Help with clutch selection for big block stroker

[fatboy.88]

Hi guys,need to replace my clutch after frying my last one in my 68.

Engine made 617 of torque @ 4300 rpm and 565 Hp @5500 rpm naturally aspirated on the dyno.
Can anyone making the same kind of power recommend a decent clutch that's been successful in their ride.
Should I go down the twin disc route,Some say there not great to drive on the street ?
Car is mostly street with some strip action so want  driveability with street maners.
I'm running 30" tyres 4.10 gears and it's 18 spline input shaft.

Thanks Neale.

[c00nhunterjoe]

Im not a big fan of twin discs until you get into big power. I ran centerforce dual frictions for years on slicks with no failures. What did you have in the car?

[fatboy.88]

I was using the Ram powergrip clutch, max HP 550.
I think it was not up to the torque level for my car.

[Challenger340]

How many here contemplating these higher pressure Clutch plates have modified their Crankshaft Thrust Bearing Oiling ?
just say'in....
we do it here on every Engine 4 spd or Auto/High Stall Converter application......and we have been doing so for a long time ?
But...
it was after seeing LOTS of damaged Cranks/Killed Thrust Bearings from guys using High Pressure Clutch Pressure Plates

Remember,
every time you step on the Clutch pedal you are in fact trying to push the Crankshaft out the front of the Block ? Higher pressure Clutchs = harder "push" on the Crank ?

That's why we install a pressurized Oil "feed" to the Rear Thrust Bearing surface on the Crank..... rather than the factory stock "splash or drip" lube system on the Thrust surface ?
Something to consider when going to ever Higher Clutch Plates ?

[Paul G]

I cant say what to use. But, I can say what I went with, McLeod Super Street Pro also rated to 550 HP. It needs 500 miles of break in, and it is not there yet. My 505ci can over power it right now. I have to be careful. It does shutter a lot if let out super slow with super light throttle. It does not like that.

Peddle feel is very good. Not to stiff for daily driving. I called Center force and McLeod before I bought one. They would not recommend a clutch to use with an engine making over 550 HP.   

[fatboy.88]

Thanks for the help and advice guys.
Auto back in then.

[alfaitalia]

Funny how you guys over are saying that a certain clutch is rated for a certain horsepower. Horsepower is not what makes clutches slip, its torque......when buying a clutch here its always rated by how much torque it can take....HP is not usually even mentioned in the specs. Torque is the turning force trying to separate the friction plate from the steel one....horsepower is just how fast your engine develops that torque.

[Paul G]

Funny how you guys over are saying that a certain clutch is rated for a certain horsepower. Horsepower is not what makes clutches slip, its torque......when buying a clutch here its always rated by how much torque it can take....HP is not usually even mentioned in the specs. Torque is the turning force trying to separate the friction plate from the steel one....horsepower is just how fast your engine develops that torque.

You are correct. But still they list hp numbers not torque...

[INTMD8]

McLeod RST is nice. Twin disc organic. Pressure plate is light as it doesn't need to be heavy with the additional surface area of the discs.

[INTMD8]

Funny how you guys over are saying that a certain clutch is rated for a certain horsepower. Horsepower is not what makes clutches slip, its torque......when buying a clutch here its always rated by how much torque it can take....HP is not usually even mentioned in the specs. Torque is the turning force trying to separate the friction plate from the steel one....horsepower is just how fast your engine develops that torque.

Not just that simple though. Could also be that when racing, you're hovering through (or trying to) be on the bubble of max average horsepower.

Geared correctly the thing will never be coupled through peak torque.

So, I could see how a clutch could hold 550ft/lbs on a stroker making 500 horsepower.

Put that 550ft/lbs at 7000rpm and we're talking 733 horsepower.   Clicking the next gear off at 7500 the clutch might have a harder time reeling in that torque plus reciprocating inertia.

[Challenger340]

Steel Bell Housings ??

Just thought I'd mention it.... just as important, and probably moreso than ANY Clutch !

I wish I had a picture of buddies recent Clutch explosion ?

Luckily it exited to the passenger side or he would have any feet left !  
But it went right through the Aluminum Bell Housing like a hot knife through butter.....
and then right through the Trans tunnel sheet metal and Blew a hole right out the Lower right Fender ...... looked like a Shotgun blast from inside out through his right Fender !  

[Paul G]

Steel Bell Housings ??

Just thought I'd mention it.... just as important, and probably moreso than ANY Clutch !

I wish I had a picture of buddies recent Clutch explosion ?

Luckily it exited to the passenger side or he would have any feet left !   
But it went right through the Aluminum Bell Housing like a hot knife through butter.....
and then right through the Trans tunnel sheet metal and Blew a hole right out the Lower right Fender ...... looked like a Shotgun blast from inside out through his right Fender ! 

This might sound stupid, but, what conditions caused this? Was it leaving a stop light normal driving, or a 7000 RPM clutch dump?

[fatboy.88]

No point winding my engine past 5500 rpm because that's where my peak HP is of 565. My torque max is 617lft @ 43300 rpm.
My Ram clutch was good for 550 Hp but went in a puff of smoke when I dropped the hammer. No max torque specs just Up max.

[BLK 68 R/T]

No point winding my engine past 5500 rpm because that's where my peak HP is of 565. My torque max is 617lft @ 43300 rpm.
My Ram clutch was good for 550 Hp but went in a puff of smoke when I dropped the hammer. No max torque specs just Up max.

Well of course it went up in a puff of smoke at 43,300 rpm 

[INTMD8]

No point winding my engine past 5500 rpm because that's where my peak HP is of 565. My torque max is 617lft @ 43300 rpm.
My Ram clutch was good for 550 Hp but went in a puff of smoke when I dropped the hammer. No max torque specs just Up max.

Ideal shift point rpm is above max hp rpm.

[Birdflu]

No point winding my engine past 5500 rpm because that's where my peak HP is of 565. My torque max is 617lft @ 43300 rpm.
My Ram clutch was good for 550 Hp but went in a puff of smoke when I dropped the hammer. No max torque specs just Up max.

Well of course it went up in a puff of smoke at 43,300 rpm 

[ChargerST]

How many here contemplating these higher pressure Clutch plates have modified their Crankshaft Thrust Bearing Oiling ?
just say'in....
we do it here on every Engine 4 spd or Auto/High Stall Converter application......and we have been doing so for a long time ?
But...
it was after seeing LOTS of damaged Cranks/Killed Thrust Bearings from guys using High Pressure Clutch Pressure Plates

Remember,
every time you step on the Clutch pedal you are in fact trying to push the Crankshaft out the front of the Block ? Higher pressure Clutchs = harder "push" on the Crank ?

That's why we install a pressurized Oil "feed" to the Rear Thrust Bearing surface on the Crank..... rather than the factory stock "splash or drip" lube system on the Thrust surface ?
Something to consider when going to ever Higher Clutch Plates ?

What do you do for oiling? Do you drill a hole in the bearing saddle and the thrust side of the bearing? Or do you file a small slot at the bearing parting line (from the middle to the rear?)?

Thanks!

[Challenger340]

Steel Bell Housings ??

Just thought I'd mention it.... just as important, and probably moreso than ANY Clutch !

I wish I had a picture of buddies recent Clutch explosion ?

Luckily it exited to the passenger side or he would have any feet left !   
But it went right through the Aluminum Bell Housing like a hot knife through butter.....
and then right through the Trans tunnel sheet metal and Blew a hole right out the Lower right Fender ...... looked like a Shotgun blast from inside out through his right Fender ! 

This might sound stupid, but, what conditions caused this? Was it leaving a stop light normal driving, or a 7000 RPM clutch dump?

My understanding is 2-3 shift at 5,500 rpm.... he was NOT rev'ing it to the moon and did NOT miss a shift..... nothing out of the ordinary, just BOOM !

[Challenger340]

How many here contemplating these higher pressure Clutch plates have modified their Crankshaft Thrust Bearing Oiling ?
just say'in....
we do it here on every Engine 4 spd or Auto/High Stall Converter application......and we have been doing so for a long time ?
But...
it was after seeing LOTS of damaged Cranks/Killed Thrust Bearings from guys using High Pressure Clutch Pressure Plates

Remember,
every time you step on the Clutch pedal you are in fact trying to push the Crankshaft out the front of the Block ? Higher pressure Clutchs = harder "push" on the Crank ?

That's why we install a pressurized Oil "feed" to the Rear Thrust Bearing surface on the Crank..... rather than the factory stock "splash or drip" lube system on the Thrust surface ?
Something to consider when going to ever Higher Clutch Plates ?

What do you do for oiling? Do you drill a hole in the bearing saddle and the thrust side of the bearing? Or do you file a small slot at the bearing parting line (from the middle to the rear?)?

Thanks!

Yep, file a small chamfer in the Bearing parting line..... simple mod and it works !   Yet nobody does it and then wonder WHY their Thrust's go away with higher pressure clutchs ? DUH ?

[ChargerST]

Thanks for confirming this! Do you start out in the middle of the bearing and chamfer to the rear or do you chamfer the whole parting line (also oil the front face)?