Can't lock up the rear. Normal?

[DB83]

So every year, we have to pass a safety inspection here in Spain, and one of the tests is a braking test on each axle individually.
The car gets put on some mechanical rollers, and you have to slowly apply the brakes until, they lock up and they take a measurement.
My fronts lock up no problem. The rears however don't. I stomp on the brakes as hard as i can, but it's not enough to lock up the rears. Is this normal? It's enough to pass the braking test, but it definitely doesn't feel like it's doing much braking. Doesn't feel right.
I'm running OEM ford pads with Steeda 2 piece rotors, and goodridge braided hoses.
Tires are Continental Sport Contact 7 in 305/30 R20 all round.
I've bled the whole system multiple times, and there is definitely no air in the system.

Is it really that the rear pads are that weak that they aren't able to lock up the rears?

I feel like that's wasted braking performance if the rear isn't able to lock the rear tyres. I know you ideally don't want to lock up the rear, but it honestly feels week.

Any thoughts or opinions on this? Anyone know who makes pads with a more aggressive friction coefficient that are still streetable?

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[Andy13186]

I am not sure if this is the correct answer for this, but anti-lock braking systems are mandatory on all cars since 2004 in the USA. Maybe they should disqualifying cars if they can lock up the brakes if its a safety inspection. Also traction control and stability control prevent this situation I believe. Have you tried just yanking the ebrake during this test?

Also not sure how much force is required to pass the inspection or if this is normal for all cars, since you said it did pass the inspection.

 

[EFI]

Why on earth would you want to lock up your rear tires? That's seems foolish and dangerous. The whole point is to NOT lockup the tires, and automakers go to great lengths to prevent that.

If you want to lock up your rear tires (for whatever reason) just yank on the parking brake.

 

[ShadesOfBloo]

So every year, we have to pass a safety inspection here in Spain, and one of the tests is a braking test on each axle individually...

...My fronts lock up no problem. The rears however don't. I stomp on the brakes as hard as i can, but it's not enough to lock up the rears. Is this normal?

Is this a real safety test, or are you trying to skid the car around and impress some friends?

It's bad enough Mustang is a verb in one country...

 

[DB83]

Yes, its an actual test, and no its not so i can behave like an idiot.
The idea of the test is to ensure your car can apply an adequate braking force to the wheels.
The rollers are calibrated so that as soon as they detect a wheel lock up, the machine stops. Basically releasing the force just at the point where ABS would kick in.
The front is fine, but the rear comes nowhere near the point of ABS kicking in. That's the point i'm getting at. It feels like the rear isn't braking enough. Even when stomping on the brake and pulling on the handbrake, the rear won't lock up at all.
My wife's Mazda 6 is able to lock up the rear, and my father in laws 20 year old Audi is also able to lock up the rear. Seems strange that a "performance car" wouldn't be able to.

Yes manufacturers go to great lengths to make sure your wheels don't lock up, and i'm not trying to change this, but if your brakes are unable to lock up the wheel, then surely your not applying the most braking force possible on the car.

Put it this way, the quickest way to stop the car is to have all 4 brakes reach the point where they are just about to lock up the wheels, but not actually lock them up. If your rear brakes aren't even close to that, then you're not braking the car as quickly and efficiently as possible. No?

 

[_zOmbIE_]

There is this thing called anti-lock braking systems its mandatory on all cars since 2004 in the USA. They should actually be disqualifying cars if they can lock up the brakes if its a safety inspection. Also traction control and stability control prevent this dangerous situation I believe. Have you tried just yanking the ebrake during this test?

I could be wrong (likely am, lol), but I don't think ABS is supposed to do much when the brakes are gradually applied, just during sudden applications?

 

[ShadesOfBloo]

...The front is fine, but the rear comes nowhere near the point of ABS kicking in. That's the point i'm getting at. It feels like the rear isn't braking enough. Even when stomping on the brake and pulling on the handbrake, the rear won't lock up at all.
My wife's Mazda 6 is able to lock up the rear, and my father in laws 20 year old Audi is also able to lock up the rear. Seems strange that a "performance car" wouldn't be able to.

I'm sure it's by design. It's safe to assume Ford doesn't like it when "Mustang" is a verb.

 

[5550snotamerc]

Is this a real safety test, or are you trying to skid the car around and impress some friends?

It's bad enough Mustang is a verb in one country...

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[WildHorse]

Give the tester a hundred Euro. Anyways, that's a stupid way to test the brakes efficiency .

 

[KeyLime]

My guess is you should be able to lock up the rear wheels. If ABS prevented that how the hell can you come to a complete stop?

 

[EFI]

If your rear brakes aren't even close to that, then you're not braking the car as quickly and efficiently as possible. No?

Are you professionally racing this vehicle on on tracks for money?

If not, I assure you that the OEM brakes are more than capable of stopping the car as needed as shown by the fact that you passed the test.

 

[EFI]

My wife's Mazda 6 is able to lock up the rear, and my father in laws 20 year old Audi is also able to lock up the rear. Seems strange that a "performance car" wouldn't be able to.

Again, you seem to equate locking up the tires with braking performance. Alot has to do with the tires also, I'm sure the tires on your wife's Mazda are alot less grippy than the 305s on your Mustang, so it makes sense that her brakes can lockup the wheels while yours can't. I assure you that the Mustang brakes are significantly better than that Mazda.

 

[Zrussian13]

How would you do amazing standing burnouts if the rears locked as hard as the fronts? My gt had always had a front bias. If you passed your inspection and you aren't experiencing issues, your probably fine.

 

[NGOT8R]

Yes, its an actual test, and no its not so i can behave like an idiot.
The idea of the test is to ensure your car can apply an adequate braking force to the wheels.
The rollers are calibrated so that as soon as they detect a wheel lock up, the machine stops. Basically releasing the force just at the point where ABS would kick in.
The front is fine, but the rear comes nowhere near the point of ABS kicking in. That's the point i'm getting at. It feels like the rear isn't braking enough. Even when stomping on the brake and pulling on the handbrake, the rear won't lock up at all.
My wife's Mazda 6 is able to lock up the rear, and my father in laws 20 year old Audi is also able to lock up the rear. Seems strange that a "performance car" wouldn't be able to.

Yes manufacturers go to great lengths to make sure your wheels don't lock up, and i'm not trying to change this, but if your brakes are unable to lock up the wheel, then surely your not applying the most braking force possible on the car.

Put it this way, the quickest way to stop the car is to have all 4 brakes reach the point where they are just about to lock up the wheels, but not actually lock them up. If your rear brakes aren't even close to that, then you're not braking the car as quickly and efficiently as possible. No?

Try unplugging the nanny plug under the hood next to the air box. It will disable the ABS and you will be able to lock the rear brakes up like conventional brakes and pass the test. Once you’re done, reconnect the nanny plug.

 

[CVN 80]

So every year, we have to pass a safety inspection here in Spain, and one of the tests is a braking test on each axle individually.
The car gets put on some mechanical rollers, and you have to slowly apply the brakes until, they lock up and they take a measurement.
My fronts lock up no problem. The rears however don't. I stomp on the brakes as hard as i can, but it's not enough to lock up the rears. Is this normal? It's enough to pass the braking test, but it definitely doesn't feel like it's doing much braking. Doesn't feel right.
I'm running OEM ford pads with Steeda 2 piece rotors, and goodridge braided hoses.
Tires are Continental Sport Contact 7 in 305/30 R20 all round.
I've bled the whole system multiple times, and there is definitely no air in the system.

Is it really that the rear pads are that weak that they aren't able to lock up the rears?

I feel like that's wasted braking performance if the rear isn't able to lock the rear tyres. I know you ideally don't want to lock up the rear, but it honestly feels week.

Any thoughts or opinions on this? Anyone know who makes pads with a more aggressive friction coefficient that are still streetable?

See if you can find the ABS fuses. Then evict them.

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