510 master cylinder - soft pedal

[ct06033]

I recently changed out my master cylinder as well as the rear drum brake cylinders and upgraded the front to 300zx calipers. I'm getting very spongy pedal feel after pressure bleeding. Any possible causes? I'm thinking to do a second bleeding to ensure I got everything but pumping the pedal does not firm everything up and I did bleed at 15psi for several minutes per wheel. Is this normal?

If not, Any thoughts around where I should start for trouble shooting?

[spriso]

I would upgrade to the 7/8" 240Z master cylinder-- and then do the normal bleeding process.

-m

[Gregs672000]

How's the firewall... any Cracking? Use a Brace? Just a thought.

[ct06033]

Greg, I did install a brace with the new master, the firewall looked fine, no cracking.

[ct06033]

I would upgrade to the 7/8" 240Z master cylinder-- and then do the normal bleeding process.

-m

I believe the 510 is 3/4.. is it too much volume? trying to understand the issue here.

[ct06033]

240z master cylinder worked like a charm.

[spl310]

240z master cylinder worked like a charm.

I was thinking that it may be a volume issue. The 1500 experience the same kind of soft pedal issue when a 3/4" master is installed - the 7/8" master works right. Good to hear you resolved the issue.