i don't wanna sound dumb but how do you do the boosted launch with the manuel. ive tried but i can't do it, im probably just not doing it right.

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oh and where did you get it and the part number or exactly what it is so i order the right thing. and thanks man.!

 

i got it from john at holland court diesl out of colorado he is on this site under jbaker i think, to do a true boosted launch you put it in the gear you want to start out with, hold the clutch, rev the beast up till you see the require boost, i do about 15, then drop the clutch as fast as you can and go threw the gears, when i drag i do 4x4 3rd gear 15psi boosted launches when im screwing with people around town i only do 2wd 2nd gear 15psi boosted launches

 

You cant really do a true boosted launch in a manual truck. As far as a clutch a full ceramic 12.25 single disc from ValAIr would be a great clutch. I beat mine to its death and i had over a year of abuse on it. Get the dual drilled flywheel with it and you will love it as long as you dont tow a trailer. The 12.25 is also cheaper than the 13 inch and will perform better in my professional opinion. We have run a few beta ValAIr Full Feramcis and a full ceramic works a ton better than the feramic for racing and abuse. Simply because the older it gets the more it holds, because it eats into the flywheel. I was only able to slip the clutch when i wanted the clutch to slip. This is the part number i would run: NMU70119-04. If you look at the 12.25 facing compared to the 13, you can visually see the size difference. Let me know if you have any other questions.

Nick
LBDP

 

jbarker, is his user name

 

yes there is a price difference between the two, but i wanted the biggest badest single disk clutch on the market and that was the only one other than the southbend which is on average $200 more than the valair

 

There is a price difference as well as the holding force difference between the two. The 12.25 wins that category too.

 

how could a smaller clutch have more holding surface than the 13"

 

the 12.25 has a 3800 pound pressure plate on a 12.25 surface(for easy math sakes). the 13 inch has a 3400/3600 depending on the material. The 12.25 has more pressure per square inch than the 13 plus havin 22% more friction material allows for more pressure to be actually applied to the given surface area.

 

really, i didnt know that i wish i would have known that before i ordered mine last may, i figure the bigger was better, wouldnt it be more grabby

 

Well good try but not right. Lets first just take your math. 12.25" (SUPPOSEDLY) has 3800 lb of pressure but has more friction surface. You will loose pounds per square inch. Take a pencil and stand it up on the eraser side and then put a five pound weight on top. Now measure the pounds per square inch. Flip the pencil over and repeat. The point of the pencil will have a much greater load with the same applied pressure. Now lets really look at a clutch. Somewhere within the clutch plate is a torque ring where it is the greatest called "means". This is determined by measuring from the ID of the friction area outward 2/3 Rd's of the way to the OD. This is the point of which you stop and measure the circumference and the torque is at its greatest. Now open up the ID, remeasure the 2/3 Rd's and the torque ring or means will be larger. The further you go out the higher the torque until you start to create a cutting tool. The lower HP semis have 14" clutches and the Higher HP semis have 15 1/2" clutches. Using your theory it should be the other way around.

Peter