Rhyscar Posted May 10, 2013 Share Posted May 10, 2013 I'm wanting to upgrade the master cylinder in the race car to get away from criss-cross proportioned brakes and have an adjustable rear bias. I have wilwood dynalites on the front and looking at doing the 2pot wilwoods on the back as well. now the issue is that I'm putting a 2zz into it with ITB's and I'm not confident I will be able to get good enough vacuum (nor does it matter don't need it for anything else..) I had problems previously with the standard booster and standard blacktop intake as I do a lot of full/part throttle left foot braking and it kept running out of vacuum on the track. not knowing when you will have vacuum or not is awfully hard to drive with! I have been told nissan master cylinders have much better internal proportioning as well as being one line for front, one for rear so I can put a proportioning valve inline to the rear brakes and adjust it that way. so I'm looking to use the a nissan master on the standard brake pedal but not running any booster. I would imagine the mounting/bracket might need some bracing which isn't too much of a biggie and not fussed on how hard the pedal is, as long as it works. does anyone see any problems with this/have experience with this type of setup? Quote Link to comment Share on other sites More sharing options...
mark105 Posted May 10, 2013 Share Posted May 10, 2013 i think it will be fine but you may need to change the pivot points for your brake pedal so it is not super hard and get some better leverage. if you look at most of the willwood pedal box setups the master cylinder attaching point is quite close to the pedal pivot which i think you might find will be quite different to your standard pedal. see pics below. you should also check the master cylinder size, if it is to heavy when you ditch the booster you might want to look at going slightly smaller in your master cylinder to lighten the pedal. Quote Link to comment Share on other sites More sharing options...
kpr Posted May 10, 2013 Share Posted May 10, 2013 ^this. run a willwood reverse mount in the starlet. even with 6:1 ratio over roughly 4:1 factory. and smaller masters, its alot heaver than the factory boosted setup. i would consider getting willwood pedal box. you wont need a bais valve, as you can run different size cylinders front and rear. plus tune the bias with the balance bar. price wise they aren't too bad for what you get. Quote Link to comment Share on other sites More sharing options...
Rhyscar Posted May 10, 2013 Author Share Posted May 10, 2013 yeah we just ordered a pedal box for dads ae82 but after getting it there is no way it is going to fit under the dash/through the steering column. everything is just in the way. and floor mounting box isn't an option I'm already sitting inline with the pillar cause I'm a tall bastard. can't move seat back much further as it hits rear seat rise/I'm already too close to main hoop for my liking.. Quote Link to comment Share on other sites More sharing options...
kpr Posted May 10, 2013 Share Posted May 10, 2013 move some stuff? which pedal box did you get? i don't know what ae82 is like. but in the starlet. i pulled out the whole factory pedal box. which also mounted the steering column. made a new bracket that mounted wilwood pedal box and the steering column. all the cylinders sit above the column and pedals drop down past it. this was the reverse mount setup with front/rear/clutch cylinders there is a guy on starletcentral that has mounted a single wilwood pedal, with 2 masters firewall mounted. maybe worth asking about. this is on a ep82 gt starlet, which is likely more similar to ae82 Quote Link to comment Share on other sites More sharing options...
Rhyscar Posted May 10, 2013 Author Share Posted May 10, 2013 yeah that is another option but also pretty much the same amount of work as using a nissan master.. ae82 and ae101 quite similar being fwd and compact in that area. the steering rack is at the back so the angle the steering column/universal is on is quite steep and right in the way. it could be possible to straddle the column with clutch/brake pedal but then have no room for masters.. got a reverse mount box prob the same as your starlet one. Quote Link to comment Share on other sites More sharing options...
mikuni Posted May 10, 2013 Share Posted May 10, 2013 Just try it? I removed the servo/booster in my old chevette and found it way better. I ran a different master in there too, which I think was larger. Not sure which way that would have gone as far as heaviness, possibly made it easier on the pedal because you are moving a higher volume of fluid with each press of the pedal? Maybe it's the other way I can't be bothered thinking about it. Anyway, this will be a pretty light car and with the right ratio of master:slaves along with pedal pivot point as ten5 mentioned, you should have it working well. I was running into similar issues of running out of vacuum in my Vectra at the track. I was considering possibly running a vac accumulator tank with a 1 way valve to store the vacuum, but by the time you much around adding all that stuff it's probably easier to just go down the path you are. Quote Link to comment Share on other sites More sharing options...
bigmatt4 Posted May 12, 2013 Share Posted May 12, 2013 another easy way is to put a diesel alternator on it with a vacume pump run an oil feed and dump pipe to pump and your good to go constant vacume 1 Quote Link to comment Share on other sites More sharing options...
Rhyscar Posted May 13, 2013 Author Share Posted May 13, 2013 Hmm yes that could work. Haven't sorted an alternator yet i can imagine it would be fairly underdriven as well due to diesels not needing a whole heap of the sparky juice... Quote Link to comment Share on other sites More sharing options...
Unclejake Posted May 14, 2013 Share Posted May 14, 2013 I'd roll unboosted and push harder on the pedal.That's how my race car was set up and it was probably a good thing in the wet. Mass is the enemy of a race car so if you can lose 2-4kgs of booster then yay. 2 Quote Link to comment Share on other sites More sharing options...
Truenotch Posted May 14, 2013 Share Posted May 14, 2013 Take a holesaw and turn your booster into swiss cheese. Weight = power. Ditto what the other guys have said though. It's worth taking some time to work out the ratio, otherwise it'll be hard as hell (like retep130's escort). Apart from that, just do it. 1 Quote Link to comment Share on other sites More sharing options...
mikuni Posted May 14, 2013 Share Posted May 14, 2013 Hmm yes that could work. Haven't sorted an alternator yet i can imagine it would be fairly underdriven as well due to diesels not needing a whole heap of the sparky juice...Diesel alternator with a vac pump sounds big and heavy, even if it is under driven and not drawing too much from the motor. Last resort if plan A doesn't work I reckon.You've inspired me and I'm currently doing something similar with my car right now. Just need to make up an adaptor to bolt master in place of booster and we'll be away. I'm just going to have it actuating from as high up the pedal as I can and hope it gives an ok pedal feel. Quote Link to comment Share on other sites More sharing options...
Rhyscar Posted May 14, 2013 Author Share Posted May 14, 2013 yeah thats what I thought as well plus the hassle etc. brakes are not really a place where you want to not be confident in the setup.. yeah I think working out pedal pressures/braking clamping pressure wouldn't be a bad idea. I think I'll start close to the wilwood ratio and work from there. any ideas on what pressure a 4 pot wilwood caliper would see in terms of pressure? either line or piston face? I wonder what wilwood recommend? Quote Link to comment Share on other sites More sharing options...
shaneo Posted May 14, 2013 Share Posted May 14, 2013 I run no booster just press harder never had any trouble on a track or the road. The Wof guy did notice and wasn't to pleased but the last one didn't even notice I only run factory barkes Go faster press harder Quote Link to comment Share on other sites More sharing options...
Ghostchips Posted May 14, 2013 Share Posted May 14, 2013 Diesel alternator with a vac pump sounds big and heavy, even if it is under driven and not drawing too much from the motor. Last resort if plan A doesn't work I reckon. You've inspired me and I'm currently doing something similar with my car right now. Just need to make up an adaptor to bolt master in place of booster and we'll be away. I'm just going to have it actuating from as high up the pedal as I can and hope it gives an ok pedal feel. i have one in the shed now they are not noticeably heavier. Quote Link to comment Share on other sites More sharing options...
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