Brakes mushy. Double pump
07-19-16, 11:09 AM
#1
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Brakes mushy. Double pump
Brake issue. 2003 430 Ls.
I have replaced 4- rotors, Ceramic pads. Master cylinder, and had checked by Dave Mungenast Lexus, and another ASE shop.
The brakes are mushy ? Will not stop correctly without double pumping. For 2 months after replacements. It did ok for awhile. I have spent big $$$$$ and ready to dump my Lexus. Only thing left is rebuild calipers. 140,000 miles. 2nd owner. Chicago dealer McGrath I purchased from. Checked all service records since new. I had wheels chromed. New timing belt, serviced. New plugs, tires. Runs A-1 HELP
I have replaced 4- rotors, Ceramic pads. Master cylinder, and had checked by Dave Mungenast Lexus, and another ASE shop.
The brakes are mushy ? Will not stop correctly without double pumping. For 2 months after replacements. It did ok for awhile. I have spent big $$$$$ and ready to dump my Lexus. Only thing left is rebuild calipers. 140,000 miles. 2nd owner. Chicago dealer McGrath I purchased from. Checked all service records since new. I had wheels chromed. New timing belt, serviced. New plugs, tires. Runs A-1 HELP
07-19-16, 11:21 AM
#2
Lead Lap
1) Do the car off brake test. Turn the car off, pump the brakes. Pedal should be firm with the least amount of pumps. If not then MC is bad.
2) Have you bleed the brakes after installing all that new hardware, and properly done the initial wear in procedure for your specific set of pads and rotors?
3) Is your caliper leaking fluid?
4) Are your slider pins working and lubed correctly?
If all that checks out then who knows
2) Have you bleed the brakes after installing all that new hardware, and properly done the initial wear in procedure for your specific set of pads and rotors?
3) Is your caliper leaking fluid?
4) Are your slider pins working and lubed correctly?
If all that checks out then who knows
07-19-16, 01:55 PM
#3
Instructor
Consolidation of LS430 soft braking notes
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 tighter brakes, I would try skipping it. It's easy enough to pull the pads out to grease later if you experience squealing.
The LS430 brakes are soft by design and especially in comparison to sportier cars - I found that the 2012 Nissan Altima and Mercedes C-class had extremely touchy brakes that required "recalibrating" my foot, and then when I switched back to my LS430, it felt like there was huge pedal travel until I was "recalibrated" again. From my one test drive of the LS600hL, I felt that the regenerative braking catch and softness was about the same as LS430. I assume they designed the LS this way so that your VIP passenger in the back is able to hand-write documents while the car is moving, and to ensure that coffee isn't spilled everywhere from a jarring stop.
That being said, the braking system does age over time, brake hoses are a wear/tear item, and natural aging of the soft braking system will make the brakes excessively soft. Try the above advice if you want firmer brakes. I find my 2002's brakes starting to become soft (at 140000kms) and will try the above advice when I find the brakes excessively soft.
Replacing with OEM rubber hose means eventually the rubber will degrade again over both time and usage. Stainless-steel-braided PTFE hose theoretically doesn't degrade and should last longer, but Google "stainless steel brake line failure" and weigh the pros and cons. Some more info about stainless brake hoses @ http://www.stoptech.com/technical-su...rake-lines-q-a
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.
The LS430 brakes are soft by design and especially in comparison to sportier cars - I found that the 2012 Nissan Altima and Mercedes C-class had extremely touchy brakes that required "recalibrating" my foot, and then when I switched back to my LS430, it felt like there was huge pedal travel until I was "recalibrated" again. From my one test drive of the LS600hL, I felt that the regenerative braking catch and softness was about the same as LS430. I assume they designed the LS this way so that your VIP passenger in the back is able to hand-write documents while the car is moving, and to ensure that coffee isn't spilled everywhere from a jarring stop.
That being said, the braking system does age over time, brake hoses are a wear/tear item, and natural aging of the soft braking system will make the brakes excessively soft. Try the above advice if you want firmer brakes. I find my 2002's brakes starting to become soft (at 140000kms) and will try the above advice when I find the brakes excessively soft.
Replacing with OEM rubber hose means eventually the rubber will degrade again over both time and usage. Stainless-steel-braided PTFE hose theoretically doesn't degrade and should last longer, but Google "stainless steel brake line failure" and weigh the pros and cons. Some more info about stainless brake hoses @ http://www.stoptech.com/technical-su...rake-lines-q-a
07-19-16, 02:35 PM
#4
I would check your brake lines. Seems like there may be a leak somewhere.
+1 on bleeding out the braking fluid. I've had multiple issues in the past. A good fluid flush and then fresh fluid seemed to be a cure to how mushy the brake pedal feels.
But yeah it seems like you got air in the brake system that's why it feels too mushy.
And like StanVanDam said, the 430's brakes generally lean towards this soft and mushy feel. I think a soft brake pedal feels much more luxurious than a harsh one. It makes sense.
+1 on bleeding out the braking fluid. I've had multiple issues in the past. A good fluid flush and then fresh fluid seemed to be a cure to how mushy the brake pedal feels.
But yeah it seems like you got air in the brake system that's why it feels too mushy.
And like StanVanDam said, the 430's brakes generally lean towards this soft and mushy feel. I think a soft brake pedal feels much more luxurious than a harsh one. It makes sense.
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