Clutch Lever Effort Reduction

[Treadmarks]

In stock form my clutch lever effort was ok, but in heavy stop and go traffic it was giving me the hand/wrist/forearm pump pretty bad. I want to go with shorty levers but that would only increase the effort on a stock system so I decided to start from scratch and build a butter soft clutch lever that still has enough clamping force to prevent slipping and enough stroke to allow smooth shifting and easy neutral finding.

Since my stock springs were pretty rusted I bought the stainless steel spring kit with red anodized caps and stainless steel bolts. I installed each spring/cap/bolt assembly one at a time and when I was finished I could not believe how freaking hard the clutch was to pull in. Closer examination of the differences indicated the stainless springs were a little thicker than the stockers and there was a considerable difference in height between the red anodized retainers and the stockers. I swapped out the pretty red retainers for the ugly stock units, leaving the new stainless springs installed. Clutch effort was much easier, but still a little stiffer than stock. I then removed two oposing spring assemblies, leaving four installed. Now the clutch is butter soft but I am concerned about slippage. On the ride to work this morning I did not notice any slippage, but I was riding pretty easy. I searched and reviewed all of the slave cylinder information on this and a few other ducati sites and decided on the 29mm yoyodyne overthruster unit. I plan to retain the stock master cylinder with a shorty crg adjustable lever, all six of the new stainless clutch springs and will ask our machinist to build me a set of polished stainless steel clutch spring retainers that are the same dimensions as the stockers and also come with a set of machined shims that will allow me to reduce spring preload as much as possible while still retaining enough clamping force to prevent slippage.

The yoyo overthruster has been ordered and I will meet our machinist tomorrow about the custom stainless retainers.

[08hyper]

Originally Posted by Treadmarks

In stock form my clutch lever effort was ok, but in heavy stop and go traffic it was giving me the hand/wrist/forearm pump pretty bad. I want to go with shorty levers but that would only increase the effort on a stock system so I decided to start from scratch and build a butter soft clutch lever that still has enough clamping force to prevent slipping and enough stroke to allow smooth shifting and easy neutral finding.

Since my stock springs were pretty rusted I bought the stainless steel spring kit with red anodized caps and stainless steel bolts. I installed each spring/cap/bolt assembly one at a time and when I was finished I could not believe how freaking hard the clutch was to pull in. Closer examination of the differences indicated the stainless springs were a little thicker than the stockers and there was a considerable difference in height between the red anodized retainers and the stockers. I swapped out the pretty red retainers for the ugly stock units, leaving the new stainless springs installed. Clutch effort was much easier, but still a little stiffer than stock. I then removed two oposing spring assemblies, leaving four installed. Now the clutch is butter soft but I am concerned about slippage. On the ride to work this morning I did not notice any slippage, but I was riding pretty easy. I searched and reviewed all of the slave cylinder information on this and a few other ducati sites and decided on the 29mm yoyodyne overthruster unit. I plan to retain the stock master cylinder with a shorty crg adjustable lever, all six of the new stainless clutch springs and will ask our machinist to build me a set of polished stainless steel clutch spring retainers that are the same dimensions as the stockers and also come with a set of machined shims that will allow me to reduce spring preload as much as possible while still retaining enough clamping force to prevent slippage.

The yoyo overthruster has been ordered and I will meet our machinist tomorrow about the custom stainless retainers.

If the easier pull is what you were after, maybe you should have gone with a 30mm aftermarket slave, seems to be the industry standard, a little less travel, a little softer than the 29mm, (I have the STM 30mm) I'm using the Speedymoto heavy springs and DP Corsa slipper clutch, with the stock lever, a nice easy pull, with a shorty lever it will be the stock clutch pull, (maybe heavier). Aloha Alex

[Caidly]

Hey, you wanna sell those red caps?

[Treadmarks]

Originally Posted by 08hyper

If the easier pull is what you were after, maybe you should have gone with a 30mm aftermarket slave, seems to be the industry standard, a little less travel, a little softer than the 29mm, (I have the STM 30mm) I'm using the Speedymoto heavy springs and DP Corsa slipper clutch, with the stock lever, a nice easy pull, with a shorty lever it will be the stock clutch pull, (maybe heavier). Aloha Alex

I was going by this chart, from another board:



This chart indicates that I would get a 31% reduction in pull force with the STM 30mm slave, and also increase the amount of travel at the lever by 44%.

I think the 29mm cylinder is a good compromise providing a 26% pull force reduction while only requiring a 35% increase in lever travel.

I have read quite a few stories about shifting difficulties or hard to find neutrals with 30% or greater pistons. I really don't want to change master cylinders so I am going to work with a 29mm slave and clamping force mods to reach my butter soft goal.

Thanks for the heads up tho!

[Treadmarks]

Originally Posted by CTarna

Hey, you wanna sell those red caps?

I need to chart them and test them a little bit first. I'll let ya know when we are finished.

[Bravo51]

That chart was built by Shazaam huh? You might find it in the Hall of Wisdom too. It's for the classic Superbikes with lousy master cylinders so the 'results' may feel different compared to the HYM with the more 'modern' raidal master cylinders.

Don't H-Ds have heavy clutch pulls, just ride those a bit more to get those left hand muscles built up!

[Treadmarks]

Originally Posted by Bravo51

That chart was built by Shazaam huh? You might find it in the Hall of Wisdom too. It's for the classic Superbikes with lousy master cylinders so the 'results' may feel different compared to the HYM with the more 'modern' raidal master cylinders.

Don't H-Ds have heavy clutch pulls, just ride those a bit more to get those left hand muscles built up!

I dunno who built the chart but it is for the older bikes. Not sure how their masters compare as far as pull effot goes. I will be finding out soon tho.

Both my harleys have butter soft clutch pull, thanks to easy cable and lever mods. Don't reallly have that option with the hyper.

[Bravo51]

This thread may have the chart on it, for some reason the pictures aren't opening for me, but Shazaam was a technical poster (author in lower right corner of your posted chart).

Ducati and After-market Clutch Master and Slave Cylinders

The older Superbikes have a lot harder pull than the HYM, I have both, but my HYM is stock. On my 748 I don't remember a harder clutch pull with new springs and retainers, but I do remember an easier pull with an an aftermarket slave. Not sure on the size though. Even with my limited experience it sounds like you're on the right track with the new slave. As far as not using all of the springs in the clutch, I think Ducati race teams leave a couple springs out for the starter…but don't quote me on that. If it works for them, should work for you I would think.

[TurboMonster]

Have you considered switching to a cable clutch? Durbahn's offers up to 50% less handforce to declutch.
http://shop.durbahn.de/shop/en/produ...ch_Conversions

Durbahn doesn't have a HyperMotard kit on his site, but I'm sure he would make you one.

[08hyper]

Trademark, thanks for the chart, usefull info there, never seen it before, but don't worry using a 30mm clutch slave with the stock master, I know of a lot of Ducati's that are using the 30mm with NO netural finding issues. (like mine) Aloha Alex