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When to go to billet clutches?

kinger

VIP Member
Joined
Jan 17, 2005
Messages
7,377
Location
Clear Lake, IA
Website
www.piergenius.com
I enjoy the stock clutching and zero issues in my apex when boosted at 250-300hp levels. New build will be pushing 400hp or more.

What would be risks on stock clutches? Also planning on reving to around 12,200 rpm. Go just primary or both and secondary??

Billet clutches look awesome but I never even considered any in the past, help me understand the benefits. I plan to run the good Ole 8DN belt.

Thank you!
 

12K+ rpm? Sounds like you'll need the Reduction Gear Set from Greg at GNS Enterprises to get the primary clutch RPM back down to more efficient RPM's and then just run the stock clutches and an 8DN belt. Hard to beat, but when you get much above 400hp you'll struggle to fit enough weight in 3 primary weights and a spring to keep the engagement high enough...
Stock Apex cam profiles won't be ideal for that high of an RPM.
 
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12K rpm is about the limit on the stock gear reduction. I looked into the GNS reduction and spinning to 13K plus but it caused all sorts of other issues with my MPI SC, oil pump, all spinning way to fast. I would probably be in the 11,900 range creeping to 12,200 on a looooong pull as it gets into OD.

The STM Rage 8 seems interesting concept to get amazing belt grip in the first 1/2 of the shift then let it lift off and use the can arms to get to proper rpm.
 
Tapp clutch users - Any Feedback?

STM rage 8 users - Any Feedback?

I think I am leaning towards the STM Rage 8 but still undecided if I should even do it.

Stock might be ok for me too to start with and I can see if I'm slipping or blowing belts from heat. I can always add the clutch just was curious what people saw. Thanks!
 
Cool build Kinger, I purchased an STM clutch for my build similar to your power level based on the fact Dave Marshall once said on this forum that the spider can eventually start to spread under those HP levels. Tapp makes an amazing clutch, but I was always leaning towards Pro 4 & STM based on the ability to use a broader range of tuning components. imo.
 
Cool build Kinger, I purchased an STM clutch for my build similar to your power level based on the fact Dave Marshall once said on this forum that the spider can eventually start to spread under those HP levels. Tapp makes an amazing clutch, but I was always leaning towards Pro 4 & STM based on the ability to use a broader range of tuning components. imo.

Thanks for the advice! Do you have a build somewhere of your sled?
 
Resized_20200401_171655_7466.jpeg Resized_20200401_170808_6496.jpeg Resized_20200401_171439_5551.jpeg Kinger this is as far as i got, I'm going to pull the engine out & run the longer Head studs Dave offers down into the block. Going to add a ported head & switch over to a Vipec but other then that its a pretty basic bare bones build that just needs motivation to be completed.
 
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