Soft brake pedal
04-24-17, 01:07 PM
#2
Lexus Champion
Most likely you have air trapped in the brake lines. Try to bleed them to see if that will resolve the problem. Also check to make sure your brake fluid level is good, and that your brake pads are not too thin.
04-24-17, 02:49 PM
#3
Can be a number of things. Master cylinder comes to mind if pedal is extremely low. Worn pads won't bring your pedal very low but more info is needed. No need to bleed the brakes unless they were opened before or there is a leak. Good luck and let us know how you make out.
04-25-17, 02:21 PM
#4
Having the same issue on an LS I picked up, as well as one a friend picked up. Both 2002's, his base, mine UL. You have to REALLY press on the break to get the car to stop. Brake pedal isn't low for me though...his issue is even after swapping out pads/rotors. We're going to bleed both brake systems and see if that helps, if not, time to swap master cylinder.
04-25-17, 03:57 PM
#5
Having the same issue on an LS I picked up, as well as one a friend picked up. Both 2002's, his base, mine UL. You have to REALLY press on the break to get the car to stop. Brake pedal isn't low for me though...his issue is even after swapping out pads/rotors. We're going to bleed both brake systems and see if that helps, if not, time to swap master cylinder.
04-26-17, 07:00 AM
#6
I had a terribly mushy pedal when I first purchased my car with warped rotors. I turned my rotors at that time and replaced my pads with OEM. No more shutter, but pedal was still mushy and did not stop well. 6 months ago when shutter had returned and pads were worn, I replaced with OEM rotors and OEM pads and I can honestly say that my car has never stopped so good after purchasing it almost 7 years ago. Thfe new OEM rotors made the difference! Yes the pedal is not as sensitive as any European car as BMWs, Audis, Benzes, and there will be some play. But when pushed hard stops this aircraft carrier quite well!
Thanks for the info, hopefully it fixes it!
04-26-17, 01:39 PM
#7
Another trick to localize the problem is looking at leaking calipers that possibly need to be rebuilt/replaced.
They sell special tools for this but using some extra hose to not damage the brake line you could squeeze off a brake line with some vise grips and work the pedal to see if it responds better; i.e. less travel.
Rotating around the car you could tell if a caliper is the problem as opposed to tackling the master cylinder. New pads and rotors, when needed are definitely a help also.
I've not tried it myself but have read about it on other sites.
They sell special tools for this but using some extra hose to not damage the brake line you could squeeze off a brake line with some vise grips and work the pedal to see if it responds better; i.e. less travel.
Rotating around the car you could tell if a caliper is the problem as opposed to tackling the master cylinder. New pads and rotors, when needed are definitely a help also.
I've not tried it myself but have read about it on other sites.
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04-27-17, 07:30 PM
#8
Instructor
Someone posts about this problem at least once a year.
2010: https://www.clublexus.com/forums/ls-...e-stumped.html
2011: https://www.clublexus.com/forums/ls-...edal-feel.html
2012: https://www.clublexus.com/forums/ls-...ad-change.html
2013: https://www.clublexus.com/forums/ls-...ake-pedal.html
2014: https://www.clublexus.com/forums/ls-...ifference.html
2014: https://www.clublexus.com/forums/ls-...-piston-s.html
^ the Lexus service manual says to grease the inside of the anti-squeal shims (presumably to enhance the anti-squeal effect), but if you want more responsive brakes, skip this. If you experience brake squeal later, taking the pads out is a very simple job.
2016: https://www.clublexus.com/forums/ls-...uble-pump.html
2017: https://www.clublexus.com/forums/ls-...ake-pedal.html
2018: https://www.clublexus.com/forums/ls-...80-brakes.html
2019: https://www.clublexus.com/forums/ls-...cel-pedal.html
2019v2: https://www.clublexus.com/forums/ls-...-bleeding.html
The likely cause of the soft pedal is old brake hoses deteriorating and a near-solid contaminant collecting inside the caliper pistons. It is likely NOT the master cylinder. To cure the condition:
1) Buy 4 new brake hoses. StopTech brake hoses don't have rubber inside to disintegrate, preventing the problem from ever re-occuring. They use a near-rigid Teflon inner tube, and a braided stainless steel exterior. However, new OEM rubber hoses should last several years before the problem returns. Rubber lines expand outward under pressure, Teflon doesn't, so use StopTech for best pedal feel. Even a few microns of expansion translates to a spongy/squishy pedal feel. By using lines that have a more rigid inner tube and reinforced outer casing, you will reduce the outward expansion of the line. DO NOT buy no-name, discount, knock-off brake lines whether they are rubber or stainless-steel-braided - these lines have been known to fail without warning, which is obviously life-threatening.
2) Buy the Lexus OEM caliper overhaul kits (FRONT CALIPER OVERHAUL KIT 04479-50130, REAR CALIPER OVERHAUL KIT 04479-50140)
3) Remove the calipers, disassemble completely, clean all parts not included in the kit, then put it all back together using the new components. Don't forget to use the correct grease at the factory-specified locations (except for the part about the shims mentioned above).
4) Bleed the brake system in the correct order and ensure fresh brake fluid runs through all calipers bubble-free.
5) Bleed the ABS system (complicated multi-step process requiring TechStream). This is key to restoring pedal feel (service manual even says so). First you have to depress the brake pedal 20+ times with the ignition off, then turn ignition ON with engine OFF, select Air Bleed in Techstream, keep your fluid reservoir full, and then bleed the air from all 4 wheels, one at a time, for Air Bleed Step 1. The system will only run for 4 seconds at a time, so repeat the air bleed until all of the air in the fluid has been bled out, then move to the next wheel. After all 4 wheels, go to Air Bleed Step 2 and do the same thing, then go to Step 3 and same thing, then go to Step 4 and same thing.
Please note that the 2001-2006 LS430 brakes are soft by design and especially in comparison to sportier cars. I drove a 2012 Nissan Altima and Mercedes C-class, both have extremely touchy brakes with very high catch and minimal pedal travel compared to the LS430. I test-drove a 2012 LS600hL and 2018 Chevy Impala - the catch, softness, and travel on both were about the same as my 2002 LS430.
I assume they designed the LS this way so that your VIP passenger in the back is able to hand-write documents with perfect precision and not spill any coffee while being driven through a city.
2010: https://www.clublexus.com/forums/ls-...e-stumped.html
Originally Posted by SH430
I have finally resolved my soft brake pedal problem! I turned out to be a sticking piston in one of the front calipers. I called my local Lexus dealer and ordered the "overhaul kit" 04479-50130 for the front calipers. The parts guy wasn't sure he had heard right when I asked for the kit, one kit does both calipers, but I wanted to try rebuilding before spending the big bucks for calipers. The calipers were easy to rebuild. The kit had all of the seals, boots and brake line seals. I also replaced the caliper bolts since Lexus recommends not reusing the old ones." " I took the car to a local shop where the owner has 20 years Lexus dealership experience. He inspected the brakes and bled the system. No surprise, right? The one interesting thing he told me was that the caliper pistons were retracting too far and leaving a gap between the piston and the brake pad. He did not have an explanation for this condition.
Originally Posted by Lynzoid
And yes, many big cars with multiple brake cylinders per wheel, do suffer from this kind of problem and it's usually just a matter of rubber seals and/or brake hoses wear. Microns of extra play in the cylinder/s (or 'bubbling' of old hoses) translates to millimetres and even inches of extra pedal travel.
Originally Posted by Lynzoid
i had by brakes become spongy at some point and hunted the problem down after spending alot of time on it. basically it was down to contaminant from old brake hoses innards collecting inside the caliper pistons. i had to replace all cylinder seals (there's oem kits for both axles), and install new brake hoses all around (oem). after that i have very strong and reassuring pedal. high catch as well. you have non-bleedable contaminant (almost solid) inside your cylinder/s. Just replace all the seals and clean out the dirt inside the cylinders. Cyl's themselves are ok, no need to replace these. Also i recommend replacing all brake hoses, cos that's where contaminant coming from - innards of hoses disintegrate with time. Yes, this is VERY common on LS430. So common, that dealers usually not arsed to fix it and just say 'it's how ls brakes supposed to feel'... what a bs.
Originally Posted by Lynzoid
This is NOT master cylinder. I repeat, NOT master. Click on my nick and check my previous treads. I had this problem, struggled with it and had it fixed. Master cyl's failure on Lexus is UNHEARD of ! Basically the problem is either disturbed dirt going back into system and/or caliper/pad misalignment. Sludge is compressable. Source of sludge in cylinders - deteriorating brake hoses.
Originally Posted by Lynzoid
Basically it's either sticky cylinder (most likely one of fronts - there's 8 cylinders in front in total) or (and) hoses deteriorating and contaminating the brake fluid (this leads to accumulation of gunk inside cylinders and that makes pedal awfully 'untrustworthy').You need to get some repair kits (there's separate kits for cylinder seals and dust boots and kit with new springs, that hold the pads in the caliper) and carefully replace everything, plus replace all 4 hoses. Then bleed thoroughly and you'll get your 'good' brake pedal back.
Originally Posted by Lynzoid
... again.... it's a sticky piston+deteriorated brake hoses... use cylinder repair kits and new hoses.
Originally Posted by Lynzoid
never grease the 'anti-squeal shims'. never since. since i found out greasing there defeats the purpose of these shims. you want firm and solid brake feel? never grease there then. proper places to apply the grease are brake pad edges. the ones that slide metal-to-metal inside the caliper. second mandatory grease point is where sliding pin contacts the 'earlobes' of the brake pads.
2016: https://www.clublexus.com/forums/ls-...uble-pump.html
2017: https://www.clublexus.com/forums/ls-...ake-pedal.html
2018: https://www.clublexus.com/forums/ls-...80-brakes.html
2019: https://www.clublexus.com/forums/ls-...cel-pedal.html
2019v2: https://www.clublexus.com/forums/ls-...-bleeding.html
The likely cause of the soft pedal is old brake hoses deteriorating and a near-solid contaminant collecting inside the caliper pistons. It is likely NOT the master cylinder. To cure the condition:
1) Buy 4 new brake hoses. StopTech brake hoses don't have rubber inside to disintegrate, preventing the problem from ever re-occuring. They use a near-rigid Teflon inner tube, and a braided stainless steel exterior. However, new OEM rubber hoses should last several years before the problem returns. Rubber lines expand outward under pressure, Teflon doesn't, so use StopTech for best pedal feel. Even a few microns of expansion translates to a spongy/squishy pedal feel. By using lines that have a more rigid inner tube and reinforced outer casing, you will reduce the outward expansion of the line. DO NOT buy no-name, discount, knock-off brake lines whether they are rubber or stainless-steel-braided - these lines have been known to fail without warning, which is obviously life-threatening.
2) Buy the Lexus OEM caliper overhaul kits (FRONT CALIPER OVERHAUL KIT 04479-50130, REAR CALIPER OVERHAUL KIT 04479-50140)
3) Remove the calipers, disassemble completely, clean all parts not included in the kit, then put it all back together using the new components. Don't forget to use the correct grease at the factory-specified locations (except for the part about the shims mentioned above).
4) Bleed the brake system in the correct order and ensure fresh brake fluid runs through all calipers bubble-free.
5) Bleed the ABS system (complicated multi-step process requiring TechStream). This is key to restoring pedal feel (service manual even says so). First you have to depress the brake pedal 20+ times with the ignition off, then turn ignition ON with engine OFF, select Air Bleed in Techstream, keep your fluid reservoir full, and then bleed the air from all 4 wheels, one at a time, for Air Bleed Step 1. The system will only run for 4 seconds at a time, so repeat the air bleed until all of the air in the fluid has been bled out, then move to the next wheel. After all 4 wheels, go to Air Bleed Step 2 and do the same thing, then go to Step 3 and same thing, then go to Step 4 and same thing.
Please note that the 2001-2006 LS430 brakes are soft by design and especially in comparison to sportier cars. I drove a 2012 Nissan Altima and Mercedes C-class, both have extremely touchy brakes with very high catch and minimal pedal travel compared to the LS430. I test-drove a 2012 LS600hL and 2018 Chevy Impala - the catch, softness, and travel on both were about the same as my 2002 LS430.
I assume they designed the LS this way so that your VIP passenger in the back is able to hand-write documents with perfect precision and not spill any coffee while being driven through a city.
Last edited by StanVanDam; 07-05-19 at 01:45 PM.
04-29-17, 12:19 PM
#10
Lexus Fanatic
The skinny on my brakes....believe the clunk I hear from time to time could be the pads. The selling dealership did the front brakes using OEM. The indie test drove it, heard the clunk, investigated, and showed me that there are no shims between the pistons and pads. He said there is never the clunk when brakes were applied. Well, I thought it was suspension so that's good I guess....at first he was guessing stabilizer bar links....I have done my Maxima both with the old shims, and none, and never heard a clunk, so I don't blame the selling dealership. Also, if applying the brakes just so, it can cause the clunk as well. I find that interesting, never woulda thunk...
Seems like the original calipers are nice, would make total sense to rebuild, but I've never done it. also, my Maxima has original 19 y.o. calipers, although a FR hose went bad. Caused the caliper to bind, since the fluid could not escape (tested the hard way, by replacing the caliper, finding it near impossible to bleed, and having no benefit, same problem with the new one. This was when the car was 18.
Seems like the original calipers are nice, would make total sense to rebuild, but I've never done it. also, my Maxima has original 19 y.o. calipers, although a FR hose went bad. Caused the caliper to bind, since the fluid could not escape (tested the hard way, by replacing the caliper, finding it near impossible to bleed, and having no benefit, same problem with the new one. This was when the car was 18.
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Mattkz
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