“Oversteer” and “Understeer” in the BTCC

During a BTCC race weekend is it common for the drivers and commentators to talk about an “under-steering” or an “over-steering” BTCC car. But what exactly is meant by the terms?

In the following animations we can see Andrew Jordan * demonstrating the two main handling characteristics in his Pirtek Civic**


First of all we will look at “Under-steer” or “being tight” as the Americans would say.

“Under-steer” is when during cornering the front tyres loose traction with the racing circuit whilst the rear tyres still have grip.

As the front wheels steer the car if they loose traction, the car will not steer and will continue to push forward no matter what steering angle is input.

In the below animation the tyres are shown so that steering input can be viewed.

(For clarity no driver correction steering action has been shown in any of the animations.)


Looking at Andrews demonstration, it can be seen that as he enters the corner and turns in the front tyres loose grip and the car continues on-wards away from the racing line and on to the grass.  The car wants to go straight on, instead of around the corner.

A few basic things a race engineer may try to do to combat under steer is to soften the front suspension with softer springs, damper settings or a thinner anti role bar to try to increase the front grip( increase the tyre contact patch with the circuit through cornering).

Other options are to increase the rake of the car (raise the  ride height at the rear or lower the front ride height)  This will cause the center of gravity to shift forward increase the downward force on the front of the car and help increase grip.

Other options to help increase front end grip over rear end grip is to increase front camber and decrease rear camber.

Over steer


Simplistically an “over-steering” car or a “Loose car” is when during cornering the rear tyres loose traction with the race track but the front tyres still have grip and the  rear of the car slides outwards with the corner force.

To try to improve the over steering car a race engineer will try to increase the grip at the rear of the car (or decrease the grip at the front) often by softening the rear suspension again my softening damper settings, spring rates or anti-role bars (stabilizing bars).

So in summary an under-steering car means not enough grip at the front and an over steering car means a lack of grip at the rear.

A balanced Car

Finding a good balance for a race car around an entire circuit can be a very difficult challenge for a race engineer and often trying to dial out over steer can result in under steer and vice-versa trying to dial out over steer can result in under-steer.

Improving the car for one corner can also unsettle it for other corners meaning a comprised balance may be the fastest setup for a certain circuit.

With a well balanced car with neither excessive over or under -steer  the driver can feel confident to push to the maximum level of grip through the car,


* A virtual Andrew Jordan was used in this blog post. (No Andrew Jordan’s were hurt in the making of this blog.)

** No BTCC cars were damaged in making this blog post.


Take a look at the rear workings of a NGTC racer.

Following on from one of my previous post where we looked at the rear suspension of  a 2012 BTCC Next Generation Touring Car (Maybe it should now be current generation Touring Car Regulations?!)

Which can be found here:


BTCC racer Rob Austin has kindly shared the below photo on his face book page. http://www.facebook.com/pages/Rob-Austin-Racing/300548846320 which shows his complete rear sub frame assembly striped out of the car.

Unlike the rest of  the NGTC grid Rob’s Audi is the only rear wheel drive car. (the BMW’s are built to S2000’s regulations with a NGTC engine fitted)

So what can we see in this photo?

Item 1 shows the Penske (http://www.penskeshocks.co.uk/) coil over dampers 2, shows the suspensions rocker, 3 the upper wishbone and 4 the  suspensions push rod. The relationship between these items is discussed in my previous blogs and a simple animation of the system I have made is shown here:

The brackets which the wishbone mounts to the subframe are highlighted with a 5. The Touring car teams will have to keep a large quantity of these spare, as we can surmise that this area will be a particularly weak spot and with the close wheel to wheel racing that the BTCC is renowned for it is likely that these brackets will often require to be changed.

The Audi’s drive-shafts can be seen in item 6  highlighted by the yellow dashed boxes. The drive shafts transfer the rotational drive from the differential to the wheels.

The differential can be seen mounted as point 7 with the splined connection shaft highlighted as point 8  the prop shaft which connects to the gearbox at the front of the car.

Pointshows the anti-roll bar which runs between the left and right hand suspension.

Feel free to leave any comments below or email me at btcctechnical@gmail.com. Also don’t forget to follow me on twitter: @btcc_technical so you don’t miss any new blog posts!

Racer eye view of a touring car

This post we will take a look at the view a touring car driver has of his racer and the controls he has at his (or her) finger tips.

The below photo is taken from the drivers eye view inside the team dynamics Honda racing Civic and was (again) published by Matt Neal  (published on https://twitter.com/ by @MattNealRacing )

ImageIThe BTCC NGTC specification dictates that a Cosworth electrics package ( http://cosworth.com/products/motorsport) is used which consists of  ECU, Dash, data logger  and switch panels.

The Cosworth electrics LCD digital dash and combined data logger can be seen in Item 1. This display not only displays crucial information to the driver but is also the vehicles data logger and stores information for the teams race engineers (and TOCA scrutineers)  to analyse after the race.

The screen has many display pages and a “warm up” page can be selected to display water and oil  temperatures and pressures in the garage. “Race pages” can be selected for the race which displays information such as RPM, speed and lap times.

Clear alarm messages are displayed on this screen should any temperature or pressure rise or fall from a pre-determined range. The background color of the screen turns from the standard “Normal condition” blue to “Alarm” red to ensure that alarms are clearly visible to the driver. In the photo the background is “alarm” red and the  message: “fuel press low” is displayed. This obviously means that the fuel pressure is low and is probably because the photo was taken in the pit garages when the fuel had been removed from the car.

Shift lights are positioned above the LCD screen shown in point 2, which illuminate and indicate at the optimum point to change gear.

The Cosworth “Membrane switch panel” can be seen in point and it is positioned so that it is within view and reach of the driver it controls all the items that may need to be switched on or off on the race car. In the below diagram I have identified the function of each of these buttons.

In addition to the controls on this panel other controls which are frequently required to be used during the race are added to the steering wheel for ease of use. These controls are:

4, This button is labelled as PTP which I believe stands for “Push To Pass” and will be used to control over boost, Not allowed in 2012 but to be introduced in 2013.

5,  Dash- This button selects the display on the LCD dash and is used to scroll through the display pages I.E from warm up page to race page.

6, Flash- This button is used to control the head lights to allow them to flash.

7, BrakeThis controls the solenoid valve which locks and releases the brake lines to the rear calipers, this is used as a type of hand brake and is pushed to release the brakes on the start of the race.

8, Radio- This button allows the driver to speak to his engineer in the pit garage.

9, This knob controls the brake biase and is wound clock wise to move the bias to the front brakes and anticlockwise to change the brake bias to the rear. Most racers of front wheel drive cars in normal conditions have the bias wound fully to the front.

10, This red button activates the cars on-board fire extinguisher and has to be positioned so that it cannot be accidentally activated but so that it can be reached in an emergency.

Feel free to leave any comments below or email me at btcctechnical@gmail.com. Also don’t forget to follow me on twitter: @btcc_technical so you don’t miss any new blog posts.


A glimpse under the hood of a BTCC NGTC!

This post we will take a look at whats under the body work at the front of next generation touring car (NGTC) The following photo was taken during the build of Team Dynamics Honda Civic touring car. (published on https://twitter.com/ by @MattNealRacing ) So what is lurking under the hood of a NGTC racer?


The TOCA specified steel tubed front sub frame manufactured by GPR Motorsport (http://www.gpr-motorsport.com/ can be seen fitted to the front of the car wrapping around the cars Neil Brown engineering 300+bhp K20 engine (http://www.nbe.co.uk/) highlighted as number 1.

The cars front left hand Penske (http://www.penskeshocks.co.uk/) coil over damper can be seen laying horizontally connected the rocker, highlighted as 2 andrespectively.The pushrod which transfers the movement of the lower wishbone to the rocker and then to the coil over damper is highlighted as number 4.

The cars anti roll (or stabilizing bar) is not fitted in this photo but the two bearing blocks which it mounts into as it runs from the left to the right of the car are visible on top of the sub-frame highlighted as number 5. Different thicknesses of anti roll bar can be used to set the car up to different circuits.

The cars three hydraulic reservoirs can be seen in number 6, with one reservoirs for the front brake circuit, one reservoir for the rear circuit and one reservoir for the clutch circuit. The bracket for these reservoirs is shown as being cable tied to the sub frame, this is probably temporary as it doesn’t look as secure as would be expected and the reservoirs could rotate around the tube with the cars vibration.

The cars alternator which generators an electrical charge to charge the battery and also help run the onboard electrics, can be seen in number 7. In the past teams have used Mclaren electronics alternators (http://www.mclarenelectronics.com/Products/Document/Alternators%20Application%20Note) part of the Maclaren F1 group.

The air induction and turbo system for the car is not fitted in this photo and the a white plastic shield is fitted over the air intake ports to prevent debris from accidentally falling into the engine, Number 8. The text “Neil Brown engineering” can be seen printed on this temporary shield.

The cars starter motor is visible in number 9 this is normally hidden from view by the car’s air induction system this is use to drive the engines fly-wheel to turn over the engine.

A heat exchange is shown in number 10 and the hose coming off to the left of the photo connects to the underside of the radiator which is not fitted in this photo.

The Xtrac (http://www.xtrac.com) sequential gearbox is shown as number 11 the shifter mechanism is not fitted in this photo and is normally located on the top side of the gearbox housing.

The coil over dampers horizontal location running from the front to the rear of the car may look slightly unusual as compared to the traditional McPherson strut suspension found in standard road cars and even to the coil over’s position of the NGTC rear suspension running left to right (as discussed in my previous blog) the following diagram and animation I have made should help to explain how the system works.

Feel free to leave any comments below or email me at btcctechnical@gmail.com. Also don’t forget to follow me on twitter: @btcc_technical so you don’t miss any new blog posts.

Update- NGTC Double Wishbone Animation

Following on from my last post I have created the following animation to illustrate how the suspension works!

Double Wishbone Movement

Double wishbone movement

A BTCC engineer who has experience of setting up a NGT car has informed me that due to the short wishbones used in the spec suspension, it is difficult to get the suspension travel required to achieve the optimal setup. Most cars will be using all available  suspension travel.

Feel free to leave any comments below or email me at btcctechnical@gmail.com. Also don’t forget to follow me on twitter: @btcc_technical so you don’t miss any new blog posts.

Looking at a NGTC Rear Subframe

The BTCC’s lattest specification “NGTC” touring cars use a common standard TOCA front and rear suspension assemblies regardless of base vehicles manufacturer. In this post we will take a look at this TOCA rear subframe assembly.

Matt Neal (@mattnealracing) has kindly published this picture on http://www.twitter.com showing his teams (Team dynamics) new Honda racing 2012 Civic.  So what can we see in this photo?

This photo is taken from the rear of the Civic, looking through the tailgate opening down at the rear floor of the shell.

Highlighted in point 1 is the common NGTC rear sub frame which is a fabricated suspension assembly manufactured for TOCA by GPR Motorsport (http://www.gpr-motorsport.com/). You can see that this assembly is similar to the front sub frame (discussed in this post https://btcctechnical.wordpress.com/2012/02/14/a-quick-once-over-of-a-btcc-ngtc-front-sub-frame/) And is also quite a considerable heavy duty fabrication made from of steel tube. You can see that it is mounted to the underside of the shell and is tied into the rest of the vehicle  at  four mountings points highlighted in point 2. These mounting points are incorporated into the cars roll cage which connects front and rear sub-frames.

The suspension provided by these sub-frame assemblies is double wishbone and as oppose to Mcphearson strut suspension found on S2000 specification cars, the dampers are laid out flat to the floor in the shell running left to right, These are shown in highlighted point 3. The NGT cars use a Penske nitrogen filled dampers (.http://www.penskeshocks.co.uk/The resevoir for the damper is local to the damper and is highlighted in point 4.  The damper can be adjusted via the adjustment nobs on this resevoir, Highlighted in point 5.  The NGTC’s use coil over dampers, springs with different spring rates can be fitted over the damper depending on the car setup.  The spring is not fitted in these photos, however I have highlighted the area where the spring would normally be fitted in point 6.

Access to the dampers will be via a removable cover which will normally hide this assembly from view, this cover is not fitted in this photo.

To the rear of the sub-frame assembly it is possible to see where the rear air-jack is mounted, The rear air jack, which raises the rear of the car is hidden from view by the flat steel sheets, however you can see the hard air lines leading to the cylinder , I have marked the approximate position of the air jack highlighted in point 7.

The fuel tank is fitted in this photo and its located forwards of the rear suspension highlighted in point 8 and the cars fire extinguisher can be seen to the left of the fuel tank highlighted in point 9.

Seeing the dampers laid out across the floor in the above photo it can be a little confusing to picture how the suspension all links together. To help clarify how this suspension works I have created the below illustration:

(Illustration not drawn to scale)

The top illustration shows the double wishbone suspension at rest and the lower illustration shows the suspension moving under load, perhaps when ridding over a curb.

You can see in this illustration that the damper is laid out horrizontaly as we see in team Dynamics photo and is connected to the rest of the suspension via a pivoting “rocker” and a push rod.

So how does this system work? As the wheel moves upwards under load the push rod pushes against the rocker which transfers the movement to a flat horizontal movement compressing the spring on the coil over and pushing the piston into the damper.

This suspension system used by all NGTC’s  is more advanced than the Mcphearson strut systems used in other s2000 touring cars and is in fact used by most single seaters and should allow some very fast corner speeds.

Feel free to leave any comments below or email me at btcctechnical@gmail.com. Also don’t forget to follow me on twitter: @btcc_technical so you don’t miss any new blog posts.

Latest sneak photos of Honda’s new BTCC machine.

Honda Racing (Team dynamics) have released some sneak photos revealing there new NGTC racer, via their face book page: ( http://www.facebook.com/HondaRacingBTCC )

Lets take a quick look at these photos and compare the new NGTC to the standard road going 2012 Civic.

So what can we see in these photos? well as intended by Dynamics/Honda not very much unfortunately…

However you can see the considerable fibre glass wheel arch extensions which have been bonded on to the shell to accommodate the new NGTC subframe and suspentions mechanical width of 1875mm, which is 105mm above the standard car width of 1770 mm, This additional width is highlighted in highlighted point 1 for the front and Point 3  for the rear.

highlighted point 2 shows that the dark plastic section of the standard civics bumper has now been colorour coded to the rest of the body,

One  interesting thing we can notice from looking at the rear images of the car is that Team Dynamics have fitted a different specification rear spoiler (or at least spoiler end plates)  to the rear of their Civic. This is shown below compared to the Specified rear wing fitted to the Toyota Avensis and RAR Audi A4.

It is quite apparent from these photos that the end plate for the spoiler is of a different shape and specification. It may be that Dynamics have had special dispensation to run this different design wing from TOCA as there is a lack of space at the rear of the Hatch back Civic to fit the large wing end plates, unlike the more traditionally saloon shaped Audi and Toyota.  It may of course be that this new shape is now available and in the regulations for all teams to use in the 2012 season.

The rear wing of a Touring car is predominately for aesthetic reasons and it serves little aerodynamic affect on to the cars other than perhaps increasing drag.  Most teams front wheel drive touring cars run the rear wings at a neutral setting as adding “down force” to the rear of a front wheel drive is not desirable.

The photos released by Dynamics show that at least one of their BTCC cars is basically complete in good time for the start of next season.

Feel free to leave any comments below or email me at btcctechnical@gmail.com. Also don’t forget to follow me on twitter: @btcc_technical!