Thoughts on improving brake pedal (feel and response)

[s13b]

I've put this in the motorsport section as some may think it less important for a road car...

Im looking to try and improve the brake feel (pedal travel and stiffness) and hopefully performance on my 325.
I've read the Wiki and some interesting options there but nothing that seems to make a big difference. I want to keep 15" wheels so am a little limited on size of rotor and caliper as an only upgrade.

My thoughts on it are that the biggest contributing factors to the "squidgy" or soft brake feel come from a mixture of the position of master cylinder / connecting bar and, possibly weaker / old seals in the MC itself.
I intend to ditch the ABS side of things so hope to improve it a bit there and think I might go down the standalone brake pedal box and MC so ditch the bar and booster all together.

Does anyone have experience with this setup?

Cheers

[rix313]

When was the last time you bled the brakes?

On a road car a non servo system wouldn't be ideal so I wouldn't go there.

[milescook]

When do you get a squidgy pedal? Brakes need bleeding or flushing with new fluid? Best advice on the wiki for brake upgrades is braided hoses if you get a squidgy pedal after hard driving. Everything g including fluid gets hot,brake hoses expand pedal goes squidgy. A goodridge set goes for about 60 new.

Apologies if this is stuff you know plenty enough about, Im no expert on the master cylinder but people that race e30s use pretty much stock parts except hoses calipers ,discs and pads,and seem happy enough.

[milescook]

Damnit beat me to it Rich!

[s13b]

When was the last time you bled the brakes?

On a road car a non servo system wouldn't be ideal so I wouldn't go there.

Bled the brakes last week, so sure there is no air in the lines. Perhaps im just used to a harder pedal feel, what makes you think a non servo system wouldnt be ideal?

Im still not convinced that the pedal feel cant be improved by removing the bar / repositioning the MC (or servo as well).

When do you get a squidgy pedal? Brakes need bleeding or flushing with new fluid? Best advice on the wiki for brake upgrades is braided hoses if you get a squidgy pedal after hard driving. Everything g including fluid gets hot,brake hoses expand pedal goes squidgy. A goodridge set goes for about 60 new.

Pedal isnt necessarily squidgy, just feel it isnt as reassuring as I would like it (if that makes sense?). Maybe bit too much travel / flex before it goes hard.
I've just flushed the system with new 5.1, so no problem there.
I have braided lines on the back, so will try some for the front.

Cheers

[Demlotcrew]

Just get a larger MC.

[s13b]

What bore are the stock ones and anyone know of a bigger one that fits off another car?

[keri-WMS]

I want to keep 15" wheels so am a little limited on size of rotor and caliper as an only upgrade.

Just in case if helps, our 280mm 4-pot kit fits in the 15" BBS and we normally specify 1.25" pistons to improve pedal feel(=less piston area than standard) which is exactly the same mechanism as fitting a larger master cylinder.

This might not be the route you're thinking, but bias boxes etc are a fair bit of work and a reasonable amount of cash too.

[Motorhole]

This might not be the route you're thinking, but bias boxes etc are a fair bit of work and a reasonable amount of cash too.

Aint wrong there bud.

[Demlotcrew]

The added advantage of a kit like Keri produces is the reduced weight/mass, I would only consider a pedal/bias box after you have upgraded your brakes.

Andrew

[Motorhole]

The added advantage of a kit like Keri produces is the reduced weight/mass, I would only consider a pedal/bias box after you have upgraded your brakes.

Andrew

Indeed, binning the servo and fitting a pedal box with standard calipers will need a lot of brake pressure, even with a 6:1 pedal ratio. Once you increase total piston surface area in the calipers (bigger pistons, more pistons or both), the required brake pressure to achieve the same braking manoeuvre comes down.

[s13b]

Thanks for the input guys some good advice. I will look into the caliped and disc upgrades again and see what i can afford. I dont feel its too much effort for a pedal box (provided you get tje right MC), but would be easier to upgrade the standard MC.
Does anyone know of an oem alternative with larger bore size? Or a larger MC and booster that fit the stock hole position?

Cheers

[Black_Potato]

http://www.e30m3project.com/e30m3perfor ... c/25mc.htm

take a look at the link... seems the e32 mc is a common upgrade.

[UweM3]

http://www.e30m3project.com/e30m3perfor ... c/25mc.htm

take a look at the link... seems the e32 mc is a common upgrade.

I have a fairly new one sitting on my shelf. 25mm . £40 plus postage anyone?

[Black_Potato]

I'll have it off you, been meaning to do this for a while. PM me your paypal details and I'll send you the pennies. Postage is to Essex.

Thanks.

[Demlotcrew]

Bargain!

[s13b]

Motherfucker... On my thread too!!!

If he doesn't have it I will

[Mikey_Boy]

Have you looked at other hopefully easy things to do? When you press the brake pedal, you are trying to emulate a solid rod between the pedal and the brake pad through the brake fluid.

Contrary to what your chemistry teacher told you at school, fluid does indeed compress a bit, so good quality new fluid is a must. Replacing your rubber hoses front and rear with braided ones makes a big difference as when the pedal moves, the rubber hoses expand quite a bit so eliminating that with braided hoses really helps - fresh seals in all your calipers helps a bundle.

Otherwise, a decent front brake set up described above and/or a bigger master cylinder can help - I use a E32 750il master cylinder on mine as described above - great upgrade

[s13b]

Without quoting myself from above, done all that except a larger brake setup and new seals.
Thinking of a trip to the local scrappy to see if I can find something with a larger bore size and same / similar bolt pattern

[driftwood]

How old are your disc pads? Are they or the discs glazed? Maybe a new or different set of pads might help.