510 master cylinder - soft pedal

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ct06033
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510 master cylinder - soft pedal

Post by ct06033 » Tue Apr 30, 2019 7:01 pm

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?
2011 Audi A3 2.0T Quattro
2005 Honda S2000
1968 Datsun 1600

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spriso
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Re: 510 master cylinder - soft pedal

Post by spriso » Tue Apr 30, 2019 10:26 pm

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

-m
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Gregs672000
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Re: 510 master cylinder - soft pedal

Post by Gregs672000 » Wed May 01, 2019 12:48 am

How's the firewall... any Cracking? Use a Brace? Just a thought.
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ct06033
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Re: 510 master cylinder - soft pedal

Post by ct06033 » Wed May 01, 2019 11:45 am

Greg, I did install a brace with the new master, the firewall looked fine, no cracking.
2011 Audi A3 2.0T Quattro
2005 Honda S2000
1968 Datsun 1600

ct06033
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Posts: 128
Joined: Mon Jul 06, 2015 12:10 am
Location: Denver, CO

Re: 510 master cylinder - soft pedal

Post by ct06033 » Wed May 01, 2019 12:32 pm

spriso wrote:
Tue Apr 30, 2019 10:26 pm
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.
2011 Audi A3 2.0T Quattro
2005 Honda S2000
1968 Datsun 1600

ct06033
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Posts: 128
Joined: Mon Jul 06, 2015 12:10 am
Location: Denver, CO

Re: 510 master cylinder - soft pedal

Post by ct06033 » Mon May 06, 2019 9:58 am

240z master cylinder worked like a charm.
2011 Audi A3 2.0T Quattro
2005 Honda S2000
1968 Datsun 1600

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spl310
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Re: 510 master cylinder - soft pedal

Post by spl310 » Mon May 06, 2019 11:35 am

ct06033 wrote:
Mon May 06, 2019 9:58 am
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.
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