215 all round...understeer ?

[skydragon]

I very recently changed over to Kuhmo V70 215/50 r13 tyres all round as well as having an engine upgrade from DVA, upping the power to somewhere around 180bhp (not been RR mapped yet).

 

The car has a Titan LSD (R500 type) and previously with circa 120bhp and 185 wide AO48's it would do donuts very happily...

 

I haven't taken the car out on track since the recent upgrades and it does appear to handle ok at normal road speeds, but I was rather suprised when I tried to do a donut at the weekend, that rather than the back end breaking away and spinning round as expected... the car just wanted to plow on in a straight line, as though the back end was pushing on in a straight line without the fronts having much effect...

 

Any ideas why this is ? Not that I'm after doing donuts regularly, but it's wierd how it now behaves (I presumed with all the extra power and grip it would donut even easier than before - maybe my donut technique needs to change? At the end of the day as long as it handles well on track and road then that's what I need).

 

1.6 K Series EU3, 2003, with DVA K05 and a few other goodies...

website here

 

Edited by - skydragon on 18 Feb 2010 14:54:45

[charlie_pank]

I would have thought that the increased power would improve donutting ability, however the increased grip means you can't break traction!

 

back here because I want to be.

[Simon.Rogers1]

I'm not sure a doughnut is the best measure of handling/understeer

But can you tell us if you have changed the ride height since fitting the Kumho's. They have very different circumference to the A048's.

 

I may be able to point you in the best direction once I know ride height and tyre pressures.

 

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[Willie.]

First question to ask here is if the rear wheels were spinning? If not, then that's the problem. If they were, then it gets a bit trickier.

 

Willie

[skydragon]

I haven't changed the ride height, as I reckoned the 7mm drop from the tyre change would be fine. TP is 18 psi.

 

to ask here is if the rear wheels were spinning

I think so but perhaps part of the problem is there is a lot more grip and as a result I'm not getting the wheels spun up as much as I was with the AO48's. Mayby it just needs a load more right foot to get things moving (as I said before, i was expecting to have to use less right foot, hence my confusion)

 

I'm not sure a doughnut is the best measure of handling/understeer

You have a point... mayby I should wait to see how it performs when I take it on track.

[Gridgway]

Whatever the donut performance it's way over-tyred at the front and probably the back.

Graham

[Nigel Fox]

Over-tyred is an interesting concept, but what exactly does it mean?

 

 

[Simon.Rogers1]

Its certainly not over tyred.

 

This set up as lowered the sprint and hill climb class records in all three classes it has been allowed in. But its not the cornering where it improves things (well it does a bit) its the braking. Its in a different league all together.

 

As far as the ride height is concerned just check you have the recommended 15mm from engine mount to rear wing (or 10mm from the start of the square tube to round tube change just to the rear of the engine mount as its easier to measure).

 

Yes they are much much more sticky 😬

 

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