power on track it was slipping due to shorter stack not receiving "enough" pressure from the spring.

With my sons clutch pack I had zero drag and it didn't slip under power.

FWIW, I'm sharing this info so others might not have the same problem. I have no agenda...
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Broseph
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10/5/2020 7:02pm Edited Date/Time 10/5/2020 7:02pm
O&GDriller wrote:
Yeah, the above pictured install procedure is incorrect for a 2019 450 SX-F. My sons OEM clutch pack confirms they come from the factory with only...
Yeah, the above pictured install procedure is incorrect for a 2019 450 SX-F. My sons OEM clutch pack confirms they come from the factory with only one 1.0 mm steel. Further, installing his clutch pack in my bike resolve my issues. His clutch has never been opened since he rolled it off the showroom floor. I even mic'd all my sons steel plates to ensure the thickness of his steel plates.

My issues were the clutch was dragging when stopped in gear. With clutch lever pulled all the way to the bars there was considerate drag/lack of disengagement.

Additionally, when under power on track it was slipping due to shorter stack not receiving "enough" pressure from the spring.

With my sons clutch pack I had zero drag and it didn't slip under power.

FWIW, I'm sharing this info so others might not have the same problem. I have no agenda...
There’s still something else going on here. As the KTM clutch pack gets shorter, the spring force increases. This would clamp it more, not less. And we’re only talking about 0.4mm (.015”), so it really should work either way.

Regarding your son’s bike: Either all the KTM literature and fiches are wrong, or his bike got 8 1.4mm plates by mistake.

FWIW, I have a ‘19 Husky 450 and it has two 1mm plates.
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BobPA
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10/5/2020 7:34pm
O&GDriller wrote:
Yeah, the above pictured install procedure is incorrect for a 2019 450 SX-F. My sons OEM clutch pack confirms they come from the factory with only...
Yeah, the above pictured install procedure is incorrect for a 2019 450 SX-F. My sons OEM clutch pack confirms they come from the factory with only one 1.0 mm steel. Further, installing his clutch pack in my bike resolve my issues. His clutch has never been opened since he rolled it off the showroom floor. I even mic'd all my sons steel plates to ensure the thickness of his steel plates.

My issues were the clutch was dragging when stopped in gear. With clutch lever pulled all the way to the bars there was considerate drag/lack of disengagement.

Additionally, when under power on track it was slipping due to shorter stack not receiving "enough" pressure from the spring.

With my sons clutch pack I had zero drag and it didn't slip under power.

FWIW, I'm sharing this info so others might not have the same problem. I have no agenda...
Broseph wrote:
There’s still something else going on here. As the KTM clutch pack gets shorter, the spring force increases. This would clamp it more, not less. And...
There’s still something else going on here. As the KTM clutch pack gets shorter, the spring force increases. This would clamp it more, not less. And we’re only talking about 0.4mm (.015”), so it really should work either way.

Regarding your son’s bike: Either all the KTM literature and fiches are wrong, or his bike got 8 1.4mm plates by mistake.

FWIW, I have a ‘19 Husky 450 and it has two 1mm plates.
Agreed. 0.015" difference should not cause such a failure. I have run stacks that measured nearly 0.100" smaller than spec...and they worked fine. I put nearly 200 hours on my stock 350 clutch and it never skipped a beat whilst measuring well out of spec.
mx317
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10/9/2020 6:45am
Broseph wrote:
There’s still something else going on here. As the KTM clutch pack gets shorter, the spring force increases. This would clamp it more, not less. And...
There’s still something else going on here. As the KTM clutch pack gets shorter, the spring force increases. This would clamp it more, not less. And we’re only talking about 0.4mm (.015”), so it really should work either way.

Regarding your son’s bike: Either all the KTM literature and fiches are wrong, or his bike got 8 1.4mm plates by mistake.

FWIW, I have a ‘19 Husky 450 and it has two 1mm plates.
It seems backwards, but if the stack is shorter the spring force gets less because you are pulling up on the rear pressure plate with the spring. Think of when you pull the clutch in and it pushes in on the spring the stack comes apart so they will release. This works the same for the cone type spring in KTMs or coil springs in others.
Broseph
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10/9/2020 8:06am
mx317 wrote:
It seems backwards, but if the stack is shorter the spring force gets less because you are pulling up on the rear pressure plate with the...
It seems backwards, but if the stack is shorter the spring force gets less because you are pulling up on the rear pressure plate with the spring. Think of when you pull the clutch in and it pushes in on the spring the stack comes apart so they will release. This works the same for the cone type spring in KTMs or coil springs in others.
The belleville that KTM uses doesn’t have a linear rate like a coil spring. It “cams over” at installed height. Pretty genius really... max spring force when clamped, less force as you pull the lever in. Also, as the clutch pack wears it clamps harder.

The KTM belleville resembles the force-adjusting variety at the bottom of this page:
https://bellevilleintl.com/engineering/load-vs-deflection/


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mx317
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10/9/2020 9:09am
mx317 wrote:
It seems backwards, but if the stack is shorter the spring force gets less because you are pulling up on the rear pressure plate with the...
It seems backwards, but if the stack is shorter the spring force gets less because you are pulling up on the rear pressure plate with the spring. Think of when you pull the clutch in and it pushes in on the spring the stack comes apart so they will release. This works the same for the cone type spring in KTMs or coil springs in others.
Broseph wrote:
The belleville that KTM uses doesn’t have a linear rate like a coil spring. It “cams over” at installed height. Pretty genius really... max spring force...
The belleville that KTM uses doesn’t have a linear rate like a coil spring. It “cams over” at installed height. Pretty genius really... max spring force when clamped, less force as you pull the lever in. Also, as the clutch pack wears it clamps harder.

The KTM belleville resembles the force-adjusting variety at the bottom of this page:
https://bellevilleintl.com/engineering/load-vs-deflection/


Sorry, just can't agree with this.
FGR01
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Fantasy
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10/9/2020 10:38am
mx317 wrote:
It seems backwards, but if the stack is shorter the spring force gets less because you are pulling up on the rear pressure plate with the...
It seems backwards, but if the stack is shorter the spring force gets less because you are pulling up on the rear pressure plate with the spring. Think of when you pull the clutch in and it pushes in on the spring the stack comes apart so they will release. This works the same for the cone type spring in KTMs or coil springs in others.
Broseph wrote:
The belleville that KTM uses doesn’t have a linear rate like a coil spring. It “cams over” at installed height. Pretty genius really... max spring force...
The belleville that KTM uses doesn’t have a linear rate like a coil spring. It “cams over” at installed height. Pretty genius really... max spring force when clamped, less force as you pull the lever in. Also, as the clutch pack wears it clamps harder.

The KTM belleville resembles the force-adjusting variety at the bottom of this page:
https://bellevilleintl.com/engineering/load-vs-deflection/


Broseph
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Stevenson, WA US
10/9/2020 12:05pm
mx317 wrote:
It seems backwards, but if the stack is shorter the spring force gets less because you are pulling up on the rear pressure plate with the...
It seems backwards, but if the stack is shorter the spring force gets less because you are pulling up on the rear pressure plate with the spring. Think of when you pull the clutch in and it pushes in on the spring the stack comes apart so they will release. This works the same for the cone type spring in KTMs or coil springs in others.
Broseph wrote:
The belleville that KTM uses doesn’t have a linear rate like a coil spring. It “cams over” at installed height. Pretty genius really... max spring force...
The belleville that KTM uses doesn’t have a linear rate like a coil spring. It “cams over” at installed height. Pretty genius really... max spring force when clamped, less force as you pull the lever in. Also, as the clutch pack wears it clamps harder.

The KTM belleville resembles the force-adjusting variety at the bottom of this page:
https://bellevilleintl.com/engineering/load-vs-deflection/


mx317 wrote:
Sorry, just can't agree with this.
Check out the paragraph in the middle of this page. Does Rekluse have it wrong too?

moto9
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Waimea, HI US
10/9/2020 1:21pm
IDK if this helps,
I had a similar issue with my 300, comparing the two parts dia. they look the same.
I don't know if the 450 has an x,y,z adjustment on the spring ring, but if it does that's
probable the issue.
I had to readjust the spring tension from the stiffest setting ...where it was set which I think is X, to the Y setting.
Also the washer (ktm calls it) that sits under the belleville spring is directional....should have "top" stamped on it.
Too much spring tension will cause excessive drag.

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