Amazon: Brakes how bad are they

[Underdrive]

Originally Posted by Clan

Indeed no one here has explained ABS properly ... it's sole purpose is:
TO BE ABLE TO STEER whilst using full brake pressure rather than the wheels locking and going in a straight line where ever you steer ...

I would disagree about it's SOLE purpose. It's certainly one of the benefits of ABS, panic/emergency braking where ABS usually comes into play will more often than not happen in a straight line.

[Laird Scooby]

Originally Posted by Underdrive

I would disagree about it's SOLE purpose. It's certainly one of the benefits of ABS, panic/emergency braking where ABS usually comes into play will more often than not happen in a straight line.

I would have to agree with that and rephrase it as "the primary purpose of ABS is to allow the driver to maintain control during emergency braking where a skid might otherwise have occurred due to a slippery road surface".

It isn't infallible though, an ex girlfriend many moons ago thought she could drive how she liked in cy conditions because she had ABS - result, one 4-wheel skid and a neat pirouette up the embankment!

Later (in warm, dry weather) same girlfriend shoved her mascara brush up her left nostril while applying mascara at 90mph on a bumpy road!

Draw your own conclusions about her driving but if a car doesn't have good tyres and suspension, even ABS won't prevent a skid in slippery conditions - it's a driver aid, no more, no less. In other words, drive like a numpty, involuntarily explore the scenery!

[Clan]

Originally Posted by Underdrive

I would disagree about it's SOLE purpose. It's certainly one of the benefits of ABS, panic/emergency braking where ABS usually comes into play will more often than not happen in a straight line.

in the many 10's of 1000's of miles i have driven in volvos since ABS was introduced in 1982 , ABS has never engaged with me . it will help in accident scenarios but it cant defy the laws of physics ie mass vesus speed verus tyre grip ... Its greatest benefit is being able to STEER whilst panic braking..

braking and steering will be an automatic reaction anyway ...

[Army]

Originally Posted by Laird Scooby

I would have to agree with that and rephrase it as "the primary purpose of ABS is to allow the driver to maintain control during emergency braking where a skid might otherwise have occurred due to a slippery road surface".

It isn't infallible though, an ex girlfriend many moons ago thought she could drive how she liked in cy conditions because she had ABS - result, one 4-wheel skid and a neat pirouette up the embankment!

Later (in warm, dry weather) same girlfriend shoved her mascara brush up her left nostril while applying mascara at 90mph on a bumpy road!

Draw your own conclusions about her driving but if a car doesn't have good tyres and suspension, even ABS won't prevent a skid in slippery conditions - it's a driver aid, no more, no less. In other words, drive like a numpty, involuntarily explore the scenery!

That sounds suspiciously like one of those "I have a friend with a problem" stories!

#####

As you say if there is to friction where the tyres meet whatever surface they are in contact with then nothing - not even a clever computer can do much about undesirable momentum...

...I've noticed (mainly on Top Gear) that cars now flash lights and indicators to draw attention to numpty activity behind the steering wheel / loss of stability / traction.

I guess these systems are going to have to get more and more advanced when cars really start to drive themselves. I assume they are going to have cameras that can sense speed in all driving conditions as well as sensors that detect changes in speed and acceleration of parts of the vehicle as well as the vehicle as a whole. GPS certainly isn't going to help - particularly at lower vehicle speeds.

If you were actually allowed to be an automotive engineer (rather than a yes man on a commitee) I think now would be a very interesting period of automotive development.

The introduction of newer thinking from some electric vehicler producers is essentially anarchy in the staid and lazy conventional automotive industry...

[Note I'm avoiding the use of the term "legacy car makers" as for some reason it reminds me of crappy computer software - can't imagine why]

[Army]

Originally Posted by Clan

in the many 10's of 1000's of miles i have driven in volvos since ABS was introduced in 1982 , ABS has never engaged with me . it will help in accident scenarios but it cant defy the laws of physics ie mass vesus speed verus tyre grip ... Its greatest benefit is being able to STEER whilst panic braking..

braking and steering will be an automatic reaction anyway ...

I've had to brake hard in my Mercedes W201 and have been startled by the pumping action feeling I got through the brake pedal - I really had to "think" [Imagine that! My freedom was disrupted by an undesirable emotion!] about not lifting my foot from the brake pedal to allow the ABS to do its job...

...I have no idea what it would be like to lock up wheels on a more modern car - especially something with fly by wire controls...

[Laird Scooby]

Originally Posted by Clan

in the many 10's of 1000's of miles i have driven in volvos since ABS was introduced in 1982 , ABS has never engaged with me . it will help in accident scenarios but it cant defy the laws of physics ie mass vesus speed verus tyre grip ... Its greatest benefit is being able to STEER whilst panic braking..

braking and steering will be an automatic reaction anyway ...

I've had the ABS engage on slippery surfaces under normal braking and only three times during emergency braking - i also used cadence braking some 20 years ago to prevent a multiple pile up on the M3 but someone behind me didn't know how to use cadence braking and didn't have ABS despite being in a new vehicle.

As i said when i rephrased the comment above, ABS is designed to help maiantain control which not only covers steering but also traction for braking and stability of the vehicle as well. Ideally you shouldn't be braking while steering but in an emergency situation those rules aren't always possible to apply.