Twitchy back end moment! 😨

[Ekona]

That's the spirit sir!

[Watola123]

Check all suspension would be first for me

[fishfire]

Reading some of these comments with interest!

 

I've had this feeling of instability at speed, on some relatively smooth road surfaces. And the twitchy back end has become a consistent thing if I get happy in sharp corners which feels like a bike about to high side (for those bikists out there 😉)

 

Recently took her to Santa pod and she was spinning up in every gear change. Now o know she's got a bit of power....but not that much!

So, tyres will be getting changed and all the geo set up at the same time, and will see what difference that makes.

 

Thanks for all the input so far ðŸ˜

 

[MG Mark]

I know the EVO incident at Marham - I was one of the organisers there for that MLR event and for the other track days we run there.

 

The driver was starting to drift over to the right, as that was the side of the runway that you would turn off at the end of it. But, he misidentified his location along the runway length, suddenly thinking that the yellow cones approaching (quickly....) marked the end of the runway where he should turn off right - that was why there was the initial drift to the right and then the sudden lift off and attempt to brake hard when he thought he was going to "run out of road". The yellow cones were actually marking the start of the lift off and slow down straight section, with about 1000 feet of the runway left to slow down in before turning off. The initial skid was then compounded when the car, already rotating and sliding to the right dropped off the 2-3" ledge of the difference in height between the main runway surface and the adjoining concrete shoulders. That's what then increased the rate of rotation and the excursion onto the grass until coming to a stop; with a flat surface to run over (nothing solid to hit) and thankfully little correctional inputs (too fast to do much) the laws of physics played out benignly (no rollover).

 

Lessons from that - the higher the speed when something happens, the faster it goes wrong. All inputs must be smooth and progressive. Know where you are. Get braking done in a straight line. If it starts to go wrong in a big way like that, take your hands and feet off everything and trust to physics until everything stops - over-correction will create a pendulum whip effect that greatly increases the risk of rolling.

 

Regarding the OP's post, my 350Z (HR engine) has happily run there on Avons, setting up the track day layouts, at over 170 in a straight line and through fast "sweepers" in the range of 100-150. It's planted, solid, stable, predictable feel and nothing goes wafty, light or fuzzy (more than can be said for the Boxster S I has before!). Recommend check tyres are the right sizes and pressures (note - raise the pressures for sustained high speed/track work) and a full 4-wheel alignment/geo check. Test the car on a smooth surface. If that doesn't rectify it, check the bushes for play/wear AND check the bump/rebound rate of the shock absorbers. I'd hazard a guess now that if things feel loose, unpredictable and horrible, particularly when cornering at speed, it'll be one or both of the last two....

 

Mark

[MG Mark]

One more thought - if that lot doesn't sort it, check the functioning of the Limited Slip Diff.

 

Mark

[Jake.Lowther]

I've had 140 out of my Zed and it still feels planted and stable, something must be wrong.