Clutch Shoes
 

Hey guys,
I'm looking for a little clarification on clutch shoe and spring selection.
From what I understand, lighter springs engauge at a lower RPM than heavier springs. Aluminum shoes engauge harder with less slip than composite shoes. But what does the combination of two aluminum and one composite fit in to the mix. Also, when running a alum/comp combination, what springs should be used.
Thx,
G

your clutch engaging at lower RPM's will mean it will bite harder, and may cause spin outs and to much power, so you want a spring combo. Most people use a combination of springs so there is a little slip, but not too much, composite shoes are lighter, so they engage quicker, but they slip a little so you can get some low end power without that hard bite that will cause spin-outs, it also puts less strain on younr engine so it spins the flywheel faster beacuase the composites are not as heavy The combo of aluminum and composite works best with 4 shoe flywheels. With 3 shoe stick with all of the same

A lighter spring will enguage the clutch earlier while the motor is making less power & cause a smother takoff & some times will bog the motor too much if poorly tuned.A heavier or stiffer spring can be identified by thicker wire hence the descriptions of .09=soft,1.0=medium,1.1=stiff & will enguage later at higher rpms when the motor is making more power & can be called violent at times causing loss of traction but will also slip more if you use a slow finger instead of whacking the throttle open.Look at someones clutch bell that uses 1.1 springs & you can usually see signs of extreame heat,the bell will have a blue & redish color on the outside & the car will rocket out of corners if traction is available.Composite shoes are usually lighter than alum & enguage later/higher rpm if using the same spring tention as an aluminum shoe & usually slip more than alum shoes causing A more friendly take off even though the motor is making more power when they hit.Some people like the 2 aluminum & 1 carbon combo but look at the inside of a used clutchbell & se how smooth it isthey usually have groves worn in them & aluminum built up on them.Now how well do you think that soft plastic/carbon shoe will hold up grinding against those groves & buildup? stick with all one or the other & you can use 1 softer spring to help get the car rolling with that one early enguaging shoe slipping some then wait for the other 2 shoes to come in a little later with heavier/stiffer springs.

Or go to a slider type clutch & have infinite adjustability.Werks & firioni both make those style.

the carbon will smooth out the clutch a little by providing a bit of slip

the composite or carbon shoes last pretty well when used with 2 ali just make sure you use a new bell from the start. generally I get about 1/2 to 3/4of the life of the ali shoes from a carbon when used together and the carbon shoe actually helps to extend the life of the CB

generally I use the next size spring down on the carbon to get the shoes to engage at the same time

eg 2 ali with 1.0 springs and 1 carbon with 0.9 spring

oh and sorry Jaz but I think you've got it all backwards

a lighter spring will engage the clutch earlier and provide a smoother take off due to less RPM at engagement, to light and it'll feel like it's bogging

A lighter shoe will engage later making the clutch more aggresive

there can also be the problem of a slipping clutch caused by springs that are to heavy and shoes that are to light this can result in a complete melt down of your CB Shoes and bearings:flaming:


Adrian:tire:

+1 on Retro's theory of clutch usage

just to add some more info on composite at least with the mugen shoes the mugen White shoes slip less than the carbon black type but slip more than alu, so you have a bit more tuning options there as well if you do run them then cut about a 1mm of the end so they sit better at rest.

I run 2 alu with 1mm springs and 1 white mugen composite with .9 springs no problems with wear at all and it works fine, as stated start off with a new bell if doing this.

You can stick with 1mm springs and tune the shoes for engagement by drilling them out as personally i find the 1.1 to be a bad fit in most clutch shoes and require removal of material to not bind, so if i want a more aggresive clutch i would normally drill some material from the clutch shoes rather than heavier springs, just my preference though