Understeer all day every day

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  • ForcedFirebird
    R3V OG
    • Feb 2007
    • 8300

    #46
    Originally posted by TobyB
    Radials like camber, and I have yet to see an E30
    wear the INSIDE edge off a track tire (unless you take a road race car to an oval track, but I digress again).
    2* fixed camber plates Palm Beach International (which is known to eat tires, though)...

    118 likes, 10 comments - WOT-Tech (@wottech) on Instagram: "Why must tires cord so often?"



    Sorry about the instagram link, but just happen to come across the pic and thought of this thread.
    Last edited by ForcedFirebird; 01-05-2016, 03:16 PM.
    john@m20guru.com
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    Transaction feedback: Here, here and here. Thanks :D

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    • berlow94
      E30 Enthusiast
      • Jan 2013
      • 1063

      #47
      Originally posted by TobyB
      Well, then.

      Many of us midmarkers in PRO3 are running springs in the 600f/700r range,
      front and rear cambers in the -4 or more range. I've driven 3 of these cars,
      not including my own, and none of them stink. (mine stinks. But I digress)

      From looking at your numbers, I'd say more relative front camber would help
      given your softer spring rates. Radials like camber, and I have yet to see an E30
      wear the INSIDE edge off a track tire (unless you take a road race car to an oval track, but I digress again).
      One of the things you have to balance on a RWD front strut car is that the front spring
      rate is the primary roll stiffener, and you don't have much camber control. So often,
      a strut car will respond differently to a spring rate change than the book says.
      Yes, if you stiffen the front, it 'should' understeer more- but if your stiffening
      massively improves your front contact patch, it might NOT understeer more.
      Or it might understeer more on initial turn- in, but then mid- corner grip
      goes way UP, and you get a better drive out of the corner. It can be counterintuitive.
      Tire temps help a lot here.
      Data logging (even just an aim solo) is also really really really really useful. Even that cheesy
      G-Tech thingy from all those years ago was a real asset.

      At the end of the day (and this post) the one way that's guaranteed to help you to go
      faster is to make one change, see what
      happens, make another change on the same element, see what happens, repeat. It can
      be a pain- but it's how you learn what works on your car at your driving level. I have spent
      entire weekends changing springs back, forth, back, forth, farther one way, farther another... You start to learn what does what, and when. And hopefully, how.

      But change things.
      t


      Pro3 and Spec E30 are also limited to a 15x7 wheel size if I'm not mistaken. Also a 205/50R15 or a 225/50R15 Toyo Proxe tire. He is using a 205 wide tire on an 8" wheel which in no way is helping the cars handling in any respect to under or oversteer. Having the proper size tires on your wheels will allow for a greater slip angle.
      More deflection and "slip" before the car loses traction and starts to slide will make driving on the limit much more forgiving.


      Sent from my iPhone using Tapatalk
      The best one-stop shopping for German car parts and lifestyle: http://www.gutenparts.com/

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      • econti
        E30 Enthusiast
        • May 2014
        • 1093

        #48
        I can't quote everyone as I'm on my phone.
        But:
        Noted softening the front springs, I'll see what happens.

        Tyre pressures are typically 32psi all around

        I mean I'm not a bad driver, an instructor I was with once said that I was very decent for not being taught
        I don't know any pros, and haven't had any instruction. Car is only just now ready to take to the track

        Would it be worth trying to source a stock LSD centre and seeing if that works? They are expensive down here
        sigpic

        (clicky on piccy to get to thread)

        Comment

        • akorcovelos
          E30 Enthusiast
          • Dec 2006
          • 1149

          #49
          32psi is going to be too low for pretty much any street tire on track. Bump it up to 35 and go from there. I have to agree this sounds more like a driving issue. I've had students in all types of cars induce under steer from poor car handling techniques. Not a bash on you at all, everyone starts from no experience and grows from there. Nothing replaces seat time, but a good instructor should be able to help you improve car control. As already stated, a great way to eliminate the car setup as being the issue is to have an instructor take you for a ride in your own car. I think you'll be surprised.

          2012 MCSCC/NSSCC CP class champ
          HSAX Instructor

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          • econti
            E30 Enthusiast
            • May 2014
            • 1093

            #50
            My issue with track time is that the local track costs about a thousand billion dollars for a session. I'll probably only go for one due to just how much money it is.
            At any rate, I've had not much success with playing with my own technique.
            I'll try the suggestions for setup, and if there are no real results, I'll try and find someone else to drive it and see what happens.

            Thought: would too much forward rake be a factor?
            sigpic

            (clicky on piccy to get to thread)

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            • kronus
              R3V OG
              • Apr 2008
              • 13005

              #51
              Yes, if you are low enough in the front you will lose camber as the suspension compresses. CAs should ideally be parallel to the ground or slightly down-angled.

              For tire temps I run 29 cold, which hits my target of 36 hot, but the sweet spot is different for different tires. I still think your tires are too narrow to work effectively.
              cars beep boop

              Comment

              • berlow94
                E30 Enthusiast
                • Jan 2013
                • 1063

                #52
                Originally posted by econti
                My issue with track time is that the local track costs about a thousand billion dollars for a session. I'll probably only go for one due to just how much money it is.
                At any rate, I've had not much success with playing with my own technique.
                I'll try the suggestions for setup, and if there are no real results, I'll try and find someone else to drive it and see what happens.

                Thought: would too much forward rake be a factor?
                Look for local clubs who run events at your track. Should be a lot cheaper than the track hosted track days.
                The best one-stop shopping for German car parts and lifestyle: http://www.gutenparts.com/

                Comment

                • TobyB
                  R3V Elite
                  • Oct 2011
                  • 5168

                  #53
                  The only time I've ever seen an E30 understeer excessively was when the person driving it wasn't really sure about what they were doing.
                  I dunno- a lowered car with stock front camber will push like crazy, unless (SpecE30) they've gone to extremes to try to balance it.

                  And yeah, agreed, a 205 on an 8" rim (especially at 40 profile) isn't gonna be ideal.
                  225-50's would make a world of difference...

                  And sorry, but track time is what it takes. I agree, it hurts to spend a bunch of money,
                  a set (or 3 ) of tires, and the time and effort to dial it all in- but it's kinda what it takes.
                  And what makes me fastest probably won't make Bob fastest. (oh, hell, I owe him money for racecar storage!)

                  t
                  now, sometimes I just mess with people. It's more entertaining that way. george graves

                  Comment

                  • Smelser
                    Mod Crazy
                    • Feb 2011
                    • 633

                    #54
                    no idea what it would do on pavement. but on dirt we run tubes in the tires and pressures around 6-16 psi, depending on the track conditions.
                    Also scale the car and try spacing the springs up and down on the rear. sometimes an inch can drastically change your weights and how the car reacts.

                    sigpic1984 318i Total conversion to a DIRT race car.
                    Check out our build on facebook @ www.facebook.com/brewstermotorsports

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                    • econti
                      E30 Enthusiast
                      • May 2014
                      • 1093

                      #55
                      Originally posted by TobyB
                      I dunno- a lowered car with stock front camber will push like crazy, unless (SpecE30) they've gone to extremes to try to balance it.

                      And yeah, agreed, a 205 on an 8" rim (especially at 40 profile) isn't gonna be ideal.
                      225-50's would make a world of difference...

                      And sorry, but track time is what it takes. I agree, it hurts to spend a bunch of money,
                      a set (or 3 ) of tires, and the time and effort to dial it all in- but it's kinda what it takes.
                      And what makes me fastest probably won't make Bob fastest. (oh, hell, I owe him money for racecar storage!)

                      t
                      I've got 205/50 at the moment, it's really not that bad.
                      I went with it because at least in my experience of radials, I found that on the limit is more predictable than with a square setup. And that I would have had trouble fitting a 225 under glorious series 2 rear arches lol.

                      So far I've got:
                      -more camber
                      -soften suspension and see what happens
                      -more psi in tyres
                      -disconnect rear roll bar and see what happens
                      -potentially find a less aggressive diff
                      -wider tyres, would need new wheels to fit

                      That about sorts me out.

                      Thanks lads. I'll report back once I've done testing for results
                      sigpic

                      (clicky on piccy to get to thread)

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                      • kronus
                        R3V OG
                        • Apr 2008
                        • 13005

                        #56
                        - raise the front
                        - don't disconnect the rear bar, doing that will make you understeer more
                        cars beep boop

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                        • e30_302
                          E30 Addict
                          • Sep 2013
                          • 453

                          #57
                          Higher tire pressure may or may not help, you really need to use a pyrometer to tell. Dropping my Rivals from 35 hot to 30 improved grip dramatically.
                          sigpic

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                          • markseven
                            R3V Elite
                            • Sep 2006
                            • 5327

                            #58
                            Originally posted by kronus
                            Yes, if you are low enough in the front you will lose camber as the suspension compresses. CAs should ideally be parallel to the ground or slightly down-angled.

                            For tire temps I run 29 cold, which hits my target of 36 hot, but the sweet spot is different for different tires. I still think your tires are too narrow to work effectively.
                            I did quite a few DEs with 205/50 summer tires on 16x8s. H&R Race, Billys, 22mm front / 18mm rear, -3° camber up front, no toe / camber correction at the rear. Full interior, sunroof, DD. The car was great for NASA Run Groups 1 - 3. None of my instructors complained about lack of mechanical grip (maybe they were too busy telling me what not to do).

                            Aaron Bitterman, the guy that runs SpeedVentures (really fast driver) drove my car at Streets of Willow and said he really liked it. That was his first time in an E30, so any negative characteristics would have been immediately apparent to him, me thinks.

                            205/50 may be too little to be competitive in TT and sprint races, but for a noobie it's more than enough, IMO.
                            I Timothy 2:1-2

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                            • ForcedFirebird
                              R3V OG
                              • Feb 2007
                              • 8300

                              #59
                              Originally posted by markseven
                              205/50 may be too little to be competitive in TT and sprint races, but for a noobie it's more than enough, IMO.
                              Actually 205/50 is a common race size for smaller cars.
                              john@m20guru.com
                              Links:
                              Transaction feedback: Here, here and here. Thanks :D

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                              • markseven
                                R3V Elite
                                • Sep 2006
                                • 5327

                                #60
                                Originally posted by ForcedFirebird
                                Actually 205/50 is a common race size for smaller cars.
                                For 15s yeah, good to know the same is true for 16s.
                                I Timothy 2:1-2

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