StasGS4

iTrader: (1)

Good evening Club Lexus members,

I have browsed this forum for about two years now and have always enjoyed the forum postings and replies. However, this time I need some help with a break question on my 2000 Lexus GS400. Yesterday, while driving my car, I had to undergo some emergency breaking and got some strange break response. Initially when I applied the brakes everything was fine, but as the car almost came to a complete stop the break pedal went all the way down to the floor and the car continued to rolled for another three feet or so. Today I have called Lexus service and enquired about this “problem” or strange break feel and they told me that they have no idea what might have caused it. They did offer to look at the car, but could not promise any results. At the end, if no problems would be found I would have to pay a $100 diagnostic bill. This is why I am turning to you, fellow club members, for the greatly needed help.

At this time I am not even sure if it is safe to drive the car. I should also say that I have changed the breaks about 2000 miles ago and everything seemed fine since then. Any help will be greatly appreciated.

Thanks in advance,
Stan

rominl

iTrader: (4)

hi stan, welcome to clublexus. from what you said, i really suspect you have bubbles in your brake line systems, that will cause the loss of braking pressure and your padel will go all the way. how many miles do you have on your car? how long it's been since you last bleed the brakes (or you have never)?

go to a good mechanic and ask him. if it's only bleeding the brakes it should be relatively cheap and it should help the problem

and for now, if you just drive slowly around the block, are you able to brake, no problem? does the padel feel very soft/

StasGS4

iTrader: (1)

Thanks for reply rominl!

To answer some of your questions:

The car has 58000 miles
The break system still has factory fluid and was never blead
The pedal feels kind of soft and if you pump it a couple of times it will get harder

Do you really think it is air in break lines?

Thanks for all your help!

LXOGOOD

Bro, you need to bleed your brakes now and replace with some fresh brake fluid. While you are at it, I would purchase some stainless steel brake lines to help with the mushy feel of the brake pedal... the S.S brakes lines are about $110.

rominl

iTrader: (4)

base on your THIRD observation, wher eyou pump it couple of time and it's back, i am almost 100% sure you got bubble in the system. bleed the brakes and it should be ok

bpc23

iTrader: (2)

Sorry for adding to such an old thread, but I don't think the previous replies are correct and I'd like to set the record straight.

Let's review the clues:

1) emergency braking
2) initially everything fine
3) almost a complete stop then pedal to the floor

I think Stan is describing the feeling from the Brake Assist feature activating. As I understand it and have felt it, during a sudden, rapid, and forceful application of the brakes (like in an emergency situation), the car will boost brake system pressure if it thinks you're lifting off the brake pedal to keep the wheels from locking (which we know won't happen because we have ABS, but something in the heads of pre-ABS Driver's Ed students makes us do it anyway). I think when the Brake Assist feature activates, the driver may feel a slightly different brake pedal pressure than you expect, and when it happened to me it felt like a spongy pedal for a split second.

In the end, if your brakes aren't consistently spongy, you probably don't need to bleed the brakes.

MJImport

iTrader: (1)

^ nice addition, I notice this while breaking in snowy/slippery conditions. Break gets soft right before coming to a complete stop. Never have the problem under normal summer driving.

tomtsops

pretty sure i need to blead my brakes as well.... i got over 90k miles on mine, an i don't know if its ever been done. where can i get S.S brake lines from? And are they a DIY type of project?

Edit:
Just found these on tirerack.
http://www.tirerack.com/brakes/brake...ar=&perfCode=S

are these what you guys used?

sakataj

iTrader: (182)

yeah, thats EXACTLY what im using...

kit cat

iTrader: (6)

ok guys, this is driving me nuts.


x = BREAK
o = brake

Not a mechanical expert but what about the brake booster?

MJImport

iTrader: (1)

^^ Thanks for the english lesson!

tomtsops

did it make a big difference? also did you do it yourself?

sakataj

iTrader: (182)

hahaha

honestly...i didnt notice alot as i changed ALOT on the brakes at the same time...
i did rotora slotted rotors, hawk pads, full synthetic fluid, brake lines all at once so it was hard to tell how much the lines did compared to how much everything else was doing you know? i can stop really well though

tomtsops

hahah i bet you can

jonathancl

I'm not sorry --- I need help.

I have experienced the same thing during the last two emergency stops.
1) Hit the pedal
2) ABS does what it needs
3) Pedal hits floor
4) Car nearly stopped but still moving

When this happens, you need to pump the brake to stop, which means longer breaking to full stop.
That's no good.

I have owned other cars with ABS.
When it activates, the pedal pushes back.
I have never managed to put the pedal to the floor in any other car.

Under all other circumstances, the brakes are great, function as expected.
I have stainless steel lines already.
I lose no fluid over time.
Fluid is three or four years, 30k miles.

So, does this mean new fluid and bleeding or a new part?
I may just have superman legs, so let's not rule that out, but I still need a fix.

Help?