How I fixed my Soft Brake Pedal (99 LS400) - Club Lexus Forums

How I fixed my Soft Brake Pedal (99 LS400)

Thread Tools Search this Thread
Old 08-06-14, 10:42 AM   #1
Pole Position
Thread Starter
Join Date: May 2008
Location: Alberta
Posts: 265
Default How I fixed my Soft Brake Pedal (99 LS400)

Hey guys,
I wanted to document this as I had a helluva time finding threads on all sorts of toyota forums that had the exact problem.
My car is the newer vvti LS400 but from Japan where it likely sat a while.
The brake pedal went to the floor but then stopped the car, it was pretty terrifying initially, stopping power was also pretty low.

I tried replacing the brake booster, which turned into 6hrs of cutting it out of the firewall, did nothing.
brake bleeds of all sorts, adjustment of pedal, notta. I bled the master cylinder with the fingers-over-ports method after it was on the car (bench bleed would be easier)

What the problem was, was pistons sticking in the front calipers. I read that if you clamp off one of the brake lines with vice grips and the pedal goes firm, you've got a caliper problem.
Pedal got harder with LF clamped but really firm with Both clamped.

Took off calipers, boots and seals looked brand new but the most of the pistons barley moved in their bore. After using compressed air and c-clamps (to hold in the pistons that were free in order to keep the pressure up to blow out the stuck ones) I removed each piston seal, greased it with marine grease and then lightly greased the bores (as per caliper rebuild) Pistons were super clean already but I sanded them lightly with 1200grit, now they move very easily in the bores.

Then a normal bleed on the calipers with a person pumping inside until air bubbles were out.

However, the brake pedal up on jack stands did not get firm, UNTIL I took the car out for a drive, as soon as I moved the wheels the brake pedal went firm. I was going out to try and his the ABS on a gravel road to clear air in there, but this proved not necessary. I've been at it for months trying bleed after bleed, this and that, and there you are. I read on 4Runner forums that people had the same problem with their 4-piston calipers, apparently the Seal rebuild kit is avaliable through Lexus or toyota, way cheaper then getting a rebuilt caliper.

I was ripping my hair out on this one, hopefully this post helps some people who search it in the future.
Kingsoup is offline   Reply With Quote
Old 08-06-14, 01:51 PM   #2
iTrader: (6)
RA40's Avatar
Join Date: May 2003
Location: California
Posts: 17,363

Thanks for the write-up and glad you found the cause. Have had similar experience on other cars where a caliper does not have smooth travel and is stuck. Same routine, bleed, check booster, master cylinder, caliper and the light bulb goes on.
RA40 is offline   Reply With Quote
Old 08-06-14, 04:32 PM   #3
iTrader: (10)
PureDrifter's Avatar
Join Date: Aug 2004
Location: California
Posts: 23,604

I rebuilt my calipers a year ago just because I was rebuilding other stuff on the front end and the centric rebuild kit is so cheap. always worth doing preventative imho.
PureDrifter is offline   Reply With Quote
Old 08-07-14, 04:44 PM   #4
Lexus Champion
iTrader: (5)
timmy0tool's Avatar
Join Date: Sep 2008
Location: 909/626/714, SoCal
Posts: 3,651

didn't think our calipers were susceptible to freezing or getting stuck, but then again we are in cali with warm weather most of the time.
timmy0tool is offline   Reply With Quote
Old 08-07-14, 08:35 PM   #5
Lexus Champion
iTrader: (4)
python's Avatar
Join Date: Jan 2008
Location: ca
Posts: 1,605

any car is susceptible if the fluids are not changed within a reasonable time frame..humidity is more of a factor than heat itself. brake fluid is 5.1 is more so than dot 4..and 4 is more so than dot 3. never use dot 5 silicone based fluid.
python is offline   Reply With Quote
Old 08-13-14, 03:18 PM   #6
Pole Position
Thread Starter
Join Date: May 2008
Location: Alberta
Posts: 265

It was a new experience with me on 4-piston calipers, I had them as well on my 3000GT but never had this problem.
I've had the car since Dec of last year but have been fighting with this problem since April so I can get the car safetied and legal on the road, finally finally got it!
Kingsoup is offline   Reply With Quote
Old 08-14-14, 07:29 AM   #7
Tuha's Avatar
Join Date: Nov 2012
Location: Namibia
Posts: 115

Thanks for the info Kingsoup. My brakes are doing this exact thing and I will definitely be taking a closer look at them when time permits.
Tuha is offline   Reply With Quote
Old 08-20-14, 05:13 PM   #8
Pole Position
Thread Starter
Join Date: May 2008
Location: Alberta
Posts: 265

I've gotten to do some more testing on this now and its totally fixed, I can hit the ABS on the dry now, you need those big calipers for a car of this size!
Kingsoup is offline   Reply With Quote

Related Topics
Thread Thread Starter Forum Replies Last Post
Front caliper piston won't retract john689089 GX - 1st Gen (2004-2009) 5 03-24-16 11:36 AM
Fitting LS400 brakes to a SC400-Detailed how to do. grm405 Suspension and Brakes 67 02-16-16 11:26 AM
Help please. Rebuild calipers - fix stuck piston(s) honasbone LS - 3rd Gen (2001-2006) 19 02-12-15 06:39 PM
More Brake Issues CPALex LS - 4th Gen (2007-present) 13 10-20-14 03:35 PM
02 GS300 Problem replacing front brake pads tyl604 GS - 2nd Gen (1998-2005) 16 09-08-14 07:17 AM

95, brake, low, ls400, pedal

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Forum Jump

All times are GMT -7. The time now is 04:47 PM.

Copyright © 2000-2016 Internet Brands, Inc. All Rights Reserved