help loss of brake peddle feel

[A31Drifter]

Hi there,

Just went a 4 piston caliper conversion and the brake peddle feels soft. Have a feeling that its the brake booster. Can anyone who has done this conversion shed some light.

Thanks

[BenA31]

Hi there,

Just went a 4 piston caliper conversion and the brake peddle feels soft. Have a feeling that its the brake booster. Can anyone who has done this conversion shed some light.

Thanks

yeah i also did the r32gtst brake upgrade recently. my brake pedal also feels soft but still firms up after a couple pumps. i'm pretty sure ur right been the brake booster. i did a mt dandy run the other week and the brakes held up well. so shouldn't be too much issue using the non turbo ceffy brake booster for now although i will be looking at upgrading it soon.

As mentioned in this thread http://www.skylinesaustralia.com/forums/sh...ead.php?t=70882

I put a BM44 from a R32GTST into my Cefi - took 15 minutes.

JK

^ i'm pretty sure he was refering to the *EDIT: Brake Master Cylinder*

Edited December 13, 2006 by skypy12

[Resin]

so does the brake booster need upgrading if it is a turbo ceffy to begin with? because u said urs was a non turbo.......

[BenA31]

sorry Resin. i would have no idea. i personally don't even know if there is much difference between the non turbo ceffy brake booster, the turbo one and the skyline turbo one. but as i said. i did a run down the dandynongs here in vic which has quite a bit of braking. and my original non turbo booster held up fine. still had alot of braking power left at the end :confused: it seems jaik might have an idea. lets hope he replies.

[cefiro]

Yeah your going to need to upgrade your brake booster to 300zx or maybe even R32 gtst, if it fits. You will prob find that the Turbo and non turbo are the same. I know my car has 4 pots on the front from S14 and Z32 2 pots on the rear . The brake booster has been upgraded on my car to 300zx.

I am sure there has been a posting somewhere on this website, also check out nissansilvia.com as its prob a bit more common.

[sky80]

turbo or na all use the single piston calipers, so going from 4 pistons in the car all up to 8 on the front and 4 at the back (assuming you did the back too) will prob need a change to bigger booster from any of the cars with 4piston fronts stock...but i found that if you only did the front brake conversion (like in my sr20 180sx) then it should hold up alright using the original...

still a good idea never the less...saftey first boy

[BenA31]

cool thanks for that sky80!

[BenA31]

Edited December 13, 2006 by skypy12

[BenA31]

hmm actually what about the brake master cylinder.....probally wrong bore size......

[r32boy]

the booster shouldn't make any difference. The booster will change the amount of effort that goes into the pedal(Smaller booster = harder pedal and vice versa). But if you have a soft pedal and you can pump it upto being hard then your problem I would have said it's your master cylinder(or there is air in the lines somewhere). The turbo and non turbos skylines use masters with a different sized bore (gtst stock is 1")

check the side of your masters for the part nubmers to work out bore size

BM44 is 15/16

BM50 is 1"

BM57 is 1 1/16"

Youd want BM44 minimum but preferably BM50.

thinking about it more if it was the master you would just get a long pedal. meh too tired to think straight.

[l6a6w6s6]

I have a spare brake booster from my sr20det 180sx I can let go cheap if it helps anyone with this stuff.

[A31Drifter]

Thanks for all your help guys but the problem i am having is that its soft until halfway down then it starts to brake. It doesn't get harder when i pump the brake. Put new brake fluid in it bleeded the brakes. ill try a master cylinder this week as that is the cheapest of the two.

Ill let you know how it goes.

[A31Drifter]

went to buy a z32 master cylinder it's different. The A31 has 3 brake lines comming from it and the Z32 has only 2 its a BM57

[r32boy]

Thanks for all your help guys but the problem i am having is that its soft until halfway down then it starts to brake. It doesn't get harder when i pump the brake.  Put new brake fluid in it bleeded the brakes. ill try a master cylinder this week as that is the cheapest of the two.

Ill let you know how it goes.

For starters, make sure you have the calipers on the correct sides (bleeder at the top of the caliper) I've seen it done before and you get a very long/shitty pedal as you can never get all the air out. Thats just one thing to check before you start spending cash, as we all have our blonde moments and do stupid things.

Next go grab yourself some of those plastic brake hose clamps to diagnose the problem. Clamp off all 4 lines. The pedal should feel normal.

so check that first before proceeding

The a31 master will have 2 lines for the front brakes whare as the z32 will have the single line which will be split into 2 at a junction box. You can get around this by installing a junction box but will require altering your brake lines. Then you can take both fronts off theck the then both rears ect you get the picture

Then if it is the master and you really cant find one to suit go get your master bored out if you end up having no luck, but abit of a pricey option. But surely there is another master out there to suit.

[GTRgeoff]

A 4 piston caliper will normally have more surface area to move under brake pressure so the brake pedal will have to travel further to overcome knockoff and make contact. No surprise it is soft. A larger master cylinder bore size should make it better. This is why brake mods are best left to the pro's, or at least get the right advice. You could completely unbalance the braking effort from end to end causing a major loss of control.

The common misconception that 4 piston calipers will magically give better braking with nothing else done is cause for real concern.

[blackdog289]

Thanks for all your help guys but the problem i am having is that its soft until halfway down then it starts to brake. It doesn't get harder when i pump the brake.  Put new brake fluid in it bleeded the brakes. ill try a master cylinder this week as that is the cheapest of the two.

Ill let you know how it goes.

For starters, make sure you have the calipers on the correct sides (bleeder at the top of the caliper) I've seen it done before and you get a very long/shitty pedal as you can never get all the air out. Thats just one thing to check before you start spending cash, as we all have our blonde moments and do stupid things.

Next go grab yourself some of those plastic brake hose clamps to diagnose the problem. Clamp off all 4 lines. The pedal should feel normal.

so check that first before proceeding

The a31 master will have 2 lines for the front brakes whare as the z32 will have the single line which will be split into 2 at a junction box. You can get around this by installing a junction box but will require altering your brake lines. Then you can take both fronts off theck the then both rears ect you get the picture

Then if it is the master and you really cant find one to suit go get your master bored out if you end up having no luck, but abit of a pricey option. But surely there is another master out there to suit.

<{POST_SNAPBACK}>

go with this one

[konect]

For starters, make sure you have the calipers on the correct sides (bleeder at the top of the caliper) I've seen it done before and you get a very long/shitty pedal as you can never get all the air out. Thats just one thing to check before you start spending cash, as we all have our blonde moments and do stupid things.

Next go grab yourself some of those plastic brake hose clamps to diagnose the problem. Clamp off all 4 lines. The pedal should feel normal.

so check that first before proceeding

The a31 master will have 2 lines for the front brakes whare as the z32 will have the single line which will be split into 2 at a junction box. You can get around this by installing a junction box but will require altering your brake lines. Then you can take both fronts off theck the then both rears ect you get the picture

Then if it is the master and you really cant find one to suit go get your master bored out if you end up having no luck, but abit of a pricey option. But surely there is another master out there to suit.

<{POST_SNAPBACK}>

go with this one

<{POST_SNAPBACK}>

Got Old post ?

[1400r]

r32boy is the go I put mine on upside down opps and had the same problem ur having all fixed