Stoptech Article Regarding Rear Brake Upgrades

[BarryC]

Came across this again last night and thought I'd share.... Guess the money associated with selling rear brake kits was too good to pass up thus their marketing is now contrary to the basic point here.


http://www.stoptech.com/tech_info/wp...upgrades.shtml

[Eddy@ApexWheels]

Originally Posted by BarryC

Came across this again last night and thought I'd share.... Guess the money associated with selling rear brake kits was too good to pass up thus their marketing is now contrary to the basic point here.


http://www.stoptech.com/tech_info/wp...upgrades.shtml

The point of a BBK is consistancy. A car with stock brakes vs. a car with a BBK running the same brake pad compound will only be ever so slightly faster at decelerating the first few times you come to a stop since the swept area on the BBK should be a bit larger. It's the BBK's ability to dissipate heat better that at the end of the day makes it significantly better.

If you go to a track day with stock like system, and you aren't a novice driver. Then brake fade will very quickly become an issue. An average session is around 30 minutes for a HPDE, not to mention real racing.

true 4 wheel BBK's will be properly biased and remain in balance. Stoptech is really good about changing the piston sizes for each application which is the proper way to make that adjustment. If you have a front only BBK (like my front brembo kit), you'll still have shitty rear rotors that can over heat (and mine do). Bang for your buck do the front only, but a proper 4 corner kit can handle even more load. Nothing cheap about being slightly faster then the guy next to you.

For a car that doesn't bring rotor temperatures high enough, no BBK is ever needed, unless you count the bling factor.

[Dartanium]

so does Stoptech make two kits for the same car? Meaning would there be a kit that is intended for front BBK only and another version that was built to run BBK on four corners? I am confused since some cars Stoptech decided they only produce a front BBK kit where some others there is a full kit...

[Eddy@ApexWheels]

Originally Posted by Dartanium

so does Stoptech make two kits for the same car? Meaning would there be a kit that is intended for front BBK only and another version that was built to run BBK on four corners? I am confused since some cars Stoptech decided they only produce a front BBK kit where some others there is a full kit...

I don't remember off hand, but at one point I remember seeing some front kits that were specifically noted to be paired with a rear. I don't know if they list them like that any more. It's piston size that's changing, not the rotor size and caliper style.

Do all applications get this treatment? I'm sure they don't. It would have to be discused with them to get current information.

[rzm3]

StopTech makes two sizes for the front: 380 and 355 mm, and one size for the rear, 355 mm.

Of course they come in slotted, drilled, red, black, blah blah blah.

As for whether the front kit should be paired with a rear kit, I have no idea.

[Eddy@ApexWheels]

As mentioned before. It's the piston sizing the determines the effect of adding a rear BBK, and then there are always proportioning valves that can adjust front to rear bias.

Piston sizes on a rear kit will be small. It's not like you'd be throwing the power of a front kit onto the rear of a car. The kit still has to function with the amount of hydraulic pressure that will be direct towards the rear of the car, which will be less then the front.

[rzm3]

What StopTech is saying is that their BBK's brake torque should be very similar to factory's, which is why a rear kit may not be needed to balance the brake bias.

However, for those who drive on the track, you should also consider that the rear factory brakes will not be as good in terms of cooling and withstanding brake fade vs. BBK, which means that the brake torque in the back may decrease when you push the car too hard, and this will result in improper brake bias. And in this case a rear kit WILL be needed.

[BarryC]

I bought my first BBK from Stoptech when they did not offer rear BBKs. This article has been around for at least 6 years (2003 is when I bought my first BBK) and since then they have started offering rear BBKs. I've owned two E46 M3s with front only kits and never had a bias or heat problem at the track.

I posted this link because my experience supports their thesis. Now my E92 has a front only PFC kit. I've only tracked the car once since adding the PFC but my experience was similar i.e., balance was good and no overheating issues. Time will tell if this continues. Personally I think a rear kit is unnecessary but that's just my opinion. I put the $$ that I would have spent on the rears towards the Moton setup which made a much more significant impact to on track performance IMO.

Thx,
BC

[Ron@Modbargains]

I agree with you Barry, that the rear brakes are not necessary. Everyone knows that 85% of your braking is done on the front. Yes there is a bias thing - but the reason that Brembo or Stoptech sell Front kits only cause the front kits factor in the OEM rear brake bias. Yes there is an added benefit but it's negligible. The amount of performance one gets from just the fronts for the $ value is far more. It's almost unless you are full race car and have to have it perfect or your are just trying to win points at car shows with the looks, in real world use the rear BBK is useless. That's my personal 2 cents on it at least.

[HP Autosport]

Originally Posted by Ron************

I agree with you Barry, that the rear brakes are not necessary. Everyone knows that 85% of your braking is done on the front. Yes there is a bias thing - but the reason that Brembo or Stoptech sell Front kits only cause the front kits factor in the OEM rear brake bias. Yes there is an added benefit but it's negligible. The amount of performance one gets from just the fronts for the $ value is far more. It's almost unless you are full race car and have to have it perfect or your are just trying to win points at car shows with the looks, in real world use the rear BBK is useless. That's my personal 2 cents on it at least.

85% may be bit high when it comes to BMW's. VW/Audi's and front wheel drives cars, maybe.

The rear brakes on the BMW's actually do some work, not just along for the ride. I have personally got the rear Brembo BBK so hot that the color of the calipers changed and if there were any clearcoat on the caliper they were gone. Track pad replacement intervals were the same for front and rear, with the front wear to be slightly higher. With the Stoptech Trophy Sport system, I have melted more than a few center caps off the rear wheels only because I was too lazy to remove them. The Stoptech calipers remain their original factory color since they aren't painted.

[quality_sound]

^^^Just to confirm, VW/Audis do indeed have most of their braking force at the rear of the car under light and medium braking. It's done to combat nosedive and maintain stability since the front wheels are already steering and powering. Under heavy braking, most of the force is done with the front brakes.

[LiM3y]

If you are running high performance 'treaded' tires, as opposed to slicks, at the track, a front BBK system is sufficient? Is it that when you have the additional traction of slicks that you might need a rear BBK?

[i.e. matching the brake system to the tire traction]

[AP Racing - Chris_B]

Originally Posted by Ron************

I agree with you Barry, that the rear brakes are not necessary. Everyone knows that 85% of your braking is done on the front. Yes there is a bias thing - but the reason that Brembo or Stoptech sell Front kits only cause the front kits factor in the OEM rear brake bias. Yes there is an added benefit but it's negligible. The amount of performance one gets from just the fronts for the $ value is far more. It's almost unless you are full race car and have to have it perfect or your are just trying to win points at car shows with the looks, in real world use the rear BBK is useless. That's my personal 2 cents on it at least.

Ron, the biggest benefit we see with people choosing a rear brake kit (aside from looks) is pedal feel. A proper rear kit will eliminate the "squish" in the rear floating caliper, giving better pedal feedback under braking. Will all drivers feel this improvement? No, but I know I'm not the only one who does.

Also, rear brakes can do more work for cars that are lowered and are running stiffer springs/dampers. Since less weight is transferred to the front axle under braking, the rear tire has a little more traction available for the rear brakes to take advantage of. Back when I worked with IndyCars, we spent a great deal of time making sure the rear brakes were doing their part. No one on the grid could out-brake our cars at the time, although we did have to run larger brake ducts to keep them from overheating.

Chris

[rzm3]

Reviving this old thread...

I was looking at E92 M3s from the Grand-Am Continental Series, and every M3 I've seen uses stock rear brake discs/calipers (not stock pads of course).

In the front, all of them have a race-spec BBK w/ ducting.

If the stock rear brakes are good enough for pro-series $100k+ race cars, it is good enough for us weekend track warriers.

From the pictures I've seen, Turner and Rum Bum uses StopTech. Fall-Line uses Alcon.

[MrHarris]

^ nice find.

[930Man]

I have always been of the same thought.. I have never upgraded the rear brakes on any car, I do a lot of tracking, good pads good cooling.. I used to laugh at the track watching guys upgrade their Porsche cup car Brakes all 4 corners... for DE's... im like dude If the pros run these cars full on races with these calipers and brakes do you really think you are pushing the car harder than them???

I think the street folks do it for looks...

i guess more money than sense comes to mind sometimes

I would think that the pros are running a upgraded by design caliper .. for heat and strength ..

[AP Racing - Chris_B]

Originally Posted by rldzhao

Reviving this old thread...

I was looking at E92 M3s from the Grand-Am Continental Series, and every M3 I've seen uses stock rear brake discs/calipers (not stock pads of course).

In the front, all of them have a race-spec BBK w/ ducting.

If the stock rear brakes are good enough for pro-series $100k+ race cars, it is good enough for us weekend track warriers.

From the pictures I've seen, Turner and Rum Bum uses StopTech. Fall-Line uses Alcon.

Not looking to argue, but Turner ran Alcon's front and rear at Daytona this year.

http://www.turnermotorsport.com/html...010/daytona24/

When they were running StopTech, AP Racing was making the rear rotors for the ST calipers. Rahal-Letterman uses AP front and rear in ALMS GT2. The FIA GT4 cars in Europe also come with AP's front and rear.

You just won't see OE sliders on the rear in professional racing, at least not at the top levels. Not that it translates directly to street vehicles, but the difference is noticeable or they wouldn't do it. Brake companies do not give much product away, so teams with limited sponsorship may not have a choice. AP Racing does not sponsor any race team anywhere, so all their customers are buying the equipment.

What I do know is that when people go for the rear upgrade, there is nothing but positive feedback regarding performance. It is almost always related to pedal feel and trail braking. Many upgrades, like the AP system for the E9x M3, are designed as a F/R system and should be used together, not separately, to get the best performance out of either.

Chris

[ff1600]

But do these race-only cars use the stock master cylinder/abs system or separate master cylinders for front/rear with driver-selectable bias adjustment?

The latter should give the driver much better brake feel than with the stock system, therefore taking advantage of a full BBK.

[JC919]

Great thread and thanks for the posts guys as I'm in the middle of a BBK dilemna over what to go with. I had a setup on my B5 S4 with the 380mm Stoptech kit upfront and stock rears. That, due to the crappy stock brakes, was somewhat unstable, but very much drivable. However, one of the primary reasons that I want a BBK is for the ability to simply 'drop' track pads in rather than remove the entire caliper.

[KiokenM3]

nice, that article just saved me some $$$

[AP Racing - Chris_B]

Originally Posted by ff1600

But do these race-only cars use the stock master cylinder/abs system or separate master cylinders for front/rear with driver-selectable bias adjustment?

The latter should give the driver much better brake feel than with the stock system, therefore taking advantage of a full BBK.

Most professional racing series allow a dual master cylinder setup, so they would certainly go that route. However, brake feel would not necessarily be affected by that change IF the total M/C area is the same. In fact, most single master cylinders are two different bores on the same shaft (tandem). The limitations are: 1) they don't allow any separate F/R adjustment, and 2) you are stuck with the OE bore sizes. Moving to dual, separate M/C's lets you use a balance bar allow for micro adjustment between the circuits. Changing M/C sizes is the macro adjustment.

So, no, brake pedal feel is not affected only by moving from a single, tandem-bore M/C to duals (generally speaking) unless you also change effective bore sizes. But what you can adjust changes dramatically. You would go from basically no adjustment range to nearly infinite between the min and max.

Chris

[HP Autosport]

I think if you were to look into the rule book, they are not allow to change the rear brakes, otherwise all the teams will look to get rid of the floating caliper and add a bigger rotor.

There is also added thermo capacity with an aftermarket BBK. In the case of the Stoptech the rear rotor size is 355 x 32 where as the oem is only 350 x 24. Not to mention more pad selection and quick changes without removing the caliper.