Brake booster question

[Christopher W.]

I have an 89 GTUs. A 20b n/a is going in. I am going to do some track days with it, mainly a street car. No real racing.

I am upgrading to a big brake kit front and rear......I don't care if you think I don't need to. :) I am also going to add an upgraded master cylinder.

My question is, is there any reason to upgrade to a TII booster?

[Phoenix7]

I'm looking at the FSM and they don't seem to be different in pressure (if I'm reading right) it says they all (NA and TII) create 312psi of pressure for 44lbs of force from our leg.

I left the stock GTUs booster for the TII swap and never had problems. A local guy has the Wilwood kit and had to disable the ABS because the fronts kept locking up in his TII. Dunno what kind of power you're looking to make out of the streetable 20B-NA though so you may need the brakes in the end you know what your needs are.

What did you upgrade the master cylinder with?

how far along on ths build are you? Looks like there are quite a few GTUs' on here. Don't forget to make a thread about your project.

[Christopher W.]

Revolution Brake is designing a brake kit. I have not decided on a MC yet. I am sure from what I see on their website that one will fit my needs. I am still trying to get them to tell me whether the rear kit has been engineered yet or not. I will probably have to get money in their face first...but very nice guys there.

As for the project, Defined Autoworks has my 20b engine. It is about half way done. We are going with semi pports. So R&D still needs to be done to start on my stuff. Custom ITBs are being engineered now as well. So that part is a long way off still. They will do the engine install and tuning. I am going for a street car. Not a daily driver at all. Maybe 3or 4 track days a year. I also want a bit of a race car bling effect for the street. Like I am going to have ac but no stereo. Full interior and I already have new Recaro Pole Postions for the car.

I have Foamsealed the car. It is currently getting the interior Lizardskined. That is sound and heat absorbtion. Roll bar is being started nextweek. Then by the end of the month all suspension and driving gear will be out for full bushing redo. Going mostly with Mazda comp.


Anyway that tells where we are now. I am starting a thread once I get a bit more done. Here is what it looks like now. Oh yea, just got the engine bay painted.

[RETed]

I am also going to add an upgraded master cylinder.

What does this mean?
You want a "beefier" brake master cylinder?
You want to change the brake master cylinder bore size?
Why?


-Ted

[djmtsu]

Alot of people do this Ted. I dont get it either. The 929 mc is a larger bore but not worth the effort to fit it.

[Phoenix7]

:dunno: Isn't the stock TII brake system fairly good to begin with? You have to be pushing quite a bit of power in order to outperform the stock brakes. Wouldn't you benefit from a good wheel/tire/pad combo for better braking BEFORE you go with new brake system?

Chris (OP) doesn't seem to want to talk about his needs much but I'm interested to see everyone's input regarding the best way to improve braking without frivolous expenses.

At what point should the braking system be upgraded? I am under the impression that "if you can't lock up your tires under hard braking then you're outdriving your brakes" but I don't know how realistic/correct this is though.

[TehMonkay]

With a good pad and fluid, on good OE rotors, and venting, you can run stock brakes from what I hear when road racing, until you hit a certain power level, then you're going too fast to keep stopping over and over again from those speeds.

[Christopher W.]

I have not specifically spoke to Revolution brake about the MC. I figured that since I will have Wilwood calipers front and back that the MC might need to push more volume. That is why I asked about the brake booster. I want all the parts to work correctly when it is all together. I understand that I will also be needing a brake bias adjuster.

It is hard to look at this stuff and say no. Remember I am not coming at this from a racer on a budget point of view...

http://store.revolutionbrake.com/wilwood-disc-brakes-wilwood-master-cylinders--fluids-and-controls.html

[Christopher W.]

:dunno: Isn't the stock TII brake system fairly good to begin with? You have to be pushing quite a bit of power in order to outperform the stock brakes. Wouldn't you benefit from a good wheel/tire/pad combo for better braking BEFORE you go with new brake system?

Chris (OP) doesn't seem to want to talk about his needs much but I'm interested to see everyone's input regarding the best way to improve braking without frivolous expenses.

At what point should the braking system be upgraded? I am under the impression that "if you can't lock up your tires under hard braking then you're outdriving your brakes" but I don't know how realistic/correct this is though.

I would love to talk about this. I just don't want people trying to tell me I don't need big brakes. The fact is is that I am getting big brakes front and rear and I would like to have a conversation about how to make that work properly. Not a conversation about whether I should do it or not.

[Phoenix7]

well, you're already doing it it so I don't think anyone is going to talk you out of it. It looks like the few that posted don't think it's necessary and don't know how to make it, a mod they've never done, work properly.

I think You should head to the 3rotor section and see if any of those guys have done/are doing something similar.

WORST CASE SCENARIO: You teach US how to make it work.

[RETed]

I figured that since I will have Wilwood calipers front and back that the MC might need to push more volume.

Then you better be asking the people building your brake kit for you, cause Wilwood brake calipers come in different bore sizes.
To assume you NEED to change the brake master cylinder (bore) is just wrong.
You're assuming "bigger is better" but not in this case.

In fact, increasing the brake master cylinder bore size drops brake caliper effectiveness (and "feel") due to physics.
Pressure through the system drops due to (you) increasing the "square inch" part of "psi" - pounds per square inch.


-Ted

[Christopher W.]

Yea, like my dad use to say, "Assumption if the mother of all fu%# ups!"

I am trying to get a handle on the brake system from a engineering stand point and not from a parts consumer stand point. I just really want the look of big brakes. I know that may sound cheesy, but I do.

I now need to make that happen and not screw up my car's balance. I will stay with stock stuff before I do that...

I have found some very good articles on Stoptech's site. I wonder if I am not suppose to be post links to different vendors. Anyway, I am sure someone will tell me if I am in the wrong.

http://www.stoptech.com/tech_info/tech_white_papers.shtml

I am not real sure how well the guys I have been talking to are not just getting parts to fit as much as engineering a brake system.

Well at least I know the stock brakes are really nice. I will do some updates when I start my build thread. I have lots of other stuff to get happening now. Mainly to get my interior back in...ugh!

[$100T2]

It is hard to look at this stuff and say no. Remember I am not coming at this from a racer on a budget point of view...

http://store.revolutionbrake.com/wilwood-disc-brakes-wilwood-master-cylinders--fluids-and-controls.html

Any time you consider making a modification, the idea of throwing money at it, or a "Hey, I can afford it, so why not?" attitude should be avoided.

I realize you want the looks of a big brake upgrade from your other post, but on top of that, with every single modification you make, you need to ask yourself what you will gain from it, is it worth the time and aggravation of doing it, etc.

"It is hard to look at this stuff and say no" is not a reason to get something. Ask yourself what the benefits are, what the drawbacks are, and then decide if it's really worth doing. Upgrading the master cylinder may not be necessary, and might result in a lot of headaches for no real gain.

[Christopher W.]

Any time you consider making a modification, the idea of throwing money at it, or a "Hey, I can afford it, so why not?" attitude should be avoided.

I realize you want the looks of a big brake upgrade from your other post, but on top of that, with every single modification you make, you need to ask yourself what you will gain from it, is it worth the time and aggravation of doing it, etc.

"It is hard to look at this stuff and say no" is not a reason to get something. Ask yourself what the benefits are, what the drawbacks are, and then decide if it's really worth doing. Upgrading the master cylinder may not be necessary, and might result in a lot of headaches for no real gain.

Yea, I totally understand your point and agree. I am not looking to upgrade a master cylinder for the sake of it. I could care less about what master cylinder is in there. I was thinking and probably wrong, that that would be needed.

But filling up my new wheels with big rotors is very appealing but it will only be done in a function over form way.

So, I seem to have my question answered though that I should stick with the n/a brake booster.

I guarantee that I am not just going to throw money or parts at this car. Believe me, I don't have that kind of money.....I am just a exercise coach and nutrition consultant. No fat money here.

[RETed]

Read the Grassroots Motorsports magazine brake primer - Pulp Friction - here:
http://www.scirocco.org/faq/brakes/pulpfriction/pfpage1.html

Pay attention to page 2, as it goes into brake master cylinder bore sizing...

Personally, I don't usually trust propaganda spewed from vendors, as they are trying to sell you something.


-Ted

[Christopher W.]

Read the Grassroots Motorsports magazine brake primer - Pulp Friction - here:
http://www.scirocco.org/faq/brakes/pulpfriction/pfpage1.html

Pay attention to page 2, as it goes into brake master cylinder bore sizing...

Personally, I don't usually trust propaganda spewed from vendors, as they are trying to sell you something.


-Ted

I agree with you about propaganda from vendors. I will say that Stoptech's whole point that I read was with a properly designed front brake system you don't need big rear brakes. I am a bit of an exception because I want rear brakes for other reasons besides just performance.

Here is a quote from their paper on rear brakes. The first quote was from a customer of Stoptech.

"The folks at STOPTECH should consider developing a rear kit to match their front setup. They'll be very happy with the performance improvement if done properly." Well, since our FRONT systems are designed properly, we save you the need to spend your money on the back axle. Let's reword that quote to reflect the STOPTECH philosophy: "Our competitors should consider developing a FRONT kit to match their stock bias condition. They'll be very happy with the performance improvement if done properly, AND will save their customers the cost of a rear brake upgrade in the process."

All of that being said I am not going with Stoptech. I have today talked to the guys at Revolution Brake and got the answers that I was looking for. They are not part fitters. They are brake engineers. They actually take in account all of the stock systems specifications and try to replicate that as close as possible with the larger Wilwood rotors and calipers. They use computer software to do this. They said that they can usually get the brake bias damn near spot on to the original specs. They said if it is a little off it usually tends to add a slight bit more towards the rear than stock.

They see no problem so far with the stock MC. They haven't crunched the numbers yet so we will see....I should have my kits by the third week in July.

[Phoenix7]

sounds cool and expensive. How much $$ you dropping for this mod? Please do a brake test so we can compare the benefits with other 3 rotor guys on stock systems.

How big are you going, btw?

[Christopher W.]

I hadn't planned on doing a before and after test but that is a really good idea. I kind of wanted to get this all hooked up while I have all of the susp. and changing the rear out. But I will think about a before and after test.

I will get back with exact specs on brakes but I think he said 12.8 or 325mm by maybe 22mm on the two piece rotors. I don't know if the backs are going to be different size than the front. We discussed the Dynalite calipers but still looking at different options once they do more research.

They also said a conservative estimate would be around 10-12lbs less per corner. Time will only tell on that... He was telling me in an extreme case their kit for a Z06 shaved 31lbs per corner, awesome!!

The numbers in general are $1400.00 for the front and quite a bit more on the back. With the additional parking brake set up probably around $2800 for the rear. I am not quite sure why the price is so much higher on the rear. I will get into specifics more when they get back with me.

[My5ABaby]

You could put Evo IX brakes on your FC. Apparently they fit fairly easily.

[Christopher W.]

Fitting and working as a well designed system are two totally different things. You got to take into account front to rear bias, peddle feel, heat dissipation and sure other things I am not familiar with.

The Evo's are not designed for this car. You might get lucky by getting some other car's brake system to fit and work properly on the RX but I kind of doubt it. Or taking a lot of effort to make something work. It was already stated in this thread or somewhere else that the guy on the other forum who has tried using evo brakes is having issue getting it dialed in.

I think worst case scenario for me will be having to add a brake bias adjuster. That's what track days are for....dialing it in.

[My5ABaby]

Fitting and working as a well designed system are two totally different things. You got to take into account front to rear bias, peddle feel, heat dissipation and sure other things I am not familiar with.

The Evo's are not designed for this car. You might get lucky by getting some other car's brake system to fit and work properly on the RX but I kind of doubt it. Or taking a lot of effort to make something work. It was already stated in this thread or somewhere else that the guy on the other forum who has tried using evo brakes is having issue getting it dialed in.

I think worst case scenario for me will be having to add a brake bias adjuster. That's what track days are for....dialing it in.
I was under the assumption that the guy on the other forum got them working.

[Christopher W.]

Yea, the last I had read the fabrication had gone ok but I think Ted said something about problems relating to the operation. I haven't check in to that thread for a couple of months now. I had definitely thought about those though..

[hIGGI]

AFAIK there is difference between S5 NA and S5 TII brake booster in USDM cars...i never had problems with my S4 brake booster, but after upgrading front calipers to brembo 4 piston calipers, my pedal feel went bad....upgrading to S5 TII brake booster and bolt-on 929 MC fixed it....bigger brakes sometimes comes with bigger pistons and upgrading MC is good idea to get back desired brake pedal feel...

[WE3RX7]

I'm a fan of custom brake systems and am currently figuring out how I want to setup my FC as well. I too will be going with a larger rotor, BB and MC.

If not to make bigger, but simply to improve upon 20+ year old technology! Aside from improved braking for 500+whp, I also want quick exchange calipers, etc for track days that will make pad replacement quicker!

Just keep us posted on your setup - I know even though you're doing it for mostly cosmetic reasons, what you discover in your system may provide useful insight...

[classicauto]

FWIW, the stoptech brake setup on an FD will fucking hang you off the seatbelts. It uses stock rear rotor's and caliper's and (according to Stoptech) maintains the proper ratio between master cyl. bore and caliper piston bore.

But man oh man does it ever stop.


The only thing I see being omitted from this discussion is the fact that power has very little to do with braking capacity required.....sure, more power means you'll be (presumably) heading into a corner with more speed, and therefore need to shave that off. BUT - the larger factor working your brakes over while stopping is WEIGHT.

If you're running a stockish FC TII at the track, you can run into fade issues because you're trying to stop a nearly 3,000lb car. Trim the fat off and the brakes are required to do less work.

[Christopher W.]

I'm a fan of custom brake systems and am currently figuring out how I want to setup my FC as well. I too will be going with a larger rotor, BB and MC.

If not to make bigger, but simply to improve upon 20+ year old technology! Aside from improved braking for 500+whp, I also want quick exchange calipers, etc for track days that will make pad replacement quicker!

Just keep us posted on your setup - I know even though you're doing it for mostly cosmetic reasons, what you discover in your system may provide useful insight...

Well, I wouldn't say mostly cosmetic reasons but that is a big factor. I love the looks of big brakes....but they gotta freakin work. And when I say work that means better than the stock brakes in every way. We will see...

[WE3RX7]

Dont take this as me attacking you, however, big brakes actually DONT work on street cars as well as you'd think. They are intended for a car that gets heavy abuse on the track... if you're going to looks, cool.. but if you do it with intentions of having better street performance, they are not what you want.

[RETed]

Dont take this as me attacking you, however, big brakes actually DONT work on street cars as well as you'd think. They are intended for a car that gets heavy abuse on the track... if you're going to looks, cool.. but if you do it with intentions of having better street performance, they are not what you want.

For someone who makes odd comments, I don't think you're qualified to make such statements.
True, "street performance" does not usually stress out the stock brakes, and most people who complain about the stock brakes are actually looking for better "brake feel".
A aftermarket (big) brake kit can mimic the stock brakes and give you better feel...if designed correctly.

Just to go over those odd things you've said...

I too will be going with a larger rotor, BB and MC.
You're another one that needs to GO READ THE BRAKE PRIMER LINK I POSTED.

If not to make bigger, but simply to improve upon 20+ year old technology!
What improvement?
Other than different brake pad materials, the brake design hasn't changed much over the past "20+" years.
You can argue about full-floating calipers versus multi-piston fixed calipers, but this technology has been around for decades.
About the only thing I noticed that changed recently is CCM rotors...on Porsches; since we're not messing with these, this point is moot.

Aside from improved braking for 500+whp,
The OP was talking about a non-turbo 20B.
Getting to 300hp should be alright, but pumping out 500+ out of such a set-up is very expensive.
Thus, this is not really applicable to this thread, and if you wanna talk about your set-up, why not start your own thread?


-Ted

[Christopher W.]

Dont take this as me attacking you, however, big brakes actually DONT work on street cars as well as you'd think. They are intended for a car that gets heavy abuse on the track... if you're going to looks, cool.. but if you do it with intentions of having better street performance, they are not what you want.

You might in the end be right....

I still think a well thought out and designed system with higher quality parts than stock and good street pads will be better than stock on street.

I myself don't know how to design that system so I hope the people I am dealing with are not full of fluff.

Hopefully sometime in the fall I will have some sort of empirical evidence.

By the way Ted that's a great article in GRM.

[WE3RX7]

Not qualified? You don't even know me....

My comment on the larger rotor was probably not put the best. I mean I'm using a larger rotor... not larger BB and MC.. the BB and MC are just new aftermarket units spec'd out for my needs. Also, I'm referring to the parts being 20+ years old and believe it or not, braking systems have come a long way in 20 years besides just "pad material".. and dont quote the term "20+", last I knew FCs started in '86 thus 2006 would make them 20+...

Please remove yourself from the pedestal you put yourself on - I am not attacking your knowledge as I definitely feel you know your way around the 7s, but your just as "qualified" as myself when it comes to forum discussions.

I'll build my brake setup the way I want it, just as Chris W will build his the way he wants it. You're so eager to attack somebody and on all the forums I've seen you on, you manage to bring a bit of negativity and arrogance...

Sorry to hi-jack your thread Chris...

Lets keep the topic going as I am interested to see what you come up with along the way...

[RETed]

Not qualified? You don't even know me....
To preface a reply with don't-take-this-as-an-attack...,and you wonder why?


My comment on the larger rotor was probably not put the best. I mean I'm using a larger rotor... not larger BB and MC.. the BB and MC are just new aftermarket units spec'd out for my needs. Also, I'm referring to the parts being 20+ years old and believe it or not, braking systems have come a long way in 20 years besides just "pad material".. and dont quote the term "20+", last I knew FCs started in '86 thus 2006 would make them 20+...
Then I think you need to brush up on your English, cause what you wrote and what you're saying now are two different things.
If English is not your first langauge, then I'd understand that bad grammar.
The only way we communicate with each other is through typing (English); if you have a problem corresponding as such, then that just creates problems after problems.
Reread what you wrote: you did say "20+ year old TECHNOLOGY."
Mightly convenient that you left off the last word above...

Please remove yourself from the pedestal you put yourself on - I am not attacking your knowledge as I definitely feel you know your way around the 7s, but your just as "qualified" as myself when it comes to forum discussions.
See above.

I'll build my brake setup the way I want it, just as Chris W will build his the way he wants it. You're so eager to attack somebody and on all the forums I've seen you on, you manage to bring a bit of negativity and arrogance...
I've got nothing against you spending your money on how you see fit.
Spewing misinformation is another thing...
Some of the crap being typed in here can be downright dangerous.
Misinformation like this can get someone hurt or even killed - this I got a very big problem against.

Negativity?
We were having a constructive critical debate until you started to place labels on me.
If you've got nothing helpful to offer, then I'd suggest you STFU.
You want to brag about how YOUR brake kit is going to be built, I'd suggest you start your own thread.
You have a PERSONAL problem with me, keep it out of the thread - that's what PM's are for.


-Ted

[My5ABaby]

Ted cracks me up. :icon_tup:

Also, I'm referring to the parts being 20+ years old and believe it or not, braking systems have come a long way in 20 years besides just "pad material".. and dont quote the term "20+", last I knew FCs started in '86 thus 2006 would make them 20+...
The building started in 85, but there were prototypes/technical crap going on for years before that. Likely the braking system was probably finalized in like 83 or 84.

Regardless of all the other talk, I've NEVER had a problem with my 22 year old brakes. This is even including the fact that many of the parts are stock. I can still lock up my brakes on command. Granted I don't have the best tires, but assuming my system was 100% operational back to stock specifications I don't see there being a problem unless I have a giant tire (assuming that would matter?).

However, I've never tracked my car so I'm not qualified to speak in regards to heat, but from what I understand, the 4 piston/vented rotor combination is way over-engineered (just like everything else on the car).

[jgrewe]

I can speak from experience on the track capabilities of the stock FC brake system with braided lines, Motul fluid, racing pads, and 3" cooling ducts on the front only. The system will pull the 2500lb car down from 150 mph to about 40-60mph twice a lap(Daytona 24hr course) over and over again with no problems and do it for 30 minutes without fading.

I like the look of big brakes too, but I'm only willing to carry what I need on the race car. Beware of unsprung weight!