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Help: Braking distance and ABS Skid Marks

Discussion in 'Gen 3 Prius Technical Discussion' started by PriQ, Mar 2, 2010.

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  1. PriQ

    PriQ CT+iQ

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    Hi everyone,

    Since I'm unable to drive my own Prius III at the moment, I would like to ask you guys for a great favor.

    Could I get one or more of you to drive at 40MPH and come to a complete stop by standing on the brakes, and then post your results in this thread.

    This should preferably be done on warm flat normal US tarmac with a warmed up Prius III (or similar car with ABS).

    I would especially like to know the distance, what the car sounded like when braking and how the tire marks (if any) looked like: How many were there, and were they continuous.

    Thanks in advance
    / PriQ
     
    #1 PriQ, Mar 2, 2010
  2. mad-dog-one

    mad-dog-one Prius Enthusiast

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    I gotta ask; is your Prius at the body shop after it was rear-ended?
     
    #2 mad-dog-one, Mar 2, 2010
  3. PriQ

    PriQ CT+iQ

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    My car was not rear ended.

    Before anyone asks. It was affected by the brakes recall and has not been fixed yet..

    I would just like to know what would happen when braking like this / think of it as a question purely out of curiosity.
     
    #3 PriQ, Mar 2, 2010
  4. bwilson4web

    bwilson4web BMW i3 and Model 3

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    I don't think the ABS leaves skid marks. I'm planning so emergency brake stops on downgrades in wet weather to compare and contrast our NHW11 and ZVW30. The reason for a downgrade is to make the stopping distance last longer. My testing on dry pavement has been it is terribly quick.

    Bob Wilson
     
    #4 bwilson4web, Mar 2, 2010
  5. PriQ

    PriQ CT+iQ

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    That is also my previous experience from other vehicles with ABS. They leave little to no skid marks because the ABS is there to prevent locking the tires.

    I would however still really, really like to know how the Prius III performs in this test.
    Or at least tell me if it takes less than 65ft to come to a complete stop.
     
    #5 PriQ, Mar 2, 2010
  6. peirhead

    peirhead Junior Member

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    Why don't you continue driving your car till the software fix is applied and then you could perform the test yourself.
     
    #6 peirhead, Mar 2, 2010
  7. PriQ

    PriQ CT+iQ

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    Because my car is no longer able to drive. It might take more than a month until the investigations by Toyota and my insurance agency are completed so repairing can commence.
     
    #7 PriQ, Mar 3, 2010
  8. ksstathead

    ksstathead Active Member

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    Why not rent a Prius and perform the desired tests?
     
    #8 ksstathead, Mar 3, 2010
  9. PriQ

    PriQ CT+iQ

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    That was also my first plan, but it turns out that my insurance doesn't cover a rental. I am still trying to figure out the financial consequences of this event. I might not even be able to afford renting a Prius, and will have to wait until I hear back from my insurance company.

    Things are not going so well at the moment.
     
    #9 PriQ, Mar 3, 2010
  10. spiderman

    spiderman wretched

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    Sorry to hear that. I can only imagine what happened.

    I would try the test but I have my snow tires with studs on and don't want to ruin them. Perhaps in another month or two.
     
    #10 spiderman, Mar 3, 2010
  11. bwilson4web

    bwilson4web BMW i3 and Model 3

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    We can model this. Use the 60-0 stopping distance from reviewers and vehicle weight and then solve for a constant braking force. Then use the constant braking force to calculate the stopping distance as a function of starting speed. To see what I mean:

    Vehicle Stopping Distance Calculator

    http://www.csgnetwork.com/stopdistinfo.html

    http://www.driveandstayalive.com/info section/stopping-distances.htm

    I'm a little busy in the lab waiting for some results. It should be amusing to work it out.

    Bob Wilson
     
    #11 bwilson4web, Mar 3, 2010
    1 person likes this.
  12. PriQ

    PriQ CT+iQ

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    Great. That might work out. I am busy answering phone calls from my insurance company and filing out stuff at the moment, but I will return to it once I get time again.

    Thanks.
     
    #12 PriQ, Mar 3, 2010
  13. PriQ

    PriQ CT+iQ

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    I don't want you to ruin your snow tires, and the stopping distance would probably be different from what I should have experienced with my summer tires on this normal road.
     
    #13 PriQ, Mar 3, 2010
  14. cossie1600

    cossie1600 Active Member

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    Wth. I have raced my Prius and it doesn't leave skidmarks under hard braking. The car comes with ABS, get over your little head over about the brake problem. If you can't stop the car using common sense, nothing is going to help you.
     
    #14 cossie1600, Mar 4, 2010
  15. PriQ

    PriQ CT+iQ

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    Thank you for your input cossie2600, but I'm afraid that my head is just too little to let this one go. Since you race your Prius, I suppose you know what the braking distance from 35 to 0 is?


    According to the web sites in the earlier links, it should be around 55ft.

    I have made a friend try this out in his 2010 Prius (which has the updated firmware). He should call back once he has had time to check it out.
     
    #15 PriQ, Mar 5, 2010
  16. cossie1600

    cossie1600 Active Member

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    I can test any speed using my performance, 90-0, 90-45, it's very easy to do with GPS based dataloggers. No matter what I do, the tires are not going to leave a skidmark unless the ABS is faulty. If the ABS is that faulty, chances are that your computer sensor will throw an error code for something that big. Plus to leave a skidmark under braking, do you know how bad you have to lock up your tires to do that? Your tires will flat spot if lock it from 45-0. It's not rocket science
     
    #16 cossie1600, Mar 5, 2010
  17. Harold Bien

    Harold Bien Member

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    Interesting. Based on my observations of evenly spaced, interrupted skid marks I always assumed that even with ABS you would leave skid marks albeit interrupted. However, a quick "Google" search yields this SAE article ( Skidmark Signatures of Abs-Equipped Passenger Cars ) (I can't read the full article without purchase) indicating that ABS equipped cars leave no visible skid marks (and this was published in 1990 - I assume since then ABS systems have only improved).
     
    #17 Harold Bien, Mar 5, 2010
  18. cossie1600

    cossie1600 Active Member

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    Computer works too fast
     
    #18 cossie1600, Mar 5, 2010
  19. adamace1

    adamace1 Senior Member

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    I have done a 45-0 mph stop, All i have to say is my Prius stops better than any of the 7 cars i have owned. And it was on dry pavement and it didn't leave skid marks, but i think i could have pushed even harder, but the force of the car stopping so fast kept me from pushing any harder on the pedal.
     
    #19 adamace1, Mar 6, 2010
  20. dr_d12

    dr_d12 Member

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    I'd like to hear from the OP some details of the accident, damages, and what the police report said (if there was one). It seems strange to be so vague.
     
    #20 dr_d12, Mar 6, 2010
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