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Slippery When Wet


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#21 JD13

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Posted 17 June 2020 - 05:59 AM

Any thoughts on the BOFIracing track alignment settings?

Have used A-Line in Dudley before, but they'll just use whatever settings I provide. The companies I know of that are experienced with MX5s are all very far away - who would be closest to the Worcestershire area? Any recommendations?
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#22 MR Wallace

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Posted 17 June 2020 - 09:01 AM

There's so many variables here that no-one can say the exact reason for you not having rear grip, it also depends how you're losing the grip ie corner entry, mid, exit, under braking, under throttle?? It could just be your driving style inducing lift off or power oversteer.

 

If the tyres are brand new they might need scrubbed, if well used and heat cycled they might be done. Tyre pressures will affect it too as mentioned.

 

Having the rear too stiff will definitely reduce rear grip and if you do have it as low as possible you might be hitting the bump stops which will definitely cause oversteer.

 

Checking the alignment is a start though, Bofi settings look ok, I run a bit more rear camber than the front which gives more rear grip/confidence and also run toe out up front to increase turn in but again this is down to personal preference. What Bofi list will be a good starter.


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#23 Zed.

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Posted 17 June 2020 - 10:02 AM

 I run a bit more rear camber than the front which gives more rear grip/confidence and also run toe out up front to increase turn in but again this is down to personal preference.

and your settings seem to work :yes:

 

as to front toe-out, I like a good amount :thumb-up: (but it can eat tyres :wallbash: )

& if your car suffers with 'bump-steer' then you're going to be working to drive a straight line on uneven roads :whistle: )

 

 

Rich.


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#24 MR Wallace

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Posted 18 June 2020 - 08:44 AM

 

 I run a bit more rear camber than the front which gives more rear grip/confidence and also run toe out up front to increase turn in but again this is down to personal preference.

and your settings seem to work :yes:

 

as to front toe-out, I like a good amount :thumb-up: (but it can eat tyres :wallbash: )

& if your car suffers with 'bump-steer' then you're going to be working to drive a straight line on uneven roads :whistle: )

 

 

Rich.

 

 

Ha thanks! Think I'm going to try more front camber as that seems the norm... but also keep thinking if it ain't broke!

 

I remember being out with a friend on track in his BMW 1 series with the coilovers silly low and on every compression it bounced, hit the bump stops and was spat sideways instantly :wacko:


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#25 noobie

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Posted 18 June 2020 - 09:53 AM

 

 

 I run a bit more rear camber than the front which gives more rear grip/confidence and also run toe out up front to increase turn in but again this is down to personal preference.

and your settings seem to work :yes:

 

as to front toe-out, I like a good amount :thumb-up: (but it can eat tyres :wallbash: )

& if your car suffers with 'bump-steer' then you're going to be working to drive a straight line on uneven roads :whistle: )

 

 

Rich.

 

 

Ha thanks! Think I'm going to try more front camber as that seems the norm... but also keep thinking if it ain't broke!

 

I remember being out with a friend on track in his BMW 1 series with the coilovers silly low and on every compression it bounced, hit the bump stops and was spat sideways instantly :wacko:

 

 

More front camber isn't the norm...its just what the pyrometer tends to suggest. On a lower power car it can be worthwhile chasing turn in through camber and caster changes rather than through the continuous drag that is added by toe. 


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#26 MR Wallace

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Posted 19 June 2020 - 08:46 AM

I've got an infra red thermometer so was looking to actually start checking things rather than just guessing on setups... but I'm no race engineer!

I'm certainly on the low power scale so think a bit more camber up front may be beneficial and hopefully not change the overall balance.
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#27 Dickie

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Posted 19 June 2020 - 05:48 PM

Hi Folks,

I have fitted extended lower control arms to increase the front negative camber when running at stock Bilstein ride height.

I will be running more front camber than rear.

I am hoping to give the car a work out in September if we are allowed back on the hills.


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#28 Woody27

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Posted 22 June 2020 - 12:38 PM

Hi Folks,

I have fitted extended lower control arms to increase the front negative camber when running at stock Bilstein ride height.

I will be running more front camber than rear.

I am hoping to give the car a work out in September if we are allowed back on the hills.

 

I'd be interested to hear how you get on. I have basically the Bofi Track/supermiata dual duty alignment on mine (-2.5 deg front camber, -2 deg rear camber) and I find it has too much oversteer on turn in. Enough that I couldn't dial it out on my setup (with front ARBs on stiffest, rears on softest and damper settings also tweaked to try combat). Pretty sure my issue is down to not having enough front roll stiffness (compared to rear) for this setup. I think either removing my rear ARB or even just going back to standard might solve it. I have the original Meister-r Zeta-s on mine so think they are 6kg/mm front, 5 kg/mm rear so you can see the front of mine is relatively soft.

 

Removing the rear ARB would have the benefit of better rear traction potentially but I think I'll instead just match my camber front and rear and see how I go for now.


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#29 noobie

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Posted 22 June 2020 - 02:16 PM

 

Hi Folks,

I have fitted extended lower control arms to increase the front negative camber when running at stock Bilstein ride height.

I will be running more front camber than rear.

I am hoping to give the car a work out in September if we are allowed back on the hills.

 

I'd be interested to hear how you get on. I have basically the Bofi Track/supermiata dual duty alignment on mine (-2.5 deg front camber, -2 deg rear camber) and I find it has too much oversteer on turn in. Enough that I couldn't dial it out on my setup (with front ARBs on stiffest, rears on softest and damper settings also tweaked to try combat). Pretty sure my issue is down to not having enough front roll stiffness (compared to rear) for this setup. I think either removing my rear ARB or even just going back to standard might solve it. I have the original Meister-r Zeta-s on mine so think they are 6kg/mm front, 5 kg/mm rear so you can see the front of mine is relatively soft.

 

Removing the rear ARB would have the benefit of better rear traction potentially but I think I'll instead just match my camber front and rear and see how I go for now.

 

 

Oversteer is most definately due to the spring rates + arb's. That is a VERY oversteer biased setup. Removing more front grip through camber imho isn't going to be enough to tame it. You need either another 2kg of springs on the front, or a 1kg increase on the front and OEM rear arb.


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#30 MR Wallace

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Posted 22 June 2020 - 02:59 PM

 

Hi Folks,

I have fitted extended lower control arms to increase the front negative camber when running at stock Bilstein ride height.

I will be running more front camber than rear.

I am hoping to give the car a work out in September if we are allowed back on the hills.

 

I'd be interested to hear how you get on. I have basically the Bofi Track/supermiata dual duty alignment on mine (-2.5 deg front camber, -2 deg rear camber) and I find it has too much oversteer on turn in. Enough that I couldn't dial it out on my setup (with front ARBs on stiffest, rears on softest and damper settings also tweaked to try combat). Pretty sure my issue is down to not having enough front roll stiffness (compared to rear) for this setup. I think either removing my rear ARB or even just going back to standard might solve it. I have the original Meister-r Zeta-s on mine so think they are 6kg/mm front, 5 kg/mm rear so you can see the front of mine is relatively soft.

 

Removing the rear ARB would have the benefit of better rear traction potentially but I think I'll instead just match my camber front and rear and see how I go for now.

 

 

Agreed with what Noobie says (BTW Noobie do you race/ setup MX5's... or race in general? You've obviously got a good knowledge of setups from whenever I see you commenting).

 

I tried a thicker rear ARB with my setup and found instantly it had too much turn in oversteer so have reverted to the standard one, I also changed the spring rates of my CRD's to even out the balance- I run 9kg front springs with the original 6kg in the rear and a 24mm front arb.


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#31 Woody27

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Posted 25 June 2020 - 12:28 PM

 

 

Hi Folks,

I have fitted extended lower control arms to increase the front negative camber when running at stock Bilstein ride height.

I will be running more front camber than rear.

I am hoping to give the car a work out in September if we are allowed back on the hills.

 

I'd be interested to hear how you get on. I have basically the Bofi Track/supermiata dual duty alignment on mine (-2.5 deg front camber, -2 deg rear camber) and I find it has too much oversteer on turn in. Enough that I couldn't dial it out on my setup (with front ARBs on stiffest, rears on softest and damper settings also tweaked to try combat). Pretty sure my issue is down to not having enough front roll stiffness (compared to rear) for this setup. I think either removing my rear ARB or even just going back to standard might solve it. I have the original Meister-r Zeta-s on mine so think they are 6kg/mm front, 5 kg/mm rear so you can see the front of mine is relatively soft.

 

Removing the rear ARB would have the benefit of better rear traction potentially but I think I'll instead just match my camber front and rear and see how I go for now.

 

 

Agreed with what Noobie says (BTW Noobie do you race/ setup MX5's... or race in general? You've obviously got a good knowledge of setups from whenever I see you commenting).

 

I tried a thicker rear ARB with my setup and found instantly it had too much turn in oversteer so have reverted to the standard one, I also changed the spring rates of my CRD's to even out the balance- I run 9kg front springs with the original 6kg in the rear and a 24mm front arb.

 

 

Yeah I think i'll try a rear standard anti roll bar and square my camber all round and see where that puts me. It's basically the cheaper route and at least allows me to see if it works OK. I take the car around Curborough a lot so a little loose/oversteering isn't a killer but the amount I was seeing was definitely slowing me down.

 

If I need to revisit the spring rates I'll do some more research as I may go much higher and try some aero.


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#32 noobie

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Posted 25 June 2020 - 04:02 PM

How much do you pay for an alignment? 50GBP? That nearly covers a set of front springs from MeisterR directly. If you use the top bolt method to change out the spring and keep static ride height identical then you don't need an alignment and finally have a balanced setup. You''ll quickly find that even 2.5 degrees of FR camber is towards the lower end of the spectrum on track. 

 

Just my opinion off course....

Also, 8/5 or 7.5/5 is perfectly fine with aero. You don't need sky high rates, a little higher ride height will be 99% as fast as a 700-400lbs/inch setup. Maybe worth a few tenths where aero adds seconds.


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#33 boosted

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Posted 25 June 2020 - 05:16 PM

Most coilover shocks you can go up or down 2kg spring and valving with be fine.

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