Here we go again with brake problems

[Tom Cimino]

After driving for 15 years with poor brakes on my E-M, I decided to try to improve them by changing to a pair of smaller master cylinders.

The car is set up with a balance bar system. I've seen the same pedal assembly in Midstates cars. I have no idea who manufactures it. It had 3/4" master cylinders. To increase the clamping pressure, I installed 5/8" wilwood master cylinders. All I accomplished was a longer pedal travel (which I expected) and the brakes are worse. I'm pulling my hair out!

The rest of the system is Wilwood 4 piston brakes on the front and Lincoln Mk VIII discs on the rear.

Aside from bleeding the brakes again (which I'm doing, right after I finish writing) does anybody have any suggestions?

[strictlypersonl]

Maybe your balance bar is bottoming out in the housing?

Brake balance bar setup

[Tom Cimino]

Originally Posted by strictlypersonl

Maybe your balance bar is bottoming out in the housing?

Brake balance bar setup

No. the balance bar is working properly, although I do have the bar centered right now.

[Tommy]

Tom,
You don't mention what "poor brakes" means, so I will assume it means you cannot apply enough pressure to the brake pedal to lock the brakes at 40 MPH on a dry, clean road.

My EM is very different from yours, but it also has manual brakes and stops fine. Here are some things to consider in sorting out your brakes. To begin, you can ignore all the stuff between the brake pedal and the calipers. The basic laws of physics are that the force you apply to the pedal multiplied by the distance it travels is equal to the force applied by the caliper pistons to the brake pads multiplied by the distance the pistons travel. Of course the balance bar and differences between the front and rear calipers will distribute that force and motion differently between the front and rear, but the totals will all add up. One thing that can reduce piston travel is expansion of your brake lines under pressure. If you have any rubber lines that are expanding when you apply the brakes, they will decrease your braking effectiveness.

The clamping force of the calipers on the discs can be affected by the types of brake pads and the size of the discs. One of the first things I would suggest is to get more aggressive pads. These can cause side effects such as excess brake dust and rapid wear of parts, but they will stop better. Mounting the calipers farther from the centers of the wheels on larger diameter discs can improve the stopping force, but it can also increase the angular momentum of the wheels/tires/discs that the calipers have to stop. Keep in mind that the brake actually stops the disc that stops the wheel that stops the tire that stops the car. If you have especially large or heavy wheels or tires, your car will not stop as well.

Finally, a few words about the balance bar. If you cannot press the brake pedal hard enough to lock either the front or rear tires, it doesn't matter where it is set. As the front tires do about 70% of the braking in a hard stop, you want the balance bar initially set to apply more pressure to the front. It is also widely accepted that it is safer to have the front tires lock up before the rear in a panic stop. So in making any adjustments to your brakes, I suggest you focus on the front system first.

[Tom Cimino]

Tom,
You don't mention what "poor brakes" means, so I will assume it means you cannot apply enough pressure to the brake pedal to lock the brakes at 40 MPH on a dry, clean road

I might have misspoken when I said "poor". Actually, I should have said" really sucky" as I can not lock the brakes at any speed, on any road surface, wet or dry.

One thing that can reduce piston travel is expansion of your brake lines under pressure. If you have any rubber lines that are expanding when you apply the brakes, they will decrease your braking effectiveness

When I upgraded to the wilwood system on the front, I used the braided stainless brake lines. However, the rear still have Ford factory rubber lines. I am in the process of re-bleeding the brakes with my Motive power bleeder. So far, I have not gotten any air out of the system. Have to go get more fluid before I can finish.


I am using the brake pads supplied with the wilwood kit on the front and still have the stock Ford pads on the rear. Something to really consider. I'll try anything about now, short of throwing out a cement block on a length of rope.

[Michael C Henry]

My car came with the Tilton dual 3/4" master cylinders and balance bar system. It has the 10 3/4" front rotors and mid sized GM calipers and Girling - Jag inboard rear brakes. I would like more brakeing power but without power brakes or larger diameter rotors not likely. I have the 16" PSE Cobra wheels. The Tilton masters are located under the floor and resivoirs are located up on firewall. Bleeding brakes has never been a problem.

[strictlypersonl]

Originally Posted by Tom Cimino

No. the balance bar is working properly, although I do have the bar centered right now.

Typically, the front calipers require much more fluid than the rears, so the balance bar must be set up biased so that the master cylinder's front stroke can be much higher than the rear.

[Tommy]

A few more thoughts: As you have two brake master cylinders, the front and rear systems should not affect each other. Therefore, the rubber brake lines on the rears should not affect the action of the front brakes.

You mentioned going to smaller diameter master cylinders to increase the pressure in the lines. The price for increasing the pressure is that you decreased the volume of fluid going to the calipers. Is it possible you are (and were) running out of master cylinder throw before the pistons are fully extended? When you bleed the brakes, compare the motion of the brake pedal when the bleeders are open (i.e., full throw on the master cylinder) with the motion when the system is bled and sealed. If the pedal moves the same distance both times, then your master cylinder is too small.

[Tom Cimino]

If you mean "does the brake pedal move towards the floor when you crack a bleeder" the answer is yes. With the bleeders closed, the pedal will go less than halfway to the floor and feels solid, not spongy. Open a bleeder and the pedal will go down. I have just finished re-bleeding the brakes and found no air again. Time to put the wheels back on and try it again.

[Tom Cimino]

The brakes are back up to where they were last year. Not great, but they'll stop the car. Going to adjust the balance bar next, and call wilwood Monday for recomendations for more agressive pads. Thanks everyone for your input, especially Tommy.

[Clois Harlan]

I think you may still have air in the lines. Fought that for months and finally jacked up the car in the rear to bleed the rear brakes then the same for the front. Finally, got good pedal and brakes. I think I am running 7/8" mc front and back.

Clois Harlan

[Tommy]

I was discussing your problem with a friend over dinner. He suggested you look for a loop or pronounced high spot in your brake line where air could get trapped. Another problem that happens occasionally is the calipers are mounted so the bleed port is not at the highest point. That can also cause air to get trapped.

[DAVID GAGNARD]

Personally,I think going to a smaller diameter M/C is the wrong way to go, you need a bigger volume of fluid with 4 piston Wilwoods as compared to OEM/Stock type calipers.By going to a smaller caliper, you decreased your volume by a bunch......I would say you would need a 7/8 master cylinder......
I don't think more aggressive brake pads will help you with the small M/C..........

David

[Tom Cimino]

I'm going to call wilwood monday to see what they suggest. Thanks all.

[Xavier]

Tom C.,

I had the same exact issues you had with my car originally; it was air in the lines, regardless of how much you bled (or thought you bled the system). Calling Wilwood multiple times will not help, as you will just throw money at the problem, they cannot look at your brakes lines and system. With no balance bar, with the worse calipers imaginable and with OEM pads the car should come to a screeching stop at some point. If you can put your finger or crayon on the rotor after even light braking without you or the crayon getting burnt (you can spit on it to, it should sizzle) you have no pad pressure getting to the rotor. Look at it this way - if you have no pad pressure, what are bigger calipers and pads going to do for the system? You have people running VW setups on older replicas with no issues stopping. You are not funning Formula 1, SS lines are nice, but you have no brakes period (or very little to the front) so what is the relevance of performance parts if you have no pressure?

As Tommy suggested in his last email - you can bleed to your hearts content, but if you have a high spot (and in my setup I have several maintenance loops) the air will get trapped in it and it is a pain to get it out. People, like me, will be in denial for a while and (like me) you will throw endless amount of money at it because we all thought because we bled it for hours on end and went through quarts of brake fluid - no air could possibly be trapped in the system. We were taught air would eventually come out - we were wrong. If you have no brakes, it is either due to leaking fluid (no pressure), mechanical setup (already discussed) or air within the lines. My pedal was firm too, so a spongy pedal is not the indefinite sign of air in the lines. Depending on MC setup and other variables, you can have what you feel is hard, and still have air within the system.

A person educated me on my problem as I would not be snapped out of denial, he took a power master bleeder to my system. Spent hours flushing fluid with it and went through a methodical process of bleeding, back and forth tapping the MC's and high points with a hammer (light tap). Eventually the air came out, the brakes worked (my fonts were completely non-functional at the time and like your setup were and are state-of-the-art) and the braking was incredible. The pedal feel only slightly changed, but obvious performance in the braking was enhanced and is great.

Looking at my system I made a few errors in the car and setting up the brake system;
- Safety loops are cool, I like them, I do not regret having them - but they hold air at the top and are a ***** to get out!
- I did not know I needed to bench bleed the MC's. At the time, I did not even know what this meant. My MC's had a lot of air in them. It was just something I was never taught...
- Pushing the air through the system from the MC reservoir, in my experience, seems to be much more successful then the traditional pedal approach, especially if working by yourself. The Power Master bleeder is the best damn tool investment I have made in a while. This is also really nice because after making a modification, you can pump up the PSI and leave it sit on the system overnight. If it holds the PSI, you know (or are fairly confident) you have no leaks.
- The biggest problem was my own arrogance; when everything pointed to air, I simply judged it as "impossible" because of the amount of fluid I pushed through the system. I have talked to mechanics since then that on one car it took less than a quart, but on another it took gallons. There is no "volume" or pedal feel indication you have air in the lines. If your brakes are not working its one of three things mentioned early on, its a process of elimination - and if you eliminated leaks, pedal throw and MCs, it only leaves you with one thing - air.

I hope this helps you, as it helped me.