Big brake kits

[motortrend]

So lately I've been looking for info on brakes and their effectiveness and I came up with a few questions:
How necessary are more than 1 pot calipers on a street car that is driven spiritedly?
If you want to brake effectively in a short distance from high speeds how much of a difference does it make?
With the traction threshold of street tires are bigger brakes really necessary? If you are going to the track in occasional outings in your performance wouldn't SS brake lines, fluid, and track pads on big 1 pot brakes be enough?

I am asking this because seeing as how the stock E9x M3 brakes are 1 piston brakes and many people upgrade to big brembos or stoptechs etc. I wondered if it is really worth the $7k that one of these complete kits cost if they will be used on the street and in some track time. Do people do this for looks? Does it add some safety on the road?

 

[Ibonibo]

Well a 1 piston brake can be better than a bad 4 piston. A movit 6 piston will blow a 8 piston D2 out of the water. Price wise too though

Those you mentioned aren't considered bad though. Though the Brembo Gt junior kit is meh. The GTR kit rocks hard though.

For the use you said, I would first go with pads, lines and fluid change. If it is enough, good. A bit more can be obtained with a different disc then if necessary. If that still isn't enough then you can go big, but I doubt you really need it (because we could all need a bit brake )

A better brake is always safer if it reduces fading, brake distance, improves water dispersion,... But a race pad for exemple is not considered safe as it needs to be warm enough....

A common tune is also to either remove or make holes in the "metal that covers the brake from too much dirt and water" as it cools the brakes better. On most cars it doesn't put to much dirt on the brakes, on other cars it's not that recommended (I suppose), so I would look that up if it's a mod frequently done on your model

Also, if you talking about your M, I would probably go either swap from another BMW M or if you have the cash (you will need a lot) go ceramic.

I been thinking a lot about the brakes too, as the old RS brakes were considered "meh" (got the mk2), and there are so many choices. Movit exchange disc, Movit complete kit (6-8 Piston, Steel or Ceramic), D2, Brembo GTR, Brembo exchange disc, Audi (RS6, RS4) Ceramic (RS6, R8, R8 Gt)....
Too many options, in the end the moneybag's size will make the decision

 

[motortrend]

Thanks for a thorough answer.
Yeah in cars that already have very good calipers they tend to change the rotors by themselves like you say.
In my case I'm not considering a BBK at all since that would cost like 1/4 of what my car cost but I am about to change brake lines for safety and maybe later on opening the brake ducts and just wondered how much better a BBK would perform.

How much different do you think something like this would be with the OEM brakes?

 

[TheBook]

When you hit your brakes as hard as you can, do they lock/does ABS kick in? Yes? You have more than enough braking force. Upgrade your tires first so that you can take advantage of what you do have. On a car that will only occasionally see track time, brake fade isn't really an issue either.

 

[Ibonibo]

^That also depends on how your ABS is set up factory wise and hasn't to do with enough stopping power. The weakest Peugeot can kick in the ABS, that doesn't equate in good brakes :S


In this particular case, I would say they would probably have hit it as there wasn't much missing from it...

But I honestly can't say by how much on a onetime emergency brake it would be better. It will be better, but how much ? The M5 OEM brakes certainly aren't bad for day to day use. For a long run on circuits, a BBK will be better as it handles mutiple hard brakes, high warmth better than the OEM.
A NOS lap is a good reference, a OEM brake will suffer after 1 lap on the green hell. BBK can run a few (20-25) rounds without hiccups. Upgraded OEM brakes will handle 1-2 laps just fine.

Also, a bigger number of pistons doesn't necessarily equate more power on the discs, it just that the power is spread more evenly. Then we come into the surface friction part, where fixed and floating discs take a meaning too.

Upgrading lines and fluid does already change a lot, your brake point will be much more precise hittable than before
Then the good pads, which can be enormeously expensive (Pagid,...) but also the EBC stuff is very good and payable.
With those two, you will be very pleased with your brakes

 

[Scaff]

Go here.....

http://www.stoptech.com/technical-support/technical-white-papers

.....read all of them.

 

[Ibonibo]

^That's a very cool link thanks 👍

 

[Keef]

How necessary are more than 1 pot calipers on a street car that is driven spiritedly?

Necessary? Not at all, really. But can you feel the difference and is it more fun? Yeah.

If you want to brake effectively in a short distance from high speeds how much of a difference does it make?

Only as much a difference as your tires will allow. Remember, every input you make to the controls must go through the tires. Every factory braking system out there is strong enough to lock the brakes of the stock car. Therefore, ABS. Will a stock Miata's brakes be able to lock up giant racing slicks at speed? Probably, yeah.

My point here is that if you want to brake harder, buy stickier tires, not bigger brakes.

With the traction threshold of street tires are bigger brakes really necessary?

These brakes are never necessary so that's not really a good question to ask. I would ask, are they useful? On any standard car that has a basic braking system the standard tires don't have the performance capability to use the more powerful brakes. You would need a tire upgrade. I have Nitto NT05 tires on my car...

...and can still lock them up without much trouble when they're warm.

If you are going to the track in occasional outings in your performance wouldn't SS brake lines, fluid, and track pads on big 1 pot brakes be enough?

Yes. Stainless lines help improve pedal feel and response because they don't expand under load like rubber lines. High-temperature fluid will help longevity during performance driving by reducing brake fade due to boiling fluid causing gas buildup in the lines. Track pads can allow better heat capacity for longevity and a much stronger bite.

I am asking this because seeing as how the stock E9x M3 brakes are 1 piston brakes and many people upgrade to big brembos or stoptechs etc. I wondered if it is really worth the $7k that one of these complete kits cost if they will be used on the street and in some track time. Do people do this for looks? Does it add some safety on the road?

The actual purpose a large-diameter rotor and multi-piston caliper is to increase brake torque and heat capacity. The larger amount of metal means it can absorb and dissipate quite a lot more heat which leads to less fade under performance conditions. The increase diameter means more torque can be applied to the axle to slow it down. The larger, more structurally sound caliper and pads will spread the load more evenly across the rotor's surface while also increasing feel and response.

Most of this has to do with feel and longevity, not with power. Unless you're running stickier tires then you won't be able to stop any quicker. You'll detect the improved feel on the street but you'll also be able to feel a $100 set of stainless lines just as well. But besides all of that, when you can afford an E92 M3, and then take it to the track, a $7,000 brake kit probably isn't the most expensive prospect. Plus, you get to show off your big red calipers to all your car buddies who think you must be able to stop on a dime despite having the same tires as them.

EDIT: Pupik provided a great link. The best place for the info is from the professionals.

 

[motortrend]

Thanks for the info and the link people 👍 I've come to notice how for linear acceleration and deceleration heat management and material compounds tend to be more important than size and force

 

[speed junkie]

Modulation is the key word. This is the overseen benefit of solid-mounted, multi-piston calipers. And THE benefit that makes the difference when braking at the limit. This is the only reason I want a "big brake" kit. For the modulation. My current Miata brakes have no problem with holding up to R888s. Stock calipers with braided stainless steel lines, Hawk HP+ pads, slotted Powerslot rotors, and Motul RBF600. But braking in a straight line is just the tip of the iceberg.

Read and learn...

Knowledge

I also highly recommend reading the rest of the articles on the web site.

 

[HELLAFLUSH240SX]

I love BBKs, Im actually looking at a kit by Futura Design. Horribly expensive. Same look as the 326 Power BBKs

 

[Punknoodle]

My car has fairly sufficient braking force, but where it really struggles is with being able to maintain that braking force. Because of the cars weight and its relatively small brakes, a few hard leans on them makes them fade. For instance, a mountain run or a few laps of the track.

A simple pad upgrade to a track compound and high temp fluid with braided lines has proven not good enough. Slotted rotors didn't do much either, it was supposed to help with the pads out gassing (the gas let off by pads as they do their job can cushion the brake caliper from the rotor) but it seems pure overheating of the rotor is the issue.

The only way to eliminate the problem is with a bigger rotor. The rotor is the only thing that dissipates the heat. That's it's job - to convert kinetic energy in to heat.

Of course to do that also means changing the calipers too. The more pistons, the more overall spread of the force the caliper has against the rotor, meaning the heat is spread better across the caliper, meaning they are more efficient.

AP racing make a kit for my car, they are a 6 piston with a massive rotor, but come with a massive price tag. I would love a set though. Even upgrading to the later model 4 pots wouldn't be that much of an upgrade as the rotor isn't much bigger, and that is where the problem lies.