Thanks to Skillshare for supporting this video. Skillshare is an online learning community
for creatives like me - and maybe like you too!
There are thousands of classes across their platform for inspiring you to take things
to the next level or finally learn how to do that thing you’ve always wanted to try.
Like digital design or video editing or creating a business around your skillsets.
If you, like me, never stop wanting to learn how to do new things or make the ideas in
your head come to life, there’s likely just what you need here: beginner, pro or somewhere
in between. For example, I’ve got a video coming up
in the next month or so that’s a little bit different and I’m working through Elaine
McMillion Sheldon’s Short Video Documentary class to help me prepare the production part
of the video. An annual subscription is less than ten dollars
a month, but we’ve got an offer for you: The first 500 of my subscribers to click the
link in the description will get a 2 month free trial of Premium Membership to fully
explore. Clic k the link below to get started. And now, on with the main video.
In a previous video we looked at ‘toe’ - the angle of the mounting of the wheels
in relation to the car’s longitudinal direction. So I thought, why not have a look at camber
which is the angle of the mounting of the wheels in relation to the vertical.
Now this video is about tyre camber but you might sometimes hear reference to road or
track camber, which is the angle of the track surface itself across its width, which could
be banked or sloped in its design. Tyre camber then. Tyres that are strapped
onto the suspension to sit perfectly aligned with the vertical are said to have neutral
or zero camber. Angle the top of the tyre outward from the
car and that’s positive camber. Angle the top of the tyre in towards the car
and that’s negative camber. Negative camber is what you’ll tend to see
on the front tyres of racing cars usually set somewhere between zero and three and a
half degrees, though I’ll be exaggerating this angle in this video just to make everything
clearer. OK, tyre basics then. With your F1 car on
track, you ideally want as much of the tread of the tyre touching the track surface as
possible. The area of rubber that meets the track at any given point is called the contact
patch and will be some flattened area of rubber forcibly smushed into the ground by the weight
of the car. Having a large contact patch is good for tyre
grip and for traction - which describes how a car can maximise the available grip.
It’s also good for reducing the wear through the tyre rubber and managing the build up
of heat as the load if being spread over more rubber. This is partly why F1 tyres are so
wide and they don’t go racing on bicycle tyres, which would be torn to shreds by the
intensity of the loads on such a small area. No you’d think neutral camber would be good
for all of the above. After all, look how planted that tyre is on the track. The whole
width of the tread is kissing the ground, just like we want.
And for driving in straight lines, that would be true. But, as observant fans have noticed,
F1 cars also turn through corners. When racing cars, particularly F1 cars, turn
there are very high forces involved in managing a change of direction under such high speeds.
The tyre rubber, through the contact patch is pushed laterally (that’s across its width)
by the track to force the car to turn in. And that’s a lot of force being handled
by the rubber. When a car turns in. Two things happen.
The first is that the car experiences load transfer towards the outside tyres.
When stationary, the left and right front tyres are loaded equally. But when the car
turns, the weight of the car is thrown outwards and the outside tyres bear more of the load
through the corner than the inside tyres. This means that the outside tyre is critical
on turn in and through long high speed corners as its bearing the high forces needed to bring
the car through the turn. Secondly, as the weight swings to the outside
of the car, this causes the body to roll - that is, pivot along its length and lean to the
outside. As it does this it causes the tyre to roll with it.
The tyre is now not flat with the track and is bearing the load through one side of the
tread. The tread is also being distorted by the lateral
forces pulling on the rubber, reducing the contact patch further and bringing some of
the load towards the sidewall. So, with neutral camber, we now have rubber
trying to work on a much smaller contact patch, leaning on part of the tyre that shouldn’t
be overly stressed. Do this too much and you’ll quickly get excessive wear, unmanageable temperatures
and a resulting loss in grip and speed through corners.
So, instead if we camber in these tyres, the tyre is now able to use the full width of
its tread much more easily, increasing the contact patch and maximising is consistency
in traction and grip. There is still some deformity in the way the
tyre meets the track, yes, but the deformity works with the cambered-in angle of the tyre
to allow the tread to properly meet the surface of the track.
There’s another effect that comes into play here which is lateral thrust or camber thrust.
The details of this are slightly complicated but a weight loaded, cambered tyre will want
to turn inwards with the direction of camber. This is a consequence of the asymmetric way
the tread is being deformed against the track and how the elasticity of the rubber pushes
against the track to try and keep its shape - not something I need to go into detail here.
[*motorbikes footnote] Just know that a negatively cambered tyre
will also naturally add to the forces pulling the car into the corner. A small bonus!
Note here that we are looking at the outside, load bearing tyre here.
If we look at the inside tyre through cornering then we see it is cambered in a way to make
it rest more on one edge through a corner and creates and even smaller contact patch.
But because the outside tyre is doing the majority of the load bearing, the concerns
of the inside tyre are minimal. In fact, depending on the suspension settings and the corner
- the inside tyre may sometimes lift completely from the track or be very close to lifting,
at least as the roll of the car and the alleviation in load literally takes the burden away from
it. So we’re happy to sacrifice the inside tyre here.
Negative camber isn’t perfect though. It does of course come with drawbacks and - as
with all setup decisions - tyre camber is about balancing its effects across different
situations. So, when the car is powering down a straight,
obviously if you’ve got your tyres negatively cambered they are resting, not flat, but more
on their inside edges. This not only adds more load to the inside shoulders, which is
bad for durability and increases the risk of punctures but adds to the wear and heat
issues we mentioned earlier. It will also reduce straight line traction,
which will have an effect on acceleration. This isn’t a huge deal as the burden of
acceleration is mostly laid on the rear tyres, which will tend to have a pretty neutral camber.
Their job is to lay down the power so they’ll want their rubber flat to the track as their
big moments come on straights. Note also that during the acceleration phase,
there is load transfer to the back tyres so the camber of the front tyres is less critical
anyway during the high acceleration moments. What is critical is braking. Braking is maximally
critical in straight lines and during braking the load is transferred forward to front tyres.
The front tyres that are cambered in and leaning - not on their full tread - but more to their
insides. Too much camber up front could have a big effect on your braking ability and the
effects from braking on your tyres durability. Furthermore, that lateral thrust we spoke
about a minute ago - the tendancy for a cambered tyre to push the car in - well normally that’s
fine on straights as the left and right tyres will balance each other out.
But if one tyre loses some traction or load if it hits a bump or something - then the
other tyre’s lateral thrust will dominate and jerk the car over a bit. This can make
the car more sensitive and twitchy in a straight line if overly cambered in.
You don’t see this much in F1 but in IndyCar, where they race in ovals, they may really
crank up the camber to use lateral thrust through the long, banked corners but be much
more unstable down the straights, riding very much on tiptoe.
Finally - and the details of this start to get into the complications of suspension - you
need to consider camber gain. So far we’ve basically talked about a static
camber - fixed under all conditions. But in reality, camber can change as the suspension
is loaded up. Suspension allows the tyres to move vertically
relative to the car through a series of springs and mountings. This means it can ride bumps
and roll through corners while keeping the tyres planted on track and the car itself
not leaping and bouncing with every bump and kerb it hits.
As the wheel moves vertically, if there was zero camber gain, the camber angle would remain
the same throughout its travel. But you could set the suspension up so vertical
movement in the wheel increases the negative camber.
This means, for example, that the car body could roll significantly, while keeping the
tyre contact patch fully planted. But this also means that under braking as
the load transfers forward onto the front wheels and brings the nose of the car down,
the front wheels can camber in further, increasing the problems explained about.
Between toe and camber, mechanics try and set up the car as the best possible compromise
to the conditions of the track available to maximise performance, handling and tyre management.