Brake master cylinder -- any upgrade or just use a GSX master on my GST?

[Rice Over Wheat]

I upgraded almost my entire brake system as a result of my brakes progressively losing stopping power since November. I put Baer Track big brakes up front and Powerslot big brakes in rear, Goodridge ss lines, and new performance pads. This helped a little, but I still have lousy stopping power. The brake booster is good. The only thing left is the master cylinder so I'm going to swap that out.

I just went through all 106 threads on "master cylinder" and most of them had to do with clutch. My question is, I read I can just bolt in a new oem master cylinder from a 2G GSX which is slightly bigger I think...is this the route I should take? Or is there any upgrade out there? I haven't been able to find one.

 

[Locke]

A bigger master cylinder will push more fluid through the same travel. (or, conversely, push the same amount of fluid will less travel) This would make the brake pedal stiffer and quicker to apply force, if used on stock brakes.

If the total piston area in your braking system has increased, this will be a great thing. If you were to put on calipers with more piston area without putting on a bigger master cylinder, the brake pedal would feel softer. You follow, yes?

Anyways, if the GSX master does bolt right up, and it does have larger pistons, it will make your brakes feel more firm. IMO, do it.

 

[underradar92]

The GSX master has a 1" bore, the GST, has I believe a 7/8 or 15/16" bore. The GSX master is a bolt in. If you wanted to get tricky, a 3000gt TT master has an even larger bore (1-1/16" I believe) but the fittings face the strut tower. Otherwise it fits.

 

[Rice Over Wheat]

Thanks guys, that's the exact type of info I was looking for and a big help.

My GST had stock 1 piston calipers in front and the Baer Track kit uses two really big pistons. This would explain to me why someone I know who has the same kit doesn't have my problem -- he has a 97 awd talon which came with bigger brakes stock and larger master. My master was already going bad on the stock brake system, so obviously in no way can it provide the pressure I need for much bigger brakes up front.

Jim, that 3000gt tt master sounds intriguing...do you know anyone who has accomplished that swap? If it just takes rerouting lines, I'd like to do that. Otherwise, I'll go with the 2G GSX master.

 

[underradar92]

I do not know anyone who has tried that, although I think elvenhome21 is considering that as an option for his AWD project, try P/Ming him.

 

[Rice Over Wheat]

Hm. I think for now I'll go with what works, a GSX master. When I know I have safe and functional brakes on my dd I'll tackle a project like that.

 

[aves911]

All 2G brake master cylinders are the same size - 1"

The Evo, 3G, and 3KGT are 17/16"

 

[Rice Over Wheat]

Where did you get that info? Because the dealership has 7 different master cylinders, and of the 4 for 2G turbos, only one of them is ABS. If they were all the same size, they should only differ by ABS or non-ABS.

 

[Morphius]

For 1g's, the turbo models are 1", regardless of ABS. NT ABS are 15/16, w/o ABS 7/8.

Not sure about 2g's.

 

[Rice Over Wheat]

I'm beginning to think he is correct. I've been checking various part sites and although there are several master cylinders listed, the part numbers for 2G turbo fwd and awd only differ by abs or non-abs.

 

[underradar92]

If you find that any of them are larger than a 1" bore, please post, as I would like to do a bolt in 1-1/16 master, if possible. As far as I know, a 1" bore is the largest with top-facing fittings, and 3s masters require drilling the tower. I still may do that.

 

[ZiggysDSM]

I do not know anyone who has tried that, although I think elvenhome21 is considering that as an option for his AWD project, try P/Ming him.

i am in the process of doing the 3k vr4 mc swap if you need any info pm me

 

[jtmcinder]

The one thing in this thread that has me really worried is the suggestion that a larger MC bore will somehow provide "more stopping power."

Assuming that the OP is trying to get "more stopping power" by increasing the clamping force at the calipers, increasing the MC bore is exactly the opposite of what should be done.

For a given amount of pedal pressure, a larger MC bore reduces line pressure and, therefore, reduces clamping force. The advantages of a larger MC bore are that the pedal feels firmer (since less movement of the pedal is required to close the gap between the pads and the rotor) and you can often modulate braking torque better, since you need to push harder with your foot to get the same amount of clamping force.

But if what you're after is simply more clamping force at the calipers, then it's a smaller MC that you need.

- Jtoby

 

[Rice Over Wheat]

I already went with a 1" 2G replacement, just haven't installed it yet. But let us know how that works out for you.

 

[underradar92]

The one thing in this thread that has me really worried is the suggestion that a larger MC bore will somehow provide "more stopping power."

Assuming that the OP is trying to get "more stopping power" by increasing the clamping force at the calipers, increasing the MC bore is exactly the opposite of what should be done.

For a given amount of pedal pressure, a larger MC bore reduces line pressure and, therefore, reduces clamping force. The advantages of a larger MC bore are that the pedal feels firmer (since less movement of the pedal is required to close the gap between the pads and the rotor) and you can often modulate braking torque better, since you need to push harder with your foot to get the same amount of clamping force.

But if what you're after is simply more clamping force at the calipers, then it's a smaller MC that you need.

- Jtoby

Is this (second post) what you mean?

A bigger master cylinder will push more fluid through the same travel. (or, conversely, push the same amount of fluid will less travel) This would make the brake pedal stiffer and quicker to apply force, if used on stock brakes.

If the total piston area in your braking system has increased, this will be a great thing. If you were to put on calipers with more piston area without putting on a bigger master cylinder, the brake pedal would feel softer. You follow, yes?

Anyways, if the GSX master does bolt right up, and it does have larger pistons, it will make your brakes feel more firm. IMO, do it.