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E36 M3 (1992-1999) {Euro - S50 B32 321hp @ 7400 rpm} {U.S. - S52 B32 240 hp @ 6000 rpm}
Total Produced: 71,212 - Years Produced: 1992 to 1999


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Old Mon, Mar-12-2012, 07:19:14 PM   #1
OneTenOctane
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Default Is a long brake pedal normal in an E36?

Are E36ís known for having typically long brake pedal travel? Compared to other vehicles I drive, it feels like my E36 has relatively long pedal travel before it hits a firm spot. It doesnít feel spongy Ė it just has to travel a long way toward the floor before it gets firm. Furthermore, when I first start the car, if I press on the brake pedal hard enough, I can push it all the way to the floor. I have to press the pedal pretty hard Ė like you would in an emergency stop Ė but I can feel the pedal hit a hard (metal-to-metal) stop. After a little bit of driving, I canít push it down to the floor, but the travel is still long.

Iím chasing some brake problems that show up when I go to the track, and Iím trying to figure out if my master cylinder is the culprit. The brakes have plenty of stopping power, and as I said, the pedal is always firm, but that firm point is close enough to the floor that when Iím threshold braking, itís hard not to hit the gas pedal with my heel unless Iím wearing driving shoes. Iíve bled the system about 10 times in the past 2 years (power & manual), so I have no reason to suspect there is air in the system. Also, I have no fluid leaks.

If you guys normally get a firm pedal pretty close to the top, and what Iím experiencing is not normal, then I think this probably points to a faulty master cylinder (internal leak), unless anyone has any other ideas.

For what itís worth, a more detailed description of the brake problems Iím having can be found at the link below, but I wanted to highlight this specific question about pedal travel here.
http://www.m3forum.net/m3forum/showt...p?p=1065392456

Thanks in advanceÖ
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Old Mon, Mar-12-2012, 07:26:51 PM   #2
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Default Re: Is a long brake pedal normal in an E36?

Mine is extremely short. It bites hard within the first bit of travel...
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Old Mon, Mar-12-2012, 07:47:09 PM   #3
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Default Re: Is a long brake pedal normal in an E36?

I'm still pondering your update in the other thread, but I can tell you that my brake pedal builds pressure fairly close to the top. The travel isn't nearly as long as you describe.

If you had an internal master cylinder leak, I don't know that you'd be able to build strong, consistent brake pressure. I've had bad master cylinders before (on another car) and building constant brake pressure was an issue... It would all just bleed away after a point. You are warping brake rotors on the track from overheating them, so it doesn't sound like your master cylinder has any problems holding pressure for sustained periods of time.
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Old Mon, Mar-12-2012, 07:56:32 PM   #4
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Default Re: Is a long brake pedal normal in an E36?

Follow up question: Where does the pedal begin to build pressure if the engine isn't running (car off, or turned to accessory?)
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Old Mon, Mar-12-2012, 07:58:23 PM   #5
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Default Re: Is a long brake pedal normal in an E36?

Quote:
Originally Posted by tbaker474 View Post
Follow up question: Where does the pedal begin to build pressure if the engine isn't running (car off, or turned to accessory?)
Wouldnt that only matter with the car running as they are vacuum boosted...
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Old Mon, Mar-12-2012, 08:03:32 PM   #6
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Default Re: Is a long brake pedal normal in an E36?

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Originally Posted by Braymond141 View Post
Wouldnt that only matter with the car running as they are vacuum boosted...
That's my point. If the problem is the same with the car off, then you're taking both the booster and the abs system/electronics out of play as potential culprits.

If the pedal is builds pressure "normally" with the car off, then you have an idea that the master cylinder is ok.
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Old Mon, Mar-12-2012, 08:06:42 PM   #7
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Default Re: Is a long brake pedal normal in an E36?

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Originally Posted by tbaker474 View Post
That's my point. If the problem is the same with the car off, then you're taking both the booster and the abs system/electronics out of play as potential culprits.

If the pedal is builds pressure "normally" with the car off, then you have an idea that the master cylinder is ok.
Err, mine (and all my cars) always goes brick hard with almost no braking power. I first noticed this on my 26k mi 01 330i.

You mean just to that super hard (but useless for braking) state?
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Old Mon, Mar-12-2012, 08:17:23 PM   #8
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Default Re: Is a long brake pedal normal in an E36?

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Originally Posted by Braymond141 View Post
Err, mine (and all my cars) always goes brick hard with almost no braking power. I first noticed this on my 26k mi 01 330i.

You mean just to that super hard (but useless for braking) state?
That's because the booster is helping you out when the car is on, it's not when the car is off. However, the master cylinder functions the same regardless of the car is off or on (you just don't have the booster multiplying the pedal force.) If he can build constant brake pressure when the car is off, then he knows the master cylinder is functioning. It's basically just process of elimination. It doesn't tell exactly what's wrong, but it could point him in the correct direction.

For reference, when I had a bad master cylinder (again, different car) I couldn't build any brake pressure when the car was off. That's one of the ways we pinpointed the master as the culprit. We knew that the ABS system and Booster were out of the equation with the car off, so that narrowed down the search.
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Old Mon, Mar-12-2012, 08:21:43 PM   #9
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Default Re: Is a long brake pedal normal in an E36?

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Originally Posted by tbaker474 View Post
That's because the booster is helping you out when the car is on, it's not when the car is off. However, the master cylinder functions the same regardless of the car is off or on (you just don't have the booster multiplying the pedal force.) If he can build constant brake pressure when the car is off, then he knows the master cylinder is functioning. It's basically just process of elimination. It doesn't tell exactly what's wrong, but it could point him in the correct direction.

For reference, when I had a bad master cylinder (again, different car) I couldn't build any brake pressure when the car was off. That's one of the ways we pinpointed the master as the culprit. We knew that the ABS system and Booster were out of the equation with the car off, so that narrowed down the search.
I know how it works, I was just pointing out the difference in feel. It just goes rock hard with very little braking power. Just trying to clarify what you're asking him to look for which is very different from when the car is on.
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Old Tue, Mar-13-2012, 02:48:26 AM   #10
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Default Re: Is a long brake pedal normal in an E36?

OK, so when I got home today, I stuck a camera down in the footwell, put a measuring tape on the far side of the brake pedal, and took a video as I worked the brake pedal.

With the engine off, once I pumped the brakes a few times to build up the system pressure, I got about 2 inches of pedal travel before it got firm. No matter how hard I pushed on the pedal (and held it), it didn't move any farther and certainly didn't sink to the floor.

With the engine running, of course, I was able to press the pedal farther to the floor. It got pretty firm about after about an extra 1 inch of travel, but if I pressed harder, I was able to get it to go another 1/2 inch or so, and I could feel and hear it hitting something.

It's a given that the pedal will sink lower when the car is running, but I thought this might be a useful reference point if anyone cares to compare with their car.

For what it's worth, I tried spinning the rotors by hand, before and after running the car. After I did my little experiment above and shut the car off, there was noticeably more friction between the pads and rotors than there was before. Is it possible the system is holding some pressure? Here's a quick video i took of the before and after:

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Last edited by OneTenOctane; Tue, Mar-13-2012 at 03:21:14 AM. Reason: Added video link
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Discussing Clutch Pedal Return Spring Install in the E36 M3 (1992-1999) Forum - {Euro - S50 B32 321hp @ 7400 rpm} {U.S. - S52 B32 240 hp @ 6000 rpm}
Total Produced: 71,212 - Years Produced: 1992 to 1999 at BMW M3 Forum.com (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X)