I just had my 2003 350Z Base model overhauled: JWP clutch and flywheel, OEM rear main seal, Wilwood clutch master cylinder with braided line, OEM clutch slave cylinder, Super Blue clutch fluid, Gates engine timing belt, both OEM tensioner pulleys, OEM fan pulley, OEM valve covers and gaskets, Z1 silicone PVC hose kit, OEM knock sensor, NGK 6240 Laser Platinum spark plugs, CZP Brake Kit Centric Rotors / Hawk Brake Pads and SS brake lines, Berk resonated test pipes and HKS replica true dual exhaust. I also had the injecters cleaned and flow tested.

Having that information should help you find my *new* problem...

My front brakes are locking up. At first I thought it was only after a short drive but right now I have the car on towers with the front wheels off.

If I turn on the car without touching the brakes, I can move the front rotors by hand. As soon as I press the brake pedal, the front calipers lock up. I go the the rotor and it's hard to move if at all.

If I pull the hose off of the brake booster, the caliper retracts and I can move the rotor by hand again. I covered the open end of the hose with my thumb and had my son press the brake pedal which is hard without the booster assist. As soon as he lets off I can move the rotors.

So my testing up to now is that the brakes lock up with the booster connected. My mechanic, who I consider extremely knowledgeble (BMWs and Mercedes his specialty), did all the work in the 1st paragraph and suggests I replace the ABS box, part number 47600-AM400. He thinks the brake lines had moisture and possibly damaged the valves in this module during the 2-3 months it took to complete the work.

I texted him with tmy test results to see if he still thinks its the module but he hasn't responded yet so I thought I'd throw this out there. Tomorrow I'll be testing the brake booster per the service manual to make sure it's operating correctly.

What do you guys think?

 

Is it both front calipers?

 

Well for one you have preformance pads and rotors now... those stop and are a lot more sensative.

Make sure your ABS fuse isn't blown and still working. But it sounds like he may have screwed up your brakes or you have a much more aggressive brake set up than you should on a daily.

 

Yah but performance pads and rotors are going to cause the ABS box to go bad, which is pretty rare I think.
I agree that perhaps something may have gotten screwed up as you said, I mean, this should have been a rather routine change, pads/rotors, upgraded or not they are a direct fit, and hr had no issues before.

I'd start with the basics checking the installation bleed breaks and then make sure no air is in the system.

 

Yea I'm not saying it's the only cause but it's common for some preformance brake set ups to be touchy and novis drivers to lock them up.

I remember my buddy got a wilwood set on his s14 and the second your pinky toe touched the pedal it would tail spin. It took him a long time to learn it even then he sold it and went with the skyline 4 piston swap.

I would check fuses and ABS system but keep in light some brake kits are way too sensative if too powerful and it could be that if nothing else.

 

Yes, def check fuses too if it's ABS, I would think he might get an ABS code if that was issue, but if electrical(fuse) it's weird...if it's just , "touchy", there are ways to adjust the pedal itself a bit too...

 

Update:

I pulled the brake vacuum hose out and noticed it has a bump like a valve inside (see pic)

Is this a one-way check valve? If so, if I blow into it shouldn't it only pass air in one direction?

I can blow from both ends without a restriction so if it's supposed to be a one-way check valve, it's toast...

 

I don't think it's a one way, it's just a rubber Hose, only issues would be if it has leaks oevenying it to Be in vacuum.... You can get. Replacement 4-ply hose for 15-20 bucks...

 

This hose has a one way check valve, It should not be blowing air in both directions. The arrow on the hose indicates the engine side.

From the FSM;

 

Lol that sounds like a pretty crappy brake setup. Loss of modulation only worsens braking performance and increases stopping distance. It's amazing how many people equate ease of lock-up with increased braking performance when it's literally the opposite.

 

Thank you, stand corrected,...still pretty cheap replacement hose, I ordered one from z1 several years ago, they probably still sell it...

 

 

@7rrivera7 , @dabazi22 I'm having this issue also. If you found another thread or resolved this, can you share please?

I replaced the brake booster and both hoses (I replace the check valve with what they have at Z1 Motorsports now, which is an external check valve, not the original that goes in the hose. Upon replacing this and the brakes and rotors and flushing / bleeding the brake lines, it seemed to be fixed. I bedded the brakes and it seemed fine. The next day, it started again and the ABS and Brake light was on. As you posted, if I release the vacuum pressure from the booster, then I can drive it, but after first pushing the brakes, it does it again. I am thinking it may be the ABS system, but wanted to know what you all thought since it's not cheap to replace (today about $1100+).

Thanks,.
Richard

 

Updating an old thread due to intereste from other subscribers...

I adjusted the brake pedal throw because it was too tight and with the new setup, when the rotors expanded due to heat even slightly, the brakes would engage on there own.