I have a very soft brake response on my stock brakes, i have to press the brake pedal more than 1/4 of the way down before i can even feel the stock brakes kick in. I tried bleeding all four calipers but the problem does not seem to be improving. I did a search on this board and someone needed to also brake the abs acutuators? Do i need to bleed the abs system as well? if so, i would i go about doing so?

 

are your pads in good shape?

 

This is not viable information when checking pedal firmness where your brakes begin to grab (it is subjective...) but what is your pedal reserve distance from the floor under spec foot pressure.
Check reserve distance and compare to specs first.

 

the brake pads are brand new oem, i replaced the brake pads thinking this would help, but it has not improved much. The car stops but the braking is kind of sluggish, I can slam on the brakes going 40mph and you feel it slowing down but not really stopping. My friend also has a sc300 and i have driven it, the brakes are a lot better then mine, and his car is a 93. I tried bleeding all 4 calipers but im thinking something else might need to be blead. Does anyone know how to bleed the ABS unit???

 

try checking all the caliper pins......if one is stuck them it will hurt brake preformance and feel alot.

 

calipers are working fine, caliper pistons are fine, none are frozen and all seem to be intact.

 

install the ls400 calipers, hopefully problem solved

 

i plan to hopefully the rotors come in by friday.

 

I have same issue. I replaced all brake pads, front rotors, and bleed all 4 corners of the car and still the brake pedal is just as soft as it was before I did all this?? Its a 92 SC400 by the way. The car stops but you have to push really really hard, every other car I have evern driven stops with ease!

WHAT ELSE IS A COMMON CAUSE OF SOFT BRAKE PEDAL??

 

Maybe still has air in the system and maybe your master cylinder is failing.

 

i have a master cylinder and two sets of LS400 brake kits for sale(calipers, rotors, lines, pads, pins, and shim kit...all greased and lubes as of today)

 

You need to make sure when you bleed the line that you do it correctly. There must be absolutely no air bubbles in the line. Another thing that could be causing this is if there is a difference in size from your stock pads/ rotors or calipers. If you push on the brake it should not be spongey it should be firm and stop high above the floor. If it is spongey there is air in the line. If the brake slowly depresses all the way to the floor, your master cylinder o rings are bad.

 

^That is a great synopsis of exaclty what air in the system is all about, "spongey.^

You can install a completely new set of everything and if you're leaving air behind you'll be in the same boat. It would be good to have ruled out the master cylinder o-rings as well

When I have bleed air from the system I use a 32oz bottle of synthetic and run most of it through. Sequence is critical. Passenger rear, driver rear, passenger front, drivers front in that order. Two people required. Using the normal hose into a sealed plastic receptor commonly available.

 

my brakes are the same also. Feels like mush... it doesnt help when youre boosting the hell out of it either.. I was thinking maybe a bad brake booster could be the problem?

 

I'm having the same issues. Had LS400 brakes on worked good for a few days then started getting soft, bled the brakes like 4 time,. nothing changed so I put the stock back on bled the lines and it become a little better still not good as when first bought car....