R33 Gtr Rear Brakes Vs R33 Gtst Rear Brakes

[Roy]

Yeh, the smallest master cylinder will actually give you more pressure in the lines. Probably explains why your pedal feels so nice. And makes me think that perhaps the R33 has a slightly different pedal ratio.

Al, i get bored i read stuff about brakes because i have a fetish. It would take Keira Knightley to pull me away from a nice set of brakes

Al, What im getting at is my thoughts are you have increased your front brake bias with the bigger rotors (More braking torque), bigger piston area, and better pads (typically higher coefficient of friction which again gives you better braking torque)

So if your locking rear brakes after a minor brake upgrade? I would go to Centreline or Tech Sport and get your car corner weiged...even ask if you can sit in the car whilst they do it. Thats where i would start.

Upgradign brakes is no different from upgradign an engine part. More power can highlight a shortcomign in your colling systems? Upgrading your brakes can fhow a weak spot in your suspension settings.

You have done an upgrade, so dont go throwing the crappy std gear back on...just give it a tweak here and there. LOL, i could be so wrong, thats why i suggest the experts. TryPurple Engineering (i think thats there name) They do the brake setups for Melbourne Performance Centre so can get their details thru them as there card is buried in a box somewhere.

I would throw the DS2500s in the front, and grab a set of Race Brakes Comp 2s for the rear. Thats what im currently running and our setups have a few similarities. The problem your having isnt brakes, its suspension

I suppose the thing we should have quantify firstly was the rear a little unsettled or was it actual lockign rear brakes?

If i didnt get distracted and read more i may have an actual answer, but this

Will always lose out to this

[discopotato03]

All those curves and Roy with no brakes ....

Edited September 30, 2006 by discopotato03

[VLHERO]

The problem your experiencing could also be due to the heavier braking force on the front causing the car to drop at the front, thus effectively lifting the rear of the car making it lighter and needing less braking force applied in order to lockup.

[Al]

The problem your experiencing could also be due to the heavier braking force on the front causing the car to drop at the front, thus effectively lifting the rear of the car making it lighter and needing less braking force applied in order to lockup.

Isn't that what i have stated already?

Do you have any thoughts for a solution?

[Abo Bob]

Further to previous discusssions in this thread about master cylinder size:

I just put what I think is a standard R34 GTR master cylinder on my car just cos it was there. Everything else stayed the same.

I actually thought I had stuffed the whole operation up because first press of the brakes yeilded next to nothing.

The end result is that I press the pedal and it goes further than before with only the lightest of braking happening then it gets to a point where you push hard and it really stops.

So I think you could say that the pedal travels further and that it's harder once you get the meaty part of the braking.

Before my brake pedal always had a bit of travel before it started braking properly. Are all Skylines like that?

You know how you drive a newish falcon for eg, and the pedal barely moves before you are braking hard. They are really twitchy. Mine is the opposite. How would get that if you wanted it?

Should I start a new thread about this?

[Roy]

You know how you drive a newish falcon for eg, and the pedal barely moves before you are braking hard. They are really twitchy. Mine is the opposite. How would get that if you wanted it?

Should I start a new thread about this?

Basically, a smaller master cylinder gives you more brake line pressure. Its a mantra that on the face of it is seems wrong... but it never is. Pressure = Force/Area

So with the same pedal travel the force will be the same. So are you reduce the piston size you reduce the area, so are increasing the pressure.

So the longer pedal makes sense. But it shoudlnt be the end of the world

What pads are you running. A friend was running Endless pads in his R32 GTSt and they are very grabby brakes. You barely had to touch the pedal. Its not exactly what you are saying, which is right, but the end result is a grabby pedal. If thats what you are after...it could be the solution?

[Abo Bob]

Got Ultimates in there now but got some Ferodo DS2500 going in this week.

[Ronin 09]

mr roy how are my rear brackets going??????

[siksII]

Before my brake pedal always had a bit of travel before it started braking properly. Are all Skylines like that?

You know how you drive a newish falcon for eg, and the pedal barely moves before you are braking hard. They are really twitchy. Mine is the opposite. How would get that if you wanted it?

I have test driven a fair few r33s and noticed that all ABS equipped cars have doughy feeling brakes. ive noticed that this is the same with 300zxs and s15s(both have abs)

R33GTRs on the other hand have good pedal feel and have ABS.. (although i have only ever driven one a fair bit, with standard new pads and fresh brake fluid etc)

so i doubt its out of the ordinary assuming your 34 has ABS. have you driven other non ABS 34s and noticed anything different?

my 33's brakes are pretty touchy with gay ultimates on, especially just after getting disks machined they were very grabby from just touching the pedal.

Edited October 2, 2006 by siksII

[Roy]

mr roy how are my rear brackets going??????

They make a good paper weight on my desk. As ppl go to the photocopier next to me they make a great conversation starter

[GTRgeoff]

Basically, a smaller master cylinder gives you more brake line pressure. Its a mantra that on the face of it is seems wrong... but it never is. Pressure = Force/Area

So with the same pedal travel the force will be the same. So are you reduce the piston size you reduce the area, so are increasing the pressure.

So the longer pedal makes sense. But it shoudlnt be the end of the world

What pads are you running. A friend was running Endless pads in his R32 GTSt and they are very grabby brakes. You barely had to touch the pedal. Its not exactly what you are saying, which is right, but the end result is a grabby pedal. If thats what you are after...it could be the solution?

No he increased the piston size by 30% so therefore the pedal should be shorter (or harder sooner).

I have put a massive stopper behind my master, flushed several times, braided lines, RB74 front and Comp 2 rear, adjusted the brake pedal up so even on hard braking the pedal still sits just above the accelerator so I can heel and toe. All will come out again soon for reco kits including the master.

In the GTR the pedal is a bit soft initially and the braking is nowhere near as linear to foot pressure, so braided lines soon, a reco kit through everything, DS2500's, my "Big Lump" ® master stopper and further adjustment of the pedal height, as well as bending the accel pedal further across near the brake pedal.

[Roy]

Bigger piston in master cylinder moves the caliper pistons quicker?

Bigger piston in the master cylinder gives you less line pressure for given pedal travel?

Smaller piston in the master cylinder gives you more brake line pressure behind the caliper pistons.

So what happens when the caliper pistons have been readily displaced to push the pad on to the rotor, and they have less pressure (effectively the N in F=uN)

[GTRgeoff]

1. Yes, reduces the mechanical advantage.

2. Yes, or more feel or more pedal control so you are less likely to stomp the pedal and lockup, and it feels like you can put your foot into it more for more braking force instead of the 'sponginess' a small master can give.

3. Yes, but it makes it feel soft when you push for more braking. For me it's an uncertain feeling and can put me off hard braking. Come try the difference in the Soarer and the track car sometime, and my fine selection of beers

4. You use more leg, and it feels like you have a more linear response to braking force applied.

Try a V8SC sometime. Very hard pedal and even though they have massive brake kits they still have to apply massive pedal pressure to get a straight line lockup, because that's what feels best. Yes they are on slicks but the compound is such that they are only good to 600hp at the most so are at their linear limit. Add corners and brakes and they fail to be able to hold all the force available in the friction circle/blobby shape . Never heard one of those guys looking for a 'softer' pedal feel.

[Roy]

You cant compare a V8 Supercar with twin reservoir master cylinders, with no vacuum assist. They run pedal ratios up around the 6.5:1 whilst our road cars are down around 2.5:1 (numbers may be a litte out, there is a general range that designers shoot for)

I dont think there is any need for most of us to upgrade the master cylinder. And i dont think it Als problem at the moment.

Your car is running the smallest master cylinder of them all GTRgeoff, and your happy with your firm pedal?

[GTRgeoff]

Absolutely, Als problem is nowhere in the master cylinder, but you know how these discussion meander.

And you can compare to the V8SC because the feel of the pedal in relation to the job it does is the most important aspect. If the operator is not comfortable then the limits are harder to reach, but if it "feels" right then you are encouraged by your interaction with the vehicle to find the limits. It's like civil construction standards. Floors could be more flexible and skyscrapers could move around more and still be safe engineering, but civil standards dictate less flexure to ensure the laymen inhabiting the structure are not overly alarmed or uncomfortable.

Am I happy with my pedal? Yes and no. It could heve less slack on first application so the master and calipers will get a seal kit through them. Do I think I need bigger brakes? maybe larger diameter 2 piece rotors on the front for more thermal capacity, but until I go to slicks they will be more than enough.

[Roy]

LOL...i still say forget V8 Supercars. They have hard pedals because they are unassisted.

[gts-4 dreamer]

so where did this go ?

swap my t setup for a full r setup same year, 33, etc, this should be ok balance wise ?

this wont throw out the abs and start having a lack of braking in areas and to much braking in others ?

I really cant afford to throw out the abs as it will have adverse effects on the active diff. Im looking for improved performance, better stopping power overall and seriously less fade over higher temperatures (yes pads make a hell of a difference).