School me on wheelie bars

Discussion in 'Manton Push Rods Top Alcohol Tech Questions' started by JMillerJr76, Jul 24, 2018.

  1. JMillerJr76

    JMillerJr76 New Member

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    ok, I know most cars in here are solid rear suspension, but I’m looking for education anyway. We have a 4 link no prep car, Twin turbo on alcohol. Struggling with the bars. I know guys look for the first small hit, pull the bars up, and hit and drag them out a few feet...we get one set of marks that are 1.5 feet long, then nothing. The car buzzes the tires. Not sure what info would be needed, but I will give the info to the best of my knowledge.
     
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  2. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
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    It's a trade off.

    More flex in the bar, longer bar, will be softer at the initial hit, but the harder you hit it, the more flex rebound you will see in the driveshaft curve. Sometimes this will lead to major problems because it gets the tires into a spin-hook cycle.

    The stiffer the bar, you have to manage the hit because there is less flex. But the advantage is there is much less spin hooks after it, so you actually can get the car more hooked up after the hit.
     
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  3. TOL

    TOL Active Member

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    Thoughts on two wheels versus one wheel?
     
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  4. Randy G.

    Randy G. Top Alcohol

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    When everyone was following the leader and changing over to shorter stiff wheelie bars I didn't. Rather than smacking a short stiff wheelie bar at the hit, rebounding, and worrying about the thing unloading and blowing the tires off I could hit it very hard at the hit with the tune up and survive with tremendous wheel speed, and the 60' time in many cases showed it. No zig-zag on my driveshaft rpm. I ran a 16 nozzle system set up where every cylinder was happy at stage RPM (zero dead holes) with 775 degree temps and a good amount of clutch so we weren't leaving anything on the table. I would replace the long wheelie bar every 50 or so runs because the spring in it would change and would make the car more prone to tire shake. It wasn't uncommon to see .915 to .920 60' times from my pile of junk. Lou Gasparrelli told me one time when he was commenting on our 60' times that the 60' clock isn't the finish line, which is true. But I'll take a .918 over a 1.005 any day.
     
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  5. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
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    In my opinion you probably weren't hitting the bar as hard as everyone else with the aggressive set up, so it had less rebound. The tire was trying to turn on it's own instead of relying on the wheelie bar to stop the car from going down.

    Not to mention there's a science to building the wheelie bar right.

    You west coast guys get 6 races a year at Pomona and Vegas doesn't hurt....
     
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  6. Mike Canter

    Mike Canter Top Dragster

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    Will, I agree with you. A turbo PM does not launch like a blown PM and is going to hit the bar very differently
     
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  7. Bjs344

    Bjs344 Member

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    I have for years been wanting to build a programmable wheelie bar. I'm honestly surprised nobody has done it
     
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  8. Randy G.

    Randy G. Top Alcohol

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    I didn't want the wheelie bar to be my source for wheel speed. I controlled power in the box and gave it as much as possible. The first motion of the car was slight squat then the back end went up as wheel speed took off, not because it bounced off a wheelie bar but because we were doing everything we could to go fast. In other words, I relied on power for wheel speed, not an artificial floor jack creating a rebound.

    Although it's an older photo this is one of my favorite pictures showing what I mean. Ignore the red light. Notice how the side wall is straight up and down, not pooched or rolled out, and the tight pattern of the wrinkle. It's up on the tire and moving forward, not recovering from a stuck tire and not relying on the wheelie bar to bounce it back up to free it up. In this picture the car is probably less than 10 off the starting line. On my computer clicking on the picture enlarges it.

    [​IMG]
     
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    Last edited: Jul 26, 2018
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  9. TOL

    TOL Active Member

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    If I could tap into the collective here, why do people still continue to run twin wheel wheelie bars on high power stiff chassis's?

    Would'nt a one wheel long semi compliant wheelie bar be more consistent and easier to tune overall?

    Just thinking and wondering out loud here.

    Thanks.
     
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    Last edited: Aug 3, 2018

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