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Too much brakes penalty

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07CobaltGirl

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Post Sat Oct 10, 2015 10:04 am

Re: Too much brakes penalty

PMP1337 wrote:
ArnRno wrote:
PMP1337 wrote:There is a reason discs all around only became standard after ABS appeared.


Weird... The ONLY cars I've ever been in with 4-wheel discs have been non-ABS cars.

Such as?


In for examples. Most modern cars are 4-wheel disc, unless they're super economy busters. Most modern cars also have ABS, as they reduce insurance costs and increase safety measurements. I have ABS on my 2007, with 2-wheel disc, but it falls into the economy car group mentioned above. I would say the opposite is true. MOST cars with 4-wheel discs have ABS, unless they are more than 10 years old. But more likely this is because many cars 10+ years ago didn't have ABS at all.
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HighOctaneLove

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Post Sat Oct 10, 2015 1:32 pm

Re: Too much brakes penalty

PMP1337 wrote:
ArnRno wrote:
PMP1337 wrote:There is a reason discs all around only became standard after ABS appeared.


Weird... The ONLY cars I've ever been in with 4-wheel discs have been non-ABS cars.

Such as?


In Australia we've had non-ABS 4 wheel disc brake cars since 1987... :geek:

http://www.carsguide.com.au/car-reviews/used-car-review-mitsubishi-magna-tn-1987-1989-13310

ABS stops wheel lock-up so you can steer the car while hard braking. ABS actually makes the braking distance worse than a full lock-up as locked wheels provide more friction and stop the car quicker.
ABS trades off distance for control by allowing the driver to attempt to avoid the obstacle rather than hope they won't hit it. You don't need ABS to control disc brakes but you need disc brakes to run ABS.
The cars with drum rears has the ABS only working on the front of the car. :D
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Leonardo9613

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Post Sun Oct 11, 2015 3:52 am

Re: Too much brakes penalty

You managed to get all of your information wrong, hol.

My car, and lots of others, have 4-way ABS, but drums on the rear. Of course, drums aren't usually powerful enough to lock the wheels, but the system is there anyway. ABS does cut the stopping distance while making the car more controllable, as locked wheels don't provide as much friction as those on the edge of locking, except on gravel and snow, but that is because if the wheels are locked there is a build up of snow and mud in front of the tyres, helping slow it down, as it's digging into the surface. Modern ABS systems counter that by allowing a small amount of lock when it detects that the surface is slippery.
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ArnRno

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Post Sun Oct 11, 2015 4:20 am

Re: Too much brakes penalty

PMP1337 wrote:Such as?


My Isuzu Trooper, and an NA Miata (US car names) - those are the only cars I've been in that were 4-wheel disc, and neither had anti-lock.

The car I have now, a newer Impreza, is the only car I've had with anti-lock, but it's disc/drum.

Leonardo9613 wrote:....Of course, drums aren't usually powerful enough to lock the wheels, but the system is there anyway...


...and see, the only time I've ever locked brakes have been drums!

My old GMC truck would lock the rears with only moderate pedal effort, of course it was a one-ton truck and usually unloaded, so there's that.
Also, my Impala was 4-wheel drum, and I have definitely locked-up all four wheels before, same with the Oldsmobile that I have now, and the Olds is a single-chambered master.

This is DEFINITELY a case of "your mileage may vary," it seems like. :)
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HighOctaneLove

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Post Sun Oct 11, 2015 2:45 pm

Re: Too much brakes penalty

Leonardo9613 wrote:You managed to get all of your information wrong, hol.

My car, and lots of others, have 4-way ABS, but drums on the rear. Of course, drums aren't usually powerful enough to lock the wheels, but the system is there anyway. ABS does cut the stopping distance while making the car more controllable, as locked wheels don't provide as much friction as those on the edge of locking, except on gravel and snow, but that is because if the wheels are locked there is a build up of snow and mud in front of the tyres, helping slow it down, as it's digging into the surface. Modern ABS systems counter that by allowing a small amount of lock when it detects that the surface is slippery.


:lol: I wouldn't say all wrong... There really have been 4 wheel disc non-ABS cars since the mid 80's in Australia!

I'll happily retract my statements regarding drums not being able to have ABS control and a full lock braking event is indeed worse than an ABS controlled one.

Interestingly there is (IMO poorly done) video evidence that skilled candence braking out-performs ABS but, in regards to Automation, ABS definitely improves the driveability score!

FYI, drums can be powerful enough to lock up rears, as the weight transfer forwards, which can unload the rear tyres. This will result in the rear brakes locking up (disc or drum) so the OP has the right idea; regardless of brake type there should be a penalty for over-powerful brakes. :D

TL;DR... Over-large brakes (of all types) need punishment, stat!
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BlastersPewPew

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Post Sun Oct 11, 2015 8:04 pm

Re: Too much brakes penalty

Not to bash you more H.O.L. but my truck has front disc, rear drum and has ABS only on the rear (single sensor on the differential, both wheels must lock before ABS activates), many many many mid/late 80s to mid/late 90s American pickups had this setup.
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PMP1337

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Post Mon Oct 12, 2015 2:09 am

Re: Too much brakes penalty

07CobaltGirl wrote:In for examples. Most modern cars are 4-wheel disc, unless they're super economy busters. Most modern cars also have ABS, as they reduce insurance costs and increase safety measurements. I have ABS on my 2007, with 2-wheel disc, but it falls into the economy car group mentioned above. I would say the opposite is true. MOST cars with 4-wheel discs have ABS, unless they are more than 10 years old. But more likely this is because many cars 10+ years ago didn't have ABS at all.

That was exactly what I said.

ArnRno wrote:
PMP1337 wrote:Such as?


My Isuzu Trooper, and an NA Miata (US car names) - those are the only cars I've been in that were 4-wheel disc, and neither had anti-lock.

The car I have now, a newer Impreza, is the only car I've had with anti-lock, but it's disc/drum.


Neither the Trooper or the Miata are normal cars. One is a 4x4 and the other a sportscar.

HighOctaneLove wrote:In Australia we've had non-ABS 4 wheel disc brake cars since 1987... :geek:

http://www.carsguide.com.au/car-reviews/used-car-review-mitsubishi-magna-tn-1987-1989-13310

ABS stops wheel lock-up so you can steer the car while hard braking. ABS actually makes the braking distance worse than a full lock-up as locked wheels provide more friction and stop the car quicker.
ABS trades off distance for control by allowing the driver to attempt to avoid the obstacle rather than hope they won't hit it. You don't need ABS to control disc brakes but you need disc brakes to run ABS.
The cars with drum rears has the ABS only working on the front of the car. :D


I'm a mechanical engineer BE. Kinectic friction is lower than static friction. That is why when something is stopped it looks like it's sticking more than when it's moving.
A perfect ABS will make the car stop faster than no ABS. Because it keeps the wheel on static friction. When wheels are locked they are sliding so the friction rate is the kinectic friction rate. The same thing for the brake pads. That is why when you lock the wheels with a certain force applied to the pads you have to get below that force to unlock the brakes.
So yes, in practice ABS can make the braking distance longer if it has low quality. But on modern cars no. ABS is generally better because it optimizes everything.

Also, you can adjust the brake force through the brake fluid itself. I believe this is how the brake bias systems in race car works. But that isn't ingame and in production cars they use the same pump for a bunch of models so they never fiddle with that.

Most times I use simple language. First because I'm not a native speaker and I don't like to go into technical aspects using wrong terms. Second because I like to things simple to understand for everyone. But sometimes, specially on forums people are condescend.

Did I say only cars with disc all around use ABS? No. Did I say cars only start using all around discs after ABS? NO.
What I said was that the ratio of cars with all around discs and cars with drums inverted after ABS appeared. This is true for Europe as far as I know.

PS: I'm not upset. I'm happy my thread got so many replies.
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