Brembo GT 380mm Big brake kit

[THEMASH]

Has anyone tried the Brembo GT 380mm 6 piston Big Brake Kit ?? thoughts/feedback ? Will it clear the stock 18" Front wheels ?

Thanks

 

[mjorgensen Woodhouse]

Some of the Comp Coupes run this and it fits the 18" wheel on them.

 

[gb66gth]

Hmm, I'ld like to know as well.
Am I the only one who thinks the Gen IV is a little "under braked" given how fast it can build up speed?

 

[Viper X]

1 - The new Brembo "big" front caliper set up applies the same braking force to the rotor that the smaller OE calipers do. It's just spread over a larger surface area which helps the brake pads (and hopefully rotors) last longer.

2 - Yes, it will fit SRT-10s.

3 - SRT-10's "under braked" - you have to be kidding. Uprade the pads and tires and you can stop as well as anything else out there in this weight class, save the super pricey carbon rotor set up, and even then it would be close.

Dan

 

[Cop Magnet]

1 - The new Brembo "big" front caliper set up applies the same braking force to the rotor that the smaller OE calipers do. It's just spread over a larger surface area which helps the brake pads (and hopefully rotors) last longer.

Well, that's true of any BBK, isn't it?

 

[mjorgensen Woodhouse]

Well, that's true of any BBK, isn't it?

Yep!

I have been using the Carbotech XP8's and XP6's rear and they are awesome, I also have 10's and 8's for the track. I have found nothing I like better and the dust they create is non-corrosive to my wheels! They do squeal though when they are cold .

 

[Tom F&L GoR]

1 - The new Brembo "big" front caliper set up applies the same braking force to the rotor that the smaller OE calipers do. It's just spread over a larger surface area which helps the brake pads (and hopefully rotors) last longer.

The braking force (actually it's a clamping force which becomes a torque when it resists rotational movement) is determined by the brake fluid pressure multiplied by the area it is applied to. Specifically, the 1000 psi or so that the master cylinder produces from you stepping on the pedal multiplied by the total square inches of the pistons in the caliper. If the Brembo 380 caliper has more total piston area (not just counting the number of pistons) than the OEM caliper, it will produce more braking torque than the OEM size.

To beat the dead horse with more explanations, swapping 40mm rear calipers on a Gen 1/2 non-ABS car increases the clamping force and adds rear braking, which fortuitously balances the front vs. rear nicely. Because the pad size doesn't change, it is the case you stated; a small pad now doing more work and will wear faster. However, since the rear pads always outlived the fronts, it only brings their relative lifetimes closer together.

It gets more complicated with ABS systems since ABS will ensure a larger caliper will not lock up. Until a wheel does, the bias of braking will shift to the end with the increased size calipers, so it may change the feel of the car. It was my opinion (and I'm asking you Gen 3/4 owners/experts) that once a caliper is "big" enough to slide a tire, going bigger won't allow you to slow any quicker upon the first brake application. A bigger caliper allows a bigger pad, so you can brake repeatedly and consistently over all conditions - why the Comp Coupes have big brakes.

If you want to get confused, investigate the braking system of a Lotus that has dynamic brake balance control. That is an electronic version of a proportioning valve, which is active before lockup and not during. Combined with ABS it means there is always an electronic adjustment of the brake balance.

 

[treesnake]

I was looking into upgrading to this set up also. I started a thread about the subject. Pretty much all agreed that the return for the money wasn't worth it...

Might try SS brake lines and different pads first....

There's a couple threads at the bottom of this page that might help...

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[Tom F&L GoR]

To many here this is old news, but a few years ago I rotated between the old EBC Greens, OEM, and Brakeman#3 pads. It was very obvious what the difference was and says a lot about what a driver gets used to. If you have never tried different pads, be aware they can be markedly different not just in how well they tolerate track use, but even upon the initial grab on the initial brake application.

For those that run their brakes hot, here is another Woodhouse "trick" that I have installed and highly recommended. It eliminates a lot of stress over which brake fluid to use.
http://forums.viperclub.org/2746320-post9.html

 

[Nine Ball]

Someone said the SRT Viper is underbraked? Change your pads and rotors, simple.

 

[xjrguy]

Don't forget your tires!!

You can have esoteric brakes with marginal/crap tires and a Viper with stock brakes and brand new sticky tires will stop better than you every time.

 

[ViperGeorge]

The braking force (actually it's a clamping force which becomes a torque when it resists rotational movement) is determined by the brake fluid pressure multiplied by the area it is applied to. Specifically, the 1000 psi or so that the master cylinder produces from you stepping on the pedal multiplied by the total square inches of the pistons in the caliper. If the Brembo 380 caliper has more total piston area (not just counting the number of pistons) than the OEM caliper, it will produce more braking torque than the OEM size.

To beat the dead horse with more explanations, swapping 40mm rear calipers on a Gen 1/2 non-ABS car increases the clamping force and adds rear braking, which fortuitously balances the front vs. rear nicely. Because the pad size doesn't change, it is the case you stated; a small pad now doing more work and will wear faster. However, since the rear pads always outlived the fronts, it only brings their relative lifetimes closer together.

It gets more complicated with ABS systems since ABS will ensure a larger caliper will not lock up. Until a wheel does, the bias of braking will shift to the end with the increased size calipers, so it may change the feel of the car. It was my opinion (and I'm asking you Gen 3/4 owners/experts) that once a caliper is "big" enough to slide a tire, going bigger won't allow you to slow any quicker upon the first brake application. A bigger caliper allows a bigger pad, so you can brake repeatedly and consistently over all conditions - why the Comp Coupes have big brakes.

If you want to get confused, investigate the braking system of a Lotus that has dynamic brake balance control. That is an electronic version of a proportioning valve, which is active before lockup and not during. Combined with ABS it means there is always an electronic adjustment of the brake balance.

Tom,
Won't an increase in piston size change pedal feel? Don't larger caliper pistons mean more fluid volume behind them? Doesn't this decrease pressure applied to the piston and increase pedal travel? Kind of like what happens with master cylinders, decrease the bore size and you increase line pressure but pedal movement increases because you have to move the piston further to move the same volume of fluid. Increase bore size and pressure drops but pedal is firmer.

In fact if you change caliper piston volume don't you really need to match the master cylinder to the change? If you don't you might not be pushing enough fluid and the right pressure.

Or something like that.

 

[Achilles99]

Mintex up front, stock pads in back work great on the track. I tried Mintex all around, and it DOESN'T work well! I would lock up my rears I think, and the back would come around under heavy braking. I lost 3 seconds a lap because of this.

Brakeman 3's seem to be more progressive in feel, but they are more expensive than the Mintex. So, I'm sticking with Mintex for now

 

[Viper X]

Achilles,

As stated above, much of your braking is tire dependent.

With good tires, i.e. Hoosier R6's in 315 or Kumho V710s in 305 up front, I've now tried a bunch of brake pads. Found Mintex up front, Porterfield R4's in the rear to be the best balance of bite and control (modulation) of all the pad combinations used so far on my ACR, but I have Aero, which really helps stabilize the car when braking from speed.

PFC's up front will really stop you (best so far) but are harder on the softer Stoptech rotors over the long run and don't modulate as well as the Mintex pads.

Brakeman III's work pretty well up front until you get "faster" lets say, then they really need to be moved to the rear and Mintex or PFC's need to go on the front.

OE pads work pretty well for beginners or guys not running longer sessions on tight tracks or on hot days.

Good luck,

Dan

PS Tom; I spoke with the Brembo guys several times during and after development of their big brake kit for Viper (they are based out here in So Cal). They told me that they worked very hard not to upset the balance of the OE braking system by not over doing the front brake caliper / piston / pad relationship. They are the ones who told me that the new big brake kit of theirs would apply the same force as the OE Brembo set up. They focused on making the pads and rotors last longer rather than trying to increase braking force or shorten stopping distances.

I haven't tried their set up yet even though they've offer me a sweet heart deal to evaluate them. Cost is kinda' high IMHO to justify buying them and replacing a system that already works very well. With the proper pads and rotors, I can already apply more force than my 305 or 315 front slicks can handle and tend to wear my front tires out well ahead of my rears (there are other issues besides braking, obviously, like turning!)

 

[Achilles99]

I'm running 305's and 335's (R compounds), so I don't think tires are my issue. I think by running Mintex all around, I had too much bite in the rear compared to the front. I assume the Porterfield R4's you use in the rear are less aggressive than the Mintex? My best combo was Mintex up front, OE in rear. I guess the important thing is to use a less aggressive rear pad compared to the front. Otherwise, you'll lock up the rears.

I'm not sure if the R4's would work for me since I don't have as much aero. All I know is that this past weekend, my car was VERY unstable under braking and the only thing I changed was pad compound (well, I installed Stoptech rotors front and rear but I assume that wasn't the problem).

Curiously, I found that running 1.5 camber in the back was too much at TGPR. I'm going to try negative 1 next time. I guess my R888's don't flex very much.

 

[Tom F&L GoR]

Tom,
Won't an increase in piston size change pedal feel? Don't larger caliper pistons mean more fluid volume behind them? Doesn't this decrease pressure applied to the piston and increase pedal travel? Kind of like what happens with master cylinders, decrease the bore size and you increase line pressure but pedal movement increases because you have to move the piston further to move the same volume of fluid. Increase bore size and pressure drops but pedal is firmer.

In fact if you change caliper piston volume don't you really need to match the master cylinder to the change? If you don't you might not be pushing enough fluid and the right pressure.

Or something like that.

Yes, and I cleverly bypassed all the volume issues by saying 1000 psi brake line pressure. So whether you push harder or farther, at 1000 psi a caliper with greater piston area will have more clamping force. And consequently when you change calipers at one end and not the other, you change the front to rear braking bias (until the proportioning valve kicks in.) When you are actually braking, the fluid is supposedly incompressible. So while the volume factors significantly apply to move the pistons into place, at some point you are "only" modulating the pressure.

I don't know the piston sizes of the 380 BBK, but if the Brembo guys matched (or very close) the piston area of the OEM 4-piston caliper and came up the same area among 6 pistons, then the clamping force is the same and the pad can be larger - that makes sense why pads last longer but braking is similar.

Mental gymnastics...

 

[Viper X]

I'm running 305's and 335's (R compounds), so I don't think tires are my issue. I think by running Mintex all around, I had too much bite in the rear compared to the front. This is very likely with 335 rears (and stock suspension?), would be less pronounced with 345 rears.

I assume the Porterfield R4's you use in the rear are less aggressive than the Mintex? Yes.

My best combo was Mintex up front, OE in rear. I guess the important thing is to use a less aggressive rear pad compared to the front. Otherwise, you'll lock up the rears. Yes. Try the Porterfield R4s at the rear. They will last longer and stop you better than the OE pads, IMHO. I ran them on my GTS ACR without aero with the SRT-10 brakes.

I'm not sure if the R4's would work for me since I don't have as much aero. All I know is that this past weekend, my car was VERY unstable under braking and the only thing I changed was pad compound (well, I installed Stoptech rotors front and rear but I assume that wasn't the problem). Stoptech rotors will add some bite.

Curiously, I found that running 1.5 camber in the back was too much at TGPR. I'm going to try negative 1 next time. I guess my R888's don't flex very much. This kinda depends on tires. Hoosier R6's seem to like more negative camber than the R888's and stick better at lower "hot" air pressures. R888's need more air pressure hot to perform best.

Good luck,

Dan

 

[Tom F&L GoR]

I guess the important thing is to use a less aggressive rear pad compared to the front. Otherwise, you'll lock up the rears.

This is in your '06? Do you turn ABS off?

 

[Achilles99]

Dan - I'm going to try higher pressures on the R888's. At 37-38psi, I can't get the fronts hotter than about 120degrees. The loaded rear gets to 160, but that's with a differential of 30 degrees compared to inner and outer tread. I read that the R888's need higher pressures to build heat. I may try the R4's at the rear, I hope they don't bite too hard.

Tom - You are right, I didn't mean lock up. I meant the ABS would kick in. But, on track that's about the same as locking up. I would get a violent shaking in the right rear, upsetting the car, and my backend would fishtail to the right (this is while braking in a straight line).

I have SS lines I have yet to install. What effect should that have on brake feel? I know it's "better" to have over rubber, but was curious about how it would change brake behavior.

I wish the weather weren't so cold, I want to run another event before spring!