Clutch Question: How does the hat height (zero) affect tuneup

will im not sure why this is but it works but i set my clutch at 785 but the book says 702 and i have .95 and .96 60fts 3 turns of base and 90 grams and it works so good i never went back 702 .55 air gap at the pedal 10" CROWER

what do you think

 

We used to run our 10 inch Crower at .740, seemed to work fine. It gave you more travel, and more room for your air gap/clutch stop. I think the bigger height changed the geometry a bit and let the car get out a bit smoother.

 

good question Will. being an a/fuel guy i have to ask, does the rockwell of the disks come into play? or should i say, would your increase your gap as your disks get harder?

 

i think the levers get more agresive with a looser stack ..740 or .785

I used to set it .015 tight and run it till ..785 or so.. thinking losing static gaining lever. Ive heard of adjusting them Italian style;is this it or is that through the hole with a cigggarett hanging out yourr mouth?

 

someone correct me if I'm wrong, but all that you are effectively doing is killing static pressure

 

my set up came from john medlin we know who he is was good friends with the late george peters i ended up with the car after he passed and in the notes i have says 785 is more aggressive 775 less aggressive i guess its right i just never heard of setting one that way thats the way i have run for two years no problems and it doesnt wear that much off the disc but normally i dont want to ask stupid questions the looks like i dont know what im doing i couldnt bring myself to set it at 702 it work so good

 

awww crap. I'm thinking backwards. hat to ring height. not pack thickness. oops. increasing static not killing

 

Ive spent more time thinking about how not to adjust the clutch than it takes to adjust it. Im not Italian though; must be the Kingsblood











whats black and blue and floats down a river?

 

If I told ya, JJ would kill me! YES, we have "played" with changing from the "book". Thats all I can say!

 

I got kicked off the computer before I could finish my last post. Before somone thinks Im nuts(or figures it out)LOL. I should explain I didnt run .100 off it in a day. In the 90's I was told .750 so .015 tight with a fresh stack .735. I think at least .010 comes off a fresh clutch in the burnout or if you seat it in. When I read the crower booklet I moved it to .700 (at the same time I changed to a high helix and made a gear change) seated it, reset it and burnt off .015 in one run. added 3 grams to each finger to get it back to .005

 

One Guy's Thoughts

As far as resetting your hat height - higher than recommended = less static lower = more static.

What it effectively does other than static is change the geometry of your levers. If you remember in the other post, I mentioned that the levers are the most efficient when the center of mass is nearly above the yoke pin on the donut. The further up and our you can get the counterweight, the more effective it is. But by making it taller, you are getting the lever closer to the max of it's travel. The counterweight will be up higher and further towards the outside, but you run the risk of bottoming out the lever on the hat as the discs wear.

Running the hat lower than recommended will be more aggressive at the hit, but the levers actually lose freedom of travel, and where the counterweight sits affects the "assist" part of the lever. In theory it should actually take aggression away from the levers because the counterwieght will be lower and closer to the center of the clutch where it doesn't move as fast.

Rockwell numbers come into play mostly in aggression and wear of the discs. In blown alcohol and A-fuel applications, I like to see low to mid 60's. This seems to be a good balance of wear, aggression and heat dissipation. Essentially disc wear is your biggest form of heat dissipation. Friction material is its own animal and it makes all the difference in the world. As far as tuning, if you're within 10 Rockwell numbers of each other, you shouldn't notice a difference. Pro Stock guys will range anywhere from 55-65 on the 6.25" application, depending on how they like the clutch to work. You won't see much of anything softer than a 70 go in a fuel clutch because they need the wear characteristics of the harder disc and the aggression is sort of nulled by the 7-8,000 horsepower on a direct drive and tuning.

For the most part, you will find different people with different opinions on Rockwell numbers, but if they are using the discs in the same application, chances are everyone would be within 10 Rockwell numbers of each other.

 

BIG question!!!!!!!!!!!!!!!!!! i have a good rockwell tester what scale and what type of ball are you using in your machine

 

It depends on the track . Let me see if I have this right : If the starting line is really good, it might be better to have the crower at .700 or a little less to strike the tire but the main load from the counterweight will come on slower than if I had it at .775. At .775 the counterweight will come in real fast;good for a good track with bold spots on the starting line. The pro stock guy's have been sciencing this out for years, it'd be nice to get ahold of one of their playbooks, Shit most of them have 13 sets of carburetors! besides the dyno ones!

 

just remember that as you adjust your hat height, you are gaining or losing base pressure.

 

It's a Phase II model hardness tester with the a certified flat/level table expanded to hold the entire disc. The problem with most of the testers is that the rising surface is only 4-6" in diameter. If that disc isn't perfectly perpendicular to the ball/shaft(heh heh, ball and shaft, heh heh), you will get different readings every time. You'll still be in the ballpark, but it won't be as accurate.