stock BMC with z32 fronts... - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

rwtf · 03-17-2013, 04:48 PM

Now i Know I need to get a z23 bmc to get the best results, but I recently replaced my stock s13 BMC mainly b/c mine leaked and needed a quick fix but my question is about pedal feel, the first time i hit the brakes it goes to the floor and then then after it it feels normal.

Now I dont know if thats normal with the z32 in front and stock rear or I still have air in the lines... any ideas?

zooopreme · 03-17-2013, 05:12 PM

The S13's stock BMC simply just isn't enough for the Z32's even if it's just the front. With the larger BMC, it'll use less force to stop the car thus why you have the mushy pedal.

But if you don't want to go that route, there's also adjusting the output rod.

rwtf · 03-17-2013, 06:16 PM

I do want to upgrade just didnt have the cash to do so at the time, I'm just wonder why does it go to the floor then it feels fine after.

cotbu · 03-17-2013, 07:41 PM

Quote:

The S13's stock BMC simply just isn't enough for the Z32's even if it's just the front. With the larger BMC, it'll use less force to stop the car thus why you have the mushy pedal.

This isn't true! Fact I run stock s13 BMC with full Z32 brake conversion, I don't have any problems, including the problems the OP is having.

OP you probably still have air in the system. I can verify my BMC size if necessary. also check you booster!

*Agamemnon* · 03-17-2013, 08:15 PM

Stop being cheap and buy a Z32 BMC.

They're only $72 on rock auto.

rwtf · 03-17-2013, 08:49 PM

Quote:

Originally Posted by Agamemnon

Stop being cheap and buy a Z32 BMC.

They're only $72 on rock auto.

really? I had no idea, I probably will, and how would I go about checking the booster? I know the check valve is good for sure.

*Agamemnon* · 03-18-2013, 01:30 AM

Quote:

Originally Posted by rwtf

really? I had no idea, I probably will, and how would I go about checking the booster? I know the check valve is good for sure.

Warm the car up. Turn of engine. Pump you brake pedal three times. With each pump the pedal should travel less and less. Start the engine again and hold the brake pedal for 30 seconds. It shouldn't move at all.

Also, go to Rockauto.com
Look for a BMC under a 1990 300zx TT.
CENTRIC Part # 13042603 - $72.29
It even has the optional 3rd line fitting for non ABS cars.

cotbu · 03-18-2013, 01:35 AM

Quote:

Originally Posted by Agamemnon

Stop being cheap and buy a Z32 BMC.

They're only $72 on rock auto.

It's not about being cheap! If it ain't broke don't fix it!

p00t · 03-18-2013, 12:36 PM

I had my doubts but I wanted to try something that bolted right up. I used a 15/16" MC off of a z31 non-ABS. The pedal feel is good, it is not super firm but the pedal effort is only a step above stock 7/8" MC.

What you need to be aware of (that I found out) is worn wheel bearings can make a big difference. So if you do the brake swap and after a few hard corners the pedal has more travel you will need to get new ones. When you have a very soft pedal it is not due to the size of the MC it is due to air/pad knock-back.

So maybe do more testing to find out where the problem is, it doesnt make sense if it is only the first time you touch the brakes.

Croustibat · 03-18-2013, 03:55 PM

Quote:

Originally Posted by p00t

I had my doubts but I wanted to try something that bolted right up. I used a 15/16" MC off of a z31 non-ABS. The pedal feel is good, it is not super firm but the pedal effort is only a step above stock 7/8" MC.

What you need to be aware of (that I found out) is worn wheel bearings can make a big difference. So if you do the brake swap and after a few hard corners the pedal has more travel you will need to get new ones. When you have a very soft pedal it is not due to the size of the MC it is due to air/pad knock-back.

So maybe do more testing to find out where the problem is, it doesnt make sense if it is only the first time you touch the brakes.

That, exactly, although i'd recommend getting a 15/15 if you decide to get a bigger MC.

if you need to pump after braking hard and cornering to get a firm pedal, your wheel bearings are shot; they cant prevent the disc from deflecting, thus pushing the pads back in the caliper.

wheel bearing cost = $$$$$ so pray it just is some air still in it.

And you dont need to change the BMC for a bigger one. A bigger BMC means a harder pedal with less travel... which means you have to modulate more to avoid locking brakes, and you lose brake feeling.

That is the only difference. Bigger = harder pedal and shorter travel. The Z32 BMCs also send less force to the rear if i remember correctly, so you def. dont want one if you only fit front Z32 brakes.

OutlawLui · 03-18-2013, 04:08 PM

I like turtles!

rwtf · 03-18-2013, 04:50 PM

Quote:

Originally Posted by Croustibat

That, exactly, although i'd recommend getting a 15/15 if you decide to get a bigger MC.

if you need to pump after braking hard and cornering to get a firm pedal, your wheel bearings are shot; they cant prevent the disc from deflecting, thus pushing the pads back in the caliper.

wheel bearing cost = $$$$$ so pray it just is some air still in it.

And you dont need to change the BMC for a bigger one. A bigger BMC means a harder pedal with less travel... which means you have to modulate more to avoid locking brakes, and you lose brake feeling.

That is the only difference. Bigger = harder pedal and shorter travel. The Z32 BMCs also send less force to the rear if i remember correctly, so you def. dont want one if you only fit front Z32 brakes.

I already know my wheel bearings are messed up, and they arnt $$$ but I got s14 hubs so I have to replaced the whole thing... the nismo shop has them for 210.

Croustibat · 03-19-2013, 08:28 AM

Quote:

Originally Posted by rwtf

I already know my wheel bearings are messed up, and they arnt $$$ but I got s14 hubs so I have to replaced the whole thing... the nismo shop has them for 210.

I found them at 110$ each for the front at the nismo shop, which is a real bargain if they are genuine bearings.
These are sold between 200€ and 400€ each where i live (which is quite some money considering they are just bearings imho ).

I am going to buy some at that price, if they can confirm where they come from. Ichibas and the like always end up dying quite fast :/

thanks !

JtWo · 03-26-2013, 03:03 AM

i had no problem running z brakes in the front with stock bmc in my old fast back. others even complimented the pedal feel when they drove it.

rwtf · 03-26-2013, 01:25 PM

Quote:

Originally Posted by Croustibat

I found them at 110$ each for the front at the nismo shop, which is a real bargain if they are genuine bearings.
These are sold between 200€ and 400€ each where i live (which is quite some money considering they are just bearings imho ).

I am going to buy some at that price, if they can confirm where they come from. Ichibas and the like always end up dying quite fast :/

thanks !

yeah that was the best deal I could find,also I need to get new pads up front, gonna get the EBC Yellowstuff up front and PBM rotors.

I'll shoot thenismo shop a email and get some more info on those hubs, gonna buy them my next paycheck

03-17-2013, 04:48 PM	#1
rwtf Zilvia Addict Join Date: Jun 2011 Location: Maryville, TN Age: 29 Posts: 830 Trader Rating: (3) Feedback Score: 3 reviews	stock BMC with z32 fronts... Now i Know I need to get a z23 bmc to get the best results, but I recently replaced my stock s13 BMC mainly b/c mine leaked and needed a quick fix but my question is about pedal feel, the first time i hit the brakes it goes to the floor and then then after it it feels normal. Now I dont know if thats normal with the z32 in front and stock rear or I still have air in the lines... any ideas? __________________

03-17-2013, 06:16 PM	#3
rwtf Zilvia Addict Join Date: Jun 2011 Location: Maryville, TN Age: 29 Posts: 830 Trader Rating: (3) Feedback Score: 3 reviews	I do want to upgrade just didnt have the cash to do so at the time, I'm just wonder why does it go to the floor then it feels fine after. __________________

03-18-2013, 04:08 PM	#11
OutlawLui Zilvia FREAK! Join Date: Apr 2011 Location: Anaheim CA Age: 35 Posts: 1,491 Trader Rating: (19) Feedback Score: 19 reviews	I like turtles! __________________ .

03-26-2013, 03:03 AM	#14
JtWo Zilvia Addict Join Date: Jan 2004 Location: 408 Age: 32 Posts: 747 Trader Rating: (0) Feedback Score: 0 reviews	i had no problem running z brakes in the front with stock bmc in my old fast back. others even complimented the pedal feel when they drove it. __________________ -Jawn

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03-17-2013, 05:12 PM	#2
zooopreme Post Whore! Join Date: Apr 2010 Location: Southern California Posts: 2,772 Trader Rating: (38) Feedback Score: 38 reviews	The S13's stock BMC simply just isn't enough for the Z32's even if it's just the front. With the larger BMC, it'll use less force to stop the car thus why you have the mushy pedal. But if you don't want to go that route, there's also adjusting the output rod.

03-17-2013, 08:15 PM	#5
Agamemnon Premium Member Join Date: Sep 2003 Location: Lake Stevens, WA Age: 38 Posts: 2,585 Trader Rating: (20) Feedback Score: 20 reviews	Stop being cheap and buy a Z32 BMC. They're only $72 on rock auto.

03-18-2013, 12:36 PM	#9
p00t Leaky Injector Join Date: Apr 2003 Location: mi, usa Posts: 71 Trader Rating: (0) Feedback Score: 0 reviews	I had my doubts but I wanted to try something that bolted right up. I used a 15/16" MC off of a z31 non-ABS. The pedal feel is good, it is not super firm but the pedal effort is only a step above stock 7/8" MC. What you need to be aware of (that I found out) is worn wheel bearings can make a big difference. So if you do the brake swap and after a few hard corners the pedal has more travel you will need to get new ones. When you have a very soft pedal it is not due to the size of the MC it is due to air/pad knock-back. So maybe do more testing to find out where the problem is, it doesnt make sense if it is only the first time you touch the brakes.