1991 TT Leaking Brake Master Cylinder

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peteharron
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Joined: Tue Nov 03, 2020 10:23 am
Car: 1991 Nissan 300ZX TT

1991 TT Leaking Brake Master Cylinder

Postby peteharron » Wed Nov 04, 2020 8:59 am

Hey what's up everyone, was a member once before but lost my old account. You guys all helped with a rebuild I did about 8 years ago, hope everyone is well.

So my 1991 TT had brake issues about 2 years ago where I lost most of my pedal. Replaced the brake master cylinder and all was good for the past 2 years. Over the summer I noticed I was losing brake fluid and saw the O rings at the reservoir of the brake master cylinder were leaking. Thought maybe I got a bad one so I replaced the brake master cylinder again that was only 2 years old and all was good. However, here I am again about 4 months later with the same issue of it leaking at the O Rings. Could there be another brake issue causing these O rings to have too much pressure in the lines and causing them to leak? Brake Booster maybe?

Note: I have started to hear kind of like creaking noise when braking. So this weekend I was going to pull all the wheels and check at the calipers. Also I used a Centric Brake Master Cylinder each time it was replaced.

Any insight will be greatly appreciated.

Thanks!
Pete
Last edited by Rogue One on Wed Nov 04, 2020 3:59 pm, edited 1 time in total.
Reason: TYPO


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AZhitman
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Re: 1991 TT Leaking Brake Master Cylinder

Postby AZhitman » Wed Dec 02, 2020 10:28 pm

Welcome back, Pete!

Those BMCs are all rebuilt units, and the QC is questionable. Possibility of no lubrication at the pins and slides (at caliper) causing additional 'the creaking but that shouldn't create a leak.

I'd pull all the calipers, clean and re-lube, flush the fluid, and replace the BMC.

itsa300zx
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Re: 1991 TT Leaking Brake Master Cylinder

Postby itsa300zx » Thu Dec 03, 2020 9:38 am

Yep, some of those Centric rebuilds are questionable, look at the warranty, only 90 days or 3 months.

The seal between the res and cylinder should not see any pressure when operating normally.
Possible the internal cylinder seals are allowing fluid to pass and pressurizing the res seal side allowing for the leaks.

The Z32 calipers do not have slide pins, they are a fixed caliper. The creaking is most likely the firewall flexing under brake application, common for the Z32. 300 degree has a BMC brace that may fix the creaking. Have someone press on the brakes while you are looking at the BMC and you can see it move up to 1/4".

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AZhitman
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Posts: 70826
Joined: Mon Apr 29, 2002 2:04 am
Car: 72 240Z RB25, 63 Bluebird RHD, 63 NL320, 67 WRL411, 67 SPL311, 68 510 SR, 77 620 SR20, 92 SE-R, 97 D21, 98 S14, 11 LS460L, 12 Titan 4x4, 20 MX5 Club.
Location: Surprise, Arizona
Contact:

Re: 1991 TT Leaking Brake Master Cylinder

Postby AZhitman » Thu Dec 03, 2020 11:32 am

Z32 absolutely have slide pins, but I concur with the firewall flex, hadn't thought of that. Good catch.

itsa300zx
Posts: 1140
Joined: Sun May 31, 2009 9:39 am
Car: 1990 300zx NA W/TT swap
2011 Nissan Rouge S
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Location: up North, Edm. AB

Re: 1991 TT Leaking Brake Master Cylinder

Postby itsa300zx » Thu Dec 03, 2020 12:12 pm

Yeah, pad retaining pins; I was thinking high load slide pins as seen in floating calipers.


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