mlevk

Lexs400

I don't know how mechanically inclined you are but check out these items.

The Booster usuallu operates on vacuum from the engine , hence if the
car is not running , you have to press the pedal very hard to stop it , like down
an incline\

Now , I would just relace the hose if I were you and NOT with a Lexus part
although that's up to you. Many stores will cut to length the type of hose required.

The other thing is that although the calipers operate , there can be a loss of pressure
from the seals around the pistons , hence losing brake pressure.

I had a very SIMILAR problem to yours EXCEPT mine was REAR PADS worn down almost
to the plates, I never heard them SQUEAK, but the caliper piston at the extreme travel, tends to
lose its "seal" and I had intermitten pedal dropping to the floor , like you and a sort of spongy
feel at time , now this related to the "seals" so either your seals MAY be failing or the HOSE may
have a hair line crack in it , remeber RUBBER does dry out and fail !

Good Luck , but try not to drive the car until it is resolved.
It would be unfortunate to kill anyone because of a mechaincal car problem.

Lexs400

mlevk,
thanks for the reply. If i understood correctly, you're suggesting that the host be replaced. which hose in specific are you referring to ? the one going from the booster to the master cylinder or the one from the enginge going to the booster ?
more over in order to replace the seals in the callipers, do the callipers need to be replaced or can the seals themselves be replaced leaving the original callipers on the car ?

mlevk

Lexs400

I'm refering to the hose from engine to booster, I don't think there
is one for booster to master cylinder , the booster just applies
the extra pressure needed by way of vacuum boost from the engine.
It may be loose or leaking, every now and then hence your sporadic
problem.

The seals for the caliper pistons usually cannot be replaced by the
avearge person , they USUALLY don't sell a kit , although that is exactly
what they do to the CORES that you return to the counter when you replace
calipers., Which is expensive of course vs a $10-$35 kit , but brakes are tricky
despite the simple concept of the design.

I'd look at replacing the hose first.

Last is the ABS , if the wheel senesor(s) is sending a false siganal to the ABS
Control unit , then the ABS valving unit would release the brake pressure on that
particular brake caliper ? But I think you would get a chattering of the ABS system
if that were true. So it may be a little far fetched .

Good luck , I'm just glad I didn't have to bring my car in because it would have been
$500-700 for the jobs vs my measly $120 for new pads and turned rotors.

Lexs400

I read a post on another website that some brakes are self adjusting and therefore should be driven in reverse and then have brakes applied.
I did the same . drove in reverse barking heard making the abs turn on a couple of times.
Interestingly the pedal did become a little better but not really where I want it to be. after about half an hour of driving however the pedal went back to the long travel where it had started from.
My question: why did the pedal feel change when the method of driving in reverse while braking was applied ?

Lexs400

As for the hose going to the booster, I checked it and doesnt seem to have a leak.
More over from what I've read a bad or cracked vacuum hose to the booster will make the pedal harder, not softer/spongy..

additude

If your Lexus dealer didn't fix the problem and you've repeatedly requested assistance and they are not responding, then take your matter elsewhere..like the New Jersey Department of Justice Consumer Affairs Division.

You can find them on the internet.

Write them a polite, non complaining letter stating all the facts and dates - time - people, what you expect as a result and let them get an answer for you.

Lexs400

I've read some posts in teh GS forum on how upgrading brake pads can help with the initial 'bite' of the brakes and also decrease the pedal travel by almost 1/2".
my question for those who have done so on their LS is, which ones are recommended on the 93 LS400 and where can I order/buy them ?
How about the upgrade to steel brake lines ? do they help ? any recommendations on those ?

strongsail

Backing up to adjust "self-adjusting" brakes only applies to drum brakes, not to discs.

I wonder about the ABS function too - has anybody checked the abs ecu for fault codes? Does the ABS light stay on? Does the car have traction control? If so, any fault codes there?

The Brake section in my SC manual is 217 pages long!

The troubleshooting chart lists the following possible sources of low or spongy pedal, in order of likelihood:

Fluid leaks
Air in brake system
Worn or damaged piston seals
Faulty master cylinder
Booster pushrod out of adjustment

Frankly, I have always thought the brakes in my SC are a little on the soft side - some of that may be just the nature of the beast, the brakes are none too big for a car this heavy, I am looking forward to the Supra front brake upgrade - this week!

O. L. T.

iTrader: (17)

Lexs400,

you have 3 threads in 3 forums. i have deleted one and merged 2. PLEASE DO NOT SPAM THE FORUMS.

One question, 3 threads in 3 forums =

One question, one thread =

Thanks.

Lexs400

strongsail,
I agree. that should be for rear drums but for some reason everytime I go through that process the brake pedal is exactly how it should be. after diriving for about 15 minutes it goes back to mushy/long travel.
I'm wondering, could there be some adjustment on the callipers that is off, which goes back into place when put in reverse and brakes are applied hard ?

O.L.T, I just wanted to see if I could get the SC or GS owners to shed some light on this since I wasnt sure if all the owners frequent all the different threads.

thanks for everyone's replies in advance.

Lexs400

the saga continues...
well i took the car to a different mech. last week. he came back and said that it has to be the abs pump/actuator that is faulty.
though there are no abs lights or any codes that are coming up in the car. the abs does activate and works at it is supposed to but his logic says that if the pump is not working properly , that would translate into a spongy pedal..
does that make sense ? i'll appreciate some reply back so i can go ahead and get the work done.
the new abs pump costs 1700 with 5 hours labor. therefore i need to make absolutely sure that it is what the problem is.
thanks.

acf

This is unbelievable. You are looking at shelling out over $4000 for a brake problem right now. You better make some heads roll at your dealership. And I wouldn't bother being polite at this point!