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Thread: Oulton park yesterday

  1. #21
    Sensible iowlee's Avatar
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    Quote Originally Posted by Toby View Post
    If you want a set of wet tyres I would go toyo r1r, if they do them in the correct size.
    Toby, runninf 7x13's. cant find any r1r's in sizes to fit.

    using 205/60/13 and 185/60/13 at moment

  2. #22
    Sensible iowlee's Avatar
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    sorry josh forgot to say front arb is a playskool one that is supposed to be more forgiving and usable that the standard westy one.

  3. #23
    Senior Member LocostJosh's Avatar
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    What pressures were you running? Wet vs dry

  4. #24
    Biding his time until D(T)-Day Steve Wells's Avatar
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    Standard locost wet set up consists of disconnecting the front arb if you have one, taking all clicks off the protechs, raising tyre pressures to achieve around 28-30psi hot and if very wet, removing the 25mm spacers all round to narrow track the car. Tyres for wet are a brand new set of A539, with nice sharp edges to the tread blocks. A539's do suffer with age. I would not use A539's (wet or dry) that weren't new that season as in manufactured that season, rather than supplied that season. The month and year of manufacture are on the sidewall as a 4 digit number i.e. 1116 being 11/2016.

    Again though, there must be better wet tyres out there. Are you on control tyres or just list 1b's?
    SEWC™ RACING Locost #7 & Locost #21. Soon to be joined by Locost #???

  5. #25
    Sensible iowlee's Avatar
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    Quote Originally Posted by LocostJosh View Post
    What pressures were you running? Wet vs dry
    Sorry Josh forgot to say increased tyre pressures, in dry i run 18/19 hot, in wet i upped it to 25/26 hot

    Quote Originally Posted by Steve Wells View Post
    Standard locost wet set up consists of disconnecting the front arb if you have one, taking all clicks off the protechs, raising tyre pressures to achieve around 28-30psi hot and if very wet, removing the 25mm spacers all round to narrow track the car. Tyres for wet are a brand new set of A539, with nice sharp edges to the tread blocks. A539's do suffer with age. I would not use A539's (wet or dry) that weren't new that season as in manufactured that season, rather than supplied that season. The month and year of manufacture are on the sidewall as a 4 digit number i.e. 1116 being 11/2016.

    Again though, there must be better wet tyres out there. Are you on control tyres or just list 1b's?
    Only have rear spacers, did consider removing them as per our conversation Steve, but Matt said not too worry if only running rear spacers.
    My 539's are new but not sure of manufacture date, probably a couple or 3 years old at a guess, as I had them as spares when I bought the car.
    No restriction on tyres as long as they are on lists a-c. Must be road legal and must be to current list, as they changed quite a few this year, more planned for next couple of years by the sounds of it.

  6. #26
    Senior Member LocostJosh's Avatar
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    Hi Steve. I agree with the raise in static tyre pressures, as the tyres run colder in the wet so less of a delta cold to hot; all good stuff.

    Also younger tyres are softer, hence the need to run new tyres as often as possible. I think we all agree the a549s are like old boots at the best of times. But they are relatively cheap.

    Where did you get the bar disconnect from? This is interesting, it appears to be a common balance adjustment. Did you do it because everyone does it or is there a balance issue that you felt it resolved in the wet?

  7. #27
    Sensible iowlee's Avatar
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    Quote Originally Posted by LocostJosh View Post
    Hi Steve. I agree with the raise in static tyre pressures, as the tyres run colder in the wet so less of a delta cold to hot; all good stuff.

    Also younger tyres are softer, hence the need to run new tyres as often as possible. I think we all agree the a549s are like old boots at the best of times. But they are relatively cheap.

    Where did you get the bar disconnect from? This is interesting, it appears to be a common balance adjustment. Did you do it because everyone does it or is there a balance issue that you felt it resolved in the wet?
    I disconnected mine following a conversation with Steve at Cadwell as per his comments re locosts achieving results. Also this tied up with the fact that others there seemed to be doing the same. Perhaps it doesn't suit my driving style?

  8. #28
    Senior Member LocostJosh's Avatar
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    Quote Originally Posted by iowlee View Post
    I disconnected mine following a conversation with Steve at Cadwell as per his comments re locosts achieving results. Also this tied up with the fact that others there seemed to be doing the same. Perhaps it doesn't suit my driving style?
    Ah! Driving style, that old massive variable

    I don't want to chase this while front anti-roll-bar conversation too much, it's only interesting because it goes against 'standard' race car engineering rule of thumb. That's not to say it doesn't work. I don't have a lot of experience with live axle cars, however I do know that they don't work their rear tyres very hard due to a lack of camber change in roll, so rear tyre temperature can be an issue. Taking the front roll bar off the car will certainly help warm the rear tyres and this could easily be a positive in wet conditions; however its counter intuitive.

    In an F4 / F3 car you would do the opposite. That said you have less weight and more power in these cars so your more traction limited around a lap than in a seven. If your not struggling for grip over the kerbs then taking front anti-roll-bar off will likely make you faster in wet conditions, where you can't trail brake as hard.

  9. #29
    Senior Member LocostJosh's Avatar
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    Any luck finding a technical manual? What westfield do you have?

  10. #30
    Sensible iowlee's Avatar
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    Josh,
    It is an SEW
    I couldn't get hold of any technical manual as such. I have a pdf of a build manual.

    Feedback from the wscc is that pretty much every one is individual. I need to take measurements of mine. After Goodwood on the 8th it will be stripped for winter rebuild so could get details of measurements then.

    Here is the reply I got from Adam (CleaR Motorsport) I was going to use Adams services to set the car up once rebuilt as he has received really good feedback from racers. He is a racer and Race instructor as well. Unfortunately he is up country so need to book out a couple of days to go and see him in the new year. Once it is set up hopefully will have figures to work from for adjustments.

    "As has been said, the 'engineering data' is related to your car. Corner weights, unsprung masses, spring rates, motion ratios of the suspension, ARB rate, CoG height, wheelbase, track and max acceleration (lateral and longitudinal) are the main ones. It is entirely possible to put a good base setup on a car just from these numbers - I've written an Excel sheet which has allowed me to do just that multiple times.



    It's possible to make a good guesstimate for most of the above values, but would need to know car weight, spring rates and which ARB you're using as a minimum to make any calculations.



    Regarding adjustments for the wet, 'taking a few clicks' off the dampers is a common one which works ok for most people - but it is a 'sticking plaster'. With your car being a live axle and only having one ARB, disconnecting it will upset the balance (amount of under or oversteer) drastically, so that's not a good step.



    Generally, if you're not as confident in the wet, adding understeer to the general balance of the car and reducing damping will help with confidence. To do this you would stiffen the front ARB. Why? The car transfers a total amount of weight side to side in a corner, and it is the percentage split front to rear of this load transfer that influences the balance. An axle has the most grip when the tyres are evenly loaded, therefore if the front axle transfers more load to the outside tyre than the rear one, it loses more grip and you get understeer. You increase percentage weight transfer by stiffening one axle relative to the other (in your case, stiffening the front ARB).



    So if your car is 50:50 weight distribution front to rear at static, and is set up so the front transfers 55% of the total lateral load (thus the rear 45%) you end up with understeer. This, by definition, gives the rear end extra traction capacity because it's not at the limit of grip - allowing you to start applying power...



    By disconnecting the front ARB, you have made the rear end transfer more load than the front and thus it loses more grip than the front... which gives oversteer / a nervous car.



    Note: I'm talking here about weight transfer percentages across the axles rather than 'letting one end roll more'. We need to treat the chassis as being stiffer than a blancmange else it gets very complicated!



    Other info to add: Damping adjustments only affect transients (bumps, corner entry, corner exit, dive from braking, squat from power application) - that is, when the wheels are moving up and down relative to the chassis. They are not a crutch for poor general over / understeer balance, this is dictated by the springs and ARBs. What softer damping can do (as long as you don't go too soft) is help to increase the amount of time weight transfer takes, thus giving the driver a bit more time to react when things start to go tits up. But, in general, the damping should be used to control 1) the extension / rebound of the springs after they have been compressed and 2) the movement of the sprung mass of the car (chassis, engine, driver, etc) - so it is matched to the mechanical characteristics of the car rather than the conditions. It's a balancing act...



    Tyre pressures: There's evidence to suggest that higher and lower pressures can help for various reasons. It really depends on the tyre, car, driver and exact circuit conditions. My tip? Leave them alone - one less thing to concern yourself with during that busy period in the run up to a quali / race session. When you really start to get dialled into the car then maybe it's worth playing around on a test day - but only if you are timing, can put together clean consistent laps and take notes so you can refer to them later.



    In reality, your best bet is to get some bum in seat time on a wet day with instruction from someone who understands the physics of all of this too. That will make you much faster much more quickly and cheaply than any car modifications "

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