From: Dave Baker
Subject: Re: Negative Camber
Date: 13 Feb 1999
>Subject: Re: Negative Camber
>From: "Andrew W. MacFadyen" <email@example.com>
>Date: 2/12/99 3:21AM GMT
>Although it give more grip even slight negative camber act a pit like too
>little castror and generally makes a car feel twitchy the reasons is tyre
>sidewalls on the outside wheels in a corner are stressed the wrong way -- in
>contrast slight posative camber pre stresses the outside tyres sidewalls to
>handle the cornering loads without "squirming" on initial turn in.
>How much camber you need depends a lot on tyres -- generally radials grip
>better with more, and low aspect ratios need less -- all to do with the
>stiffness of the side walls.
>On a road car I would never run more than 0.5 -0.75 degrees because of tyre
>wear considerations unless I had a very good reason -- ie. a rear swing
Plenty of standard road cars have more neg than that to start with without
undue tyre wear problems. The Alfa range especially like Suds, 33, Sprint, had
up to 2 degrees on the front. 1 to 1.5 degrees of neg makes a huge difference
to cornering power - more in my opinion than wasting money on fancy tyres and
huge wheels. Most drivers can't extract the optimum out of the standard tyres
fitted never mind the 17 inch 225/45 soft compound stuff that seems to be all
the fashion these days.
Take a standard Fiesta XR2 - lower 40mm - add 1.5 degrees negative camber on
the front, set the tracking properly, uprate springs to about 170lb front and
rear, good shocks like Konis, add decent tyres in the standard 185 size,
replace all the shagged rubber bushes - if anyone can find a tintop road car
that goes round corners appreciably quicker than the above I've yet to see it.
Many years ago a car mag put a good race driver in an Audi of some description
on a racetrack to try different tyre combinations out. Standard, a bit wider
and a bit lower profile and finally much wider and ultra low profile. There was
only a second or so difference in the lap time and most of that because the
driver was good enough to exploit the grip of the low profile tyres. Low
profile tyres break away very fast and don't give the nice comforting squirm
and squeal that average road drivers need to tell them they are pressing on a
bit too quick. They just go "grip, grip, grip grip - shit I'm in the trees"
Just because you can hang the back end out in 30 mph corners on a Mk 1 Escort
with remoulds on doesn't make you a good driver. Try the same thing at 70 mph
in a good modern saloon with 205/50s and see how far you get. I can push my car
to the limit at about 50 mph - anything faster and I chicken straight out. On a
race track you need to be on the limit at over 100 mph - most drivers have
enough trouble going in a straight line at that speed.
On a road car fancy tyres might make you a tad faster in corners slower than
40/50 mph - above that I doubt that 1 in 100 drivers get anywhere near the
limits of the standard rubber never mind the fancy stuff. Of course all you 20
years olds who reckon you are God's gift to a steering wheel will no doubt post
in how wrong I am.
I am not sure where I am heading with all this so I'll regroup a bit. I think
what I'm trying to say is that a well maintained car with subtle mods like a
bit of neg on the front, lightly lowered and stiffened (not on the bloody
bumpstops like the kids think is cool) and 4 good matching tyres and shocks is
all you need. After that it is more down to the driver than the car. Oh - and I
bloody hate 4 inch drainpipes sticking out from under the rear valence too -
but then you all guessed that by now anyway.
Just to end on a funny story to show how it seems to be that fashion and street
cred is more important than actual performance to kids these days. I was down
at the local rolling road with a race car a year or so back and we were waiting
for a road Pug 205 to finish. It had 1.9 badges and wheels and a fecking huge
piece of tubing sticking out the back end like something off an oil refinery.
It also had air filter, chips and assorted stuff under the bonnet. Now a good
standard 1.9 puts out about 105-110 bhp at the wheels and this thing was
showing 90 ish. I couldn't help going up to the spotty youth with the baseball
cap on the wrong way round who was standing by it to ask him what was wrong
with the engine.
It seems that nothing was wrong at all except for the fact that it was a 1.6
with 1.9 badges on it. Now I can understand putting 1.6 badges on a 1.9 to piss
off all the other 1.6 owners but in reverse ??? That way you get laughed at by
other 1.6 owners as well as 1.9s. I guess he just had to cruise around and not
dare actually floor it against any other car for fear of getting blown off -
what price street cred eh ?
Perhaps I'm getting old :)
Dave Baker at Puma Race Engines (London - England) - specialist flow
development and engine work. .