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Softer setups?
PSpirine - 3/12/13 at 08:34 PM

So my Westfield (narrowbody SE) is still very much in the early build stages in the garage, but I got thinking.

The other day I was fortunate enough to have an F-type, which was a V6S, and aside from everything else, the thing that I noticed most is that on the Costwoldy country roads around here, especially B-roads and the trickier sections of the Fosse, it was FAR too stiff.

To the point where it just kept trying to light up the rear tyres and step out, even in the higher gears at high speed in a straight line.

In contrast, I know for a fact that I can cover the same bit of road quicker in an Audi TT or even in a new Range Rover Sport, purely because they are more compliant, and don't spend every second trying to find a ditch when there's a tiny imperfection in the road.


Has anyone here set their car up for effectively country roads, rather than track-based, which I imagine would result in similar hairy handling as I experienced in the F-type?

If there's anything I need to do early on in to get the Westfield correct for ROAD rather than track, i'd rather do it now.

Cheers
Pavel

iank - 3/12/13 at 08:55 PM

Colin Chapman tended towards soft springs and more damping at least on light cars. Certainly, intuitively, seems a better idea on roads less smooth than a circuit (i.e. pretty much anywhere on our roads these days).

ashg - 3/12/13 at 09:11 PM

it wont be the suspension it will be the runflats. they make for a horrible ride and want to kill you on anything other than a glorious sunny day.

PSpirine - 3/12/13 at 09:18 PM

quote:
Originally posted by ashg
it wont be the suspension it will be the runflats. they make for a horrible ride and want to kill you on anything other than a glorious sunny day.


Not runflats!

Definitely the suspension trying to kill me.


As Ian said, pretty much any public road here in the UK doesn't qualify for a smooth-surface setup. At least not near where I live!

daniel mason - 3/12/13 at 09:27 PM

you want to try driving a very stiff race car on a wet track with a stiff setup! undriveable.ask me how i know?

britishtrident - 3/12/13 at 09:28 PM

Tyres are the first secret section size and tyre pressures
I changed my tintop from 215/55R x 16 to 195/65/15" tyres the difference in ride is amazing the cost is steering less sharp response.

13" wheels and taller tyres would work well on your Westie.

You are a bit limited on fitting soft (lower rate) springs because of the lack of suspension movement available.

britishtrident - 3/12/13 at 09:41 PM

quote:
Originally posted by iank
Colin Chapman tended towards soft springs and more damping at least on light cars. Certainly, intuitively, seems a better idea on roads less smooth than a circuit (i.e. pretty much anywhere on our roads these days).



Chapman used long travel suspension with very soft springs with a huge amount of pre-load istr the front of baby Elan used 70lb/in springs that were compressed to less than 1/2 the free length. To reduce roll the front ant-roll bar was stiff and the roll centres were a bit higher than used on Locosts and Westies The damper settings weren't that hard just firm compared to ordinary 1960s cars.

unijacko67 - 3/12/13 at 10:14 PM

Just go with what the other chaps use spring wise, then test your dampers on runs. springs are cheap so you can try either harder or softer as you like. I've found out of my 15 damper settings, as the car is quite light (not as light as yours) I only use/need about 4 clicks. Rear dampers any lower than 3 and it knocks the hell out of the car/axle and any harder than 6-7 and its to hard for the weight of the car, so 7 to 15 will all seem to be the same as its too stiff. Basically trial and error, but you must have starting points as other people have similar cars. I could be talking crap, but that's how mine feels.

matt_gsxr - 4/12/13 at 09:32 AM

If you go for soft then you need to be absolutely certain the springs don't bottom out.

It also makes you more sensitive to centres of roll, because there is more roll!

GeoffT - 4/12/13 at 01:35 PM

quote:

If you go for soft then you need to be absolutely certain the springs don't bottom out.


...this is the problem I had with 150lb springs on the rear of my car, I had to have the shocks fairly hard to prevent bottoming (which bloody hurts...) thus giving a fairly harsh ride.

As an experiment I tried 200lb springs, which enabled me to back the Gaz shocks off to zero clicks without bottoming. This seems to give a more compliant and softer ride, which for an old fart like myself is more important than ultimate handling....

CNHSS1 - 4/12/13 at 02:31 PM

Caterham use really long dampers with long dual rate springs on their more road biased cars. Long springs reduce the chance of bottoming and the dual rates wind of thesprings gives a soft ride in roll until you really get the thing loaded up when it stiffens up nicely.

Paul Turner - 4/12/13 at 02:55 PM

In the 25 years I have had my 2 Caterhams I have had probably 5 different setups from memory. The first car had a live axle and needed a very different set up to the 2nd De-Dion car. I will try and summarise what the specs were on each and their advantages/disadvantages. Some of the spring rates for the first car are probably a bit out, it was over 20 years ago but they will be close.

First car (live axle) delivered with spax dampers and road springs, it had a 1/2 front ARB and no rear ARB. The spring rates were approx. 130 front and 75 rear. The car was nothing like I expected, very soft and wallowy even to a novice, on the track it rolled like a Citroen and brake oversteer was sudden and dangerous.

Changed to Caterham "race" springs 160 front, 110 rear. The car was much better but still needed a better set up on the track.

Bought a set of springs from SPR who at the time ran several Caterham championship contenders and winners. They transformed the car. 260 front, 150 rear.

When I built the De-Dion car I junked the Caterham supplied springs before it hit the road. Spoke to SPR who sold me a set of their latest spec race springs which were 260 front, 180 rear. Together with the SPR recommended 19mm front ARB and adjustable rear ARB the car was excellent on the road and track.

After 12 or 13 seasons the dampers were feeling a bit tired and a company called Freestyle were offering Caterham handling packages at a very good price with excellent press. The company was run by 2 ex Caterham employees/racers. For Road/Track they recommended a set up using AVO dampers specially valved to their specs with spring rates of approx. 320 front 150 rear (they did not actually disclose the rates but I calculated them myself from set up info - they agreed with my calcs) using my existing rear ARB with an adjustable front ARB. I was very sceptical at first but they offered me my money back if I was not happy. I expected major understeer with the much stiffer front and softer rear. Initial road use indicated it was much more compliant over the bumps but at a track day I quickly realised it was very good there as well. I have never adjusted the front ARB and with a couple more clicks on the rear dampers compared to the fronts the car handles beautifully. Very chuckable with slight understeer but with a bit of right foot the rear drifts nicely.

me! - 4/12/13 at 07:23 PM

quote:
Originally posted by PSpirine
it was FAR too stiff.


I agree with you there! I haven't driven a V8 one properly yet but apparently they are best described as 'scary'. The roads around the west mids do seem to be greasier than a greasy thing at the moment though

ceebmoj - 4/12/13 at 10:06 PM

quote:
Originally posted by daniel mason
you want to try driving a very stiff race car on a wet track with a stiff setup! undriveable.ask me how i know?


Have you seen the adjustable blade type anti roll bars on this thread on piston heads look on the last page PH link

phelpsa - 5/12/13 at 10:26 AM

There's a difference between 'soft' and 'compliant' suspension. Modern cars with big wheels, big stiff tyres and big brakes can have a bit of a problem when it comes to unsprung mass and wheel nat. frequencies. This generally requires them to run quite a lot of high speed damping. The likelyhood is that they aren't actually that stiffly sprung.

So in conclusion, minimize your unsprung weight and buy the right dampers and you'll have a much more compliant car than one which just has 'soft' springs.