4396 replies to this topic

[james_ly]

Surely a softer spring will have more give and the inside tire is more likely to spin up Which is why I was thinking Rear ARB Where scuffers when you need him

 

Scuffers was always adamant that rear ARB was a bad idea. Given that most performance cars have a diff, I still don't understand why Lotus say you don't need one, even a 911 has one with those huge rear tyres and similar rear bias.  

[WrightStuff]

The Exige V6 cup cars have a rear ARB.

[Rosssco]

The Exige V6 cup cars have a rear ARB.

  All S3 Exiges have a rear ARB.

[CHILL Gone DUTCH]

The shocks were originally specced by mbr Springs and helpers included Do all s3 exige s have a lsd ?

[CHILL Gone DUTCH]

Surely a softer spring will have more give and the inside tire is more likely to spin up Which is why I was thinking Rear ARB Where scuffers when you need him

  Scuffers was always adamant that rear ARB was a bad idea. Given that most performance cars have a diff, I still don't understand why Lotus say you don't need one, even a 911 has one with those huge rear tyres and similar rear bias.  

Do you mean LSD ?

[james_ly]

Yep

[Nev]

Looking at your issue from a more empirical standpoint, it sounds like you are consistently and fairly violently spinning up the inside wheel when applying power on a corner, which seems quite a foreign concept for me. With the Quiafe ATB in my gearbox for the last 8 years or so I simply don't get that issue (ie the inside wheel on mine never noticably spins up independently). If I really do apply too much power, the entire back end will fly out and either pirouette or snake the car (as both wheels spin up when the ATB gets overwhelmed and has no more available traction to bias to either side).

 

HTH and gives you some idea of what a Quaife ATB would do, based on your and my observations.

Edited by Nev, 14 May 2018 - 02:59 PM.

[CHILL Gone DUTCH]

I'm Deffo getting more grip from the rider wheels ( loaded side ) but I never thought for a second this would unload the unloaded wheel so much and this in it's self can unsettle the car which means I'm making to many deviations instead of driving through the corner

[Exmantaa]

What front rates and ARB do you have? The front springs & ARB should keep the chassis level (until you lift the inside front), to give the rear inward tire as much load as possible. A rear ARB will lift the inside rear more... But with enough power youre probably looking into an LSD. Or sticky tires. Or simply give it less boot... :-)

[Nev]

I'm Deffo getting more grip from the rider wheels ( loaded side ) but I never thought for a second this would unload the unloaded wheel so much and this in it's self can unsettle the car which means I'm making to many deviations instead of driving through the corner

 

It sort of/partly makes sense to me that with wider wheels that you'll spin up the inside one more. This is because the difference in grip levels between the fully loaded wheel and the unloaded one are more pronounced now.

 

If you had an imaginary car with infinite traction on one rear wheel and almost no traction on the other, if you tried to accelerate (with an open diff) you'd just spin up the low traction wheel all the time (and oversteer wildly). In effect, every hard corner you're going round is having this effect. To solve it, you can either implement torque biasing of power (ie ATB diff) or you can try and add positive camber to the inside wheel to plant it more perpendicularly on the tarmac (ie rear ARB).

 

Do you know someone else with a VX220 with an ATB diff in? Maybe they'd let you have a drive and you could see how it works on a largish roundabout (with plenty of space and no traffic obviously) - try feeding the power in and out and I think you'll be pleasantly surprised by the lack of inside wheel spin.

 

I have a test roundabout near me that I use for any tweak I make, it's about 15 foot wide. I've set my car up so I can promote oversteer with power and mild understeer with no power. And I never get an inside wheel spinning up. As I said, if I overcook the power then the whole back end steps out, though it's quite progressive and the snap away point comes on slowly so there is plenty of warning when you are getting close.

 

Edited by Nev, 14 May 2018 - 04:03 PM.

[CHILL Gone DUTCH]

What front rates and ARB do you have? The front springs & ARB should keep the chassis level (until you lift the inside front), to give the rear inward tire as much load as possible. A rear ARB will lift the inside rear more... But with enough power youre probably looking into an LSD. Or sticky tires. Or simply give it less boot... :-)

1" ARB is on full stiff Ep one 600 lb front springs

[Nev]

1" ARB is on full stiff Ep one 600 lb front springs

Crikey. With the ARB on full stiffness goodness knows how much more poundage is transferred (added) to the loaded spring. Does anyone know?

Edited by Nev, 14 May 2018 - 04:46 PM.

[jonnyboy]

Just ring EP and order 450/575 springs they should be perfectly adequate and not ruin it for road use as an added bonus. I can't get my head around 600/800. I had quantums on my old Elise with 275/350 springs and got no body roll. Limits are a bit higher on yours mind but that has to be a place to start.

[leevx2.2]

Mine is the same mate with same tyres  but have a diff  .

[hughcam]

As what Jon said, your spring rates seem pretty high for no aero Chris. Personally I would be looking at aero if you want to make a drastic lap time improvement. A well designed wing and splitter combo from somewhere like djracecars would net you 3-5 seconds a lap, although at that level I would be looking at cages HANS device etc..

 

Dales car is a boggo sport 350 with an eltech wing and splitter, although he told me yesterday he swapped to new Avon ZZR's for croft. He is running 215 fr and 265 rear (standard cup sizes).

 

The V6 Exige is quite a developed platform over the s2 in terms of stability especially when coupled with the Bosch learning TCS and better ABS. 

 

You're doing well to be competing with him and he can be beaten. He uses the car with the TCS in race mode and a really quick driver can go quicker without it on.

[CHILL Gone DUTCH]

Most of his time has come from from being there on Saturday He really homed in And picked it up the next day quickly It took me three laps to find my feet

[Captain Vimes]

Most of his time has come from from being there on Saturday He really homed in And picked it up the next day quickly It took me three laps to find my feet

This. It must be cheaper, more efficient and more fun to spend time and money learning the car and track rather than keep playing with the setup.

[CHILL Gone DUTCH]

Most of his time has come from from being there on Saturday He really homed in And picked it up the next day quickly It took me three laps to find my feet

This. It must be cheaper, more efficient and more fun to spend time and money learning the car and track rather than keep playing with the setup.

Bad planning by me I finished work AT 6:30 am the day of trackday

[fiveoclock]

THere is nothing up with the loaded rear wheel there plenty of grip there and I'm able to control that with my right foot what I'm saying is the unloaded wheel is spinning/smoking etc it's not causing a issue with the loaded one it's just spinning making lits of smoke and probably pulling rubber of the surface of my tire Other thing to remember is this is on very cold tires in a sprinting scenario

What tyres and what compound?

[CHILL Gone DUTCH]

R888r GG