Soft pedal / dead zone after new pads

[ZionsWrath]

interesting...

[juliog]

Been having this issue again and again and again, after going trough a couple set of front pads and replacement rotors.

After 1-2 track days the brake pedal gets very mushy. Bleeding helps but doesn't eliminate the softness completely. A couple days after bleeding it usually suddenly gets noticeable better, but still a far cry from what it should be.

The end result is that the braking feel is not linear and I have a lot of trouble being consistent with initial application and release, making threshold braking very difficult at the track.

[wparsons]

What fluid are you running? It sounds like you're boiling the fluid a bit and it's not recovering.

[juliog]

Was on Project Mu GFour, then changed to RBF660. Stock calipers and DBA4000 rotors. Doing a full flush this weekend with Torque RT700.

[Black Tire]

Originally Posted by juliog

Was on Project Mu GFour, then changed to RBF660. Stock calipers and DBA4000 rotors. Doing a full flush this weekend with Torque RT700.

Digging up this old thread, but it is relevant to me right now. Did the full flush with Torque RT700 do the trick? What bleeding method did you use?

[juliog]

No problems since I switched to AP Racing Sprint Kit + Torque RT700. I think I might have had air somewhere in the lines that didn't go away until I did the install of the BBK and put some fresh SS lines. Since then, virtually no degradation after 4 track days. Might bleed after the 5th just for the peace of mind.

Using the same fluid now on a S2000 with stock brakes (my daily), again it's holding up much better than the Motul, 2 track days and many canyons and brake pedal still feels right.

My roommate's FR-S with OEM brakes is still on RBF660 and has to bleed after every single event, pedal gets noticeably softer. And he's a low-intermediate driver. He'll be switching to Project-Mu or Torque soon...

For the record, I have the Motive power bleeder but most of the time I just use the two-man method to bleed the brake fluid.

[CSG Mike]

Originally Posted by juliog

No problems since I switched to AP Racing Sprint Kit + Torque RT700. I think I might have had air somewhere in the lines that didn't go away until I did the install of the BBK and put some fresh SS lines. Since then, virtually no degradation after 4 track days. Might bleed after the 5th just for the peace of mind.

Using the same fluid now on a S2000 with stock brakes (my daily), again it's holding up much better than the Motul, 2 track days and many canyons and brake pedal still feels right.

My roommate's FR-S with OEM brakes is still on RBF660 and has to bleed after every single event, pedal gets noticeably softer. And he's a low-intermediate driver. He'll be switching to Project-Mu or Torque soon...

For the record, I have the Motive power bleeder but most of the time I just use the two-man method to bleed the brake fluid.

Two man method is just so much faster once you get coordinated...

[ZionsWrath]

Originally Posted by CSG Mike

Two man method is just so much faster once you get coordinated...

Probably but it's hard when you have no friends 😢

When I bled my clutch I had to teach my girl what is a clutch pedal ❤

[solidONE]

Originally Posted by juliog

1) Put on new front brake pads —old ones were worn out.
2) Bled brakes with help of another person. Brake pedal felt very firm.
3) After starting engine, brake pedal feels very soft the first 50%, almost (but not quite) like a dead zone. It does not become firm again after shutting down engine.

Drove for a couple days. Successfully bedded my pads at night with no traffic around (no more squealing on these PMU CR). Tried bleeding brakes again, two person method plus vacuum pump, same result.

Any hints or tips? I've changed pads and bled brakes several times in the past, but never had this problem. Could it be air? Should I try bleeding again?

You can reverse bleed the brakes feeding from the bleed nipples up to the reservoir if you want to get really anal.

Here a vid so you get an idea what I'm talking about.
[ame="https://www.youtube.com/watch?v=FB8kzUEqK3U"]Phoenix Systems V-12 DIY Reverse Brake Bleeder Walkthrough - YouTube[/ame]

You really dont need any fancy tools to reverse bleed, although they do make the job much faster. You can make a brake fluid IV (gravity feed insead of assisted by pressurization with a tool) with some hoses and fitting from homedepot.

edit:

[Spacemane969]

I just did my full flush and I have about 80% play in the pedal before the brakes apply. It still feels good but I need the firmness back. Two things could have caused this: I used the one man IV method and on my last wheel the bottle fell to the ground. Not sure if air got sucked in. Second forgot to go front right in sted of front left. What's the most simple fix here?
Thanks