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Prawn and BigAls A3 Track Car

Discussion in 'A3/S3 Forum (8L Chassis)' started by Prawn, Dec 29, 2010.

  1. bigal 1
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    bigal 1 Active Member

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    [Apr 16, 2014]
    It was very skittish when braking hard from high speed. The back straight at Hullavington is about 120mph before the left hander and under hard braking the back felt as though it wanted to break loose. Just the fitting of the rear wing cured that and the other BIG difference was the splitter. We have an alloy diffuser but haven't got around to fitting it yet. One day soon???
    The car was a little lively before the aero. It is so well planted now that altering the wing might not produce anything better. The grass is not always greener on the other side. However we might experiment in small doses just to see what happens. A slightly deeper wing is available from the same source so that could be a starting point.
  2. Prawn
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    Prawn My other car is a MINI!!!!

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    [Apr 16, 2014]
    As Dad said really.

    The car was always fairly 'loose' before, and it suited my driving style, but as the tracks got faster, and the car got more powerful, and stiffer, it changed from 'playfully loose' to 'easily crashable'

    I found this out the hard way, and Dad had a not too dissimilar incident ending in a 115mph spin at Goodwood a month later.

    High speed stuff over 100mph became very skittish, and coming off the power at speed wasn't fun at all. Perhaps the car wasn't getting any worse, but it certainly knocked my confidence to push on.

    Since adding the aero it's SO much more stable at speed it's unreal, even in a dead straight line the difference is hugely noticeable, it just fills you with confidence now where it didn't previously.
    bigal 1 likes this.
  3. daz-20vt
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    daz-20vt Well-Known Member

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    [Apr 16, 2014]
    A simple yes would have been fine.
    Joking aside thats very interesting to hear actually. Mad how different its made it!!
  4. bigal 1
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    bigal 1 Active Member

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    [Apr 16, 2014]
    "A simple yes" no no no, can't do anything by halves !!!
  5. daz-20vt
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    daz-20vt Well-Known Member

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    [Apr 16, 2014]
    137 page build thread. Suppose your right hahaha.
  6. RobinJI
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    RobinJI Member

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    [Apr 16, 2014]
    Map sensors wouldn't give anything quantifyable, they can be a good way of measuring change but you'd need to take an insane number of samples to get any usable data for calculating quantities. Not to mention all sorts of issues with pressure change caused by flow across them.

    The much, much easier method would be ride height sensors. If you log their output and normalize it enough to get a decent sample of the difference in ride height at speed compared to static, you'll know front/rear downforce levels pretty accurately.
  7. Prawn
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    Prawn My other car is a MINI!!!!

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    [Apr 17, 2014]
    :iagree: See! I said he'd know how to do it! :blackrs4:
  8. daz-20vt
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    daz-20vt Well-Known Member

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    [Apr 17, 2014]
    That mans one of them genius's.
  9. Prawn
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    Prawn My other car is a MINI!!!!

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    [Apr 17, 2014]
    new ABS plug and wire on the way from Ben, I span the wheels up the other night and the ABS light popped back on, I've had intermittent issues with the front right ABS sensor for about 5 years now :laugh:

    I'm also stealing some 335x32mm discs from Marc87 to mock up for a 335 fitment on mine. need to get some caliper shims ordered up from Reyland to widen the calipers :)

    Is it likely I'll need new crossovers for a 4mm increase in caliper width? or should i be able to tweak the existing ones?
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  10. daz-20vt
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    daz-20vt Well-Known Member

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    [Apr 17, 2014]
    Id imagine new ones would be needed. Last thing you want is to try to force them in and cross thread them. 4mm will be adding angle to what should he going in square. Carefully try it?
    So your calipers split downt the middle then?
  11. daz-20vt
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    daz-20vt Well-Known Member

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    [Apr 17, 2014]
    They brass crossovers?
  12. Prawn
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    Prawn My other car is a MINI!!!!

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    [Apr 17, 2014]
    The calipers split down the middle yea. Reyland do a kit that replicates the external shape and internal holes of the AP caliper perfectly to widen it by 4mm.

    this allows a 32mm disc to be used, and I'd just need to space the caliper carrier 4mm away from the hub, which I'll do with some 4mm alloy plates.
  13. Prawn
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    Prawn My other car is a MINI!!!!

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    [Apr 17, 2014]
    Crossovers are just normal copper pipe. Will look into new ones and see what sizes / lengths are available
  14. daz-20vt
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    daz-20vt Well-Known Member

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    [Apr 17, 2014]
    Your on a 28mm disc now? So the advantage of 32mm is a bigger gap between the disc? Helping cooling?
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  15. bigal 1
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    bigal 1 Active Member

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    [Apr 17, 2014]
    Bang on. :yahoo:
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  16. kwistof
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    kwistof South East Events Moderator Regional Rep

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    [Apr 17, 2014]
    Great that you're going down the 32mm route now!

    I'm all ears now dude on your brake set up :)

    You keeping the same custom bells and sourcing larger rotors I imagine?
  17. Prawn
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    Prawn My other car is a MINI!!!!

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    [Apr 17, 2014]
    yup! The bells were carefully considered when we got them, such that they'd allow me to save costs by floating my existing 330x28mm rotors initially, and also allow me to upgrade to 335x32 without changing bells of brackets. that was another appeal of the Cp5200 caliper also, the fact that it's easily widened.

    This should be the last change to the braking setup now, as it's pretty much where we want it :)
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  18. kwistof
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    kwistof South East Events Moderator Regional Rep

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    [Apr 17, 2014]
    That's great to hear this is practically your last change to the brake set up as I'm just diving in at the deep end with what I've got! lol

    I'd love to be in the motor when you slam those bad boys on as you're around the 1100kgs IIRC!?

    You will be out braking may exotic vehicles I reckon if/when you come across them :)

    Sorry - I have to admit I haven't read the full 137 pages (well not yet)- but I'm guesstimating you have the 300mm set up (at the least) at the rear also to compliment the fronts?
  19. Prawn
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    Prawn My other car is a MINI!!!!

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    [Apr 17, 2014]
    it does indeed outbrake pretty much everything it seems now, it's around 1100kgs, just a bit over, and with the slicks on you can just brake SO late it's crazy.

    On the rear we have standard S3 256mm vented discs with mintex 1155 pads. Because most of the weight has been removed from the back, it doesn't need anything more really or the rears would be locking up. I may look into trying a 284mm kit that's being developed at some point, but i don't think i'd ever go as big as 300 :)
  20. kwistof
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    kwistof South East Events Moderator Regional Rep

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    [Apr 17, 2014]
    Extra scene points? :jester: :lmfao:

    I mean you already passed the splitter scuffers test on FB :laugh:

    You got an idea on what or where you're sourcing the rotors from? What have you found best for your driving - J hooks or Slotted?

    I am genuinely quiet surprised you are on a standard rear S3 set up tbh - but if it works for you then no need to change/upgrade just yet.....have you had a corner weighting session done on the car before out of interest?
  21. Prawn
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    Prawn My other car is a MINI!!!!

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    [Apr 17, 2014]
    I don't think I've ever posted it on splitter scuffers myself! Has someone else? Eek. That lot are evil.

    The stock 256 rears seem to be doing just fine :) most of the fwd race cars you see retain the stock rears as they do so little

    It was corners weighted a while ago, but really needs don't again, but I'm reluctant to do it when I keep changing things so regularly!
    Il dig out the pic, but to give you an idea it was ~190kgs on the rears and ~370kgs on the fronts, obviously with some deviation, I think I had 49.9 on the diagonal cross.
  22. kwistof
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    kwistof South East Events Moderator Regional Rep

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    [Apr 17, 2014]
    haha- yeah 1 of your mates did it I think the other week....I did comment just to get the notifications and nothing was too negative at all....I think you are pretty well known across the VAG scene fella :icon_thumright:
    It was the pic of you parked up at Sainsburys IIRC - with the caption....My mate casually going shopping :)

    49.9 on the diagonal is very good.....I suppose if the 256s are doing there job then there's no need to change/upgrade just yet :eyebrows: Could help with balancing out the rear with a larger set up, could be worth adding a few more kgs either side of the rear to find out if you get even better handling and stability in the long drawn out 100+ mph corners, then into heavy breaking or changing direction. Just a thought mind as you sound like you are very happy at present with your set up.

    If it ain't broke and all that :)
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  23. bigal 1
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    bigal 1 Active Member

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    [Apr 17, 2014]
    "If it ain't broke and all that"

    I don't think the rear needs balancing out at the moment. What we have to date is pretty damn good. The faster the corner the better it holds the road and stability is spot on. That is not to say that it can't be improved. Slower corners can be improved, probably by adjusting the rear ARB and playing with the front one. Flat floor and diffuser is probably the most logical next step. (don't forget the longer chord diffuser that we might try) We don't have any handling or stability probs at high speeds. I can't see the rails it is obviously running on. (age thing)
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  24. Lewis583
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    Lewis583 Active Member VCDS Map User

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    [Apr 17, 2014]
    Robin's ride height sensor idea is a good shout. Could maybe look at re-using some xenon levelling sensors. Of course to maintain consistency you would have to log the output voltages on same day/speed/road etc. This would also probably need some sort of microcontroller (Arduino/Raspberry Pi etc)

    Measure voltage at normal ride height then add some weight and re-measure ( to learn how the voltage scales with height ).
    Get vehicle to a set speed (60mph officer :busted_cop:) and log voltage reading. Convert voltage to mm and compare to static measurement.
    Take the difference and you can then use the spring rating of the KW's to work out roughly how many kg/lbs of downforce the aero is generating.

    The above is in all likelihood far to intensive for non competition purpose but it's good to dream eh? Haha. Would be interesting to "see" on paper the effects the flat floor/diffuser would have though.

    /Car nerd mode

    Looking forward to some developments Nick :thumbsup:
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  25. RobinJI
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    RobinJI Member

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    [Apr 18, 2014]
    Pretty much exactly what I had in mind Lewis. Although if you're calibrating the sensors by putting weight in the car, there's no need to convert that to movement then back to weight. You'd want to calibrate them with several weights in there, to check the output's linear.

    The main issue would be what to log with, as you'd need to average values from a decent sample size to eliminate the suspension just doing it's job and absorbing bumps, so couldn't just glance at a readout. I've seen cheap oscilloscope set-ups for use with a laptop, which would probably be the best bet.

    It may well be too much work for Nick to be bothered with, but the geek in me (which I think might be the majority) want's to know figures haha. I'm actually thinking I may well do this on my MX-5, as I've got some aero plans and I should be able to log the sensors output through the megasquirt ECU.
  26. Prawn
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    Prawn My other car is a MINI!!!!

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    [Apr 18, 2014]

    :iagree:

    :laugh: :racer: :laugh:
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  27. daz-20vt
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    daz-20vt Well-Known Member

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    [Apr 18, 2014]
    So thanks for the recommend on the harness's. Now how the hell do you lossen them?????
    Its a total ball ache i must he missing a trick?
  28. Prawn
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    Prawn My other car is a MINI!!!!

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    [Apr 18, 2014]
    you really are. Lift the front of the buckle up, and they just slide undone dead easy!


    On another note..... ABS. has anyone ever looked into removing it completely on a car of this nature?

    Bill: if you're reading, did the Ibiza have ABS originally? and have you removed it?
  29. daz-20vt
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    daz-20vt Well-Known Member

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    [Apr 18, 2014]
    Ohhhh very brave!!
  30. Prawn
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    Prawn My other car is a MINI!!!!

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    [Apr 18, 2014]
    fecking thing is playing up, I think the controller has had it really. it's 16 years old and done over 200k so I guess it's fair enough.

    Bought a new controller on ebay for £20, hopefully that'll sort it. If not I'll be changing the pump as a short term solution, then make plans to ditch the ABS and fit a bias controller over winter perhaps. Just not sure about routing new lines with the engine still in place, so for now, I'll just make the ABS work again.
  31. kwistof
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    kwistof South East Events Moderator Regional Rep

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    [Apr 18, 2014]
    I ran without ABS for 9/10 months - but that was due to a problem with the ABS control unit which caused it to not work. Still used the car as I normally would though.

    The thought about running the car without it forever did cross my mind tbh (was looking at forking out on a brand new unit which was silly money) - I just thought I could remove the unit and code out the light using VCDS and voila ? It's not as if I have any ESP to worry about. (Pre-facelift FTW :rock: )

    Be interested to hear if there's further work required though - cue Bill?
  32. Prawn
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    Prawn My other car is a MINI!!!!

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    [Apr 18, 2014]
    well, on my car, and I believe S3's also, there is no mechanical bias valve to control the rears, it's all done through the ABS module.

    it seems that when you get a pump error, and the light throws, you still have rear bias control.

    Apparently, if the control module goes on to fail fully you'll also get the handbrake light comming on, and lose all rear brake bias control. which would lead to the rears locking up before the fronts.

    hopefully a module will sort it. if not, we'll see!

    Driving with the ABS light on makes me go insane though. can't deal with unwelcome lights!
  33. kwistof
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    kwistof South East Events Moderator Regional Rep

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    [Apr 18, 2014]
    This was exactly the issue I had, Re: control module fault.
    It was 'unreadable' so to speak from VCDS and it was fried once it was opened up. Cannot for the life of me remember the exact Fault Code it threw 100% - and those number were on my mind for 10 months easily! (Possibly 65535 IIRC)

    Changed every sensor (long+lat+wheel sensors) also before it was fully diagnosed as an ABS control module fault as it would only appear randomly at first. I 100% didn't have the handbrake light on and I'm pretty sure the rears didn't lock up but wouldn't be able to confirm if they were working as they should as I didn't test them but I didn't feel any difference in the braking itself.

    I hate warnings light also fella- whether it be windscreen wiper fluid or ABS, drives me insane- especially all those bloody bleep bleep bloody bleeps! Arghhhhhhh

    Hope you get it sorted - £20 is a steal. I have an ABS control module in my spare bedroom somewhere I didn't get round to fitting tbh. lol
  34. 16Klappe
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    16Klappe RacecaR forward is RacecaR backwards. Supporter

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    [Apr 20, 2014]
    [​IMG]

    Sunday boost.
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  35. Prawn
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    Prawn My other car is a MINI!!!!

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    [Apr 21, 2014]
    Another little pic from jardo yesterday :)

    [​IMG]
  36. Gops
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    Gops 6th gear @7000rpm

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    [Apr 21, 2014]
    I did a little test with the abs/ traction control yesterday. I have michelin ps3's at the front and winters at the back. The fronts grip but the back end just comes out (which is fun!). But with the TC on, it applies the brakes to keep the rears in check! It kept changing my map everytime I did it!! Was freaky but cool lol!
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  37. Prawn
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    Prawn My other car is a MINI!!!!

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    [Apr 24, 2014]
    So, I fitted the new abs control module this evening. What a horrible job!

    [​IMG]

    The 4 screws which hold the module to the pump are underneath:

    [​IMG]

    I ended up unbolting the pump itself and gently bending the hoses so I could access the model bolts underneath:

    [​IMG]

    And it seperated like this:

    [​IMG]

    [​IMG]

    Refitting is the reverseof removal as they famously say!

    [​IMG]

    Job done. Abs working again. Good result!
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  38. daz-20vt
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    daz-20vt Well-Known Member

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    [Apr 26, 2014]
    Thats a strange looking contraption? Lol
    So abs is back, you think you would ever be tempted to remove it or no point? Do btcc cars have abs?
  39. Prawn
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    Prawn My other car is a MINI!!!!

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    [Apr 29, 2014]
    Having spoken to a few people recently, ABS is staying.

    In the wet it's a nice safeguard and a warning you're pushing too hard, and in the dry we have so much grip it's not kicking in anyway, so I'm happy to leave it for now certainly.

    there's a pistonheads pub club meet this evening at the West Meon Hut from 7pm if anyone half local fancied a trip out :) I'll be there
  40. Alex C
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    Alex C Well-Known Member VCDS Map User

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    [Apr 29, 2014]
    When does project ground effect start?

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