Long Brake Pedal

Seb Harvey · January 21, 2009

Hi all,

I have (what I would assume) is a long brake pedal. It has always been the case since I brought the car second hand, however, I'm having to push the pedal to the floor before I get any braking.

Is this normal? If not, how can I resolve it?

I have recently serviced the car, replaced brake pads, discs and brake fitting kit and drained/refilled brake fluid, but it hasn't shortened the pedal push.

Car: Lexus LS400 '96

ManicMark · March 4, 2009

Hi all,
I have (what I would assume) is a long brake pedal. It has always been the case since I brought the car second hand, however, I'm having to push the pedal to the floor before I get any braking.

Is this normal? If not, how can I resolve it?

I have recently serviced the car, replaced brake pads, discs and brake fitting kit and drained/refilled brake fluid, but it hasn't shortened the pedal push.

Car: Lexus LS400 '96

Hi I belive it is probably your brake servo unit ,if you are standing in front of the car it is to the left near the air filter down by the chassis rail it has several brake pipes attatched to it. dont dream of buying a new one they are more than the cost of the car, you should get an used one cheap as its not a common part to fail.

steve2006 · March 4, 2009

Hi,

You need to determine what is causing the problem so the 1st thing is does the brake pedal come up more if you pump it?

To check the brake servo operation pump the brake pedal with the engine off until it is a hard feel keep your foot on the pedal then start the engine you should feel the pedal drop a little if the servo is working.

I am not sure about the Lexus but I know on some cars you can adjust the servo pushrod I will look into this for you.

Seb Harvey · May 21, 2009

Hi,

The pedal firms up when the engine is off and then depresses when the engine is started. I can pump this up and works okay for the first few brakes, but then goes long again. I'm also not getting any leaks from the car (just fixed a massive Power Steering leak on the high-pressure pipe, and I know the car isn't leaking anywhere else!)

Just this weekend replaced discs (old ones warped) and pads and is still long.

Just to rule out anything else, I'm getting my fuild changed this afternoon.

TigerFish · May 21, 2009

and drained/refilled brake fluid, but it hasn't shortened the pedal push.

Just to rule out anything else, I'm getting my fuild changed this afternoon.

For the second time?

When you say drained, you mean you let the whole lot run out before topping up? Did the brakes bleed correctly? Sounds like you have some big air bubbles in the system.

steve2006 · May 21, 2009

and drained/refilled brake fluid, but it hasn't shortened the pedal push.

Just to rule out anything else, I'm getting my fuild changed this afternoon.

For the second time?

When you say drained, you mean you let the whole lot run out before topping up? Did the brakes bleed correctly? Sounds like you have some big air bubbles in the system.

Agreed either the above or a faulty master cylinder and or servo unit but if pumping the brakes improves the pedal travel it is normally air in the system however faulty master cylinder seals can allow air into the system.

BTW does the fluid level in the reservoir go down indicating a loss of fluid?

Keynsham1 · October 8, 2013

I know this is an old thread but I am suffering from the same problem. My brake pedal is hard when the engine is off but when the engine is started, the pedal slowly moves right to the floor. It takes about 4-5 seconds to do this. There cannot be anything wrong with the master cylinder as this would show up whether the engine was running or not. I have no fluid leaks and the servo is operating perfectly. When driving, the pedal doesn't move to the floor under braking but I haven't tried braking really hard yet.

I suspect air somewhere in the system and I am going to bleed the system fully this weekend. I notice in the manual that the brake actuator should also be bled as well as each wheel. Could this be the problem perhaps?

runsgrateasanut · April 14, 2014

I'd be interested to know if you fixed the problem and what was the cause. Just bought a Lexus and footbrake travel surprised me as my Merc was much sooner to apply breaking. Getting new pads on shortly and will have system bled. Brake fluid perhaps a little lower than should have been but not much.

AdeV · May 8, 2014

Years & years ago I had Granada which did this; but it was using fluid (no visible leaks). Turned out to be the master cylinder leaking into the brake servo reservoir - we must have found about 3 pints of brake fluid in it!

I always find that servo-assisted brakes do seem to operate closer to the floor than non-servo brakes (apart from Dad's Subaru Impreza, which gave me whiplash every time I drove it, the brakes were so close to the top of the pedal). Zero braking effort until you think you're pushing a hole into the floor usually means one of the two circuits is not operating; either a siezed caliper (unlikely) or air in the system (much more likely).

Spacewagon52 · November 19, 2015

I appear to have a similar problem. There are no apparent leaks but the pedal, when pushed hard, will go down to the floor. It still brakes. Getting the fluid changed tomorrow - so will see if that works - handy to know the other options. Can't understand how air can get into the system when it has been working fine - no loss of fluid.

Will post the outcome tomorrow.

steve2006 · November 19, 2015

Also check all the brake flexible pipes, they can bulge out under pressure but look OK.

Does the pedal become harder to press and stay right at the top when you pump it with the engine off and then drop slightly under your foot if you then start the engine?

Your problem can also be caused by low fluid in one of the dual brake circuits so check that the reservoir is full in both front and rear sections.

Spacewagon52 · November 19, 2015

Thanks Steve, Will pass this info on to the garage. I am not mechanically savvy and rely on my garage (very trustworthy but are not familiar with a Lexus) but the advice and information is very welcome. Keeping my fingers crossed it is not the servo! £££££££