Brake pad swap = mushy brakes

[surlynkid]

This happened to me in October to a lesser degree (but a mid event bleed fixed it) but not in November but now again for this weekend's event. I swapped to my Pagids and now the brakes are mushy. I have bled each caliper twice now, and I am still getting way too much pedal travel. I basically have to double pump it. I never open the bleeders to swap pads. Anybody have a similar problem? If so, what fixed it? I have Stoptechs at all 4 corners. This is getting annoying. Unless someone has an idea, I am just going to suck out the reservoir and start from scratch with a liter of SRF.

[bigjae1976]

I'd bleed in fresh fluid. I know E46s would have the brake booster go out which would cause a mushy pedal...might want to check that. It was a slight hissing sound...not sure if it's the same on an E9x.

[PrimeBMW]

Please don't pull a "PurpleDurple".

[///M Ryder]

Scott, get some new fluid...........Phil

[pkimM3r]

Thats strange. Do you check your reservoir while you swap pads? I usually dont but after i swap one side, i pump the brake pedal until it stiffens up before moving to the next.

[Black Gold]

sounds scary

I had the same thing happen to me on my old Porsche when I swapped in new pads and retracted the pistons to get the pads in, and the problem that time was that the brake master cylinder had broken. it was my fault for not pumping the brakes before swapping the other side out. apparently this is very common on 997s, but haven't heard this about the m3.

hope you can get it sorted out.

[surlynkid]

The fluid was new and completely flushed Oct 27. Worked perfect until pad swap.

[surlynkid]

Can I mess anything up pushing pistons back into calipers without lid off reservoir?

Never a problem before. It is odd.

[Sebringjetta]

my pedal felt the same so over the last 2 days i flushed all my fluid changed pads and put on a fresh set of rotors up front....only thing is i didnt flush the clutch so i guess we will have to see what happens at laguna tommorow...

[surlynkid]

Bled it again. Could master cylinder be goobered up? First push goes soft and almost to floor. A quick second push is tight. Same thing repeats every time I use brakes.

[Black Gold]

That's exactly what I felt when mine was damaged...

[Z K]

I always open the bleeder to swap pads then flush fluid after the change. Pushing dirty fluid back up through the ABS system and master cylinder can damage it.

[TXmtrhed]

Originally Posted by surlynkid

Can I mess anything up pushing pistons back into calipers without lid off reservoir?

Never a problem before. It is odd.

Doubtful. Reservoir lid is vented and I always push the fluid back into the reservoir when I retract the pads.

Strange since all you did was replace the pads. Now that you're bleeding the brakes are you remembering to bleed both sides this time?

I can't figure out how it would occur but it sounds like you either have air in the master cyclinder circuit or it's faulty.

[surlynkid]

Gave up for this weekend. Taking Porsche.

[surlynkid]

Originally Posted by TXmtrhed

Doubtful. Reservoir lid is vented and I always push the fluid back into the reservoir when I retract the pads.

Strange since all you did was replace the pads. Now that you're bleeding the brakes are you remembering to bleed both sides this time?

I can't figure out how it would occur but it sounds like you either have air in the master cyclinder circuit or it's faulty.

That was just one side of one caliper while trying to do it the rain. Brain fade.

Reservoir never went empty, so no air should be in master. I think master is messed up but am just going to take it to momentum Monday.

[bigjae1976]

The caliper is a pretty simple device. There's passage that carries brake fluid and pushes out the pistons. As long as you get a steady stream of fluid out of the bleed screw AND there are no fluid leaks...the caliper is good to go.

Did you ever run the reservoir dry? That means you need to cycle the ABS pump since you may have introduced air into the system especially if you used a pressure bleeder.

Are you losing brake fluid?

If not then its probably a brake booster, master cylinder, or a vacuum leak on the booster line.

[surlynkid]

Yes. Caliper is simple.

Reservoir never dry.

No leaks. Not losing fluid.

[1MOREMOD]

Originally Posted by PrimeBMW

Please don't pull a "PurpleDurple".

major bonus points there.

[bigjae1976]

Originally Posted by surlynkid

Yes. Caliper is simple.

Reservoir never dry.

No leaks. Not losing fluid.

A stupid question...have you driven the car?

BTW...have fun at the track. Be aware that T15 CCW tends to eat up P-cars

[CanAutM3]

Were your Pagids new or already used?

If they were already used, is it possible they had some un-even wear? And when you re-installed them, they were not seating flat on the discs. The pads deforming/moving when pressure is applied will cause a mushy pedal. Hapenned to me in the past.

[1MOREMOD]

Originally Posted by CanAutM3

Were your Pagids new or already used?

If they were already used, is it possible they had some un-even wear? And when you re-installed them, they were not seating flat on the discs. The pads deforming/moving when pressure is applied will cause a mushy pedal. Hapenned to me in the past.

good point.

[bigjae1976]

Btw...what's a purple derple?