11 replies to this topic

[Shadyfox]

I have a Mini Vtec Zcar with a K20A 

 

I have a handling issue at high speed when I let my foot of the accelerator the car goes light at the rear end and wants to turn left then right from the rear very unnerving heart stopping stuff, I have to feather the brake peddle and sort of hang on. Can any one shed some light on what things it could be do I need a rear wing or diffuser or both or none good advise will be welcome, this was on the road not on a circuit.

 

thanks Tim 

[johnR]

A weight distribution/suspension issue? - perhaps a visit to someone who can check the corner weights etc 

[Renessy]

How about your wheel alignment?

 

This may help....

[Bat]

Hi,

It sounds like lift-off over steer. This is caused by the rear suspension uncompressing and shifting the weight towards the front.

What are your current geometry settings and corner weights? 

Cheers 

[KaneH]

Has it always been that way or is this a new issue you're experiencing? By the sounds of it the rear geometry needs looking at. Take it to someone to find out how the camber/toe settings are changing over the suspension travel. I'd also be looking at bushes/mounts etc. Worn bushes could be causing dodgy toe settings as the rear unloads.

Also worth looking at the rebound settings on your rear shocks if they're adjustable.

Edited by KaneH, 23 June 2018 - 08:18 AM.

[Shadyfox]

Thank you all for the replies.

 

• No never had the corner weights done 
• Wheel alignment, is there a standard Zcars setting or base line, or do we start with parallel front and rear?
• Lift of over steer, I get it but the engine is in the back, there are not any bushes only rose joints and all ok 
• I did this once before on a circuit but I was off the racing line on a 1000m straight so I thought it was the track.
• Shocks are Pro shocks all round with 1&1/2 inch shock top lift as the car used to bottom out a little so we gave it a small lift.
• Do you know any where in Essex or Kent I can get the car geometry set up with all four wheels done with a good Lazer system?
• The suspension hardly moves its very stiff.

[Mervyn]

Sounds like the rear has excess toe-out

Makes the car exceptionally scary


Merv

[robj2502]

I havent personally used them but Abbey motorsport are just outside the M25 round by Godstone which isnt too far for you. I believe they have a good reputation with Jap cars and do suspension setup (especially coilovers), laser alignment and corner weighting. 

 

http://www.abbeymoto...n-and-alignment

 

It may also be worth speaking with Zcars as they are now based in Ashford (Kent) and suspect they have the equipment at least to get it back to the base setup and ensure that all of the original fittings are in tolerance

 

https://www.zcars.org.uk/

 

Hope you get it sorted out 

Edited by robj2502, 02 July 2018 - 09:25 AM.

[Shadyfox]

Thank you guys for the heads up I will get this looked into with the suggestions you have, and post the results when sorted.

[Renessy]

Look what I found!

Hope the lay-out is ok.....

Zcars mini basic setup

Nsf Osf

Toe In parallel each side Toe in parallel

Castor 3.5 deg + Castor 3.5 deg +

Camber .5 deg - Camber .5 deg -

Shock clicks 6 Shock clicks 6





Nsr Osr

Camber .75 deg - Camber .75 deg -

Toe in 1mm each side Toe in 1mm

Shock clicks 6 Shock clicks 6

Tyre pressures front 18psi
Tyre pressures rear 20psi

Ride Height road 90mm front, 100mm rear
Race 75mm front 85mm rear



ZCars recommend all cars are correctly 4 wheel aligned when completed please ask for more info as if done wrong the car will not perform to its true potential.

[Bat]

Hi,

Now I've read you've raised the ride height, I'd start there. If it was bottoming out you may have been better fitting stiffer springs...

Cheers 

[Shadyfox]

Look what I found!

Hope the lay-out is ok.....

Zcars mini basic setup

Nsf Osf

Toe In parallel each side Toe in parallel

Castor 3.5 deg + Castor 3.5 deg +

Camber .5 deg - Camber .5 deg -

Shock clicks 6 Shock clicks 6





Nsr Osr

Camber .75 deg - Camber .75 deg -

Toe in 1mm each side Toe in 1mm

Shock clicks 6 Shock clicks 6

Tyre pressures front 18psi
Tyre pressures rear 20psi

Ride Height road 90mm front, 100mm rear
Race 75mm front 85mm rear



ZCars recommend all cars are correctly 4 wheel aligned when completed please ask for more info as if done wrong the car will not perform to its true potential.

ok thats good info the car is at Zcars and has been for the last 18 months getting a lot of work done,I spoke well I do speak to David allot and today he said the car will be getting set up for corner weights and alignment I will send the settings to Zcars Kent and see what they say about this setup for my car.