my brakes were less then good so replaced set up with ap racing 4 pots/ferodo ds2500 pads/braided lines/new master cylinder and bled the system fanaticly
problem pedal still feels spongy/brakes pull me up fine but pedal does not inspire confidence
rear calipers not seized
other then air in system still is it poss abs is knackered when i bleed with engine off get fluid at all 4 corners/with all valves shut and pump pedal pedal is firm and when engine starts pedal goes down a bit which is correct
has anyone bled the system with engine running before as read that mitsi 300gt need this as i am also running abs i wondered if this was a possability
hoping u guys can help as i am stumped

 

The pedal will have longer travel than it did with the stock calipers because the AP calipers take more volume. One remedy (that worked very well on my car) was to install the larger-bore 929 master cylinder.

Other than that, did you bench-bleed the master cylinder? If not, you might have a bunch of air in the MC or ABS unit that will take a ton of bleeding (lots of volume) to clear. If you didn't bench bleed (install the MC, but route the output lines right back into the reservoir and pump the pedal until air stops coming out of the output lines), I would go back and do that.

I did all my bleeding with the engine off using a pressure bleeder from Motive Products. It turned out fine (excellent pedal feel), so I don't think having the engine running is a requirement.

-Max

 

Do you still have the original rubber brake lines? If yes, its possible that one of your lines has a weak spot and is "ballooning" out under pressure (think aortic anuerisms). I suggest that if you are indeed running the original lines, replace them with new rubber pieces or get some SS Braided lines for that extra bit of quality assurance.

 

He said braided lines, so I'm assuming he's not using the stock rubber lines.



rx7veilside,

There are also two adjustment points on the pedal. One adjustment point is for how much the piston is pushed into the MC at pedal rest, the other is for the engagement point of the piston.

You can used these two adjustment points to adjust your pedal play. Just be sure no to push the piston in too far as it will cause your brake pads to drag.

 

whole front end has been replaced calipers/braided lines/master cylinder(just removed old one and attatched new one and filled with fluid)..am going to replace rear calipers incase they are sticking slightly then bleed again/if not replace abs and bleed again then servo and bleed again

 

You should try adjusting the pedal before going through all that trouble. I found that once I rebuilt my front calipers and changed to SS lines, me pedal play was just off. After adjusting both pedal points, things were just fine.

 

I don't know if this is urban legend or fact, but I have seen recommendations to bleed your brakes as usual, then turn the ignition on (don't actually start the car) and bleed again with the ABS system activated. Seems like an easy enough thing to do - anybody have comments on whether this actually makes any difference?