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Thread: Salisbury or Quaife ATB?

  1. #21
    Originally posted by SNasello:
    Brian,

    those ramp angles sound like pretty good choices to me to start with. If you end up using the diff over the next few years you can slowly build up a range of spare parts for it that you can use to tune it on the new car.

    You should also look into getting shims of various thicknesses to adjust the preload, if possible. Also, think of a method to measure the preload in your diff, so you can check if it is in spec when you do find a setup that you like.
    Also by using some wheel speed sensors on the inboard side of your diff you can log your actual %sip or bias through corners to help quantify how the changes in ramps and preload are affecting the performance.
    South Dakota State University Alum
    Electrical/Daq/Engine/Drivetrain/Tire guy '09-'14

    Go big, Go blue, Go JACKS!

  2. #22
    Originally posted by SNasello:
    You should also look into getting shims of various thicknesses to adjust the preload, if possible. Also, think of a method to measure the preload in your diff, so you can check if it is in spec when you do find a setup that you like.
    Will do, thanks for the advice.

    Originally posted by jlangholzj:
    Also by using some wheel speed sensors on the inboard side of your diff you can log your actual %sip or bias through corners to help quantify how the changes in ramps and preload are affecting the performance.
    I am working on that as well. We have a Race Technology DL2 that has been collecting dust for three years that I want to integrate into this year’s car. The retaining nut on the back of our spindles is already slotted so all I really need to do is come up with a mounting solution for the sensor.
    Brian
    Drexel Racing 2010-Present
    Powertrain Captain

  3. #23
    Hi Brian, excellent discussion you started. I will leave my input (although it will only guide you to what you have already decided).

    I was in my team from 2007 to 2010. Driving AutoX and endurance from 2008 to 2010 (at MIS). We have used a Torsen for ages (since our first car in 2002). In 2008, we finally got to a VERY reliable design, that didn't break and was light. It costed the team a lot of effort and testing to get there. The same design has been used since then.

    In 2008, having tested like crazy during 2007, we moved up in the field considerably (from usually 35+ in AutoX, to the top 15). But it was first year doing so and we had many other things still to take care of. Through 2008, 2009, we were in the top 15 in performance, and in 2010 we did a loooot of performance testing: car setup, electronics, bla bla bla. Long story short, I would have liked (as a driver and being in the vehicle dynamics team) an adjustable diff to make the car even better. It takes a bit to get to that point, but not too much, and it's not rocket science either, AND you will eventually get there.

    I would say keep the Salisbury, and leave it almost as an open diff. It will give your drivers more time to understand everything else and then you start locking more (if the setup asks for it). Keep in mind that with slick tires, good track temp, and a LSD diff, you will be able to tell who could be a good driver and who won't. Maybe an open diff does not filter this too much, I don't really know, but anyway.

    AND what you said about keeping basically the same car (at least all that is not considerably wrong with it) and focus on testing is PRICELESS for a team in the situation you described yours. Incredibly, a LOT of people won't buy this, because their engineer minds won't let them. People seem to forget that testing is also engineering, and they try to win the competition in SolidWorks. This has been a problem in my team for years, every years someone tries to comeup with new things to design instead of new ways to analize data, organize tests, increase testing times, use each test more, etc.

    Good luck!

    JP

  4. #24
    Well I can tell you what diff I think you should run.....
    With our diff you make adjustments to the chassis. Springs , ride height and sway bar. It will act the same way as it did on day one.... 4 years from now. there are not parts to wear out. Send me an e mail. I will give you some good tech info Brian..
    scotty
    Taylor Race
    scotty@taylor-race.com
    taylor-race.com

  5. #25
    Originally posted by jpusb:
    Hi Brian, excellent discussion you started. I will leave my input (although it will only guide you to what you have already decided).

    I was in my team from 2007 to 2010. Driving AutoX and endurance from 2008 to 2010 (at MIS). We have used a Torsen for ages (since our first car in 2002). In 2008, we finally got to a VERY reliable design, that didn't break and was light. It costed the team a lot of effort and testing to get there. The same design has been used since then.

    In 2008, having tested like crazy during 2007, we moved up in the field considerably (from usually 35+ in AutoX, to the top 15). But it was first year doing so and we had many other things still to take care of. Through 2008, 2009, we were in the top 15 in performance, and in 2010 we did a loooot of performance testing: car setup, electronics, bla bla bla. Long story short, I would have liked (as a driver and being in the vehicle dynamics team) an adjustable diff to make the car even better. It takes a bit to get to that point, but not too much, and it's not rocket science either, AND you will eventually get there.

    I would say keep the Salisbury, and leave it almost as an open diff. It will give your drivers more time to understand everything else and then you start locking more (if the setup asks for it). Keep in mind that with slick tires, good track temp, and a LSD diff, you will be able to tell who could be a good driver and who won't. Maybe an open diff does not filter this too much, I don't really know, but anyway.

    AND what you said about keeping basically the same car (at least all that is not considerably wrong with it) and focus on testing is PRICELESS for a team in the situation you described yours. Incredibly, a LOT of people won't buy this, because their engineer minds won't let them. People seem to forget that testing is also engineering, and they try to win the competition in SolidWorks. This has been a problem in my team for years, every years someone tries to comeup with new things to design instead of new ways to analize data, organize tests, increase testing times, use each test more, etc.

    Good luck!

    JP
    Thanks for your advice and support. Sounds like we should start with the 80/80 ramps we have in there now and then add locking to the acceleration side or just add preload if we need it. Since I am one of the more experienced drivers of the group now, I'll probably be doing at least some of the testing. Hopefully this will help as I can get direct feedback on changes.


    Originally posted by scotty young Taylor Race:
    Well I can tell you what diff I think you should run.....
    With our diff you make adjustments to the chassis. Springs , ride height and sway bar. It will act the same way as it did on day one.... 4 years from now. there are not parts to wear out. Send me an e mail. I will give you some good tech info Brian..
    Email sent. Thank you for your input.
    Brian
    Drexel Racing 2010-Present
    Powertrain Captain

  6. #26
    Originally posted by Brian S.:
    I appreciate everyone’s help in making this decision. I am going to order some new ramps and any parts I need for servicing the diff from ICP. We are currently running 80x80 ramps, so I was thinking of getting 45x80, 60x80, and 60x70. Do these sound like good choices?

    Brian
    Just keep in mind that if you guys are running a slipper clutch (or decide to at some point), the decel ramp angles dont matter that much.
    UCONN FSAE: Old Guy #2
    www.facebook.com/uconnfsae

  7. #27
    Quote Originally Posted by kcapitano View Post
    Its dependent on weight transfer. If the weight on the rear tires is evenly distributed between them then both tires will resist changing speeds an equal amount and the car will want to go straight. If, however, there is a large percentage of weight on just one rear tire then that tire will react more longitudinal force then the opposing rear tire and a yaw moment will be introduced. This affect can lead to power on oversteer during hard cornering with a spool setup.

    In regards to your original question, learning to maintain and tune your current diff would, in my mind, be a much more effective use of your time than redesigning your powertrain to accommodate the MK2. Without experience tuning your suspension and differential setup you won't be able to validate the effect of changing your differential. Redesigning everything for the new diff will also require more resources during the design phase, which won't help you finish the car sooner and without validation you will be right back where you are currently in a few years.

    That's my two cents. To tell you a little of my experience, in 2012 I redesigned my team's drivetrain to work with a Drexler after having used a Torsen for over 10 years. My motivation was purely for reliability and finishing the car sooner and we never really looked at how the diff affected the car. Our drivers haven't noticed a significant difference, but this summer we are looking at doing some diff testing to validate its effects. Unfortunately its difficult to change the setup and because we don't now very much about it the diff testing is very low on our priorities list.
    So did you ever end up validating the switch over to the Drexler? Our team at UCD is currently thinking about making the switch over to Drexler from the Torsen T1, and would greatly appreciate any input as how your switch went and if you saw any performance increases.

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