Do all cars really need bigger brakes? (2024)

In reply to Pete. (l33t FS) :

Sounds like Nissan nailed the pad choice.

They were (gack) NAPA Ultra Premium or whatever their top tier ceramics were called. They didn't work worth a flip when cold and wet, though, which is the only similarity the two cars had

This was close to twenty years ago, I am sure things have changed since then.

Tom1200 PowerDork
6/11/24 8:53 p.m.

ShawnG said:

If you can lock up the wheels, you have enough brake.

What you want is good modulation and fade resistance.

I've been on record before that I vehemently disagree with that line of thinking.

For example on old motorcycles with drum front brakes; lets say 15lbs of lever results in point .5g deceleration and then 20 lbs results in .6G of deceleration............after that you get nothing until at 50lbs of lever pressure which finally results in the tire locking up.

That is not a modulation problem; that's a basic design problem usually a result of undersized brakes.

Standard Datsun 1200s have this issue; at high speeds there is a point where increased pedal pressure offers no more increase in deceleration and eventually an exponentially higher pedal effort results in wheel lock up.

I know the whole if you can lock a wheel thing is widely accepted but it's an oversimplified statement that simply isn't accurate.......I could add examples ad nauseam (and probably have)

In reply to Tom1200 :

It sounds more like a design problem in the brake linkage. If that force isn't transferred to the pads you might get that sort of behavior. There could be a lot or reasons for it. Flex, mechanical limits, leverage changes in motion range. Better designed brakes might help, but larger brakes... maybe just as a byproduct of fixing design issues.

Tom1200 PowerDork
6/12/24 3:54 p.m.

theruleslawyer said:

In reply to Tom1200 :

It sounds more like a design problem in the brake linkage. If that force isn't transferred to the pads you might get that sort of behavior. There could be a lot or reasons for it. Flex, mechanical limits, leverage changes in motion range. Better designed brakes might help, but larger brakes... maybe just as a byproduct of fixing design issues.

I'll stick with the Datsun for the moment

The stock front brakes are 8" rotors with 42mm x 62mm pads. These are fine for a 1600lbs car traveling 60 mph but ratchet that up to 80 mph and the brakes aren't really capable of bringing the tire to the point of lock up.

So you end up with the aforementioned monster pedal force before they finally lock up; thebraking doesn't really increase between 50lbs of pedal pressure and say 150lbs where the tires finally lock.

There are numerous economy cars from the 70s and 80s that suffer the same fate; they were never designed to be making hard stops above 70-75mph.

So back to more modern cars. My 2011 Outback is boderline. The pedal effort between very hard stop and threshold braking to tripping the ABS is not linear. The brakes are adequate but it really needs more/bigger brakes.Granted in the 14 years I've owned it a brake upgrade would have been truly used 5-6 times. 99.9% of the people driving them would never notice.

In reply to Tom1200 :

I've had pads where the response was decidedlynonlinear. More pedal force did not lead to more deceleration once past a certain point. This is definitely a pad composition issue. It's like pads that are grabby but with the knee in the curve further out. New/different pads always cured it.

Last week I had a vehicle with a "spongy pedal/pedal goes to the floor" concern. The pedal feel was actually rather good, but it took so much force to slow down that you were able to mush things through. The pads had no initial bite and they never really increased in force from there.

Tom1200 PowerDork
6/12/24 8:32 p.m.

In reply to Pete. (l33t FS) :

So early on with the 1200 we went with Ferodo pads and for the street they were pretty good. The initial bite was good and they got rid of the wooden feel but the overall issue was still there.

I do realize most modern cars will never have this issue but older Japanese cars had very undersized brakes........especially the economy cars.

Tom1200 said:

theruleslawyer said:

In reply to Tom1200 :

It sounds more like a design problem in the brake linkage. If that force isn't transferred to the pads you might get that sort of behavior. There could be a lot or reasons for it. Flex, mechanical limits, leverage changes in motion range. Better designed brakes might help, but larger brakes... maybe just as a byproduct of fixing design issues.

I'll stick with the Datsun for the moment

The stock front brakes are 8" rotors with 42mm x 62mm pads. These are fine for a 1600lbs car traveling 60 mph but ratchet that up to 80 mph and the brakes aren't really capable of bringing the tire to the point of lock up.

So you end up with the aforementioned monster pedal force before they finally lock up; thebraking doesn't really increase between 50lbs of pedal pressure and say 150lbs where the tires finally lock.

There are numerous economy cars from the 70s and 80s that suffer the same fate; they were never designed to be making hard stops above 70-75mph.

So back to more modern cars. My 2011 Outback is boderline. The pedal effort between very hard stop and threshold braking to tripping the ABS is not linear. The brakes are adequate but it really needs more/bigger brakes.Granted in the 14 years I've owned it a brake upgrade would have been truly used 5-6 times. 99.9% of the people driving them would never notice.

I think you're missing the point. I'm not saying it doesn't happen. I'm saying its likely to poor design decisions in the brake system not directly related to the brake size. The ability to lock up at any pressure suggests that the SIZE is okay. It just need something else fixed. Lots of cheap slide calipers for example will flex like crazy. A really non linear pedal doesn't sound like a brake sizing issue. I'd bet cars with these really non linear pedals get bad pad taper if used in that region much.

I also strongly disagree with the miata.net chestnut thatbeing able to lock the wheels up meansthere's enough brake.

By this logic the ideal brake diameter would just be a few inches and you just need a caliper rigid enough to clamp it hard enough to stop the axle from rotating.

It completely ignores what brakes are actually used for, which is slowing the car WITHOUT locking the wheels. Nobody actually wants the axle to stop turning completely, that's not a real use case.

This mantra was repeated over and over to me and it held me back for years. The stock 1.8 brakes on a miata are not adequate for a car with 250+ whp. They just aren't. The end. They can't shed enough energy quickly enough. Because that's what brakes do, they turn the kinetic energy of the car into heat energy. If the pad area is too small, there will be too much heat in very very short order and the disc will rapidly expand, the pad will start melting, and the brakes will not be predictable or reliable, and modulation, which is actually super, super important, will go out of the window. Brakes are for shedding energy. Not stopping the axle from turning, that's just a side effect of their function.

Tom1200 PowerDork
6/13/24 12:36 p.m.

In reply to theruleslawyer :

Both the 1200 caliper and the 280ZX are sliding calipers......trust I understand the whole flexing brake parts (I raced vintage motocross) but in this case it's a brake sizing issue.

dr_strangeland said:

The stock 1.8 brakes on a miata are not adequate for a car with 250+ whp. They just aren't. The end. They can't shed enough energy quickly enough. Because that's what brakes do, they turn the kinetic energy of the car into heat energy.

For street driving the weight of the vehicle (or combined vehicle in the case of towing) is much more important to the brake size than the horsepower. A car with double the stock horsepower will accelerate twice as fast, but assuming you're driving in a normal wayit doesn't really change how often you brake, or how much speed you bleed off when you brake. Track driving is obviously a totally different case.

There are also other reasons for wanting to upgrade the stock brakes, such as improving modulation and reducing unsprung weight.

Tom1200 PowerDork
6/13/24 3:46 p.m.

codrus (Forum Supporter) said:

There are also other reasons for wanting to upgrade the stock brakes, such as improving modulation and reducing unsprung weight.

I think upgraded brakes on the Outback would benefit the modulation; I can't stand brakes that are the least bit non linear.