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MR2 track car


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1 hour ago, Tony said:

Because it's a ZZW30...... But without the DNA kit. Anyway this is a bit out of the blue? Have you added racing to your gliding portfolio :o

I've always had an interest and karted and hill climbed in my younger days.  My son inherited the petrolhead gene and we rebuilt the engine and supercharged his old Celica GT for the track. Sold that to a gentleman that brought a trailer over from Holland to pick it up. Sale helped to purchase an Evo IX which was overbored and fitted with uprated turbocharger which he tracked ...see vid.

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Deciding having the Evo as both track and daily driver was a bad idea it was sold and a cheapo standard Celica acquired as a daily before the 'ZZW30' was purchased.

A 3.5 litre V6 (ex Lexus IS350) occupies the space where the original 1.8 sat plus a fair bit of space behind the seats in the cockpit.  A large radiator, oil coolers and two big electric fans sit where the spare wheel used to be so apart from the hardtop, door skins and a few suspension bits there's not a lot left of the ZZW30.

It ran in white and orange livery last year but after the rear offside wheel shed its rim at the end of the season we decided to redesign/rebuild the front and rear aero together with a complete wrap in dark metallic grey. Finished it the Thursday night before Castle Combe Spring Action Day Saturday 30th March. It ran very well and glad to report nothing fell off!

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It corners really well, bags of torque exiting enabling a lot of speed to be carried through. However, looking at video taken from the side of the track it seemed to bounce a little accelerating out of a few of the tighter corners. The springs are very stiff although there's little or any preload and the shocks on the rear are at there softest setting. Was hoping to load the relevant footage so Tony could give his opinion, preferably before the Rotrex S/C is fitted in a month or two.

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Main issue with the ZZW30 is the front becomes very light and with all the rear airo even lighter.... Even my car without the extra engine weight and airo becomes very twitchy at speed..... Do you know what poundage the coils are?.... Reads like it's high so about 5mm of pre-load and a higher damper rebound would be advised.

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We'll give it a go, Already adjusted the damper rebound. Cannot really equate the weight characteristics of a ZZW30 with this car as although the 3.5 is a bit heavier it's a lot further forward  and the front under tray/aero and cooling mods also move the weight forward. The rear aero is 2mm aircraft spec aluminium and the wing is carbon fibre so very light.  The full roll cage weight also has a front bias. Would really like to corner weight the car to know for certain.

It certainly sticks to the ground, not twitchy at all at speed but I guess the torque when booting it out of the slower corners when the front aero has little or no effect will try and lift the front end. Couldn't feel any bounce or loss of traction coming out of corners but the video footage clearly showed it.

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On 14/04/2019 at 09:26, Tony said:

What suspension is it on?

BC Racing RM Series

Everything polybushed and Whiteline adjustable ant-roll bars. The car was originally one of two built by Rogue Motorsport for class 3 of the Britcar 24 Hours race.

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I know of Rogue Motorsport and their not stupid when it comes to suspension. The RM coilovers are designed around the principle of reducing unsprung weight which is critical on the very light ZZW30 chassis.

Having adjustable roll bars is another wise move but keep working with the adjustments because there's so many variables given the coil pre-load, dampening and bars.

On some of the race cars we set my motto is "never be satisfied?".... Reason for this is perfection is a journey and like any journey you can always go back.

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1 hour ago, Tony said:

The rebound is wrong.... Corner out under squat the coils are loaded but the rebound isn't under control.... I would be inclined to either up the rebound or reduce the coil pre-load. 

We've upped the rebound but cannot reduce the coil preload as it's already on the minimum. Softer springs perhaps? Puts the power down OK but could be better.

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If the coil pre-load is zero then helper coils will definitely help. Obviously if the drive wheels load under squat and rebound then corner out there will be some loss in grip. If you think about it you can funnel the condition down to a moment during transition.  Applying thrust as the suspension loads is the critical moment of concern.

Looking at the vid i don't think the lateral loading is a problem or the tyre grip/ saturation limits..... It's definitely suspension.

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  • 3 weeks later...

Banzai magazine made contact after the Spring Action Day sessions at Castle Combe, requesting an interview and photoshoot. Photo session took place this morning, don't know what issue the feature and pics will be in. Photographer asked if he could also take a few shots of the IS-F, some with the track car, but not sure why.

Will be running at Japfest, Silverstone tomorrow.

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On 05/05/2019 at 22:06, Rich said:

Awesome, will the article be online?

Mag will be on sale at Donington Japfest which is 13th July so presume it's in the July edition (there's 13 issues per annum). Digital on-line editions require a subscription.

Car performed OK at Silverstone but the long corners showed a strong tendency to oversteer. Underestimated how much the R888's pressures increase as they get up to track temperature and they're also a bit old so need new ones.

Could do with a supercharger too...:ninja:

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21 hours ago, Tony said:

Are the roll bars adjustable?

They are TTE  adjustables Tony . I think I stated earlier in the post that they were Whiteline adjustables as Rogue told us, but they're TTE's.

I've attached a few samples from the track vids showing the problem which I think is due to tyre overinflation at track temperatures. Doesn't help that the R888's on the rear are 7 years old so the compound may be a little harder than ideal. New tyres ordered just for the rear as the fronts were changed a couple of months ago.

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Oh no that's definitely wrong.... The condition is "steady state cornering", Basically there's an imbalance between lateral transition -V- resistance. Roll bar adjustment, coil pre-load and obviously the tyres heat cycle all factor in.

Looking at the vid the oversteer is not progressive so there's no single reason for the condition, if there was a single factor the event would be finite meaning there's a collection of conditions listed above.

My first line of solution would be the roll centre, meaning what angle are the rear four-links and is the front lower wishbone in the same radii as the steering arm?

What is the coils pre-load -mm- from chatter?..

This kind of condition is not directly a geometric condition because the geometry should compliment the chassis at the final stage.

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