Balance counter weight on finger

Discussion in 'PSI Superchargers Tech Questions' started by dcwinters, Jan 9, 2009.

  1. dcwinters

    dcwinters New Member

    Joined:
    Jan 3, 2006
    Messages:
    123
    Likes Received:
    0
    I know weight is weight, but do you guys balance the nuts and washers so that the weight is equal on both sides of the bolt in the finger?

    I know it becomes a pain when you re-adjust counter weight, but having most of the weight on one side of the finger does not look good. You would think that the finger is being torqued to one side at high RPMs and a lot of counter weight on the finger.

    Thoughts?
     
    #1
  2. Creech

    Creech Member

    Joined:
    Dec 5, 2008
    Messages:
    307
    Likes Received:
    1
    I do. I don't worry about it when I adjust it but I set it up as even as possible.
     
    #2
  3. Mike Canter

    Mike Canter Top Dragster
    Staff Member

    Joined:
    Mar 10, 2004
    Messages:
    4,630
    Likes Received:
    189
    That amount of mass spinning at that RPM you need to keep the weights within a cetain range of each other. What that range is I don't know. All my weights have been matched to weight. All my bolts of the same length and all my nuts and washers weigh the same. That is the way the weight box is set up. If I have to split weight then I will do it on every other finger. So if I only want a 3 gram total increase the one washer on every other finger.
     
    #3
  4. dcwinters

    dcwinters New Member

    Joined:
    Jan 3, 2006
    Messages:
    123
    Likes Received:
    0
    Mike, I agree with you there. However, I was talking about the weight on one particular finger. Lets say you have a 6 finger clutch and 72grams of counter weight, 12 grams per finger. Do you try to put 6 grams of weight on each side of the finger? Or do you just screw a bolt into the finger and hang the necessary weight on the other side of the bolt. Like a 3/4inch 1/4 bolt weights 6.5 grams, that leaves you to add a couple of fat washers and jam nut.

    Would it be best to put one fat washer on one side of the bolt before you screw it into the finger, then the other fat washer and nut on the other side? This would help balance out the weight that that particular finger sees. Otherwise, most of the weight would be on one side of the finger creating an uneven torque. OR does it not matter and I am splitting hairs?
     
    #4
  5. Creech

    Creech Member

    Joined:
    Dec 5, 2008
    Messages:
    307
    Likes Received:
    1
    You are not splitting hairs. Think of how much force is being applied by the levers. If all the weight is hanging off one side of the lever it can't be good. The pins in most of these clutches aren't that big and are pushed to they're limits as it is. My levers are threaded for the bolts, if I'm running 13 to18 grams per lever I put a small and a big washer on a 1 1/4 bolt and thread it in the lever and hang the rest off the other side.
     
    #5
  6. JustinatAce

    JustinatAce Member

    Joined:
    Oct 20, 2008
    Messages:
    599
    Likes Received:
    9
    It's good practice to keep the weight on the lever balanced. As Marty pointed out, lever pin and yoke pin fatigue can occur more rapidly if all your weight is on one side, but it won't cause total failure. You lever pins will gall on one side, reducing the lever's ability to move freely, costing plate load. On a good track, you're looking at almost 900 lbs/lever worth of force at the shifts in a typical TAFC.
     
    #6
  7. Chas116

    Chas116 Top Alcohol

    Joined:
    May 13, 2007
    Messages:
    35
    Likes Received:
    0
    Skeh-Chi

    we spend a lot of time making the clutch flat, parallel and perpendicular to the crack shaft center line, I would take the time to even out the applied pressure
    to the clutch surface, both static and dynamic, I have seen, some times, on the simulator a chattering effect when the static or dynamic weight is unbalanced considerably. When adding weight to every other lever evenly and leaving levers with no weight dose work well, but this will cause a different approach to the dynamics you will have levers more aggressive then others. all and all try to be as consistent as possible, and record your data.
     
    #7
    Last edited: Jan 12, 2009
  8. Mike Canter

    Mike Canter Top Dragster
    Staff Member

    Joined:
    Mar 10, 2004
    Messages:
    4,630
    Likes Received:
    189
    Having weight on some levers and maybe none on others does not make the application of the pressure from the lever come on at a different rate. If the length of the levers is all the same from the pivot hole to the hole were the weight is and the angle of the fingers is all the same then the weight is going to be applied at the same time regardless of the weight differential on the levers. That is the law of physics. The aggresiveness of the clutch is controlled by the shape of the levers and the position of the pivot hole (fulcrum). By not having the same amount of weight or close to it can warp the pressure plate or break the hat due to so much pressure being applied on smaller areas. This is one reason RAM went to nine fingers to help spread out the force.
     
    #8
  9. JustinatAce

    JustinatAce Member

    Joined:
    Oct 20, 2008
    Messages:
    599
    Likes Received:
    9
    Not surprising but Mike is absolutely right. We've found you can add 10-20% more plate load @ RPM with the same counterweight just by positioning the counterweight mounting holes slightly higher on the lever.
     
    #9
  10. Chas116

    Chas116 Top Alcohol

    Joined:
    May 13, 2007
    Messages:
    35
    Likes Received:
    0
    misunderstood

    Mike you are absolutely right! I understand Newton's law's of physics. bad choice of a word on my part. Changing the profile radius of the lever will change the center of mass of that lever, making it react differently to the application of the pressure on a different rate of RPM. My point was to suggest to evenly apply the pressure. By doing that you will distribute the friction, heat, and force, evenly, reducing the chance of the pressure plate to warp, which I have seen causes the clutch to chatter and shake the tire.
     
    #10
  11. Mike Canter

    Mike Canter Top Dragster
    Staff Member

    Joined:
    Mar 10, 2004
    Messages:
    4,630
    Likes Received:
    189
    Sorry Charlie, I misunderstood what you were trying to say. It sounded like that you only put all the weight on every other finger or put a fraction of the total weight on every other finger. I know racers that do this thinking that the lesser weighted fingers would apply at a different rate so you could vary the application time of the total pressure on the plate and there by changing the aggressiveness of the clutch.
     
    #11
  12. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
    Staff Member

    Joined:
    May 6, 2003
    Messages:
    6,706
    Likes Received:
    132
    counterweight

    So what you are trying to say is that regardless of if the finger has no weight on it or if it has 12 grams bolted to it, it "comes in" at the same point, just with a different plate load?

    So that would mean based on the finger design, let's say a 220 crower lever, comes in at 8000 engine rpm (assuming all other things remain the same). That finger will always be fully applied at 8000 rpm regardless of whether it has no weight bolted to it or 20 grams? In otherwords, the only difference is the amount of plate load applied.

    Kinda like Uncle Bob, I've always thought in simple terms. When I was a kid, my dad explained counterweight to me like a rock on the end of a string. I can stick an average size rock on the end of that string and have it slung out with a flick of my wrist, where I'm really going to have to whip my wrist fast to sling that string out with no rock...

    I've always been taught that you can smooth out the application of the counterweight by gradually staggering the weights on the fingers, making some levers come in slightly earlier than the others....

    Also, why is it sometimes more counterweight requires more air gap at the same stage rpm?

    Maybe I'm misunderstanding or just having trouble digesting this.

    **Edit. I guess I should clarify "coming in." What I'm discussing is actual finger travel. I realize given the same finger, with weight bolted vs no weight will apply more plate load at any given rpm than the lighter finger, so one could say the 'clutch came in earlier,' referencing the amount of plate load applied.

    What I'm getting at is actual travel of the finger, which has a significant affect on plate load applied.
     
    #12
  13. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
    Staff Member

    Joined:
    May 6, 2003
    Messages:
    6,706
    Likes Received:
    132
    clevice

    Also, isn't the right side of the clevice always going to see most of the load, regardless of distribution of the weight on an individual finger due to the rotation of the motor?
     
    #13
  14. JustinatAce

    JustinatAce Member

    Joined:
    Oct 20, 2008
    Messages:
    599
    Likes Received:
    9
    Will, you are correct about the right side seeing more of the force. You can tell by looking at the wear on your pins when you have the clutch apart. As much as we try to get the pins to wear evenly, physics is against us. The levers should be able to wiggle just a hair, but shouldn't seem loose. The only reason the wiggle is even there is to allow the freedom of motion.

    As for the staggering of weight, it just depends on the forces you are trying to exert. As long as the engine is turning, those levers are wanting to kick out, bringing to light the counterweight assist. All counterweight does in terms of physics is give the lever an advantage to overcome the opposite forces being exerted on it, namely the forces of the disc & floater pack(friction, materials themselves, heat expansion, escaping gasses & friction material) pushing back on it.

    The problem is that when pressure plate loads are calculated, it is usually calculated with equal weight per lever. Say you have a 60g setup on our 9.5", according to my calculator program 12g on 3 and 8g on the other 3. The total lever force is 2 lbs. more by staggering @ 7,000 and 5 lbs. more at 9,000 compared to the similar setup with 10g all around. The difference per lever is roughly 120lbs more per lever on the 12g than the 8g. These numbers are based off our own dyno testing using equal weight per lever.

    As soon as we get some free time I'm going to have the engineers fire up the dyno and do a staggered weight test for poops and giggles. I'm tired of theory and I want to see the actual profile. :D
     
    #14
    Last edited: Jan 13, 2009
  15. Mike Canter

    Mike Canter Top Dragster
    Staff Member

    Joined:
    Mar 10, 2004
    Messages:
    4,630
    Likes Received:
    189
    That would be interesting test on the staggered fingers on the clutch dyno.

    I say that according to the laws of physics that all the levers come on at the same time and rate regardless of the stagger of the weights. The ramp up curve and time will be the same to the lockup point regardless.

    So Justin what we say is if you keep the same total weight on the clutch fingers say 30 grams so 5 grams on each finger, run the dyno and watch the time and the ramp to reach total plate load or lockup (don't know which would tell you more. I have never run a clutch dyno). Then keep the same total 30 gram weight but now divide it up so you have 2 grams on every other finger and 8 grams on the other three fingers. Now run the same test again with the same RPM parameters. The question being does the total applied force from the fingers have a different ramp up to the fully locked up point from one weight configuration to the other? Maybe also does that lock up point change from one configuration to the other?

    Will, on your first two paragraphs I say the answer is Yes to both.

    As far as the third paragraph I believe you are comparing apples to oranges but maybe I don't understand what you are doing with the rock and string. From what I read I don't believe it is a valid comparison.
     
    #15
  16. aj481x

    aj481x Member

    Joined:
    Jan 27, 2004
    Messages:
    976
    Likes Received:
    18


    Absolutely correct ! Clutch parts are really dumb, although people tend to give them magical qualities. :p
     
    #16
  17. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
    Staff Member

    Joined:
    May 6, 2003
    Messages:
    6,706
    Likes Received:
    132
    split hairs....

    sounds good to really get into and talk about, but the bottom line is more weight is more plate load, just like more static is more plate load.

    often times staggering the weight around has as much to do with getting the 'just right' total weight number rather than trying to slow down the application by staggering.
     
    #17
  18. JustinatAce

    JustinatAce Member

    Joined:
    Oct 20, 2008
    Messages:
    599
    Likes Received:
    9
    I love the phrase "splitting hairs." Expecially since I'm pretty sure my ex-wife got all my hair in the divorce settlement as well, so I've got nothing to split.

    I think it is a good discussion and at the risk of sounding as dumb as my clutch parts( :) ), my curiosity is getting the better of me. My thoughts (this is the sounding stupid part) are that while you have a certain number of levers doing most of the work at a given RPM, do the levers contributing less create any kind of added work for the heavier weighted levers to overcome, creating the less aggressive effect? Just by hanging more weight on a lever, you are making it hit a certain load before the same lever with less weight. Does the law of averages apply to the laws of physics here?

    I understand that weight gets staggered just to get the correct total weight, which is usually within at least a couple grams of each other, if not closer. I'm talking about staggering the weight in bigger differentials like Mike had mentioned.

    What I can do with the clutch dyno is spin it up to RPM and usually every 50 RPM's it takes a data point for plate load. What that can tell me is how aggressive the plate load actually gets applied vs. RPM's for any given setup. Alcohol Pedal Clutches sound like jet engines when they go on this thing, which is interesting since usually theres 520 or so cubic inches of blown alcohol engine covering it up.

    P.S.: My apologies for the nerding up of all this stuff.
     
    #18
    Last edited: Jan 14, 2009
  19. Mike Canter

    Mike Canter Top Dragster
    Staff Member

    Joined:
    Mar 10, 2004
    Messages:
    4,630
    Likes Received:
    189
    Justin you ain't nerding it up. These kind of questions are in our heads all the time and we would love to have it proven one way or the other.

    I totally agree with adding 1-2 grams on a few alternating fingers to make small changes and I think that is permissible as long as the weights are even and evenly positioned as to maintain the balance of the clutch.

    I am sure we would all love to see the results of a dyno test with the big weight stagger.

    What makes the noise on the clutch dyno? Is it the rubbing of the disks against the metal surfaces while it is slipping?
     
    #19
  20. JustinatAce

    JustinatAce Member

    Joined:
    Oct 20, 2008
    Messages:
    599
    Likes Received:
    9
    Actually it's the clutch cutting through the air that makes most of the noise. The electric motor is surprisingly quiet until you hit the brakes. Consider the outer edge of a 10" clutch @ 10,000RPM's is moving almost 300mph. It pretty much makes a small tornado inside the the bell.

    I will be sure to post the results, but I wouldn't expect them for a few weeks. We've been hammered here lately.
     
    #20

Share This Page