Brake Balancing
Discussion
I accept that ABS is at the moment the safest braking system but that aside if a car had equal size brake discs and callipers would a car handle better under most hard braking manoevres if front and back brakes were adjusted to give an equal amount of braking.
I understand that under normal braking the front brakes do 80% of the stopping and so weight transfer comes into it.
When racing cars have brake balancing done by the driver as he is racing does this mean left and right or front and back.
If weight tranfer and so front wheel braking is a deffinate advantage then why does`nt a car manufacturer design a car with front wheel drive and bigger wheels on the front rather than the back.
And finally if 80% braking on the front and 20% braking on the back is the best way of braking surely dics brakes on the rear of a average car are unnessesary, unless its for cost or weight reasons.
I understand that under normal braking the front brakes do 80% of the stopping and so weight transfer comes into it.
When racing cars have brake balancing done by the driver as he is racing does this mean left and right or front and back.
If weight tranfer and so front wheel braking is a deffinate advantage then why does`nt a car manufacturer design a car with front wheel drive and bigger wheels on the front rather than the back.
And finally if 80% braking on the front and 20% braking on the back is the best way of braking surely dics brakes on the rear of a average car are unnessesary, unless its for cost or weight reasons.
gdaybruce said:
I once attended a course where this issue was vividly demonstrated on a car with the ABS disabled. By using the handbrake at the same time as the foot brake, thereby increasing the braking effort at the rear, the overall stopping distance was reduced by about a third.
This is what i was thinking.
Now stay with me on this one, it might sound a bit redical.
If the speed limits 50 years ago were for the average car with average stopping distances, lets say a Ford Pop and may be 100 feet at 30 mph then stopping distances have improved.
The highway code says 30 feet plus 45 feet making it 75 feet so instead of saying the speed limit is 30mph why don`t they say a 75 feet stopping distance.
This way manufacturer might improve 60 mph to 0 instead of 0 to 60 mph times and so distances.
Of course this might have to include a new test as part of the MOT just to prove that your car will stop quickly.
This way you could do 45mph as long as your car could according to munufacturers spacifications stop within 75 feet.
Stopping distance from 70 mph is 315 feet so beef your brakes up and drive faster on the motorway.
No i don`t think it would get accepted either but nice to dream.
gdaybruce said:
One of the advantages of track days is that you get the chance to brake as hard as possible from high speed and to see what happens.
Next time you get chance do a little jink to the left then a jink to the right just as you slam the brakes on, only try this in the wet i might add.
Watch what happens, but don`t bottle out, keep you foot firmly planted.
Stick with it and you should complete a 360 or lift off at 180, but if you intend lifting at 180 get ready to be looking out your back window.
And for my next trick.....
I think now we are getting to the point were the term "Driving by the seat of your pants " comes in.
When i took my car test 33 years ago nobody mentioned pumping the brake peddle if the brakes lock up, but when i took my HGV test 17 years ago they made a big point of it .
Now i would guess that with ABS being the norm even on the HGV test they don`t bother mentioning it.
What i have noticed when you brake that hard (lets say in the wet) that wheels start to lock up, you have to listen and "feel" which wheels are locked and which ones are turning.
If the back is trying to come round on you, the backs locked up.
If the steering is non existant, the front is locked up.
Have you ever expearienced a "tank slapper2 on a motor bike, I have at 90mph going into a curve when i backed off the throttle.
This is caused, so i am told because the frame becomes less rigid and so snakes what you are supposed to do is accelerate out of it to make the frame rigid and so stop the tank slapping motion.
If a simmilar principal is taking place when a four wheeled vehicle is braking then i just thought that rear wheel braking should be a bit more important than it seams to be.
Still its all part of the fun ar driving, I don`t think any of us want too many driving aids, do we?....
When i took my car test 33 years ago nobody mentioned pumping the brake peddle if the brakes lock up, but when i took my HGV test 17 years ago they made a big point of it .
Now i would guess that with ABS being the norm even on the HGV test they don`t bother mentioning it.
What i have noticed when you brake that hard (lets say in the wet) that wheels start to lock up, you have to listen and "feel" which wheels are locked and which ones are turning.
If the back is trying to come round on you, the backs locked up.
If the steering is non existant, the front is locked up.
Have you ever expearienced a "tank slapper2 on a motor bike, I have at 90mph going into a curve when i backed off the throttle.
This is caused, so i am told because the frame becomes less rigid and so snakes what you are supposed to do is accelerate out of it to make the frame rigid and so stop the tank slapping motion.
If a simmilar principal is taking place when a four wheeled vehicle is braking then i just thought that rear wheel braking should be a bit more important than it seams to be.
Still its all part of the fun ar driving, I don`t think any of us want too many driving aids, do we?....
GarryM said:
I can't quite see how chassis flex would cause the tank slapper you experienced. It sounds more like weight transfer as mentioned earlier in this thread:
RobM77 said:
If you decelerate in a bend, the front will get more grip than the rear and you will start to oversteer; and if you accelerate the opposite will happen...
When you say "the front will get more grip" surely if its gripping then more grip is not an issue.
I am certainly no expert when it comes to bikes although i passed my test at 19 and have quite a few bikes but not in the last 10 years.
When i had my little expearience i had a mate behind on his bike and said he thought i was going to get spat off the bike.
All i did was ease off the gas, i was no were near the limit of grip so i think the rear wheel moved forward a fraction causeing the whole bike to become less rigid and so it flexed.
The tank slapper started and got worse but as i was trying to slow down without braking and the curve became less the slapping motion eased and i got back on the gas and chased after my other mate who had pulled away by about 400 yards.
Oh how we laughed afterwards but i was shitting myself at the time and looking for the softest place to land, the lad behind said he really did think i was going to get thrown off.
A more rigid frame and rear swinging arm lessen the chances of a tank slapper with a bike but i don`t think oversteer on a car can be cured by taking this route.
If the front of the vehicle is slowing down better than the rear of the vehicle then the rear will try to come round on you, somehow.
Now i`m stating the bleeding obvious, sorry i`l get my coat.
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