I like RWD, but I also like FWD, but which is best?

Another great pub debate question, of course 4WD is the best solution, but some purists would call that cheating.

Technically its a very complex subject, not least because RWD or FWD is only a small part of the whole picture. Suspension geometry and weight distribution are critical, but also tyres have a dramatic effect, and a cunning change of rubber can change the car’s handling characteristics utterly.

Best traction is usually found when the most weight is bearing down on the driven wheels, favouring FWD or mid engine RWD, but of course the engine is usually less than 15% of a cars weight, and at speed the aerodynamics take over, so even that rule is not set in stone.

There are, of course, rules of thumb. Most dynamics engineers reckon that FWD works best for up to approximately 300 bhp, above that and the weight shift rearwards when accelerating favours RWD.

When accelerating out of corners, FWD will tend to accelerate the car in the direction the front wheels are pointing in, more or less, where as RWD will tend to accelerate the car along its centre line, which on a corner where the front wheels are pulling the front away from that line so the driving force pushes the back end out, so FWD cars can get on the power sooner. But as ever, either case can be engineered around.

Going fast down the road also depends to a surprisingly high degree on how well the car suits your driving style; if your car does exactly what you are expecting, under or over steering, then you will get the best from it. It’s that predictability and familiarity that allows you to place the car accurately and easily just where it needs to be. That’s why two team mate’s F1 cars from the same stable are often set up to handle very differently. Also visibility is important, if the corners apex is masked by a massive A pillar then you cant judge your position properly on your mountain road. Confidence is key.

This may go some way to explain why some people swear by one or other set up, there will always be die-hard RWD fans who just cant get to grips with FWD, and equally there are hoards of FWD evangelists who can’t understand why anyone would want a car that spins off the road when you accelerate round a corner.

Advertisements

About Ralph Hosier

I love exploring everything the world has to offer, the fabulous beauty and intricacies of nature, the stunning majesty and grandeur of the universe, and the fascinating range of chocolates available from the local sweety shop. I have led a charmed life, sure there has been extremes, but the highs far outweigh the lows. I get paid for arsing about in very fast cars, I get to write about them and amazingly get paid for this too. My days are usually filled by making prototype and concept cars for car companies, a dream job. I have lived many of my dreams, worked all over the world, raced cars built by my own hand (and hardly ever crashed really badly), seen things and done stuff. But nothing compares to the love of Diana and my son Peter, beyond my greatest hopes. I am a chartered engineer, a member of the Institute of the Motor Industry (IMI), and of the Institute of Engineering and Technology (IET) and I am a member of the Guild of Motoring Writers. A pleasing fact is that there are now more letters after my name than there are in it ;) R.Hosier B.Eng(Hons) C.Eng MIET MIMI MGoMW
This entry was posted in Technology Explained.. Bookmark the permalink.

2 Responses to I like RWD, but I also like FWD, but which is best?

  1. TheoryOfDriving says:

    great write up, you hit the nail on the head when you mentioned ‘tyres’. You could have the very best handling super car in the world, put wrong rubber on it and it’ll handle like a bag of spuds.

    Tyres, tyres. tyres !

  2. Ken Divjak says:

    It also depends on what you’re in the market for;

    Nowadays, hot hatches only come with FWD.

    And even if they do offer 4WD like one Jap Special,
    the Focus RS proves that FWD can be as much fun in anything but the current weather.

    So it’s more down to suspension tuning et all more than just FWD or RWD like Ralph points out.

    RWD on the other hand demands a higher skill level to extract the most out of,
    but is supposed to be even more rewarding when you get it right.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s