Nose dip when hard braking

[Slowmo]

I noticed in some of my previous cars, some cars does a nose dive when doing hard braking and some doesn't - you just feel the entire car going lower.

 

Does it have anything to do with rear disc brakes vs rear drum brakes? Or its essentially the brake pump system thats the culprit?

[Mach]

More likely front suspension/ shock absorbers too soft

[Genie47]

Nope. It has everything to do with momentum. The suspension influences this as well. I like this dipping action. To me, that is weight transfer. Excellent when I need that extra traction for that tight turn.

[Slowmo]

Hmm, I beg to differ, the weight transfer from back to front sort of scares me. I'm not sure why but I feel sharper over steering around corners as if i'm just rushing towards the wall when I hit the brakes during a bend. Is this due to a FF vehicle or because of the nose dipping characteristics?

 

The other type of 'dipping' is the entire car goes lower (i think), but the shift from back to front is not that prominent although engine is always heavier infront.

 

 

If as what the bro above said, then very likely the suspension for the nose diving car is not as good as the other that doesn't nose dive?

Edited August 1, 2007 by Slowmo

[Eyke]

yes, soft suspension causes nose-diving on braking as the weight transfer from back to front compresses your front springs, and it's not a good thing.

 

sit in old taxis and you will definitely notice it.

 

so either you change to better (harder) suspension or moderate it by avoiding hard braking and do your braking before the bend (not during a bend).

[Icetrap]

It's a very complicated issue to factor in a lot of things,. Example, Friction coeiffeicent of brake pad, amount of braking force, tyre adhesion, weight transfer, etc all play a part!

 

Our Brake biasing for FF cars (Front engine, Front wheel drive) example like around 80% front 20% rear. If your rear brakes are stronger than your front, it may cause your rear brakes to lock up. When you turn, you will know the feeling of spinning out or fish tailing out of it.

 

Braking causes the lift force exerted by the ground on the front tire, to be greater than lift force exerted by the ground on the rear tire.

 

Literally, in simple English, the rear end gets light, to correct the nose diving, you can have a stiffer front suspension setup, better rear brakes. You can also change the suspension setup for the car.

 

This is normal. My car has upgraded brakes for the front and rear. But the front still bites so much better and it tends to nose dive when I brake hard.

 

On Brake Pumps

 

A brake pump system usually does not effect the nose diving effect, only pedal sensing of your brake pad. Braking distance is not really improved, though most drivers perception is that it improved.

 

But the brakes get sensitive as in, when you press little, you know that the brakes bite earlier. For instance, you used to depress 4cm to deaccelerate at 20km/s, now maybe you need say, 2.5cm to achieve that, by changing the master cylinder piston area. It is due to this, people think their brake got better.

Edited August 1, 2007 by Icetrap

[Icetrap]

I'm not sure of your car, but i assumed it is a FF Car (Front engine, Front wheel drive) For driving FF cars during track, please use the "Slow in, Fast Out" Rule

 

Please avoid braking and turning at the same time. While you are turning and braking can cause the vehicle not to

 

1)Slow down as much

2)turn in as well as before the corner

 

Trackies and Races follow in a certain line. They usually brake Hard at the correct point, make the corner, then use the accelerator. Too much braking, means your car is not able to pull out the corner, also if your car is not a high powered one, your revs will drop too much

 

In the straights before and after the corner has its own purpose and separation of brakes and turning gives the best traction for the vehicle to make a desired corner. Which in simple english, there is one Best point to brake before the corner.

[Genie47]

FF car no choice. Weight transfer is advantageous for maneuvers. You have to take advantage of that for really hard turns.

 

Not anyone can do it. BTW, I practise left foot braking.

Edited August 1, 2007 by Genie47

[Icetrap]

Same here. I do it too, but only if I'm in the mood.

[Slowmo]

FF car no choice. Weight transfer is advantageous for maneuvers. You have to take advantage of that for really hard turns.

Probably I have not enough experience in this weight transfer phenomenon to be able to take advantage of that. In the end what happened is that I will take corners purely using steering and engine. But I believe at speeds not as fast as what you are doing on tracks.

 

 

Not anyone can do it. BTW, I practise left foot braking.

 

I do that only at junction stops to rest my right leg.

[Slowmo]

Thanks for taking the time to write such a long post

Our Brake biasing for FF cars (Front engine, Front wheel drive) example like around 80% front 20% rear. If your rear brakes are stronger than your front, it may cause your rear brakes to lock up. When you turn, you will know the feeling of spinning out or fish tailing out of it.

What happens if the breaks are equally balanced? I mean, to the extend that car's front don't dip but doesn't fish tail either? Possible? I've driven some cars that doesn't exhibit the front dip, but I can't be sure if it fishtails, because I don't take corners that hard.

 

On Brake Pumps

 

A brake pump system usually does not effect the nose diving effect, only pedal sensing of your brake pad. Braking distance is not really improved, though most drivers perception is that it improved.

But what if there is 'tuning' (not sure if this is possible) to have the rear brakes bite earlier or harder than the front brakes? Will this remove the 'nose dipping'?

 

 

I'm not sure of your car, but i assumed it is a FF Car (Front engine, Front wheel drive) For driving FF cars during track, please use the "Slow in, Fast Out" Rule

 

Please avoid braking and turning at the same time. While you are turning and braking can cause the vehicle not to

 

1)Slow down as much

2)turn in as well as before the corner

i think i've experienced #1 and #2 when the car is going 'fast' and braking during the corner. It felt like a total change of inertia.

 

Trackies and Races follow in a certain line. They usually brake Hard at the correct point, make the corner, then use the accelerator. Too much braking, means your car is not able to pull out the corner, also if your car is not a high powered one, your revs will drop too much

I'm curious about this line thing, isn't there always an ideal 'line' to follow on any road/track? As in, the shortest path, which is in the inner portion of any curves?

 

In the straights before and after the corner has its own purpose and separation of brakes and turning gives the best traction for the vehicle to make a desired corner. Which in simple english, there is one Best point to brake before the corner.

Sounds simple but gives me headache when i try to visualise it

Just a curious question, how fast usually before a bend and how much deceleration?

[Eyke]

it's simple, just brake before the turn, which'll transfer weight to the front wheels for added traction.

[Unfazed]

Left Foot Braking is strongly discouraged by driving experts or trainers. It is a technique created from nowhere and goes against the fundamentals of driving. May get you into trouble pal if unfortunate situation occurs, pal.

[Unfazed]

I'm not sure of your car, but i assumed it is a FF Car (Front engine, Front wheel drive) For driving FF cars during track, please use the "Slow in, Fast Out" Rule

 

Please avoid braking and turning at the same time. While you are turning and braking can cause the vehicle not to

 

1)Slow down as much

2)turn in as well as before the corner

 

Trackies and Races follow in a certain line. They usually brake Hard at the correct point, make the corner, then use the accelerator. Too much braking, means your car is not able to pull out the corner, also if your car is not a high powered one, your revs will drop too much

 

In the straights before and after the corner has its own purpose and separation of brakes and turning gives the best traction for the vehicle to make a desired corner. Which in simple english, there is one Best point to brake before the corner.

 

That's a gd golden rule. Yes we should all moderate our speed or brake before a bend, ensure we are in the right gearing and accelerate out of the bend gradually. If enters into a corner too fast then brake, weight transfer will happen as the weight shift more to the front and the gripping of the whole vehicle might be compromised, understeering may occur if I m not wrong. Many drivers in Sg have no regards for corners, how many times have we seen cars braking when they are taking corners? Plentiful... and that's y we r named as lousy drivers up north.

[Icetrap]

Thanks for taking the time to write such a long post Smile

 

Sure, no problems. I do love to discuss about technical issue. It's through the forums we learn more from each other and share information to gain knowledge.

 

What happens if the breaks are equally balanced? I mean, to the extend that car's front don't dip but doesn't fish tail either? Possible? I've driven some cars that doesn't exhibit the front dip, but I can't be sure if it fishtails, because I don't take corners that hard. Lips Are Sealed

 

Seldom you will see a car with a rear brakes bigger than the front. To fully understand this, we need a science/physics lecture. Calculations need to be done and will bore everyone here. However, let me reply in layman's term : Brakes should not be equally balanced.

 

Physics Lesson 1

 

Braking causes a weight transfer. The rear weight of the car is transferred to the front. Imagine, if your brakes are better at the rear; Which means, you can do a takumi drifting style pattern everytime you stop at the Corner.

 

Remember how do people do handbrake turns? Pulling the hand brakes right while accelerating? So in short, it will cause a pivot kind of pattern where, a simple turn of the steering wheel will get you drifting while the front is still moving, aka, Car is fishtail! For the pros, I used a lot of wrong terms and theory, but this is simpler to understand

 

But what if there is 'tuning' (not sure if this is possible) to have the rear brakes bite earlier or harder than the front brakes? Will this remove the 'nose dipping'?

 

Yes, if you increase your calipers/brake pads(braking coefficient) at the rear you will have less 'nose dipping' Take note it may also be easier for your to 'drift' your car if you were to turn sharply suddenly. Note that our car manufacturer spent time doing proper research to design a car and how it brakes. Most car are usually setup so you are able to brake properly.

 

Let me paint you a scenario. I've tried to increase my Rotors and Calipers size of my car for the Front. Yes, braking is much much better! But, I have to modulate my brake peddle properly or else it will cause my front end to 'nose dive' slightly when hard braking. Trying to correct it, I changed my rear from drums to disc, however the braking is still 'nose diving' when i slammed my brakes.

 

Reason : I messed up the weight transfer/balancing/braking for my car as per compared to manufacturer stock specs.

 

I'm curious about this line thing, isn't there always an ideal 'line' to follow on any road/track? As in, the shortest path, which is in the inner portion of any curves?

 

There are different lines to take at different speeds. Some cars may perform better using different lines. A 4WD, FF or FR Car corners different! But do keep to your own lane in Singapore! I've seen heros taking the racing line in 99 corners, that's simply asking for death.

 

In the track, it's a different story. The 'ideal' line may be outer/Inner/outer. Take note although there be different variations. It's hard to show lines without drawings here!

 

You can refer to the website below for racing lines: http://www.xxxxxxx.com/articles/article.p...pageid=1&view=1

 

Sounds simple but gives me headache when i try to visualise it Laugh

Just a curious question, how fast usually before a bend and how much deceleration?

 

Again every car performs differently with different mods. How fast usually? Different cars can take corners at different speed. Different lines means, different braking points, different acceleration point!

 

Experience will tell you how fast you can go dude! When your car ends up hitting the curb or diving into the wall, that is too fast.

 

Ok, jokes sides! The car should not be understeering or oversteering at the speed you are at taking the corners, that will be the best speed.

 

In short, when you turn, the car should turn and not go straight instead. When you turn, the car backside should not be fishtailing and spinning you out of the corner.

Edited August 1, 2007 by Icetrap

[Icetrap]

No la you cannot blame some drivers here. Most people who are speeding tend to brake too late. Only when in the corner, you start to panic and it will be too late!

 

Experience on the same road and same corner will tell you how fast you can take the corner, when you can accelerate out from the corner.

[Slowmo]

Thanks for the replies!

 

One question (refer to attached diagram below)

 

is there a problem taking a line like this one?

2 scenerios:

1)

a. slow to 140km/hr

b. increase rev, maintain 140km/hr

c. 140km/hr accelerate

 

2)

a. slow from 140km/hr to 130km/hr

b. start acceleration with high rev

c. should hit about 160km/hr by this point

 

 

if at point b where brakes are stepped, the front of most car tends to dip very low and somehow feel that i'm heading straight for the nearest kerb. signs that the suspensions are gone?

 

disclaimer: speeds just for theory discussion and does not reflect my current or previous driving.

Edited August 2, 2007 by Slowmo

[Unfazed]

Yup these are the ppl who only know how to speed but dunno how to gauge. The golden rule is like what u said slow in fast out. The sooner we can accelerate outta the bend, the higher the chances we can be fastest when outta the bend. I learn this in my yrs of riding and I applied it into driving. Bcos for bikes, there's no room or only very little room for mistakes, enter into a corner too fast then brake, we find ourselves heading towards kerb, if lucky enuf by then speed may drop and the bike will listen to the rider again but somehow it will be near the kerb. For bikes, to counter this is to lean more but that will depend on the balls of the rider. Cheers...