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Discussion Starter #1
Hi Group...Just installed new Rotors, Pads & SS lines....Did the standard bleed..Pedal pressure is firm when car is not running...Start car & pedal is really, really spongy...I bled a 2nd time with a very slight improvement but enough to go out & drive the car & bed the brakes...However, the pedal feel is considerably worse than before I changed everything tonight.

So with that, would it be best to bleed the old fashion way with a 2nd person in the car working the pedal? If so, what if any effect does it make to the bleeding process if the car is running? Again, the pedal is firm when the car is turned off.

Thanks,
 

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if you introduced air into the DSC/ABS system then pretty much nothing short of doing the bleed routine with a GT1 is going to work. first off how are you bleeding the system, gravity? don't waste your time. if you don't have a pressure or vacuum bleeder then get another person. bleed in this order, RR LR RF LF, open the bleeder on the RR caliper, then have your helper stomp the pedal to the floor and hold it, then close the bleeder, repeat several times on each caliper and keep an eye on the fluid level in the reservoir. this method works well, remember bleeder open before he stomps the pedal, you dont want to pump the pedal with the bleeder closed as this pushes the fluid around in the lines and tends to break up one bubble into many smaller ones which you dont want.
 

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Discussion Starter #3
Nightcrawler, thanks for your insight. I was using a pressurized brake bleeder.
I will try your suggestion about opening the bleed valve & then have my wife stomp the pedal to the floor...
I have always been used to the stomp/pump the pedal & then open valve....fluid out, then close valve....Repeat procees.

So should I do this with the power on? Again, my pedal is firm with the motor off & only spungy when the motor is on.

Thanks again,
 

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you can just do it on your own but you need some feel, a long clear hose and some spare brake fluid in a container to help stop return air.
just release the bleeder with a snug fitting clear tube attached, slowly pump the (hard) brake pedal and get some fluid going, keep slowly pumping for 10 to 20 half strokes and then run around a tighten things before you get air return.
works brilliantly for me, only down side is it's bloody hard on the leg, or even arm if you wish...
 

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Discussion Starter #8
OK Guys,
Still having brake problems...Spongy like air in the system but absolutely no possible way air is in system. Not only did I bleed brakes the old fashioned way but also took car to M5 Tech buddy who did not only the same bleeding process but also bleed with diagnostic machine.
So prior to brakes, stock pads, rotors, lines & fluid...Upgraded to Stop tech pads & vented/drilled rotors & installed new ss lines. One significant change is that I switched to Super Blue Racing fluid & I just can't get a good pedal feel. In fact if I stand on it hard I can get the pedal to floor. Also panic stop manually on slippery surface, rebleed & still same problem...

Noted rpm drop when brake pedal is depressed...Could this be a booster? Seems strange that 1 day it worked & then next after the brake upgrade that it doesn't work???

HELP & thank you
 

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don't say "absolutely", cause i can just about gaurantee you still have air trapped somewhere in the system. i ran into the same problem last summer when i did the ss lines. how did your friend do the bleed procedure? fyi you need two people to do this with the GT1. as one person has to sit in the vehicle. also this procedure usually has to be repeated several times. the bleed routine with the GT1 goes like this,

step 1- open bleeder on rr wheel
step 2- start bleed routine service function on GT1
step 3- after the activation finishes the person in car pumps pedal 5 times, holding it to the floor on the last stroke
step 4- with pedal held to floor, close bleeder. repeat on remaining wheels.
 

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and its not the booster, if the booster went bad you'd have a very hard pedal not a soft one. aside from air in system the only other possibility is the master cylinder went bad and is leaking internally. i doubt it though...
 

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Discussion Starter #11
OK Forum Members..Still have brake issues...My dealership tech has had the car since Friday...hooked up to the machine bleeding & bleeding the old fashioned way, we still have a mushy pedal. Can still depress pedal to the floor. He can get the ABS to engage on the slick/slippery shop floor.
One other issue to note is that when the car is idling & he depresses the brake hard, the engine rpm drops by about 300-400r's?

So this morning we will try going back to stock BMW brake fluid instead of the racing SuperBlue that I installed to see if we get any change.

Other items to note...NO fluid leaking from an caliper pistons. NO fluid leaking from where the SS lines were installed.

I have a hard time thinking it is the master cylinder as the brakes worked perfectly GREAT prior to swapping out the pads, rotors & SS lines.

Any input would be greatly appreciated.

Thanks,
 

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if the master cyl is leaking the leak is internal, you wont see any fluid. it is unlikley but always a possibility that from all the aggressive pumping of the pedal down past its normal point that a seal inside the mc got damaged. the ss lines could be the problem as well, are they the correct lines for the car? if they are too narrow inside you wont have a correct pedal feel/function as well.
 

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Discussion Starter #13
Good morning nightcrawler, thanks again for your advise...
Hopefully I will hear back from my tech today if swapping back to BMW brake fluid made a difference. If not, I too was thinking that it could be the SS lines. I may go back & install the stock lines to see if that is where the problem is. It could be the MC but then again...Immediately after installing the ss lines I had the mushy pedal problem & it worked perfectly fine prior to swapping out the lines.
The lines are Stoptech & came from Zuchhousin.

Will keep everyone updated..
 

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. It could be the MC but then again...Immediately after installing the ss lines I had the mushy pedal problem & it worked perfectly fine prior to swapping out the lines.
quote]

what im saying is that the MC may have been damaged from all the bleeding attempts. it is unlikley but it is not out of the realm of possibility. switching the fluids is not going to make any difference, not the problem.
 

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Have you tried bleeding by removing the calipers off their mountings, using a piece of wood to make up the space the disc normally takes and moving the caliper to such a position that any air would be directly under the bleed nipple?

I'm not sure of these calipers but several don't have the bleed nipple at the highest point, meaning that some air can remain in the caliper.

You might also need to flush the fluid through, allowing a lot of flow to help shift any trapped air, not a teeny 10degrees at the nipple but opening it at least a full turn.

Also, I always believed that you still had to pump if using a pressure bleeder and, not to have too much pressure as it can foam the fluid (especially if you get a tiny leak between bleeder and reservoir).

Hth.
 

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Discussion Starter #16 (Edited)
OK Group...Still dealing with this issue...After getting the car back from my BMW tech, where he hooked up the machine to bleed the fluid, I still have the same issue...that is...If the engine is off, I have a hard peddle, but keep a hard leg into the pedal I can get the pedal to depress about 1/2-3/4 down. If I turn on the engine and stand on the brakes, the pedal will go all the way to the floor.

Just the other day I changed out the master cylinder...Went through the bleeding process the old fashioned way & guess what...No improvement, same brake pedal depression as described above whether the car is off or on...WTF....I spoke with Dave at Zuckhausen, I did order the proper ss lines...

One thing that I haven't checked is to pull the caliper back off the car to make sure that the pistons are in fact coming out all of the way,,I know when I installed the pads that I pressed the pistons in all of the way so that they were flush with the caliper...Maybe they are getting hung up at the point when they are putting some mild pressure against the pad & can't go any further??

HELP...would really like to start driving this car again..In the meantime I did a CF wrap to the interior.
 

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OK Group...Still dealing with this issue...After getting the car back from my BMW tech, where he hooked up the machine to bleed the fluid, I still have the same issue...that is...If the engine is off, I have a hard peddle, but keep a hard leg into the pedal I can get the pedal to depress about 1/2-3/4 down. If I turn on the engine and stand on the brakes, the pedal will go all the way to the floor.

Just the other day I changed out the master cylinder...Went through the bleeding process the old fashioned way & guess what...No improvement, same brake pedal depression as described above whether the car is off or on...WTF....I spoke with Dave at Zuckhausen, I did order the proper ss lines...

One thing that I haven't checked is to pull the caliper back off the car to make sure that the pistons are in fact coming out all of the way,,I know when I installed the pads that I pressed the pistons in all of the way so that they were flush with the caliper...Maybe they are getting hung up at the point when they are putting some mild pressure against the pad & can't go any further??

HELP...would really like to start driving this car again..In the meantime I did a CF wrap to the interior.
pedal going to the floor with the engine running/in park and you're putting constant pressure on it is normal. my car does the same thing and most other bmw's do as well. how do the brakes work otherwise? pretend you never did anything to the brakes, take the car for a ride and slam on the pedal. objectively rate the performance of them, probably fine.
 

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Discussion Starter #18
Hi Nightkrawler, objectively, I would rate them like ****tttttt. Prior to doing any work, the brakes were 10x's better. Never in my wildest dreams would I have made this stoptech upgrade if this was what I was going to end up with. The brakes simply don't stop properly & though I didn't try a panic stop today when i took it around the block to test out the new ssk, the last time the ABS didn't engage....I am taking the car up to my race shop in Sacramento to see if they can figure it out...So much for an easy DIY project. I'll try a panic stop tomorrow when I bring the car to have Timmays tips & muffler delete.

Thanks,
 

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fine but the master cyl is not your problem and being able to push the pedal to the floor at a standstill is normal as well.

assuming all the air is out of the system the only other thing i can think of is that the SS lines are smaller inside diameter than the stock ones. therefore cant move as much fluid.
 

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Discussion Starter #20
Good thought...I considered switching back to the stock lines & starting over.
Does anyone happen to know the inside diameter of the stock line? I could cross reference with the stoptech & maybe find that to be the problem. Stock lines would be fine since I don't track the car...just thought the ss lines would be a nice upgrade...

Thanks,
 
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