Ducati.ms - The Ultimate Ducati Forum banner

1 - 10 of 10 Posts

·
Registered
Joined
·
401 Posts
Discussion Starter #1
Good morning to you all.
Please share with me your thoughts on the following.

Most of all, have faced the problem of the hard clutch pull.
From what I have read here and elsewhere, there are two ways to tackle the problem.

1. Change the slave cylinder with a larger piston diameter, with the disadvantage of losing some travel. (this is the option I 've selected myself-MPL 28mm).
2. Remove two (out of the six) opposite springs, where some slippage may occur depending on the condition of the friction discs.

I tried to approach the problem from a different angle.
Please share your thoughts on it.

The force of the spring depends on the total length, diameter, number of coils (spirals) and the diameter of the spring wire.
If I consider the first three constant, what If I could get someone to make a spring that would have a slightly smaller wire diameter. Wouldn't that decrease the pull force, retaining the travel at the same time?

Please chime in with your thoughts.

Thank you
 

·
Old Wizard
Joined
·
3,006 Posts
The force of the spring depends on the total length, diameter, number of coils (spirals) and the diameter of the spring wire.

If I consider the first three constant, what If I could get someone to make a spring that would have a slightly smaller wire diameter. Wouldn't that decrease the pull force, retaining the travel at the same time?
Yes, you will change the spring stiffness if you change the wire diameter. The pull force at the lever will be reduced . However, the total force pushing the clutch plates together will also be reduced.

The force exerted on the plates is produced by the stack height of the plates, that in turn determines the preload force in the spring.

Here's a handy calculator:

Spring Stiffness Calculator
 

·
Registered
Joined
·
3,977 Posts
the constant you need to keep is seat pressure. softer springs with more preload will reduce the pull pressure a little, but it's not a great amount.

adding another friction plate will allow you to lower the seat pressure with less or softer springs to a greater extent.
 

·
Premium Member
Joined
·
441 Posts
I swapped the stock clutch slave for a nice aftermarket unit getting slightly reduced lever effort. But I did the swap more because I like to tinker and "work" on the bike and not because I felt the lever effort needed attention. I haven't been around Ducati bikes very long having my one and only for just over four years now, but others I have tried have not had what I consider a "hard" pull.

Just my opinion.

Joe
 

·
Registered
Joined
·
651 Posts
When I replaced my stock springs, I went with a stainless set from Corse Dynamics.

There was a noticeable reduction in force-required at the clutch lever. I'm not saying it was huge, but a noticeable improvement.

According to this vendor, many aftermarket springs are longer and/or heavier than stock, increasing force required. Don't know how true that is, just putting it out there.

Are you currently running stock or aftermarket?
 

·
Registered
Joined
·
401 Posts
Discussion Starter #7
Hi all, thank you very much for your time to share your thoughts.

Shazaam, your eDucating is a always top notch. The site is excellent, so if I can find out the correct parameters- wire material- of the springs I can design whatever I wish in terms of stiffness. I understand that if you decrease one force, the exact opposite will be decreased as well.

Based on the assumption that the guys that have removed 2 out of the six springs (~33%)have no slippage, if I decrease the spring force by let's say 25%, it will be sufficient both ways.

Another idea would be to try and decrease the preload on the springs by putting some shims directly under the allen bolt and the aluminium cup, before I try to fiddle with the springs.

Bradblack, if I add another friction disk I might exceed the max. stuck height of 38.5 mm. I have already applied the silent mode, by removing one steel and adding one friction. I need to study a bit your suggestion.

Joe 05 ST3, I am running stainless springs and bolts. There was no difference from OEM, as I can recall.

Thanks again
 

·
Registered
Joined
·
138 Posts
It's bizarre how a solution exist and people respond to it. I can't believe how much I have read on the subject of how heavy the clutch is, and nothing on how heavy the throttle is!
 

·
Registered
Joined
·
3,977 Posts
the pack thickness is irrelevant on the normal post 89 pack as long as you understand the implications and limitations of what you're doing. pack thickness is really only critical on slipper clutches.
 
1 - 10 of 10 Posts
Top