What is the spec for pressure plate travel? '03 WR450


8 replies to this topic
  • jpgolf14

Posted December 16, 2015 - 09:29 PM

#1

Anyone know what the pressure plate travel is supposed to be?

 

Situation:

I have owned this '03 WR450 for about a month.  Its been cold here and I have never had the bike above 140 degrees.  Finally yesterday I got in some traffic and the coolant temperature rose up near operating temperature.  At 180 degrees I began to notice that the clutch was not fully disengaging.  I had to use the brake to keep the bike stopped.  At 190 degrees it was really pretty bad.  At that point the shifts in and out of neutral were harsh.  I came home and read all about the washer modifications and so on.  So tonight I decided to do the first oil change on the bike and open up the clutch cover and see what was going on.  I watched the spring as I worked the clutch and the spring did not appear to bottom out like suggested by some people regarding the washer mod.  I measured the clutch handle free play to be between 11.8 and 13mm, which is upper range of in spec according to the manual.  Now this bike appears to have aftermarket clutch and brake handles so I was not so sure I could trust the geometry of the handle to be the same as stock.  So I decided to remove the doubt by measuring the pressure plate travel.  I measured the travel to be between 0.037 and 0.041".  I then adjusted the handle to basically remove all free play and found when I did this I get between 0.058 and 0.061" of pressure plate travel.  Even with no free play, the clutch bottoms out on the grip when pulled.  Is this normal or should there be a stop that prevents this?  Again I am curious because of the unknown of my handles.

 

So I am wondering if anyone knows what the travel is supposed to be?

 

I suspect this was my issue and maybe I don't need to do the washer mod.  Thoughts?

 

With no free play, the clutch handle is pretty far away from the handle bar and not all that comfortable.

 

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  • Krannie McKranface

Posted December 20, 2015 - 09:33 PM

#2

It's a very short travel system

You need to download the manual from Yamaha's site to get  the gap numbers.

.03 seems about right.

This clutch is not very well designed, and unless all the parts are new, it will drag

Even then, it will usually drag.

You can modify the basket for better oil flow, which helps as lot (more holes)

This is the nature of most off road clutches which get abused.

If the bike has been running with stock jetting, it has been running very hot, and that warps the metal plates right away.

 

The washer trick makes it drag more, not less. It just makes it easier to pull.

 

You just have to get used to it. Always shift into neutral while still in motion. Use really good gear oil with no Moly.



  • jpgolf14

Posted December 21, 2015 - 11:03 AM

#3

It's a very short travel system

You need to download the manual from Yamaha's site to get  the gap numbers.

.03 seems about right.

This clutch is not very well designed, and unless all the parts are new, it will drag

Even then, it will usually drag.

You can modify the basket for better oil flow, which helps as lot (more holes)

This is the nature of most off road clutches which get abused.

If the bike has been running with stock jetting, it has been running very hot, and that warps the metal plates right away.

 

The washer trick makes it drag more, not less. It just makes it easier to pull.

 

You just have to get used to it. Always shift into neutral while still in motion. Use really good gear oil with no Moly.

I do not see any travel values in the manual.  The plates in my clutch look brand new.  No heat discoloration.  I belive the logic behind the spring trick is that people were not getting full pressure plate travel due to the springs coils bottoming out.  By spacing the pressure plate out with the washers, you are allowing for more pressure plate travel although at lower spring pressure.  I don't see how this could possibly cause more dragging.  If you put washers on the springs themselves (not what I am talking about here), that would shorten the spring and increase the spring pressure, and I could see how that would cuase more dragging. 

 

Surely doubling the pressure plate throw will improve the dragging situation but I would still like to understand what the spec says.



  • Krannie McKranface

Posted December 21, 2015 - 11:39 AM

#4

I have no idea what you are talking about, spacing out the pressure plate.

Sounds like a terrible idea.

The throw is not limited by the springs, but by the leverage of the clutch cam and clutch lever ratio/ cable pull distance



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  • bikedude987

Posted December 22, 2015 - 06:13 AM

#5

No one is talking about spacing out the pressure plate?  

 

The washer mod simply reduces the spring preload, nothing to do with travel.  Krannie, this would nott cause more drag.  If anything, it would cause less by virtue of your hand not getting as tired and therefore pulling the clutch in less than normal.  Unless, of course, there is slippage at normal riding pace which would heat and expand the clutch discs, causing drag.

 

OP:  Set the free play to 3-4mm (or less) and your clutch will be better.  You should NOT need to pull it in to the bar, only a centimeter or so to disengage.  That said, my old WR had the most drag of any clutch I've ridden, hot or cold, new plates or old.  I stopped using the clutch to shift and it was muuuch smoother, just time it right.  Finally fixed it for good by putting the rekluse back in, giving it to my wife, and buying a new KTM for myself ;)



  • jpgolf14

Posted December 22, 2015 - 08:58 AM

#6

Guys.  It is probably my fault.  I am new to motorcycles and my terminology is probably not correct.  I come from a car background.  See link below, post 9.

 

http://www.thumperta...-grabby-clutch/

 

If what they are saying is true, these guys are having the springs bottom out (no more travel possible) before the clutch can fully disengage.  By adding washers under the pressure plate two things happen.

 

1.  The clutch engaged spring pressure is lower.

2.  There is more room for the spring to travel, allowing more clutch disengagement.  Again this assumes what was limiting the travel was the spring bottoming out.  In my case, my travel seems to be limited by the clutch lever bottoming out on the grip.

 

bikedude987,

I am definitely going to give that a shot.  I am still curious what the travel is supposed to be though.  Sounds like it is locked away at Yamaha somewhere.



  • Krannie McKranface

Posted December 22, 2015 - 12:28 PM

#7

Guys.  It is probably my fault.  I am new to motorcycles and my terminology is probably not correct.  I come from a car background.  See link below, post 9.

 

http://www.thumperta...-grabby-clutch/

 

If what they are saying is true, these guys are having the springs bottom out (no more travel possible) before the clutch can fully disengage.  By adding washers under the pressure plate two things happen.

 

1.  The clutch engaged spring pressure is lower.

2.  There is more room for the spring to travel, allowing more clutch disengagement.  Again this assumes what was limiting the travel was the spring bottoming out.  In my case, my travel seems to be limited by the clutch lever bottoming out on the grip.

 

bikedude987,

I am definitely going to give that a shot.  I am still curious what the travel is supposed to be though.  Sounds like it is locked away at Yamaha somewhere.

 

I'm not sure what you are reading, but the post is about putting washers inside the springs, effectively lengthing the bolt at tension, so the spring tension is reduce at preload, making clutch pull lighter, and having more room to disengage and drag less.

 

This is assuming your lever is taking advantage of the extra throw-out.

It's mostly about spring tension for easier pull and less drag due to less spring tension, not more plate gap.

 

 

You do not put anything under the pressure plate....



  • jpgolf14

Posted December 22, 2015 - 12:58 PM

#8

I'm not sure what you are reading, but the post is about putting washers inside the springs, effectively lengthing the bolt at tension, so the spring tension is reduce at preload, making clutch pull lighter, and having more room to disengage and drag less.

 

This is assuming your lever is taking advantage of the extra throw-out.

It's mostly about spring tension for easier pull and less drag due to less spring tension, not more plate gap.

 

 

You do not put anything under the pressure plate....

 

Agreed, I had the picture wrong in my head.  Washers are between the screw and the pressure plate.  Other than that, we are saying the same thing.

 

I disagree about the spring tension and the drag though.  With the clutch disengaged, all the spring tension is doing is fighting your hand.  There should be no dragging at this point.  Sure if the springs are softer the friction created by the dragging will be reduced, but that is fixing the symptom and not the cause.  If you can move the pressure plate further, you should be able to eliminate the friction.

 

Anyway, this is getting way off track.  After Christmas I will get the bike back together and I'll see if it worked.  What I do know, 0.03" pressure plate travel is not enough.



  • Krannie McKranface

Posted December 22, 2015 - 01:01 PM

#9

Once oil is introduced to the clutch system, there is a TON of drag at all times. The plates all stick together.

That's one of  the big problems with the WR clutch basket. The oil does not flow, it sits in the basket.






 
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