I am considering upgrading my crx's master cylinder to a prelude SI cylinder
I know some people have done this and there are guides, they all seem to mention a brake line needing to be bent

My question is which line needs to be bent?

If it is the front one my brake hose system won't fit

does anyone have a picture of a prelude si master cylinder installed on a crx or otherwise?

 

I'm assuming you're talking about the 88-91 Prelude 15/16ths master cylinder.

The front line is the one that needs to be bent. It's not a huge deal, it will be obvious how once you mount the MC. Just don't kink the line.

 

Not really an upgrade at all.

Anyway, you can bolt on a 90/91 Sedan EX MC and it is 15/16" (to support the larger front brakes).
Direct bolt on with zero line bending.

 

Probably the best choice for EFs. Only problem is most parts stores will sell you a 13/16ths instead, so you have to make sure you really are getting the bigger master.

 

right, well what i need to know is what direction the line bends, i am using AN hoses the whole length of the car and the adapters don't allow much space
does the front line go through the side? or the top?
i have seen pictures (probably stock) with the openings on both sides

 

anyone?

 

It's a direct replacement Fuel Injected 90-91 Model 15/16

The bending is just moving when I consider all to be nothing of a modification

 

Why do you need a bigger master cylinder? Front brake swap?

There are three different master cylinders that are a direct fit. Which size you "NEED" depends on your brake setup. When your dealing with hydraulics, there is no such thing as an "upgrade". There is either the correct size, or the incorrect size.

-88-95 13/16"
-88-95 7/8"
-90-91 EX 4dr 15/16"

So what's your brake setup?

 

Consider the piston size to caliper piston size ratio. The larger the bore of the MC (the closer it is to the size of the caliper piston) the more pedal effort is required.

You do not need a larger MC to support larger brakes, however its advantage is that since pedal effort is increased (you have to push the brake pedal harder) it can give the driver more direct feedback, possibly improved thresh-hold braking modulation and an overall improvement in "firmness".

 

What do you mean by"pedal effort"?
To me, that means the pedal will be harder to press on - sort of like removing the power assist.

Here's a quick diagram/explanation:
Figure a brake setup with just one wheel (for illustration)
In the caliper - the piston is pressed outward during braking. Fluid fills the void behind the piston.
The MC has a piston as well. When you press on the brakes, the MC forces the fluid through the lines and into caliper to fill up that bore behind the piston.

If you swap to different calipers, then they may have a larger bore and will require more fluid to move the piston outward.
Without changing the master cylinder, the driver will have to press down further on the brake pedal to get the caliper pistons to move and start braking.
If you exaggerate this scenario and put on a HUGE caliper, then the driver could push the pedal to the floor and the caliper would move so little that the pads would not connect with the dis and it won't be able to stop the car.

So you get the opposite if you keep the stock calipers and add a larger bore master cylinder.
The driver will press less on the pedal to achieve braking.
Exaggerated, with a HUGE master cylinder, the driver would barely push on the pedal and the wheel would lock up and skid.
Basically like an on-off light switch.
This is NOT desired as the driver will have less "brake feel" - or the ability to select various ranges of pressures applies to the brakes.

For a daily driver, it won't be as apparent with a slightly oversized master cylinder, but it's far from a performance upgrade in any way.
In tight braking situations or on a race track, the driver will want to achieve the best braking they can.
This is done by braking really hard, but NOT locking the wheels.
Once the wheels lock up, they slide and it will take longer to come to a stop.
If the wheels do lock and slide, the driver will let up on the brakes and press down again for maximum braking without sliding.
Basically the same as what anti-lock brake systems do.
You don't want the on-off light switch, but you do want a dimmer.

Putting too large of an MC on a brake system reduces brake feel and can become unsafe in tight situations where maximum braking is demanded.

 

From my extensive research of different Honda/OEM brake setups, this is what I've determined. The important factors in determining MC size is the front calipers AND the presence of ABS. As far as Civics are concerned, there are 3 standard front caliper piston sizes, and here are their typical matching MC piston sizes.

50.8mm caliper = 13/16th MC (standard Civic 9.4" brakes)
54mm caliper = 7/8" MC (EF FWD Wagon, 90-91 CRX Si, 93+ EX coupe non-ABS, 99-00 Si, Del Sol VTEC, JDM Civic SIR)
57mm caliper = 15/16" MC (90-91 Civic EX, 92-95 Civic ABS, All Integra including R, JDM Civic Type R)
57mm caliper + ABS = 1" MC (All Integra w/ ABS)

As you can see, when ABS is added, Honda uses a BIGGER MC to allow the driver to reach lock-up easier. This is something you do NOT want if you don't have ABS. It hurts the drivers ability to modulate the pedal at the threshold.

BTW: Even the EK Civic GX got a bump in MC size from 13/16" to 7/8" when they added ABS. The calipers remained the same size. And the Del Sol VTEC bumped up to a 15/16" MC when Honda added ABS in 95 (same caliper piston sizes).

 

I have a prelude 92-96 master and booster on my crx.. ! 1"

 

Yeah.....And we are trying to keep people from making the same mistake you did.

 

Right, so i was just asking which outlet moves and where, simply because my brake hoses use adapters that stick out a bit and it is already a snug fit

 

????

 

a. Did you add ABS to your CRX?
b. What's your front brake setup?

 

92 Prelude S:



92 Prelude Si/VTEC:


I might consider the 15/16" if I had an integra brake upgrade. But the 1" is too big unless your adding ABS.

BTW: You can look up these pictures for any year/make/model over on CentricParts.com. One of the greatest places for OEM brake system information ever!

 

Thank you for the pictures, looks like they exit on the opposite side of the master cylinder, which will work for me
I am using stock brakes at the moment but i do intend to upgrade as time passes
I have car length braided stainless AN brake hoses, no hard lines in the system
Stock discs up front, drums in the rear
This car is not for road use at all

 

just realized those bolt holes are not going to line up with a crx booster

I will just buy a reman

 

Or... if you are serious about the brake upgrade in the future, then go for the 90-91 Civic Sedan EX MC. It is a direct bolt on replacement to all 88~91 Civic/Crx booster and brake lines.

 

i bought a re-man MC
bench bled it on the car
hooked everything up
and got the air out of the system

my brake pedal is very firm




note: i used a 7/8 crx si mc for a 90-91


update note: I bought the Autozone M55002 I ran it hard in my road race car and it is now failing (blow by and soft pedal) So swapping it out under warranty
I have also since put 91 si rear trailing arms with discs on the car and will eventually swap the front calipers for 91 si calipers