How can a driver know that wheels are close to locking ?

mithun · 14th May 2007, 06:05

How can a driver know that wheels are close to locking in a non-ABS vehicle ?

Based on my knowledge : As the front wheels tend to lock, small tugs can be felt through the wheel actually pulling away from the locking road wheel. When these tugs are felt it's the right time to ease off the brake pedal a fraction and stay at the threshold without exceeding it.

Is there any other methods/tips/tricks to identify that the wheels are getting locked up so that we respond defensively ?

Vid6639 · 14th May 2007, 07:56

yeah what you said is right. you do feel the skidding of the tyres from the pedal and accordingly modulate teh brake pedal.

Ofcourse this cant be done everytime.more often than not this is not the case for panic braking wherein you just stand on the pedal and pray for dear life.

theMAG · 14th May 2007, 09:10

Since its more likely the front wheels will lock up first, another sign would be the steering tightening making turning difficult

srishiva · 14th May 2007, 10:48

Quote:

Originally Posted by theMAG

Since its more likely the front wheels will lock up first, another sign would be the steering tightening making turning difficult

Or is it steering easy but the car keeps moving straight ahead.

theMAG · 14th May 2007, 10:52

Quote:

Originally Posted by srishiva

Or is it steering easy but the car keeps moving straight ahead.

Nope. Try turning a steering whose wheels are locked at speed. The car might move forward due to inertia. This scenario is for FW lock anyway

v1p3r · 14th May 2007, 11:56

Yes it moves forward, but the steering actually feels a lot lighter.

Vid6639 · 14th May 2007, 12:01

Exactly it does get lighter when locked. If it was heavier means it would be doing something and there would be friction. the fact that you lose steering when locked shows that the steering feels lighter.

No grip = light steering.

1100D · 14th May 2007, 23:46

There are a lot of tell tale signs based on the situations underwhich you are detecting a locked wheel. For a corner entry, its generally associated with a sudden understeer (which is more than the predicted understeer if any with the car). For straight line braking its generally the vibration on the car felt thru the pedal (steering provides understeer information while cornering), but it is generally felt naturally. As normal motion when the wheels are rolling is smoother and the moment the wheel locks its a little jerky at that point you just release a fraction (wont be able to quantify) till that jerk goes away (without failing to keep braking even while you release a bit).

But the best way to feel the locking is to do it actually on a relatively free piece of road and feel the responses rather than reading about it. But be cautious not to overdo it to flat spot the tyres.

mithun · 16th May 2007, 05:54

But all these happens within a nanosecond and to take counter actions seems to be a little difficult for most of the drivers. So how should we practice to save ourselves from such emergency situations ?

bottle · 16th May 2007, 09:34

learn to pump the brakes, guess older drivers will know how

srishiva · 16th May 2007, 10:01

For normal drivers its very difficult to know. You may lose direction if you are trying to turn. If you are going straight and didn't turn the steering at all, its difficult to know if the wheel has locked. For a turn you can modulate the braking and turn away. For a straight one its difficult. Well, the easy way to get prepared for the worst - ABS, Airbags.

Surprise · 22nd May 2009, 09:06

I wanted to open a thread on this subject, but thought how could it be a topic without this in TBHP, did a search and here is the thread on this
-------------

Quote:

Originally Posted by Dose

A few days ago, a friend of mine, driving an Alto, almost had a head-on accident with a lorry that was driving on the wrong side of a one-way, divided national highway under construction. It happened between 20:00 and 21:00 on an inclined S-curve under dry conditions. The Alto driver was driving downhill at 55-65 Kmph in the right lane and was in the process of overtaking a truck in the left lane, came around a curve, and saw the oncoming truck, which luckily had its headlights turned on, driving in the right lane.

The Alto driver had the reflexes to take evasive action but the surprise and danger of the moment caused them to lock up the servo-assisted, non-ABS brakes. As the brakes locked up, the truck in the left lane moved enough ahead to make space in the left lane for the Alto. Due to experience, the driver had the sense to release enough brake pressure to unlock the brakes and swerve into the left lane as the oncoming truck drove past.

I have never experienced "Brake locking" and do not want to be a newbie in a desperate situation. Read that locking of brakes can be done even at 40 KMPH. I wanted to experience locking of brakes on an empty ground, can someone guide me on how to do that. My understanding is standing on brakes will lock

, is there any other thing that needs to be uncovered. Tips/do's and dont please

cooldude1988765 · 22nd May 2009, 10:40

From what i experienced in my jeep (the wheels lock really easily)
1.If only one of the front wheel locks, it pulls to the side of the locked wheel. All you need to do to get back control is release brake and jab it again while turning steering the opposite side of the pull.

2. If only one of the rear wheel locks i start drifting in the opposite side of the locked wheel. This time i just enjoy the drift, never felt that any corrective action needs to be taken. My rear wheels usaully lock when i enter a corner at high speed (40-60kmph; i am talking about a jeep so it is a high speed corner

) and jab the brakes in the last second to avoid overcooking the corner.

3. When both my front wheels lock the steering judders violently and if i leave the steering it sometimes turns lock to lock but i still go straight. Release brakes and floor it again to regain steering control.

4. When both my back wheels lock the tyres screech like hell and is useful to scare off pedestrians walking in the middle of the road. Easiest way for me to lock the rear wheels is jab the brake really hard once lift and floor the brakes again. There are no adverse effects to steering or brake performance when the rear wheels lock.

It is only after driving the jeep i realised what i should do when my wheels lock.
Gurus please correct me if any of my ways are flawed. It has worked for me so far, but better be safe than sorry.

My tyres make some kind of noise before the wheels lock (Just before the screeching) Hard to explain but it sounds like rubbing a granite stone on a cement road.

Also when nothing else works shift to second and leave the clutch. This slows me downt to about 5-10kmph in the jeep.

greenhorn · 22nd May 2009, 10:45

I think the easiest ( and somewhat dangerous) way is to have your tyres actually lock up at some point - best this be done under controlled circumstances , say at a track. THen you'll know how much your tyres can hold.

I found out the hard way when my tyres lost grip on a waterlogged down ramp of a multi level parking lot. Now i know better

Again , grip will vary depending on conditions like dust. moisture nature of surface etc...

swift8847 · 22nd May 2009, 11:43

I've had a bad experience with wheels locking.

In my case the tires(Eagle F1) were at fault and the speed was about 130-140.

In this incident I never got any clues that the tires were locking, had to stop the car quickly, used engine brakes, braked hard and then the wheels lock.

Maybe I should try checking this thing in a controlled environment.

IMO the only alternative is good set of tires and brakes.

14th May 2007, 06:05	#1
mithun BANNED Join Date: Jan 2006 Location: Cochin Posts: 2,195 Thanked: 268 Times	How can a driver know that wheels are close to locking ? How can a driver know that wheels are close to locking in a non-ABS vehicle ? Based on my knowledge : As the front wheels tend to lock, small tugs can be felt through the wheel actually pulling away from the locking road wheel. When these tugs are felt it's the right time to ease off the brake pedal a fraction and stay at the threshold without exceeding it. Is there any other methods/tips/tricks to identify that the wheels are getting locked up so that we respond defensively ?
	() Thanks

14th May 2007, 07:56	#2
Vid6639 Team-BHP Support Join Date: Jul 2006 Location: Bangalore Posts: 17,709 Thanked: 44,135 Times View My Garage	yeah what you said is right. you do feel the skidding of the tyres from the pedal and accordingly modulate teh brake pedal. Ofcourse this cant be done everytime.more often than not this is not the case for panic braking wherein you just stand on the pedal and pray for dear life.
	() Thanks

14th May 2007, 09:10	#3
theMAG Distinguished - BHPian Join Date: May 2006 Location: Avon, CT Posts: 7,196 Thanked: 1,821 Times View My Garage	Since its more likely the front wheels will lock up first, another sign would be the steering tightening making turning difficult
	() Thanks

14th May 2007, 11:56	#6
v1p3r Senior - BHPian Join Date: Feb 2005 Location: BLR / DXB / LON Posts: 5,359 Thanked: 7,449 Times View My Garage	Yes it moves forward, but the steering actually feels a lot lighter.
	() Thanks

14th May 2007, 12:01	#7
Vid6639 Team-BHP Support Join Date: Jul 2006 Location: Bangalore Posts: 17,709 Thanked: 44,135 Times View My Garage	Exactly it does get lighter when locked. If it was heavier means it would be doing something and there would be friction. the fact that you lose steering when locked shows that the steering feels lighter. No grip = light steering.
	() Thanks

14th May 2007, 23:46	#8
1100D Senior - BHPian Join Date: Jun 2006 Location: Calcutta Posts: 4,390 Thanked: 4,116 Times View My Garage	There are a lot of tell tale signs based on the situations underwhich you are detecting a locked wheel. For a corner entry, its generally associated with a sudden understeer (which is more than the predicted understeer if any with the car). For straight line braking its generally the vibration on the car felt thru the pedal (steering provides understeer information while cornering), but it is generally felt naturally. As normal motion when the wheels are rolling is smoother and the moment the wheel locks its a little jerky at that point you just release a fraction (wont be able to quantify) till that jerk goes away (without failing to keep braking even while you release a bit). But the best way to feel the locking is to do it actually on a relatively free piece of road and feel the responses rather than reading about it. But be cautious not to overdo it to flat spot the tyres.
	() Thanks

16th May 2007, 05:54	#9
mithun BANNED Join Date: Jan 2006 Location: Cochin Posts: 2,195 Thanked: 268 Times	But all these happens within a nanosecond and to take counter actions seems to be a little difficult for most of the drivers. So how should we practice to save ourselves from such emergency situations ?
	() Thanks

16th May 2007, 09:34	#10
bottle Senior - BHPian Join Date: Sep 2006 Location: Chennai Posts: 1,641 Thanked: 293 Times View My Garage	learn to pump the brakes, guess older drivers will know how
	() Thanks

16th May 2007, 10:01	#11
srishiva Senior - BHPian Join Date: Nov 2006 Location: Bengaluru Posts: 4,372 Thanked: 2,260 Times	For normal drivers its very difficult to know. You may lose direction if you are trying to turn. If you are going straight and didn't turn the steering at all, its difficult to know if the wheel has locked. For a turn you can modulate the braking and turn away. For a straight one its difficult. Well, the easy way to get prepared for the worst - ABS, Airbags.
	() Thanks

22nd May 2009, 10:40	#13
cooldude1988765 Senior - BHPian Join Date: Feb 2006 Location: Bangalore Posts: 1,055 Thanked: 222 Times	From what i experienced in my jeep (the wheels lock really easily) 1.If only one of the front wheel locks, it pulls to the side of the locked wheel. All you need to do to get back control is release brake and jab it again while turning steering the opposite side of the pull. 2. If only one of the rear wheel locks i start drifting in the opposite side of the locked wheel. This time i just enjoy the drift, never felt that any corrective action needs to be taken. My rear wheels usaully lock when i enter a corner at high speed (40-60kmph; i am talking about a jeep so it is a high speed corner ) and jab the brakes in the last second to avoid overcooking the corner. 3. When both my front wheels lock the steering judders violently and if i leave the steering it sometimes turns lock to lock but i still go straight. Release brakes and floor it again to regain steering control. 4. When both my back wheels lock the tyres screech like hell and is useful to scare off pedestrians walking in the middle of the road. Easiest way for me to lock the rear wheels is jab the brake really hard once lift and floor the brakes again. There are no adverse effects to steering or brake performance when the rear wheels lock. It is only after driving the jeep i realised what i should do when my wheels lock. Gurus please correct me if any of my ways are flawed. It has worked for me so far, but better be safe than sorry. My tyres make some kind of noise before the wheels lock (Just before the screeching) Hard to explain but it sounds like rubbing a granite stone on a cement road. Also when nothing else works shift to second and leave the clutch. This slows me downt to about 5-10kmph in the jeep. Last edited by cooldude1988765 : 22nd May 2009 at 10:53.
	() Thanks

22nd May 2009, 10:45	#14
greenhorn BANNED Join Date: Apr 2007 Location: KL-01 Posts: 7,878 Thanked: 4,910 Times View My Garage	I think the easiest ( and somewhat dangerous) way is to have your tyres actually lock up at some point - best this be done under controlled circumstances , say at a track. THen you'll know how much your tyres can hold. I found out the hard way when my tyres lost grip on a waterlogged down ramp of a multi level parking lot. Now i know better Again , grip will vary depending on conditions like dust. moisture nature of surface etc... Last edited by greenhorn : 22nd May 2009 at 10:46.
	() Thanks

22nd May 2009, 11:43	#15
swift8847 BHPian Join Date: Aug 2007 Location: Bangalore/Houston Posts: 324 Thanked: 2 Times	I've had a bad experience with wheels locking. In my case the tires(Eagle F1) were at fault and the speed was about 130-140. In this incident I never got any clues that the tires were locking, had to stop the car quickly, used engine brakes, braked hard and then the wheels lock. Maybe I should try checking this thing in a controlled environment. IMO the only alternative is good set of tires and brakes.
	() Thanks