Brake Pedal Travel - What is normal?

[Bmsluite]

I have three cars. One of them is a track car. I have bled the brakes multiple times on all of them. On the track car when I slam the brakes on the circuit I need to push the pedal sooooo far. I noticed its the same way on the van and the RSX.

To my understanding I thought a brake pedal should only move a little bit and then it should be pressure based from there right? I have hard lines and SS rotors on the track car along with monoblock 6/4 piston Brembo rotors. What is compressing? Where is the fluid going when I press the brake pedal? I do understand the brake pedal needs to move to press the piston against the brake pad and to the rotor but shouldn't it stop at some point and go no further?

What am I missing here?

Yes, I properly bled the brakes and have bled the master as well as the ABS. Really all the cars I have driven ever (about 40) have a longish travel.

Side note: what is the deal with bleeding the brakes with the car on to get the booster to help out? I have heard of some guys doing this with the big 6 piston rotors as they are a pain to get all the air out and it seems to help.

2nd side note: What is the deal with bleeding the ABS by cracking the outlet lines one by one instead of using an OBD unit that moves the solenoids around? Is this another way or does this do absolutely nothing? One would think that if air could get out that way then it would travel down the line anyways and come out of the caliper eventually.

 

[c502cid]

Not saying it's the cause of anything, but did you use the same brake fluid on all three vehicles?

 

[eljefino]

If you upgraded to these multi-piston brembo calipers but kept your stock master cylinder you've got a mismatch. Since the calipers take more fluid (compared to stock) for a given pad movement your pedal goes further towards the floor.

 

[Dave9]

To my understanding I thought a brake pedal should only move a little bit and then it should be pressure based from there right?

How would that be a good thing? Everyone likes the feel-good assurance of a firm brake pedal but at the same time, too firm does not allow to modulate the brake pressure in as fine a granularity, based on how much you push on it. Best compromise is it just reaches full pressure, at (nearer) full pedal travel. Similarly, you don't want a gas pedal where you barely touch it, and the vehicle shoots off like a rocket. Okay some geeks want that but not for public roads if you're over ~25 years old.

Granted in the era of ABS, things changed a little, but not that much if you like to be able to control your braking before letting the potentially less intelligent computer logic take over.

Just sayin', why would a brake pedal have so much travel if you couldn't make use of all of that travel? That is within the context that all the vehicles brake systems are working normally.

If you don't understand bleeding with ABS on a particular vehicle, either more research or farm the job out to someone who has done that.

 

[Bmsluite]

How would that be a good thing? Everyone likes the feel-good assurance of a firm brake pedal but at the same time, too firm does not allow to modulate the brake pressure in as fine a granularity, based on how much you push on it. Best compromise is it just reaches full pressure, at (nearer) full pedal travel. Similarly, you don't want a gas pedal where you barely touch it, and the vehicle shoots off like a rocket. Okay some geeks want that but not for public roads if you're over ~25 years old.

Granted in the era of ABS, things changed a little, but not that much if you like to be able to control your braking before letting the potentially less intelligent computer logic take over.

Just sayin', why would a brake pedal have so much travel if you couldn't make use of all of it?

The reason is heel toe. I need to be able to press press the brake and gas at the same time on track. So if the pedal goes further down the the gas I cannot do this. Right now I have tons of shims behind a race pedal attached to the brake pedla to move it back. But it's quite high up and a bit awkward to press. Answer: race car stuff

 

[Bmsluite]

If you upgraded to these multi-piston brembo calipers but kept your stock master cylinder you've got a mismatch. Since the calipers take more fluid (compared to stock) for a given pad movement your pedal goes further towards the floor.

I do understand this but there is no upgraded MC for these cars. Stock is a 1 1/16. I cns get a 1 1/8 but that's going to be hardly an different. Ideally I would have a 1.5 or even 2 but I know of nothing that has that size outside of an International truck

 

[Bmsluite]

Not saying it's the cause of anything, but did you use the same brake fluid on all three vehicles?

Actually no. The track car has high temp fluid and the other two have Prestone DOT 4

 

[brages]

When you let off the brake, the pistons retract slightly. I'm not sure why, elasticity of the seals? Design of the master cylinder?

Then when you press the pedal, you have to take up take up that clearance before the brakes engage.

On my bike, you can adjust the amount of pad retraction/free play.

 

[Bmsluite]

When you let off the brake, the pistons retract slightly. I'm not sure why, elasticity of the seals? Design of the master cylinder?

Then when you press the pedal, you have to take up take up that clearance before the brakes engage.

On my bike, you can adjust the amount of pad retraction/free play.

Motorcycle or bicycle? I know there is a master cylinder piston adjustment but I think it is good. If you jsut barely touch the pedal it begins to brake. It's jsut it travels multiple inches to get to full power. And by full power I mean 120 mph slamming on the brakes right just before ABS kicks in

 

[inquirer]

Not saying it's the cause of anything, but did you use the same brake fluid on all three vehicles?

Fluids are not compressible. Different fluids would not make any difference, except when reaching their boiling point.

 

[Jetronic]

I have three cars. One of them is a track car. I have bled the brakes multiple times on all of them. On the track car when I slam the brakes on the circuit I need to push the pedal sooooo far. I noticed its the same way on the van and the RSX.

To my understanding I thought a brake pedal should only move a little bit and then it should be pressure based from there right? I have hard lines and SS rotors on the track car along with monoblock 6/4 piston Brembo rotors. What is compressing? Where is the fluid going when I press the brake pedal? I do understand the brake pedal needs to move to press the piston against the brake pad and to the rotor but shouldn't it stop at some point and go no further?

What am I missing here?

Yes, I properly bled the brakes and have bled the master as well as the ABS. Really all the cars I have driven ever (about 40) have a longish travel.

Side note: what is the deal with bleeding the brakes with the car on to get the booster to help out? I have heard of some guys doing this with the big 6 piston rotors as they are a pain to get all the air out and it seems to help.

2nd side note: What is the deal with bleeding the ABS by cracking the outlet lines one by one instead of using an OBD unit that moves the solenoids around? Is this another way or does this do absolutely nothing? One would think that if air could get out that way then it would travel down the line anyways and come out of the caliper eventually.

You can't bleed the ABS properly without activating the pump and solenoids. The air gets pumped back to the reservoir (that's the pulsing you feel, the pressure working against your applied pedal force) and not to the calipers. Cracking the lines to get fluid to the ABS unit is not even half the job.

Pedal travel is influenced by the ratio between the brake master diameter and the brake piston diameters: go bigger (or more) on the brake pistons and travel will increase but you will have more brake control aswell.

 

[Bmsluite]

You can't bleed the ABS properly without activating the pump and solenoids. The air gets pumped back to the reservoir (that's the pulsing you feel, the pressure working against your applied pedal force) and not to the calipers. Cracking the lines to get fluid to the ABS unit is not even half the job.

Pedal travel is influenced by the ratio between the brake master diameter and the brake piston diameters: go bigger (or more) on the brake pistons and travel will increase but you will have more brake control aswell.

So I have a few options then and would like your opinion

1: deal with it as is
2: get more agressive pads. Less modulation but less travel, however, the pedal will remain light like it is now so it may just become very difficult to modulate
3: figure out how to fit an MC from a truck. I am a decent fabricator but this seems tricky and maybe a bit dangerous. I have modified nearly the entire vehicle but messing with the brake system seems like a toss of the dice.
4: go to manual brakes with a 6:1 ratio and no booster. I have never had manual brakes and have never driven a car with manual brakes so I don't even know how this would go. The kit is expensive and I am not exactly sure which piston diameter it has

 

[Jetronic]

Bigger master would be the way to go IMO. You can likely fit the master and booster from a truck directly. Or fit just the master if the (usually 2) bolt holes are more or less the same distance apart.

 

[Jetronic]

Just sayin', why would a brake pedal have so much travel if you couldn't make use of all of that travel? That is within the context that all the vehicles brake systems are working normally.

You absolutley don't want to run out of travel with half of the system leaking: so you need to get to full brake force in less than half of the brake pedal travel on a fully operational system.

 

[Bmsluite]

You absolutley don't want to run out of travel with half of the system leaking: so you need to get to full brake force in less than half of the brake pedal travel on a fully operational system.

Are bolt hole distances on MCs standardized? I think getting the correct diameter of the MC to fit into the booster is going to be hard. Unless that is standardized as well

 

[John105]

imho there shouldn't be any "thought" behind it, meaning, if it's noticeable, something likely isn't right. Right now we have a German, a Japanese, and an American car. I would say the American is the softest pedal, German is the firmest, but this is feel, not travel.

Also, I know from having replaced the ABS/DSC hydro pump (had it rebuilt) in the BMW, that per BMW, you cannot bleed the ABS pump manually, and you must perform an ABL bleed at all 4 calipers one at a time, using the vehicle's computer....my .02...

 

[Dave9]

You absolutley don't want to run out of travel with half of the system leaking: so you need to get to full brake force in less than half of the brake pedal travel on a fully operational system.

I agree, the context was working properly, not leaking. I'd rather not have a pedal so firm that you barely touch it and slow down too fast, at least not for a daily driver.

 

[JHZR2]

I agree, the context was working properly, not leaking. I'd rather not have a pedal so firm that you barely touch it and slow down too fast, at least not for a daily driver.

Imo there’s a difference between “digital” on/off pedal, and having a relative amount of firmness early in travel.

Domestic trucks seem to have a much softer pedal than say euro cars. When I had some air in the lines of my MB, the pedal felt about like new domestic trucks.

 

[dumkid]

I like a pedal with some resistance to it. Some pedals you barely push it (force) and it's so boosted that it travels far and almost locks up the brakes, some pedals have little resistance and long travel but also aren't grabby, and the ones I like don't move very far before the brakes bite but it takes significant force to lock up the wheels.
Dodge minivans have the weirdest feeling brakes. There's no resistance to the pedal until it hits the floor but the brakes lock up almost at the beginning of the pedal travel. I like BMW brakes until the vacuum pump/lines get old and don't make enough vacuum at idle for the brake assist to work

 

[Marcozi]

In the end I bet, as noted, you have a caliper-master cylinder mismatch.