Master Cylinders and Brake Boosters

[mattdk318i]

Well, in the process of doing my swap ive gone through quite a few combinations and ive finally found something that works and i like at the same time

I went with The 320 booster and 735i Master Cylinder and i couldnt be happier. The 944 booster was paper thin and ended up bending(as seen in pic)

But i decided to take some pics of some boosters and master cylinders for reference. Ill try to answer any questions to the best of my ability

Does anyone have a pic of a IX booster they can contribute?



Stock E30 on left and 735 on right. Remote resvoir is also in picture and is needed to use the IX booster


Closeup


From left to right 320i, Porshe 944,Stock E30, Stock E36 M3









My current setup

[e30polak]

Wouldn't the bigger master cause your brake pedal to feel mushy?

Also I am running the 320 booster setup, and you might want to run a vacuum reserve canister from summit to help with brake assist. You'll see what I mean when you have to pump the pedal to get the car to stop. ;)

[matt]

Wouldn't the bigger master cause your brake pedal to feel mushy?

Just the opposite. Bigger M/C = firmer pedal.

[So Live]

Wouldn't the bigger master cause your brake pedal to feel mushy?

Also I am running the 320 booster setup, and you might want to run a vacuum reserve canister from summit to help with brake assist. You'll see what I mean when you have to pump the pedal to get the car to stop. ;)

I know how you feel and i hate it. Im seriously tempted to try to go manual brakes with a VW M/C. They have a ton of sizes, pretty similar fluid hook ups and id have to make an adapter for the firewall anyway.

OP do you have the lack of vacuum feel with your set up? Or is it just because our M/C's are too small?

Then i could make a sweet vacuum manifold off the brake booster vacuum bung and not have to run a T fitting...

[mattdk318i]

Right now im running E36 m3 front brakes and TI rears. And the car stops DAMN quick with little effort on the pedal. And there isnt any "mush"

[mattdk318i]

I know how you feel and i hate it. Im seriously tempted to try to go manual brakes with a VW M/C. They have a ton of sizes, pretty similar fluid hook ups and id have to make an adapter for the firewall anyway.

OP do you have the lack of vacuum feel with your set up? Or is it just because our M/C's are too small?

Then i could make a sweet vacuum manifold off the brake booster vacuum bung and not have to run a T fitting...

The vacuum on mine feels perfect. Ive only driven it a few miles but im tickled pink. My last effort with the 944 booster left me stranded with locked up brakes

[RobertK]

I notice there are many different brake booster setups to accomodate the intake but I think I'm going to go with the modified intake to accomodate the stock brake booster instead.

Unless you are boosting your M5x/S5x it's the easiest way to fit the engine and you get to keep your stock brake feel.

[matt]

I notice there are many different brake booster setups to accomodate the intake but I think I'm going to go with the modified intake to accomodate the stock brake booster instead.

Unless you are boosting your M5x/S5x it's the easiest way to fit the engine and you get to keep your stock brake feel.

NO. Don't do that!

The intake manifold is designed to distribute the air evenly between cylinders, changing the shape of it could screw that all up. You could end up with a cylinder that runs rich or lean, or with vacuum leaks or whatever. Swapping brake boosters is stupid easy, and you can end up with the same or better pedal feel.

PS: If it was the easiest way, don't you think more people on here would do it?

[dude8383]

what would pedal feel and overall braking abilities feel like if one was to use the 320i booster with the stock m/c?

i am thinking about keeping the stock m/c but i also have the bigger m/c too.

[evil_twin]

I'm running the stock M/C and a 944 booster... The pedal is pretty firm. Is there any way I can make it a bit softer?

[Mike B.]

I'm running the stock M/C and a 944 booster... The pedal is pretty firm. Is there any way I can make it a bit softer?

You can use a smaller dia. master cylinder or change the pedal ratio.

[BigD]

Wow you put in a 25mm MC with a 320i booster and you like it? I wouldn't recommend running that MC with anything less than a normal E30 booster. The extra assist in the iX booster balances out the shortened throw/extra stiffness with the 25mm MC nicely though... as well it should, since that's the setup in the E32 735i and E34 M5.

[evil_twin]

Ya... I mean, my pedal is super firm, it just doesn't seem like I can lock my brakes up though.

[BigD]

Ya... I mean, my pedal is super firm, it just doesn't seem like I can lock my brakes up though.

I was actually replying to the OP. The unassisted pedal effort in your setup is stock. The stiffer pedal feel comes from the smaller booster - for an extreme example of what you've done by going to a smaller one, try turning off your engine as you come to a stop as you're rolling and try stopping. This is why, although it's harder to clearance, I recommend guys use the stock booster if they can figure it out, or the iX. I like pedal assist, and my legs aren't exactly weak.

[mattdk318i]

I was actually replying to the OP. The unassisted pedal effort in your setup is stock. The stiffer pedal feel comes from the smaller booster - for an extreme example of what you've done by going to a smaller one, try turning off your engine as you come to a stop as you're rolling and try stopping. This is why, although it's harder to clearance, I recommend guys use the stock booster if they can figure it out, or the iX. I like pedal assist, and my legs aren't exactly weak.

I dont know if this would make a difference, but im using E36 M3 front calipers. So im pushing alot more volume into them. And it hasnt resulted in a
stiff pedal, Or me needing more vacuum assist.