buZy Posted January 12, 2006 Share Posted January 12, 2006 Ok did a search but did not find what I was looking for. Can I run the AZC standard 240z front and rear brake kit Without using a power brake booster? In other words... Can I adapt a larger master cylinder that uses no booster? Is this possible? Or ever done? Like for a race car? The reason I thought if my motor has low vacuum I could build my brake system to work with the car. Thanks everyone! Brian Quote Link to comment Share on other sites More sharing options...
mark Posted January 12, 2006 Share Posted January 12, 2006 I used to run my 240 like that. I made a plate that adapted the stock master cyclinder to the fire wall and had to make an adjustable push rod but it worked well. Quote Link to comment Share on other sites More sharing options...
blueovalz Posted January 12, 2006 Share Posted January 12, 2006 I've wondered this myself, but a couple of points made me decide on keeping the booster. First, a larger MC would aggrevate the situation in that the mechanical advantage would be decreased with a corresponding increase in MC bore (provided no change was made to the SC). You'll be losing not only the advantage of the booster itself, but also increasing the effort needed by using a larger MC. Second thought. Well, how about if I used a smaller MC, which would allow me to gain back some of the assist I lost by removing the booster? The problem with that was I did not have enough fluid transfer to push the larger pistons of the brake upgrade firmly against the rotor. I could have experimented to find a size that would provide this (right at the edge), but I wanted a margin for safety in case the system ever was compromised. Quote Link to comment Share on other sites More sharing options...
Ed260Z Posted January 12, 2006 Share Posted January 12, 2006 There are a few system you can buy that will do that for you. But if you ever plan on useing this car on the street I would keep the booster for a lot of reason. I can live with no power steering, but no power assist brakes. A race course is a controlled environment, the street isn't. Quote Link to comment Share on other sites More sharing options...
mark Posted January 12, 2006 Share Posted January 12, 2006 The car was mainly used for auto X and track days. Little street time. The pedal effort was increased but it was not bad and easier to modulate the brakes. Quote Link to comment Share on other sites More sharing options...
buZy Posted January 13, 2006 Author Share Posted January 13, 2006 Ok what is a "Dual 3/4 masters with a bias bar "? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 13, 2006 Share Posted January 13, 2006 Ok what is a "Dual 3/4 masters with a bias bar "? http://www.stockcarproducts.com/pedassy.htm Quote Link to comment Share on other sites More sharing options...
buZy Posted January 13, 2006 Author Share Posted January 13, 2006 Ok I see...Thanks. Could I use one of these or will I have the same problem Terry talked about? The booster is starting to look like the way to go. Quote Link to comment Share on other sites More sharing options...
blueovalz Posted January 13, 2006 Share Posted January 13, 2006 The double MC provides front to rear biasing, and is not for pressure assistance. A double MC set-up would allow you to eliminate a brake bias regulator (proportioning valve) often used for the rear brakes. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 13, 2006 Share Posted January 13, 2006 They also have a different pressure ratio Terry. I think the Z is 5:1, and these are 7:1 so they give you more pressure at the master just due to the position of the pivot pin and the length of the pedal. The big deal about these is that a proportioning valve doesn't limit the rear brakes proportionally. It kinda goes up a ways and then cuts off more than proportionally. I had no idea about this until about a year ago. It's kinda weird, but here's the basic idea if you really care: http://www.stoptech.com/tech_info/wp_proportioning_valves.shtml Quote Link to comment Share on other sites More sharing options...
johnc Posted January 13, 2006 Share Posted January 13, 2006 As Jon said and the Stoptec article states, a porportioning valve just reduces pressure at some predetermined rate. Generally they are used to get brake balance right for hard braking under dry conditions with good tires. A balance bar fine tunes brake balance for changes in vehicle load, tire and brake wear, and track conditions. Quote Link to comment Share on other sites More sharing options...
PeterZ Posted January 13, 2006 Share Posted January 13, 2006 Good article. I was taught the valve tapers off the rear brake pressure under hard braking to reduce rear whell lock-up due to weight transfer. I need to do some work on my car as I still have front wheel lock-up. I like the height adjusting valves (Toyota Truck) because they compensate some for additional weight in the bed. On my old BMW 2002 ITB cars we had to put an adjustable valve in the front brakes. Not fun as the calipers each had two brake lines. (The master cylinder had 5 lines-4 to the front calipers) Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 13, 2006 Share Posted January 13, 2006 For safety the standard prop valve is the way to go for sure, but think about when you're at the end of the straight at 100+. Your rear brakes aren't doing squat for most of that braking zone, and possibly all of it. Then at slow speeds the dual masters kinda sucks, because you can apply more pressure to the rear brakes at low speeds than you can at high speeds without lockup. I am going to try and run both, and choose a rear master which is too agressive for the front master, but cut it down with the prop valve and hopefully that will end up with some more balanced braking in all situations. It really is something of a guessing game at that point though. Might have to try a couple different prop valves before I find one with the right "knee". Putting a prop valve in the front brakes is somewhat verboten Peter. I'm surprised that worked at all, for the same reason as stated above. The harder you step on the pedal the less pressure gets there (proportionally). Quote Link to comment Share on other sites More sharing options...
tube80z Posted January 13, 2006 Share Posted January 13, 2006 I am going to try and run both, and choose a rear master which is too agressive for the front master, but cut it down with the prop valve and hopefully that will end up with some more balanced braking in all situations. It really is something of a guessing game at that point though. Might have to try a couple different prop valves before I find one with the right "knee". That's pretty much what I did. I used a tilton balance bar assembly and modified a stock pedal box to accept dual masters. Then I used the tilton prop valve to get the initial rear bite just right. The beauty of this setup is that I have enough variation to be able to handle wet or dry. In the new car I can display brake pressure on the dash from the datalogger so setting bias becomes very simple. Cary Quote Link to comment Share on other sites More sharing options...
PeterZ Posted January 14, 2006 Share Posted January 14, 2006 Putting a prop valve in the front brakes is somewhat verboten Peter. I'm surprised that worked at all, for the same reason as stated above. The harder you step on the pedal the less pressure gets there (proportionally). Well said, Jon. I like the solutions listed above such as overdoing the rears and bringing it back with the adjustable valve. The Maxima rear kit was smallish anyway. Thanks. The tandem master set-up works well for my DSR chassis; excellent work on the mounting. Quote Link to comment Share on other sites More sharing options...
clarkspeed Posted January 14, 2006 Share Posted January 14, 2006 Tube80z, What size masters did you end up with? Quote Link to comment Share on other sites More sharing options...
tube80z Posted January 14, 2006 Share Posted January 14, 2006 Tube80z' date='What size masters did you end up with?[/quote'] I'm using 3/4 and 7/8 with dynalite 4 pucks in front and 2 pucks in the back. Front rotors are 10.5 and rears are 10.25 to fit under the 13 inch wheels. It would have been a lot easier to work with 15s but I'm pig headed. The pedal is solid and has little movement. I've been told a lot of drivers prefer short and stiff (no jokes please) but long and soft is better for the car (referring to travel and effort). I don't think I'll make any changes this year as I have more than enough things to keep my busy. Cary Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 14, 2006 Share Posted January 14, 2006 Here is a spreadsheet you can use to figure out what size masters to get. http://sth2.com/Z-car/Brakemath.xls In talking to Cary about this previously we were figuring on about 1.5g deceleration. That would be truly awesome if I could get my car into that realm. I think Cary is already there. Anyway, you'll see that the bigger the rear master the less the ultimate g force you can get, because you'll lock the rear up first. If you go tiny on the rear, you can get ridiculously high g forces on the spreadsheet, but that basically just means that the rear brakes aren't doing anything, which is also something you don't want. So my plan was to go with something that got me in the 1.1g range or 1.0g range, then cut that rear down with the prop valve. Don't think there is a "right" way to do this, but if Cary or anyone else has any input on my plan I'd love to hear it... Quote Link to comment Share on other sites More sharing options...
tube80z Posted January 15, 2006 Share Posted January 15, 2006 So my plan was to go with something that got me in the 1.1g range or 1.0g range, then cut that rear down with the prop valve. Don't think there is a "right" way to do this, but if Cary or anyone else has any input on my plan I'd love to hear it... That's pretty much how it went. I was overly optimistic on how much braking force the car could generate. I've routinely seen the range you show above. I've been able to get to 1.2 only in a few straight line tests. I really couldn't understand why the car can corner at 1.4 to 1.5 and only stop at around 1. I found out last year that it was the tires that are my limiting factor. This year I plan on logging brake pressure to try and get better at braking. I know that I'm not very good at that and need to improve. Cary Quote Link to comment Share on other sites More sharing options...
buZy Posted January 16, 2006 Author Share Posted January 16, 2006 Cool thread! Have been reading all the posts and learning quite a lot. This website is the best place on the internet. Ok here is what I found out over the weekend... The booster check valve is good. The booster on the other hand does not hold vacuum and needs replacement. Quote Link to comment Share on other sites More sharing options...
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