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-   -   Brakes are giving me the breaks. (http://www.maxbimmer.com/forums/showthread.php?t=147664)

InfiniteDice 12-11-2011 06:54 PM

Brakes are giving me the breaks.
 
Seriously I'm no newbie to thins crap but I'm not having any luck.

So..

I swapped out my master for another good master I had figuring it might solve my recently softer than usual pedal feel.

Didn't change anything.

So I figured hey... it must be a seal the booster then. So I changed my ATE booster out with the shinier Girling one I had sitting on a shelf for a few years.

So after all the BS of swapping it out... I go to bleed the right rear and get my GF to pump it up then hold... I loosen the bleeder and drop.... .... .... drop.. ... . So it's not holding pressure, I even pulled the bleed screw right out.

Now I'm wondering if the Girling booster is compatible with the ATE master I'm using.

Tomorrow I'm going to try all over again swapping to another ATE booster I found, I know it works but it's not as pretty as the Girling.

Another question... the valve on the booster to throttlebody hose, is that supposed to let air into the throttle body? or let air from the throttle body into the booster?

Thanks guys. It must be something simple. And yes I have a new seal between the master and the booster. :)

Red_Rocket 12-11-2011 07:10 PM

Yes, that hose is supposted to be there. That is how your vacuum booster gets vacuum, and thats why your pedal feels different when your cars not running.

DIY 12-11-2011 07:31 PM

so what he means to say is its sucking air to the throttle body....

could you have pinched a brake line from hitting something?
considering the brakes should work without vacuum, I find it hard to believe that the booster would be the problem...

the only thing I can think of is theres a pinch/blockage... unless something could be backwards

Ceeker 12-11-2011 08:10 PM

how about changing the dribbling caliper? maybe it it contaminated? Try bleeding the other side to see if you get the same result.
the throttle body sucks air from the booster creating a vacuum.also may want to try to pull the line free from the caliper and see if you get flow when you depress the pedal.

dble Trouble 12-11-2011 10:19 PM

Ernie clear your inbox man, it's full and I couldn't send you a pm. Email me asap please! john_venditti@hotmail.com

Sorry for the thread jack but need to talk to da boss!

InfiniteDice 12-12-2011 03:51 PM

Okay, well swapped out the swapped in booster. Yes I'm tired.

Turns out the Girling booster didnt have that metal shaft inside the booster hole, that goes into the master hole... lol.

So I borrowed my neighbors pressure bleeder and bled the calipers. Now I have pressure but it's not that good. Kinda like I need to go 1/2 down before it has pressure.

I'm going to try re-bleeding tomorrow, maybe there is some air someplace.

I hate brakes. I'm used to having brakes that can lock up the tires.

InfiniteDice 12-12-2011 05:45 PM

Okay I drove to the store and if I mash the pedal down fast I can lock up the front tires. I just don't like how it has crappy light pressure response. I get light response about 1/2 way down then it starts actually doing something.

Grrr. might just pony up some dough and get that larger master from the 7 series. Anyone here using that with an e30 ATE booster?

Ceeker 12-12-2011 07:04 PM

Quote:

Originally Posted by dble Trouble (Post 1538985)
Ernie clear your inbox man, it's full and I couldn't send you a pm. Email me asap please! john_venditti@hotmail.com

Sorry for the thread jack but need to talk to da boss!


hey John, called your house...left message.

Ceeker 12-12-2011 07:08 PM

Quote:

Originally Posted by InfiniteDice (Post 1539083)
Okay I drove to the store and if I mash the pedal down fast I can lock up the front tires. I just don't like how it has crappy light pressure response. I get light response about 1/2 way down then it starts actually doing something.

Grrr. might just pony up some dough and get that larger master from the 7 series. Anyone here using that with an e30 ATE booster?

I'd say the best thing is gravity bleed the brake system first. then proceed with bleeding through the pedal. it's hard to determine why they get half peddle or late pedal response. It can be a number of things. If sufficient vacuum is available and there are no audible leaks then you should be getting a good pedal providing there is absolutely no air in the lines. I just did my cabrio because the pedal was hard and braking was delayed. I changed the booster, master, seal and bleed the system completely. I have lock up happening at half pedal. I used used parts since I had them lying around. the brakes work fine now. But it doesn't respond like my coupe.

I would keep bleeding the brake system. you may still have air. did you bench bleed the master? I wonder if air can be trapped in the ABS pump?

InfiniteDice 12-13-2011 11:53 AM

No abs. Hence it's very simple. I'll re-bleed it and see what happens.

My only question is... when you press the brake pedal down with the car off, should the one way valve between the booster and the TB blow air? I can hear a hiss from my air filter when my trusty GF pushes the pedal down.

Bullet Ride 12-13-2011 12:13 PM

Quote:

Originally Posted by InfiniteDice (Post 1539196)
No abs. Hence it's very simple. I'll re-bleed it and see what happens.

My only question is... when you press the brake pedal down with the car off, should the one way valve between the booster and the TB blow air? I can hear a hiss from my air filter when my trusty GF pushes the pedal down.

It's not blowing air, it's releasing the vacuum. Yes it should do that. They have that valve so if car shuts off you'll retain regular braking force for at least one application of the brakes (i.e. to stop safely).

InfiniteDice 12-13-2011 01:01 PM

Yeah I figured it would release the vacuum at some point, it can't just build vacuum indefinitely. :)

On some cars you'll see the one line coming off the brake booster, it then divides into two lines... one goes to an open port on the throttle body on the intake side of the TB and plugs into the air boot before the TB. The other line dead ends at a closed off throttle body port.

My system has the one line. Coming from the brake booster it goes into the one way valve, then into a plastic connector, from there the plastic connector plugs into the rubber intake boot and goes to a small port on the TB.

I'm not familiar with the logic of this routing. Why does the booster release air in front and in behind the TB at the same time? I've read that the engine vacuum is what opens the valve, but if that's true then why can I blow through it so easily?

Perhaps the engine vacuum counteracts the air coming from the booster to prohibit the flow from the booster, but since it's one way it can't actually supply air to the booster.

Okay I need a coffee. :)

Bullet Ride 12-13-2011 03:31 PM

Quote:

Originally Posted by InfiniteDice (Post 1539206)
Yeah I figured it would release the vacuum at some point, it can't just build vacuum indefinitely. :)

On some cars you'll see the one line coming off the brake booster, it then divides into two lines... one goes to an open port on the throttle body on the intake side of the TB and plugs into the air boot before the TB. The other line dead ends at a closed off throttle body port.

My system has the one line. Coming from the brake booster it goes into the one way valve, then into a plastic connector, from there the plastic connector plugs into the rubber intake boot and goes to a small port on the TB.

I'm not familiar with the logic of this routing. Why does the booster release air in front and in behind the TB at the same time? I've read that the engine vacuum is what opens the valve, but if that's true then why can I blow through it so easily?

Perhaps the engine vacuum counteracts the air coming from the booster to prohibit the flow from the booster, but since it's one way it can't actually supply air to the booster.

Okay I need a coffee. :)

The cars with the two line set-up have that second hole in the TB finished, itís not a dead end. BMW eventually revised the system to the single line on the late model cars and stopped finishing the one hole on the TB. I think the original idea behind the dual line is to help maintain good vacuum to the booster during open throttle conditions (for left foot trail braking while racing*th-up*) but I donít know that for a fact.

El Gato Liso 12-13-2011 04:00 PM

im using a 7 master on my 3 booster, works lovely and i even discovered my ABS actually works!

InfiniteDice 12-13-2011 04:10 PM

So if air can pass from the booster to the engine without passing the afm/maf then wouldn't that affect the control of metered air?

Cool, thanks Gat. The prices are getting stupid on some parts. I'm going to try bleeding these brakes a couple more times, a few days apart to be sure it isn't an air pocket someplace, if that fails I'll think about the 7 series master, it's only slightly more $$$ than the e30 ones.


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