Drag Clutch Decision

[Lessen]

Ok fellas, I'd like some mechanical input here.

I'm trying to decide what type of clutch to use for my funny car project. I've been doing some surfing and it seems pretty obvious to me that centax clutches seem to be the standard for r/c drag racing. However, my project is NOT so standard. As you may know I'm using an O.S. car 4-stroke engine instead of a normal big block 2-stroker. Although this type of engine offers a broader range of torque than most 2 strokes, it has a significantly lower rpm limit. Realistically it will see 20k at best. The car will probably be at least a 3-speed so the engine will see it's mid range a couple more times per run than a 2-stroke single speed car.

So... any input on how this will affect clutch performance?

This is a long term project for me so I'm willing to do some custom stuff if necessary. First off, the O.S. FS26S-C is NOT an SG shaft, so if I went with a centax or Werks style clutch I'll need a custom clutch nut for sure. If I stay with a standard style clutch I won't need anything out of the ordinary.

 

[Coach Z]

I'd think the big thing mwould be adjujstability so that you can match it for the lower revs so a werks style is a good choice for that and then the second issue would be making sure it hooks up and doesn't slip so maybe gor for the red rulon shoes which are supposed to grab very well. Check out the orion clutch which is similar to the werks setup but has six shoes rather then four.

Anybody know more about that new Fioroni clutch that is similar to the Losi 8ight's setup???

 

[Lessen]

Yes, I can definately agree with the idea of tunability. so that would take traditional clutches out of the list.

So without regard to brand.. what would work better for this situatio? A centax or traditional/adjustable.

The way I see it a traditional/adjustable (not sure if there is a better term for these) still uses the same outward motion to contact the inside of a (traditional style) CB.

A centax transfers the outward motion to a forward motion where it contacts a special centax CB in a fasion more like a real 1:1 clutch.

It looks like the Penta clutch by Fioroni is a traditional style clutch just judging by the fact that it uses clutch springs in the traditional manner.

 

[Coach Z]

Yeah the penta is sort of a hybrid of the "typical" clutches but I think it would hook up really well with five aluminum shoes thats why I threw it into the mix. What do you think about the orion/werks, same principle as the centax but opens up your clutch bell options to whatever you like.

 

[Lessen]

yeah, those Orion/Werks(Fioroni makes one too) are what I'm referring to as traditional/adjustable. They look very similar to a Centax but they do not operate in the same manner. you're right about CB options though, that may be helpful. Plus, they are very adjustable like a Centax. I just wonder which one will suit this application better due to the limited rpm range of the engine. I guess what I'm wondering is.. which type will grip better at lower rpm with when there is still a lot of torque?

the Werks/Orion styles have less mass to move so the shoes are essentiall lighter but I'm guessing that a Centax has a greater contact area.

 

[Lessen]

Anybody have any opinions?

 

[vbgagnon]

What do those pulling trucks use, they seem to handle the torque pretty well.

 

[Lessen]

Hmmm. good question

you know I just thought of something... even though engine rpm will drop with gear change, the ratios probably wouldn't be such that they would drop so low to the point where grip may be lost at the clutch. Being a dragster the engine wouldn't really ever see low rpm like a touring car might see coming out of a tight hairpin turn except at launch... where you actually want wheelspin and it woulnd't hurt to allow the clutch to engage a tad later anyways. A "tad" later most likely wouldn't encounter the low end of the higher gears range.

Well I'm doing my ordering now so I think I'm gonna pickup that Orion setup. Mostly because it allows me to use a standard clutch bell.

I'm still open to suggestions and thoughts though. I can always return it.

 

[Rolex]

I would be looking into a clutch that would engage at high RPM. Tight spring, light shoes, but serious grab. Once you bring the revs up and then hit full throttle, it should launch with some real punch. From there to the end, the clutch would stay engaged as long as you hold full trigger.