Kyle Harty

iTrader: (17)

I got my LS400 front brakes on the other day and haven't been able to get a firm pedal feel back. I also removed and painted the rear calipers.

We bled all the calipers thoroughly, but it seems like there's still some air in the system somewhere, the reservoir got pretty low at one point and it's possible I got some air in the master cylinder although I don't think the reservoir was completely dry.

Is there a good way to bleed the master cylinder/brake booster? Do I need to do something with the proportioning valve? We weren't getting any fluid out of the rear brakes at the end until I turned on the key and the booster kicked in.

Any other ideas or suggestions?

RICHYRICH

iTrader: (5)

I had the same problem when me and some friends did my supra install... We had to bleed from back pass all around on a flat surface until all the air was gone I cant remember what was the main problem but once we did that again it was fine. I think it has to do with the Lexus abs system and it requiring a special pump for it, Good Luck bro sorry I wasn;t more help!

Kyle Harty

iTrader: (17)

Thanks Rich, I've been trying to bleed these things since Friday; gone around the car multiple times and I'm getting no air out of any of the calipers but the pedal still gets real soft as soon as I turn the car on. This is stressing me out, my car's been on stands for a week working on this project!

The guy I've had helping me is a very competent mechanic and he's kinda hit the wall. If there is air somewhere in the system traditional bleeding methods are not getting it out.

This couldn't have anything to do with the LS400 calipers in the front throwing the system off? I would think if that was the case we would be aware of it with the number of people who've done brake upgrades.

PHML

iTrader: (33)

were these LS400 calipers re-built before installation? It maybe possible that a piston has seized...and no addtl amount of bleeding will get you the pedal feel you suppose to get.

GS300ToM

iTrader: (32)

u can check if they are seize by pulling them off the rotor and pushing on the break pedal to see if the pistons moves out or not... and as far as your bleeding goes, the only manual way to do the rears are to turn on the keys so the abs can be pumped.... i didnt figure that out until like 20 minutes later after doing my breaks haha but yeah it flows really fast when the key is on... alway check the resevior for fluid and possibly u might of gotten some air in the system but just redo it and double check.... gl

Kyle Harty

iTrader: (17)

Thanks guys, I'm gonna have to check this after work, I'd considered the possibility since they haven't been rebuilt or anything but hadn't checked the calipers themselves since I'd never had it affect the feel of the pedal on other cars when a caliper has siezed. It would make sense that it could if you've compressed the pistons and installed them with a problem.

I wasn't sure if that was normal to be getting no fluid out of the rears with the key off; at least I know that's not a problem!

PHML

iTrader: (33)

The front caliper pedal feel is separate from the fluids to the rear.

No fluids to the rears is NOT normal. I remember bleeding my buddy's GS400 rears....and no fluids came out of the rears for some time....we kept on pumping and pumping the brakes, turned on the engine for the boosters to kick in...eventually...fluids to the rears started to flow.

We had 3 of us...one checking the brake fluid is FULL at all times....one pumping the brakes/brake booster....and last guy bleeding the lines.

Kyle Harty

iTrader: (17)

I checked and without removing the calipers, I could see that all 4 pistons on each caliper were extended the same distance to the pads after being fully compressed before install. Would you be satisfied with that or still feel the need to remove them and test?

I guess I'll bleed some more tonight and see if I can get anywhere. The repair manual says to use some handheld tester to bleed the brake booster, is there a good way to do this without the tool or does anyone know what this tester is?

tom steele

i had a rebuilt caliper that was leaking at the piston when i did mine then a rear brake line busted so i know what your going thru but i bleed mine with the car on starting at the rear left tire then to the right rear then to the front right then last the front left i noticed i had to have the car on to bleed properly that seemed to work for me but i still think i need some kind of vacuum booster to help out with the brake booster i think the supercharger is making so i don't have enough vacuum but i could be wrong anybody else have this issue with superchargers

Kyle Harty

iTrader: (17)

I wish I had the experience to help with a supercharger issue!

I don't see evidence of any leaks, I'm gonna take a hand-vacuum and see if I can pull any air out of it, if not I'm probably gonna have to limp it to a shop and see if they can figure it out. Trying to avoid that since it'll be at least 15 miles with bad brakes to get to a brake shop, 45 min. if I need a dealer. (Yes, I live in the middle of nowhere!)

GS300ToM

iTrader: (32)

well good luck

dani

just open all the bliders at the same time and let it loose for some time, put a backet under each wheel and make sure that the master has fluid. wait to bleed the air out about 10-20 minutes for all the calipers at once. do not press brake pedal just let the gravitational force do the work for you.

denut-L

iTrader: (11)

I'm sure you guys know what you're doing but just had to throw this in, did you bleed the brakes in order from passenger rear to driver rear then passenger front to driverside with the key in the on position?

Gl on this kyle

pingu

Did you make sure you put the key in and turned the key to ACC iirc, so that the master is pumping?

Kyle Harty

iTrader: (17)

I put the wheels back on and took it for a test drive earlier, it's driveable. The pedal feels about like my 95 Cadillac that doesn't get the maintanance it should, a bit soft but I'd be comfortable driving it. Not as firm as I expect or it was before but the car stops.

I came across an article on the Stop-tech site discussing the fluid (and I would think potentially air) that can be trapped in the ABS system and the specialized tool that's used to open the valves in the system. They said to go out and activate the ABS by slamming on the brakes to open the valves and flush the fluid out, not quite the professional way but worth a shot in my case. I went out on a gravel road and did some emergency stops. I'm gonna rebleed tomorrow and see if I got some air out of the ABS pump/brake booster.