cariza

After the ATI procharger install, I have been having trouble with the brakes. Since the install the brake pedal gets mushy with a much longer travel. The car still brakes but I need to push the pedal further down.

I though it could be air in the brake lines so I bleeded the lines once and found air in the right front brake line. I went for a ride, the car was good for a couple of days but then again came the same problem. I bleeded AGAIN the lines and for the second time, air came out from the front right brake line. Problem only went away for a couple of miles but still went bad again.

If I activate the ABS to come on by braking hard, the pedal would come back to normal for a couple of miles and then return to feeling mushy with longer travel. So everytime I hit the brakes hard, the pedal would go back to normal. I believe it must be something with the ABS then. Air, in the ABS pump?? Any ideas???

I wasnt getting too worried abiut this problem since the ATI procharger has made the car so much fun (see race between z and M3 http://www.turbois300.com/home/videos/M3_vs_350z_SC.mpg ) but now this brake problem is really getting me desperate.

jesseenglish

Do the brakes feel mushy when you are just coming off boost, or any time you're just cruising around.

The cause of the brakes feeling mushy could be a problem with the brake booster check valve. If the brake booster is losing vacuum because of positive pressure in the vacuum lines, then the booster becomes non functional. In the pic below I point to the vacuum line which is supposed to provide the vacuum signal for your brake booster.

The Procharger shouldn't cause this problem, but if the check valve is bad or is allowing too much air to pass through then it could cause this problem.

As to why there is air in the lines, that's a question for someone more knowledgeable on the operation of our master cylinder.

jesseenglish

come to think of it, even if the check valve was working, this could still be the problem. If you're on boost a lot, your booster will eventually run out of vacuum, causing the mushy pedal feel. The only fix for that, would be a nice big vacuum reservoir.

cariza

I doubt that its the check valve or a vacum problem because I added an extra check valve in line with the stock one and still the same problem occurs. Also the problem occurs without boosting, the car could be just started up and the brakes would get mushy right away.

Air is getting in the front right brake line, dont know why or from where, but its getting there. If I bleed the lines it would solve the problem temporarly. I think it has something to do with air in the ABS pump. Where can I purchase a service manual for the 350z???

peptidbond

iTrader: (2)

As far as the mushy pedal feeling goes, I have said many times that I get this and I do not have a procharger. When at the track, I get it at the end of the straight. After going on WOT for a little bit, all the vacuum is gone and the brake booster does nothing. The pedal is not all that mushy, but I definity have to press harder. It only lasts a split second, but you definity can tell that it is there. Others (Enthuz) have mentioned the same problem. If you recall correctly, one of the problems that Greddy faced early on with their kit was this very issue. Just my $0.02, your mileage may vary.

punish_her

iTrader: (8)

I've never had any issues with mush brakes an I've been pushing almost 20psi for several years now. I do notice some brake fade when they heat up. They get a little mushy. That was solved by going to a higher rated brake fluid and braided clutch lines.