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]

Originally Posted by Christopher W.

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]

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/wil...-controls.html

[Christopher W.]

Originally Posted by phoenix7

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]

Originally Posted by Christopher W.

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/te...e_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]

Originally Posted by Christopher W.

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/wil...-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.]

Originally Posted by $100T2

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/p...n/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