I keep reading this problem on the boards but nobody ever posts the RESULTS from what fixed it after they get it done!

Sooo... need help. I just replaced pads, rotors, and wear sensors on the '07 S. Brake pedal is fine with car off. When car is running, brake pedal is very spongy. If you hold the pedal, it just gradually goes to the floor. It can pump back up with about 5 pumps, but when you hold it, it just falls to the floor. No fluid leaking anywhere.

Please don't say its air in the system. The system was never opened. We bled the brakes afterwards just to make sure that wasn't the problem. No air came out.

I did notice when I pushed the calipers back in, that fluid spilled out from the reservoir (or somewhere) as expected when you replace pads. Not sure if that's a factor, but I'm listing it here.

All intelligent responses are welcome!

(sorry I posted this in the 1st gen forum by mistake also, this is actually for 2nd Gen car)

 

No, that's an issue.
When recessing the calipers, you want the fluid to go out the bleeder screw and not back into the master cylinder and fluid reservoir.
Sounds like a seal could have been broken.

- Erik

 

I plan on replacing my front brakes and rotors on Saturday. I read the original post regarding spongy brakes and share this concern. I see the response below, and this is the first time I've seen this. My Bentley manual doesn't mention opening the bleeder screw on the caliper either.

I thought you did not want to open the bleeder screw so air does not enter the system. What is the proper procedure?

Also, Stylin99, did you get your problem solved??

 

The point of bleeding after installation is the very reason to remove any air / water condensation that's in the brake lines.
You want to flush the system and get new fluid throughout the system.

- Erik

 

Well, I now know why no one ever posts the resolution to this... because they're too embarrassed as to the resolution. It was the brake pads installed incorrectly. When I did the rears, I picked up two pads and they looked identical so I thought they were universal. Installed those 2, then looked at the other side, yep, identical. What I didn't realize was that I put two inner pads on one side, and two outer pads on the other side. Sooo... fixed the pads. Brakes work perfectly now! Yes, we all have dumb moments.

Hopefully my admittance of stupidity will help some other poor fool out.

 

Thanks stylin99, that helps give me a bit more confidence when doing the job. It will also make me look twice at the pads when installing them.

Glad to hear you found the problem and got it resolved.

 

I admire your honesty

if you read multiple tech books on this subject you get different opnions

The "open the bleed valve" is in my opinion a contested issue.

one version

If the system is closed, pushing the piston in only forces good fluid back up

or

open the bleeder to make the piston retraction easier AND remove contaminated fluid

MINI says you should be replacing the fluid anyway so if you are doing that what's the dif?

I drove my o2 90k miles and 3 sets of pads - never replaced the fluid - 1 Dragon trip

 

Not stupid, just an oversight. I don't think there is a person out here that hasn't screwed something up while working on their cars. I know I have. More than once. You learn from it and move on. Good job in figuring it out.

 

I just changed my FRONT PADS ONLY and have this exact problem. pumps up tight when engine off / when engine is on it gradually goes to floor.

I did not install anything incorrectly.

Any other ideas on a fix???

I have to drive it to work in the AM.....

 

When I had a similar problem in my last car (a Honda CRX), it was a brake master cylinder whose seals were failing internally. The symptom was that everything was fine until I sat at a light with my foot on the brake. Then the brake would slowly sink to the floor. If I picked up my foot and applied it again, it was firm for a little bit.

If yours is just plain dropping without any pressure on the pedal, I'd suspect a possible leak in from the master cylinder into the booster. Uhh, assuming these cars use a standard vacuum-based booster.

 

Start the car and push the pedal hard. If it sinks to the floor it's probably the master. If it goes down to a certain point but not to the floor it's probably air in the lines. I would suspect air in the lines since your car is an 08. Shouldn't be master cylinder yet (we hope anyway).

 

I drove to work, brakes work but not great. pedal goes to floor gradually when stopped but holds.

I have been changing my own brakes for 30 years, I know what I am doing. I am a pretty good backyard mechanic.

I believe it may be a damaged valve or diaphram from when the calipers were pushed back. Strange that pedal only gradually goes towards the floor (when pressed) when the engine is running. Make me think it is vaccum/Power related.

I don't know just guessing. I will look further tonight if I have time

Any help appreciated

 

I had my Mini dealer flush my brake fluid and after that, when stopped at a traffic light, the pedal would slowly sink to the floor when applying constant pressure on the pedal. It stopped OK otherwise. Dealer wound up replacing the master cylinder, but didn't have one in stock because they claimed they didn't go bad. Sorry about the mixed signals, but once the master cylinder was replaced(2 yrs ago) it's been fine.

 

So it came time to replace my brakes all around, I bought EBC ultimax slotted rotors for the front, Zimmerman plain coated for the rears and EBC red stuff pads all around.

Last night it took me nearly 4 hours to replace it all, it was a bit of a nightmare since it started to get dark as I was doing the rears and I could barely see anything. I borrowed a caliper tool kit from a former Mini technician I know, pushing the pistons back wasn't much of a hassle. It just took awhile to get the springs on how they're supposed to be on the rear calipers.
But anyway, when all four wheels and the car was on the ground ready to go out for the bed-in session I felt my brake pedal nearly hit the ground once I started the car. The ABS, DSC and TPM light came on all at the same time as well. It was too dark to diagnose anything, all I did was pump the brake pedal a few times and check for leaks, thank God my driveway was dry from brake fluid.


This morning I ran my OBDII scanner and found no fault codes, meaning my ABS system is ok. Last night, I was convinced that I had junked my ABS module since I din't open the bleed screws to push the pistons back in. As of now I believe there are air bubbles in the lines because of that, but I'm not understanding why the DSC and TPM lights came up.

Any ideas of what might be going on that I am missing?????

Any help will be appreciated

 

When you push the brake pistons back in, it always requires some extra pedal to push the pistons back out to where they contact the pads and then start to press them into the rotor. So that part is perfectly normal.

In some cars, that may be enough to set off a brake system warning. I could see a brake system warning causing the DSC warning light to come on. I'm not sure about the TPM light, though.

There are two different TPM systems used on MINIs. One has the transmitters in the wheels and tells you the actual pressures in the tires. The other one uses the ABS sensors to see how quickly each wheel is turning. If a tire is significantly low in pressure compared to the others, it will turn faster due to being a smaller diameter. That will turn the TPMS light on.

Oh, and the DSC uses the signals from the ABS to figure out what is happening with each of the wheels as well!

It looks like the ABS sensors are something all three of those have in common. So:
Could you have unplugged or messed up the ABS sensors in any way?

 

I figured out what was causing my pedal to go so low. I jacked my car up on four jack stands and had a buddy pump the brakes with the car ON as I inspected each caliper. I found the entire assembly on the right rear to flex back and fourth. Turned out that the bracket bushings were bad, this also explained the reason for the uneven pad wear on that side.

Once I found the issue I ran to my computer and ordered these with hopes that it would get here before the weekend. (although it wont)

http://www.waymotorworks.com/tyrolsp...-and-rear.html

Now as for the ABS/DSC and TPM, what you mentioned there made a lot of sense, I din't know why the TPMS light was coming up when I don't even have TPM's on my wheels. I was considering ordering a speed sensor as well, but when my bushings arrive I'll look around to see if the wires came loose or something.

 

If you just installed the wheels, try resetting the TPMS by pressing the button under the handbrake lever. Sometimes with switching wheels, this light will appear. That should reset the light if all four wheels are properly inflated