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Thread: Interchangable Sprocket for different events

  1. #1
    I am considering designing a range of sprockets to suit each event, ie. acceleration, sprint etc. If i were to do this, would the car require rescrutineering for each sprocket change?

  2. #2
    I believe there is a distinct list in the rules, of what you can and cannot change after going through tech inspection.
    Any views or opinions expressed by me may in no way reflect those of Kettering University, it's students and administrators, or our sponsors.

  3. #3
    This is the rule Ace was referring to:

    Once the vehicle is approved to compete in the dynamic events, the ONLY modifications permitted to the vehicle are those listed below. They are also referenced in Part S of the Formula SAE Rules – Static Event Regulations.
    a. Adjustment of belts, chains and clutches
    b. Adjustment of brake bias
    c. Adjustment of the driver restraint system, head restraint, seat and pedal assembly
    d. Substitution of the head restraint or seat insert for different drivers
    e. Adjustment to engine operating parameters, e.g. fuel mixture and ignition timing, and any
    software calibration changes
    f. Adjustment of mirrors
    g. Adjustment of the suspension where no part substitution is required, (except that springs, sway
    bars and shims may be changed)
    h. Adjustment of tire pressure
    i. Adjustment of wing angle, but not the location
    j. Replenishment of fluids
    k. Replacement of worn tires or brake pads
    l. The changing of wheels and tires for “wet” or “damp” conditions as allowed in Part D of the
    FSAE Rules – Dynamic Event Regulations.
    m. Recharging low voltage batteries
    n. Recharging high voltage accumulators

    You can adjust/change you belt or chain, but it looks as if you can't change sprockets. Maybe if you designed your system to have two (or more) sprockets always on the car (like a bicycle sprocket) and then just changed the chain, that might pass.
    IMO though, don't worry about it. You'd only realistically care about a different final drive ratio for acceleration. But honestly, optimizing that ratio might gain you a few hundredths, maybe a tenth, which equates to about a 5 point gain overall. But a tenth of second of wheel spin off the long completes negates that gain. So unless you have a legit launch control system that can launch the car perfectly every time, don't worry about it.
    San Jose State University

    FSAE Chassis and Ergonomics Lead '12-'13
    FSAE Chief Engineer '11-'12
    FSAE Chassis Technical Lead '10-'11
    Formula Hybrid Chassis Grunt '09-'10

    "A designer knows he has achieved perfection not when there is nothing le

  4. #4
    Adam is correct. The answer is definitely, NO!!

    Michael Royce,
    Technical Scrutineer,
    Formula Student.

  5. #5
    What if your chain tension is adjusted via differently sized sprockets?
    "...when this baby hits 88 miles per hour... you're gonna see some serious shit" - Dr. Brown

  6. #6
    You could easily "break" a sprocket, exchange it and ask for a re-scrutineering. This usually takes less than 2 minutes and should not be illegal. You are of course taking the risk that a scrutineer might not be available and thus lose runs in dynamic events.
    I would, as RobbyObby did before, question, whether it is worth the hassle.
    This rule, by the way, has an enforcement problem, in my opinion, as it should be impossible to seal or mark all the affected parts which are not allowed to be changed.
    Therefore I think, that many teams got away with changing parts in the past without re-scrutineering, because they broke a part and exchanged it and the team did not know that re-scrutineering was necessary.
    Unless another team protests this is usually not discovered, if it does not make the car illegal in general. A changed sprocket for example will not be discovered in Parc Fermé, which by the way not all competitions do implement anyway.

    Scores under pressure

  7. #7
    If a vehicle breaks down, or suffers a crash of some sort. I have seen Mr Royce walk up and tear scrutineering sticker off the vehicle...

  8. #8
    "Tear", no. "Remove", yes, if I felt that the damage was such that we needed to check out the repair. I think that the scrutineers at all the events do the same thing.

  9. #9
    I think that the scrutineers at all the events do the same thing.
    We do.


    Formula Student Germany
    FSE Rules & Organisation

    Not many people know the difference between resolution and accuracy.

  10. #10
    What if some cone sprockets with two or three alternative ratios were permanently fitted and scrutineered ?
    Cheers, Tony

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