Brake pedal travel

[Barryb97]

The last couple track days my brake pedal has seemed to have a little extra travel. I've bleed the brakes between events and it hasn't seem to help. Did some searching on the forums but haven't found anything. No sign of leaking, pads are fine, rotors are fine. Brakes seem to stop fine but the pedal is down a couple engines which makes heel toe almost impossible. I read another post about someone having to replace their master cylinder but I don't want to jump to conclusions. Any advice at what I should look at next?

[seank]

If you have over heated the fluid, which is very likely unless its BLUE or similar, bleeding wont work.

[Barryb97]

ATE Blue. This morning I get in to go to work and the pedal goes almost to the floor. Two pumps and it is back to normal all the way to work.

[kvnchu]

How old is the fluid? Brake fluid even if it is in the bottle and never used will go bad unless sealed.

Why dont you just try a full flush with fresh fluid first?

[seank]

Originally Posted by Barryb97

ATE Blue. This morning I get in to go to work and the pedal goes almost to the floor. Two pumps and it is back to normal all the way to work.

Pedals don't go to the floor due to any condition of the fluid. You have another issue that i would deal with asap.

[Kgolf31]

How are you bleeding the system?

If you are pumping the pedal, and doing a 2-man job you can easily ruin the master cylinder seal if you do it incorrectly

[inTgr8r]

Originally Posted by Kgolf31

How are you bleeding the system?

If you are pumping the pedal, and doing a 2-man job you can easily ruin the master cylinder seal if you do it incorrectly

further thoughts on this???
I'm not sure i follow you.
do you mean the possibility of moving sediment etc into the seals if you bottom it out too far?

[Kgolf31]

Originally Posted by inTgr8r

further thoughts on this???
I'm not sure i follow you.
do you mean the possibility of moving sediment etc into the seals if you bottom it out too far?

Yea, if you're pumping and you push the pedal all the way to the floor there is a chance you can ruin the seal

[Barryb97]

Using the Motive power bleeder.

[Barryb97]

I may just try another full flush with new fluid and see how it feels.

[3002 tii]

Originally Posted by Kgolf31

Yea, if you're pumping and you push the pedal all the way to the floor there is a chance you can ruin the seal

I was thinking cooked brake fluid or this, the master cylinder.

I personally am no longer a fan of ATE blue, sure it's cheap but it stains the reservoirs and can reach boiling point pretty easily. For a few bucks more I buy RBF 600 or PFC RH 665.

[inTgr8r]

Originally Posted by 3002 Tii

I was thinking cooked brake fluid or this, the master cylinder.

I personally am no longer a fan of ATE blue, sure it's cheap but it stains the reservoirs and can reach boiling point pretty easily. For a few bucks more I buy RBF 600 or PFC RH 665.

^+1 on the fluid

[The HACK]

How much pad is left?

[Barryb97]

About 50% pad left.

[kennyfrc]

Originally Posted by Barryb97

The last couple track days my brake pedal has seemed to have a little extra travel. I've bleed the brakes between events and it hasn't seem to help. Did some searching on the forums but haven't found anything. No sign of leaking, pads are fine, rotors are fine. Brakes seem to stop fine but the pedal is down a couple engines which makes heel toe almost impossible. I read another post about someone having to replace their master cylinder but I don't want to jump to conclusions. Any advice at what I should look at next?

Solution:

[seank]

Originally Posted by kennyfrc

Solution:

This is the solution for his pedal going to the floor?

The brakes weren't bled at all or he has a mechanical issue.

Boiled fluid wont put your foot to the floor!!!

[StickMon]

I'm sometimes wrong, but this sounds like master cylinder failure.
I've had them fail on 2 Chevy trucks and 1 Toyota, and that was pretty much the symptom.

[yousefnjr]

There has to be a leak somewhere. Fluids don't compress; if you aren't able to maintain hydraulic pressure via the pedal, the fluid has to be going somewhere. As others stated, master cylinder is a good place to start looking if you aren't seeing brake fluid on the ground.

Edit - this is assuming the system is bled of course

[F360C]

Originally Posted by 3002 Tii

I was thinking cooked brake fluid or this, the master cylinder.

I personally am no longer a fan of ATE blue, sure it's cheap but it stains the reservoirs and can reach boiling point pretty easily. For a few bucks more I buy RBF 600 or PFC RH 665.

How many track days were you using the fluid for before you got it to boil? Even when I get the brakes this hot (see pic below) I still don't have any meaningful brake fade but so far I think I am the only one that doesn't have a problem with the superblue.

How are you liking the PFC fluid? I think that is what i am going to use next as I am only hearing great things about it and it isn't as expensive as the liguid gold Castrol SRF.

[3002 tii]

Originally Posted by F360C

How many track days were you using the fluid for before you got it to boil? Even when I get the brakes this hot (see pic below) I still don't have any meaningful brake fade but so far I think I am the only one that doesn't have a problem with the superblue.

How are you liking the PFC fluid? I think that is what i am going to use next as I am only hearing great things about it and it isn't as expensive as the liguid gold Castrol SRF.

First time I faded was ATE Blue was my last day Summit Point Main, it was my 4th day. The first two were at VIR full course.

Second time was NJMP Lightning, probably had 6 days since it was last bled, and I was running Motul 600 then.

PFC was good, never had fade but over the years I've learned not to go on an entire season (about 12 days for me) without at least bleeding the brakes once or twice in between. So that means I do a full flush beginning of season which is around March and then bleed once in June and once in Sept. If I feel like I've been especially hard on the brakes, I may just do another flush mid-season.

I've hear from buddies that run Castrol they can go an entire year or two w/o bleeding them and they never encountered fade lol.

[kennyfrc]

Originally Posted by 3002 Tii

I've hear from buddies that run Castrol they can go an entire year or two w/o bleeding them and they never encountered fade lol.

[The HACK]

Originally Posted by Barryb97

About 50% pad left.

There you go.

This seems to be the primary reason to go with fixed calipers, since based on my experience, the pad wear makes little to no appreciable difference in a fixed caliper, multi-piston unit because the fluid is distributed over 4-6 times the number of tiny pistons rather than a HUGE one.

So as the pad wears down, pedal travel increases. Especially for track use, the larger single piston means more fluid volume is getting compressed over a spread out pad surface, resulting in what feels like further pedal travel, and as you brake hard for track use, flex in pad over the single pivot resulting in further feel of softness in pedal travel.

Typically, I ditch my track pads when they get down below 35% of pad left because on the stock sliding calipers, it gets increasingly difficult to get a good sense of how much braking you still have due to the increased vagueness of the pedal travel.