tires and wheels HELP! My brakes suck.

[scottiesharpe]

Patient: This is a 67 car with single line brakes. I've upgraded the brakes about as much as I can and they still suck!

here's the current setup: 320i rear drums. All the components are brand new. Up front I am running Ireland Brembo single line single pots. I'm using ventted, slotted rotors. Stainless lines.

Wheels are BMW 325is 14x6.5. Suspention is Ireland coilvers up front with 325 lb springs. rears are ireland 300 lbs springs cut one coil, ireland hollow three-hole sway bar up front, infinitely adjustable in back. No interior. no roll cage. The car is VERY light.

Symptoms: The rear end locks up way to fast. It's not balanced and I have WAY WAY WAY too much free pedal travel.

I have tried to adjust the rears to be as loose as possible. Still they lockup and I have too much pedal travel.

What can I do to improve my brakes? I think I need to use a more powerful cylinder and a biasing valve. What are your thoughts?

Thanks!!!

Here's the patient with bottlecaps on (bottlecaps are for sale, btw: all 4 for $90 with decent michelins in SF Bay area - see parts for sale section)

[mixamson]

A tii master cylinder would probably help with pedal travel. Perhaps using volvo girling calipers (4 pistons) would be a better setup for the fronts? Or perhaps all you need is a bias valve.

2 cents.

Mike

LOL camber.

[Mike Self]

specialilzes in racing parts make an adjustable bias valve? Even if not, you should be able to buy a high pressure valve that will accept flare fittings and then experiment with it until you have it set correctly...

cheers

mike

[TJW]

You said,

320i rear drums. All the components are brand new. Up front I am running Ireland Brembo single line single pots

Transfer of fluids, you have put on bigger rear expander units which mean it takes more fluid to expand them. pedal travel.

You use the term 'single pot' for the fronts that normally means single piston which means smaller than four pot which is what you should have,

You don't mention the master cylinder, that should be upgraded.

So you have a bigger surface area at the back so they come on stronger.

[Paul7002]

system so it's not as easy as just slapping in a tii mc 'cause that is for the later dual line system. You'd need to run some new hard lines too. Which isn't very expensive or difficult, actually. e21 s were also a single line system so maybe you could go with an mc from a 320i.

But I think I'd go ahead and switch to the later 2002 dual line system, ditch those bembos and go with the volvo caliper, e21 vented rotor and tii mc set up.

The 320i rear drums are 250 vs 230 mm so I don't think that's such a huge difference to explain the rear brake bias.

Perhaps you do need a biasing valve - Try Summit.

Are you sure your current calipers and rotors are properly matched?

Have you bled the brakes lately. Maybe you have air in the front lines.

Just a few thoughts

[FL02]

I've heard using a differnt MC from a E30 will make the pedal stiffer. Either way a Master Cylinder upgrade would help the pedal.

[Guest Anonymous]

Concur with above -- go with the Volvo setup.

[andrewro]

You have a Volvo setup for sale, don't you? You could do the conversion with those parts...

[scottiesharpe]

Ok! Thanks for the ideas guys. To clarify, I don't want to go with the dual line setup. I don't like the way the volvo calipers are mounted. I don't want to use spacers on the caliper. The brembo units are single potunits and are quite huge. They look like this: (not my kid - don't know who's kid that is)

I am going to upgrade to the e23 745i master cylinder and introduce a brake biasing valve into the rear circuit.

Will keep you posted!!!

[Lee]

Hi Scottie.

Too much pedal travel? Adjust the rear brakes by using the eccentric and get a 25.4mm MC from a 750iL (p/n 34 31 1 156 643). Bolt-on installation that will only require a line splitter, available from BMW for $8.

Problem with bias? Get real good pads in the front, and switch to ungrippy ones in the back. Tuning with pads is a very common way to fix brake balance. Get a good carbon pad upfront

[peteinjp]

basically your increased the amount of weight transfer dramatically (suspensiona nd tire set) over what the original bias was set up for. In addition you increased the braking power in ther rear relative to the power in the front. A bias valve may be the easy way to go- or you could put back the original 230mm drums and smaller wheel cylinders on the back. I'd try to get it as balanced as possible with the hardware and pads- then add the bias valve for track tuning. I have porterfield pads and shoes and I love them.