why do rally-bashers drive sideways on bitumen?

why do rally-bashers drive sideways on bitumen?

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btwango

Original Poster:

26 posts

252 months

Tuesday 24th April 2007
quotequote all
the heading asks it all. I thought driving side-ways on bitumen resulted in slower times. I mean you dont see tin-tops going side-ways (i mean deliberatley) on asphalt tracks.

thanks for the replys,
b

sosidge

687 posts

216 months

Tuesday 24th April 2007
quotequote all
On certain courses there literally isn't enough space on the road to navigate the tight corners using the "racing line", so they bring the back end around and slam on the power early.

Plus for a lot of the drivers sideways is their "style" and they find it hard to adapt to the tarmac rallys. Hence the multitude of tarmac "specialists" over the years.

Loeb was seen as a tarmac specialist at first though, so it shows that a less sideays style can be fast in all conditions.

TheOriginalGT40

334 posts

205 months

Tuesday 24th April 2007
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I'm no expert in the art of driving fast on the black stuff, but does it allow the driver/car to maintain a higher degree of momentum by going sideways, rather than braking sooner and loosing speed through the corner..?

munter

31,319 posts

242 months

Tuesday 24th April 2007
quotequote all
Tighter corners. The rally cars dont get it sideways on the nice sweeping corners either. But when you need to turn 180 in 12 feet then the car's got to slide. That said if you watch the BMW's in this years BTCC theres a bit of sliding around going on there...

FNG

4,178 posts

225 months

Tuesday 24th April 2007
quotequote all
Also, rally drivers don't get to approach 12 corners repeatedly and perfect the line, approach, turn-in, etc.

A lot of the skill of rallying is translating the notes into meaningful info that prepares you for the basic corner and how to exit it correctly for the next one.

But the rest is adapting to what you encounter at the corner and adjusting the speed in, turn-in position, throttle-on point etc accordingly.

They just can't take a perfect racing line based on the notes and prior view they get of each corner as they approach it.

So arriving at the corner with the car unsettled allows adjustment of approach by scrubing off more or less speed than they might initially expect, assessing the grip on entry and in the middle of the corner, and altering the throttle application as a result.

Basically, it makes it possible to slide the car sideways to scrub speed off if approaching slightly fast, or adjust the line for an earlier apex and earlier throttle application if not approaching fast enough.

Same principle for gravel, just more sideways and more scrubbing speed going on as a matter of course.

cptsideways

13,551 posts

253 months

Tuesday 24th April 2007
quotequote all
It allows you adjust your line on the entry, an increase in speed widens the line, decrease tightens it. Or keep it in to carry on.

Requires considerable skills to drive blind without pace notes like they used to!

Jungles

3,587 posts

222 months

Tuesday 24th April 2007
quotequote all
btwango said:
the heading asks it all. I thought driving side-ways on bitumen resulted in slower times. I mean you dont see tin-tops going side-ways (i mean deliberatley) on asphalt tracks.

thanks for the replys,
b

Some factors in no particular order:

1. Many professional gravel rally drivers feel more confident driving sideways than "clean". They're just doing what they feel to be most familiar, even on tarmac.

2. Some rally cars do not cope well with tarmac-friendly setups, and need to slide to obtain maximum acceleration around bends.

3. Very tight corners in slippery conditions can often be negotiated faster by hand-braking or power sliding, depending on setup.

As an aside, back in the pre-70s days, when most racing cars had cross-ply tyres and drove on dinky tarmac roads/tracks, drifting around corners was the order of the day. This was especially the case with understeer-heavy cars, like the Mini, which needed to be driven very aggressively. Even F1 cars did a lot of four-wheel drifting.


Edited by Jungles on Tuesday 24th April 15:59

mat205125

17,790 posts

214 months

Tuesday 24th April 2007
quotequote all
Taking the topic from the other direction, the reason that more circuit tin top cars do not slide their cars more is that it would:

- make them very open to a little tap to spin them off of the track

- wear their tyres to an extent that would damage their overall race performance

- touring cars these days are largely FWD

- GT racers have far greater mechanical grip and aero grip than a rally car, and therefore can deploy all their power without sliding - a rally driver points the car in the direction he wants to apply power to.

GreenV8S

30,209 posts

285 months

Tuesday 24th April 2007
quotequote all
Just a guess, but if the car had a locked or very tight diff then it might be prone to understeer until the tyres had been broken loose but more balanced once it was drifting?

Nick_F

10,154 posts

247 months

Tuesday 24th April 2007
quotequote all
I spent a day on gravel in a GpN Impreza last year and it took me most of it to get my head around trail braking and the other counter-intuitive stuff needed to make a front-engine 4wd car go fast on gravel. I asked the instructor what the fastest method on tarmac was - and he said the same, trail brake to get turn-in and then boot for the exit as soon as the car is pointing the right way.

The technique only generates dramatic drift in slower corners, and it eats tyres like nobody's business, which I guess is why you don't see it going on on the track even when the corners are tight enough to make it work.

mat205125

17,790 posts

214 months

Wednesday 25th April 2007
quotequote all
Nick_F said:
I spent a day on gravel in a GpN Impreza last year and it took me most of it to get my head around trail braking and the other counter-intuitive stuff needed to make a front-engine 4wd car go fast on gravel. I asked the instructor what the fastest method on tarmac was - and he said the same, trail brake to get turn-in and then boot for the exit as soon as the car is pointing the right way.

The technique only generates dramatic drift in slower corners, and it eats tyres like nobody's business, which I guess is why you don't see it going on on the track even when the corners are tight enough to make it work.


Great fun though ain't it evil

MrKipling43

5,788 posts

217 months

Wednesday 25th April 2007
quotequote all
mat205125 said:
Taking the topic from the other direction, the reason that more circuit tin top cars do not slide their cars more is that it would:

- make them very open to a little tap to spin them off of the track

- wear their tyres to an extent that would damage their overall race performance

- touring cars these days are largely FWD

- GT racers have far greater mechanical grip and aero grip than a rally car, and therefore can deploy all their power without sliding - a rally driver points the car in the direction he wants to apply power to.


And (with current tyre technology) it's far slower than driving round properly.



Edited by MrKipling43 on Wednesday 25th April 09:00

BEP

346 posts

206 months

Wednesday 25th April 2007
quotequote all
Nick_F said:
I spent a day on gravel in a GpN Impreza last year and it took me most of it to get my head around trail braking and the other counter-intuitive stuff needed to make a front-engine 4wd car go fast on gravel. I asked the instructor what the fastest method on tarmac was - and he said the same, trail brake to get turn-in and then boot for the exit as soon as the car is pointing the right way.

The technique only generates dramatic drift in slower corners, and it eats tyres like nobody's business, which I guess is why you don't see it going on on the track even when the corners are tight enough to make it work.


Are you meaning left foot braking by 'trail braking'?

MrKipling43

5,788 posts

217 months

Wednesday 25th April 2007
quotequote all
BEP said:
Nick_F said:
I spent a day on gravel in a GpN Impreza last year and it took me most of it to get my head around trail braking and the other counter-intuitive stuff needed to make a front-engine 4wd car go fast on gravel. I asked the instructor what the fastest method on tarmac was - and he said the same, trail brake to get turn-in and then boot for the exit as soon as the car is pointing the right way.

The technique only generates dramatic drift in slower corners, and it eats tyres like nobody's business, which I guess is why you don't see it going on on the track even when the corners are tight enough to make it work.


Are you meaning left foot braking by 'trail braking'?


Probably not, they're very different things...

Nick_F

10,154 posts

247 months

Wednesday 25th April 2007
quotequote all
No, I'm taking about braking deeper into the corner than I would consider with a RWD car in order to keep the weight over the front wheels and help turn-in.

BEP

346 posts

206 months

Wednesday 25th April 2007
quotequote all
Aha no worries with you now, can't say i've ever heard a rally driver use the term 'trail braking ' that's all.

I'm taking it he also taught 'left foot braking' to counter the turbo lag through the bend + to keep a semblance of balance?

Funny old thing rear wheel drive on gravel is that it takes a while to get your head around flicking the car right before a left hander and vice versa so as to unbalance the car so to speak and get better turn in,took me a few events that one!!LOL


Edited by BEP on Wednesday 25th April 14:21

Nick_F

10,154 posts

247 months

Wednesday 25th April 2007
quotequote all
In fairness I don't think the instructor called it trail braking either, just me...

Using the left foot wasn't on the agenda - too much to tackle in a single day, I guess.