Archive for March, 2008

Continental Corporation acquires Siemens VDO

Competition is expected to increase for parts supply tenders for local automotive manufacturers after Germany’s Continental’s purchase of Siemens VDO announced last December. Siemens VDO currently sells instrument panels as well as a range of motors, electrical components and exports all the instrument binnacles for BMW motorcycles. The impact on local Australian after-market parts suppliers remains to be seen.

Visit here for the full article.

March 22, 2008 at 5:43 am Leave a comment

Our Experts on: Hot Tyres and the Grand Prix

Our tyre experts are a bit motorsport mad over here at CarbonBlack, so they’re currently quite engaged in the Melbourne Grand Prix. This year, the high temperatures generated trackside at Melbourne during the first 2008 Formula 1 Grand Prix brought quite a bit of comment about “Tyre Grain” and its effect on tyre adhesion. Here’s one of our tyre experts, David Matthews:

During a race tyres generate heat, mostly within their interior. The most heat is produced when the tyre is new, and gradually declines as the tyre wears away its rubber tread and settles in, the latter happening very quickly at formula 1 speeds. But the heat generated in the tyre can’t get away quickly when the road is a hot 52 degrees, and the ambient temperature is in the high thirties as it was in Melbourne.

The tyre surface rubber undergoes a chemical change called “reversion’, the physical state changes, it becomes less resilient, and “goes gooey” on the surface, and in the tread rubber interior as well. Under the high slip which the car generates at extraordinarily high cornering, acceleration and braking forces, the degraded surface rolls up into little balls of rubber. The fact that it is now the driver controlling these forces, instead of a “you beaut” computer, probably accentuates this because of driver variations in technique.

The cars are very light, the tyres do not deflect much, which helps to keep them running cool. The lack of deflection also diminishes the effect of the “standing wave” which is extraordinarily destructive on tyre casings. Basically, this is caused by the tyre not having sufficient time to recover its shape away from the road contact patch, before it’s back on the road again!

As the tyre wears, there is less reversion of the rubber because the interior of the tyre tread is not generating as much heat (because it has worn away), and the ‘gooey balls” may disappear, and lap times improve.

Reminds me of the old jingle, now paraphrased a little to read:-
“The tyres drove on the burning road
Going round and round like mad
Rolling it up in sticky balls.
Driver says “that’s bad””.

As for last year, the rules now state that drivers must use tyres of different compounds for at least part of the race, such variations being discernible from the white stripes painted in the tyre tread grooves. If you want to know more about the difference between “hard” and “soft” compounds, go to “all about tyres” formula 1 at www.carbonblack.com.au.

Most teams ran “hard” tyres for as long as they could because they run cooler under the conditions experienced. The rule was introduced to give team managers yet another tactical variable to control to get the best result for their car, for a particular track and conditions.

What is significant is that I did not see a tyre failure on any car during the race. Take a bow, tyre engineers!

March 17, 2008 at 4:34 am Leave a comment

Our Experts on: Tyre pressure, part 2

We explored Tyre Pressures on the CarbonBlack blog in the last post. Now, let’s move on to a specific example, using our newfound tyre knowledge for some detective work.

First, consider the tyre pressure for a VX/VT series Commodore. According to the Tyre and Rim Association load tables, 4 tyres under a Holden Commodore inflated to 250 kPa (36 p.s.i.) can carry a load of 2.6 tonne. That’s a pretty overloaded Commodore. With two passengers and luggage, you’re weighing in at about 70% of that. According to the Tyre Standards, that means you only need about 23 psi in the tyres of your average Commodore.

But if you look at the actual tyre placard on a Commodore, it says to inflate the tyres to 26-29 psi. Why the difference? First off, because engineers generally don’t specify pressures that are barely adequate – that way lies trouble. Secondly, a Commodore with tyres inflated to 23 psi would handle like mush. As we’ve noted before, the higher the pressure, the better the handling.

Here’s where our detective work comes in. What if we look at the tyre placard for a Calais? For those not acquainted with it, the Calais used to be thought of as half of a limousine ride – a luxury car. However, if you look at the tyre tables, the tyre pressure specified is 36 psi, significantly higher than the Commodore. That gives you some quite twitchy steering, and means you feel a lot more bumps – not exactly what’s expected when you buy a luxury vehicle.

So what caused the engineers who designed the VE Series Holden Calais to specify such high pressures? GMH is very coy about the weight of the car- it cannot be found in the owner’s manual, only the maximum weight permitted over each axle. The answer might be found in the delays that accompanied the release of the new VE model Holden. Loaded with extras, the VE Calais did not meet the intended design parameters for fuel consumption. Reportedly, the engineers were chasing a figure 0.1 litres per 100 km lower. Their solution apparently was to increase the tyre pressures. This lowers the rolling resistance of the tyres, and improves fuel consumption. There is a lesson here for all of us, if the fillings in your teeth can stand the ride – increase the tyre pressures, and your fuel consumption will reduce. Even maintaining the pressure at that intended will pay off in lower fuel consumption.

So have a look for your tyre pressure placard somewhere on the car, or in your car handbook. Mostly, it’s on the driver’s door or door pillar. It specifies the pressures that the car engineers are happy with to make the car ‘handle’ the way they want it to. If the fillings in your teeth can’t cope with it, accept that there is a penalty involved, paid for at the fuel bowser.

DISCLAIMER.
The writer drives a VX SS Commodore, and would just love to get his hands on a VE 6 litre “SS”, because “it handles”.

March 3, 2008 at 8:11 am 4 comments