Suprjdmbro

So on both of my LS400's (93 and 95) i have basically the same brake issue. The 95 had drilled and slotted rotor, stainless lines ebc pads and stock calipers. The master cylinder went out so I bought a reman'd one, bench bled it and the pedal improved, however nowhere near how good I think it should be. As well as having a meh pedal, when I press the pedal, it is hard at first, let off and press again and its soft, and has little pedal pressure for probably 1/2 the stroke, get towards the bottom and its hard and brakes well.

So on the ucf10, I just did a ucf20 front brake swap on it and rear pads and rotors. It stops much much better than before, however The every other soft pedal on this car is extreme. The hard pedal is great, however when I brake and it's soft it seems like i travel 3/4 of the stroke before i get any pedal. It did this before I did any of the aforementioned work to it as well.

On both cars I have generously bled the brakes and flushed out all of the old fluid, if there is an ABS procedure for these cars then I have missed that. Does anyone have any input/expereinced this before? To me it seems like the master cylinder on the 93 is going out, but since my ucf20 does (almost) the same thing I'm not quite sure.

dicer

Yes ABS needs to be bled as well as trac if you have that. Things have to be powered up to do that

Suprjdmbro

Thanks, I will look into bleeding the abs and trac system (95 doesnt have trac) and report back!

RA40

iTrader: (6)

Not just the brake pedal, check all the vacuum lines. A drop in vacuum will effect other vacuum assisted functions.

Suprjdmbro

Ok guys so I Have very thoroughly rebled the brakes and it has not solved my issues. I "bled" the ABS system by getting abs to engage on a dirt road a very times as well as a few times on gravel, then I bled all the brakes several times with the key in the on position. I also bled the trac system as per instructions on this site and the fsm. I have checked "all" of the vacuum lines, I did not find any problems.

I did all this on the UCF10 as the 20 is under construction right now. I am really leaning towards the master, however even when my pedal is soft, when you get to the point in the stroke that it becomes firm, if I hold the pedal down it does not go down, it holds pressure. I ordered some speed bleeders and I'll see if i can remedy my solution with that.

jaaa

Last year when I was replacing a boat load of hoses, I managed to get the wrong hose for one of the brake vacuum lines. It kinked a little more than the original. It would brake fine on first application and then they didn't work. Turned out I wasn't paying attention to what kind of hose I was replacing and it bit me.

Suprjdmbro

mmk minor update, this morning while i was on a quick drive, The pedal was basically gone for most of my drive. Then I stopped at O'rielly's to check stock of a master cylinder, got back in the car and it was 1000x better. Now 85% of the time the brake pedal is solid, it only goes a bit soft if I'm constant on the brakes(slow drivinig, braking in traffic), and when it does go soft, it does not drop to the end of the stroke like it did before.

I did a little vacuum booster test, after the car was running, slowly pumped the brakes 3 times, 1st time to the floor, second almost to the floor, and then on the third pump the pedal was rock solid right at the top. I remember reading this somewhere, saying if this happened, it meant my booster was leak free, is that true?

dicer

I "bled" the ABS system by getting abs to engage on a dirt road a very times as well as a few times on gravel,


So tell me,,,,,,,, how did you bled it when you were driving it? A small trained dog to open and close the bleeder valve? You can't bleed the ABS by driving the car, you either need to make or buy the SST to do it.

Suprjdmbro

I did not mean literally that I bled the ABS system, I read a few times on this site, as well as others that if you activate the ABS on a gravel/loose road, then somehow it will improve. I was just trying most everything people have recommended in the past in hoped to fix the issue.

YODAONE

Anyone care to post Special Service Tool information and proper procedure for bleeding 1st and 2nd generation LS400 Brake lines and Antilock brake actuator

Safety suggests being an infomed Lexus owner when you act independently ...if you or your indy repair shop do not possess this tool then don't bleed your brakes...go to the dealer...

Anyone unwilling or unable to afford safety, then please stay off the road.

aptoslexus

Suprjdmbro

Thanks, this is exactly what I'm looking for. My all data does not quite give me this detail. I have bench bled the master cylinder already and bled the lines countless times, the pedal pressure is good but still not where I think it should be. I've done some master cylinder tests on both cars, both are inconclusive. So I am thinking there must be some air trapped in the ABS pumps on both cars.

Don't get me wrong, both cars stop well, and the 93 no consistently, just not exactly how I want them to.

djamps

Mines always had a soft 'initial' pedal since I got it about 10k miles ago. From googling around it looks like it's just the way it is for most LS's. Basically the 1st 1/2 of the travel is almost nothing. When stopped, I can barely put my toes under the pedal it's so close to the floor. Previous owner put a new master on it at the dealer and it didn't help, and after googling around seeing alot are the same way I haven't bothered messing with it given I can still lock it up if I need to. Just a bit annoying when switching between cars as every other car I drive has way more bite up top.

Suprjdmbro

This is exactly the input I was after, thanks! This is the case for both of my cars, I was really just wondering if that was normal or not? Anyone else's pedal do the same?

aptoslexus

Or make your own: http://faculty.ccp.edu/faculty/dreed...atech/bleeder/

Ready made one for Mercedes: https://mercedessource.com/store/pressure-brake-bleeder
I think you could just substitute a lexus brake reservoir cap and be good to go.