YviE

iTrader: (3)

Hi guys,

When I bought the GS it braked just find. I changed the front pads myself after a while. But when doing this, I didn't open the brake fluid reservoir when pushing back the caliper pistons.

Ever since the brake feel hasn't been the same. Flushing hhe system did not change much. The BMC seems to operate normally.

Can anyone help me?

Thanks!

CleanSC

If you only changed the pads and not the rotors, you are having friction issues trying to bed in the new pads against the new rotors.

Or,

You installed pads that are not as good as the ones you took out.

My suggestions:

1: The right way: Install new rotors and new OEM pads.
2: The cheaper but still good way: Remove the rotors and have them turned if they are thick enough to machine. Reinstall the pads.

After you do one of those, follow proper bed in procedure to mate the pads up well with the rotors.

As an aside, you made sure NOT to touch the pads or rotors with your greasy hands, correct? Any grease/oil/dirt you get on the friction surfaces simply by handling them is enough to cause problems.

Report back and let us know!

YviE

iTrader: (3)

Thanks for your answer.

To give you a more complete picture of the situation. I installed new pads and rotors, OEM equivalents (ATE rotors, Ferodo pads). I thought that I didn't do a proper bed-in, so I replaced the pads after 3.000 miles or so. Same problem, even after properly bedding them in.

I was very cautious not to contaminate the surfaces of the rotors and the pads, so the problem is not coming from there.

I really have the impression the problem is coming from the BMC area by not removing the cap of the reservoir. (an online tutorial of the LS400 specifically mentioned to remove the cap before replacing the pads)

GS4_Fiend

iTrader: (22)

Try bleedin out the brakes

YviE

iTrader: (3)

I'm gonna do that and while I'm at it I'll change the front brake lines too. I hope that'll solve the issue...

CleanSC

What exactly is it that doesn't feel right? Spongy pedal? Poor braking? Lower pedal?

YviE

iTrader: (3)

The pedal isn't spongy at all, it's too firm. You really have to put a lot of pressure to get decent braking.

GS4_Fiend

iTrader: (22)

The new brakes probably needs to brake in

CleanSC

You may have a stuck piston from retracting them not perfectly square.

Or, your new pads are not broken in correctly against the existing rotors.

We can't really help much from here without having the car in front of us.

Do you have all the old parts? Reinstall them all and see how it feels. This will narrow down your suspects.

13loody

Just a guess here, but perhaps it's your pads. Did you get ceramic pads that needs to heat up before biting down?

Also, I'm pretty sure if your pedal is firm, you don't have air in the system.

YviE

iTrader: (3)

Got all my parts in. I'm rebuilding the front calipers, replacing the front brake lines and, inevitely, changing the brake fluid. I'm also changing my LBJs with Moogs.

YviE

iTrader: (3)

Quick question ... I am in the process of rebuilding the front calipers. So, do I need to bleed the rear brakes also?

clos430

iTrader: (21)

If you only open the front caliper lines then no you don't HAVE too, but if I were you I'll do it anyways.

YviE

iTrader: (3)

Thanks. I'll probably skip doing the rear, as I had the fluid replaced not that long ago.