10 pedal or 11 pedal clutch

Discussion in 'Manton Push Rods Top Alcohol Tech Questions' started by aafa760, May 7, 2018.

  1. aafa760

    aafa760 Member

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    Hello everyone
    I have both clutches in a two disk setup for a 7.0 pro dragster 451 BBC with 6:71 and 4:30 gear 1:96 low three speed B&J.
    We ran 4 passes this past weekend and it shook hard on 4 trips. 7.5 8.0 air in beadlocks 4k to 6k launch
    BTW it wore .005 off disk for all the passes.
    Clutch is due for recert and I was wondering what the differences in 10 inch to 11 inch clutch in the setup might be.
    11 inch has more surface area on disks so at say 2 turns static and 93 grams will 10 or 11 hook harder?
    if both had same rockwell disks and 3 cutters in floaters. Car has been 7:02 at 191 with 10 in it.

    thoughts Will ? Mike Canter?

    Bryan
     
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  2. Mike Canter

    Mike Canter Top Dragster

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    What slicks are on it and what does it weigh? Is it shaking right off the line or further down track?
     
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  3. jay70cuda

    jay70cuda Member

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    Seeing a timing curve would help too. Or a racepack photo of the run. If you don’t wanna share that public then you could send one to mike, me or will. They’re auto guys. I just took my clutch out and joined the dark side. lol
     
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  4. sammy christian

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    I'm not going to try to tell you where to go with the clutch other than put more in it(weight and /or base) and drop those tires down to 6-ish, doesn't matter what kind.
     
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  5. aafa760

    aafa760 Member

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    Jay the computer quit on first pass. I would have loved to see the drive and engine rpm curves. but with it only wearing off .005 in 4 runs I am thinking no slippage
    track temp was very high 120-130 easily
    Mike
    Hoosier 33X15x15 D05 on 15X14 rim. tries 7.0 7.5 7.8 8.0 pressures. Beadlocks
    One thing that I am lost from the weekend. I staged one run at 4K ran 1.20 60' at 7:38 then next run 6K 1.25 60' at 7:48 both runs at 181 and change. no change in clutch settings between runs. DA was 3100 first run 3825 second run.

    first round I took static to 2 turns from 3/4 turn just for a major change no weight change it made shake worse but seemed further out from starting line 60' was still 1.20
    it has run 7:02 with 110 60' but way cooler track and DA 1989 verse 3789.
    First round Sunday am

    Sammy
    No timing curve Mallory Mag Heritage rules.
     
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  6. turbo69camaro

    turbo69camaro Member

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    What kind of clutch? What weight are the levers ? Whats your shift rpm ? how often do you service the clutch and what do you do when doing that ? how much static pressure are you running in LBS not turns ? with .005 total wear your locking it up almost at the hit and spin shaking
     
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  7. rb0804

    rb0804 Member

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    Says video is unavailable? Is this just me or are others having the same issue? What compound clutch discs are you running? Are you running bronze floaters?

    Just because two discs have the same Rockwell doesn’t mean that they are close in their friction abilities. A little history on Rockwell is that this is a surface hardness test. They take one spot on each pad on each side and then average them together to get the Rockwell number that is written on the disc when you purchase it. Now if for some reason the manufacture hits a “soft” spot or a “hard” spot on any of those one pads, they really don’t care and average the numbers anyway, even though it may not be a true representation of the “aggressiveness” of the disc. Now if you purchase a brand new disc and let it set on the shelf for a year and then re-Rockwell it, it will be different. If you run it in the car and then re-Rockwell it, again it will be different. Take that same disc, cut it so that it is fresh, and Rockwell it again, and guess what? It’s a different yet again. So knowing all of this I completely disregard Rockwell as a means to batch discs, I still record it in my disc database but I built a fixture to test the friction holding capability of my discs before they go in the car, when they come out of the car, and after I cut them before they go back in the car. If I was to chunk a disc or wear one out, I can dig through the trailer and either; (A) find a disc similar in friction ability and replace it or (B) re-jockey the pack to achieve the same overall friction ability, if that is the goal. This way I can always repeat or I could also make the pack more or less aggressive whenever I like. I’m not saying you need to build a clutch fixture yourself, I’m saying all of this to drive home the point of don’t put too much stock in the Rockwell number, it’s more of a guide. You could however buy your own Rockwell machine and keep track of the numbers so when you get wierd readings you can disregard the junk data. If you have an established program where you cut them every pass or if you just zero it, just make sure you do it the same all the time. Don’t deviate. It is also a good practice to not change all of your discs at once, try to work one into the pack while you still have a good known disc(s) in there.


    Really need to get the computer fixed and see what’s going on with the engine and driveshaft. A 2000 rpm swing in stage rpm is huge, more stage rpm equals more lever force equals more clutch clamping load at the hit. You also have more power with more RPM so this can complicate things if you are already over clutched. I dont like to vary more than a couple of hundred rpm either way from my stage rpm, which is usually dictated by track conditions. Tire pressure seems a little high too. I don’t like to be more than 6.8 with 6ish being the norm. Good luck.
     
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  8. jay70cuda

    jay70cuda Member

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    8 psi is way to high. Start at 6 psi. How much lead do you have in the clutch switch ? Also how fast is the timing coming back in?
     
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  9. turbo69camaro

    turbo69camaro Member

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    lol also what kind of disks 5191 5135 5050 ?
     
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