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Discussion Starter #1
My brake master cylinder failed on my 66 GTV (with single booster). It was a new master cylinder about two years ago, so I think I'll try and replace the seals. I have ATE calipers all around. But I'd like to positively identify the master cylinder before ordering a seal kit... and I'm feeling a bit too lazy to pull it off before ordering the kit. Can anyone identify this on sight?
Thanks,
Carl
(PS, it failed gradually, so no problems. I noticed the spongy and somewhat lower pedal. I live on a big 20% grade hill, so I was thankful for that.)
 

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Hey Carl

We all presume you have diagnosed the brake master cylinder as the problem.
How did you get to this diagnosis.
Just wondering if you did the usual checks before you suspect the brake master cylinder.

Robert
 

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Hey again Carl.
The brake master cylinder is off a single circuit braking system that was mainly used with the Dunlop brakes.
This is what was standard on the Australian delivered cars.Maybe something different on oversaes cars.
The brake master cylinder shown is a copy of the original.NOt an original.You might have to consult the seller as to getting a kit for it as it might have different internal piston and seals from an original.

Robert

Robert
 

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Discussion Starter #4
Robert,
How did I diagnose it? Well, I can't yet say I'm "positive", but everything points to the master cyl:
- pedal was a bit soft during last week, and then when I got in the car 3 days later it was soft and very near the floor, can pump it back up but then it quickly becomes soft again and low again
- no fluid leaks that I can find anywhere (all junctions and calipers look clean)
- reservoir is full of fluid, nothing lost
Could be I'm missing something, but a rebuild kit is cheap, about US$15 for the master cylinder. Figured I'd order one before crawling under the car again and pulling the master for inspection.
C
 

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There are two or three variants of the US single-circuit floor MC for 105 cars with boosters. Dunlop, ATE, Benditalia. They all fit in as a complete unit, but require different rebuild kits. Early Duettos have a further different unit that looks the same but is a different internal diameter, for use without a booster.

Offhand I don't know which you have. I'm not sure kits for all the makers of MC are available, but if anyone does, AlfaStop in the UK does. You can also just get a new MC from Centerline. Note that the in and out pipe fittings on the various MCs can be different; different angles and locations, and different fittings in some cases.

Andrew
 

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Carl

I have two MCs that externally look identical to the one on your car. Internally they have different pistons and seals.

I just ordered two different seal kits today, which should arrive mid next week.

I will let you know what develops.

Peter
 

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Discussion Starter #9
Got mine apart, mine is like Peter's (Biscione's) one on the left. Removing and installing a new the seal around the piston was a real pain, especially as one doesn't want to mar the piston. I used a kit from IAP, seemed fine, but came with an extra rubber part, like a cap, that I couldn't find a use for. Also, it appears there is a small seal on the end of the spring, and there was no replacement for that.
C
 

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Discussion Starter #10
Extra Seal

On the left is the seal I removed and replaced. On the right is an extra seal that came in the kit... can anyone identify it?
Thanks,
Carl
 

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On the right is an extra seal that came in the kit... can anyone identify it?

Carl
Updating an old thread. When my single circuit, non-servo (non-booster), all Dunlop wheel cylinder-ed, '66 Duetto came to me in 1984, it came with a 22 mm Ate' master cylinder. Since the car's engine and transmission are currently out, I can see that the rubber bellows have deteriorated -despite the brakes working well. And this is with no booster.

IMAG0364.jpg

I ordered a seal kit from C/A, which is the same kit as shown at the bottom of post#11 but was unable to use any of the seals. however, the rubber bellows from the kit does appear to fit my Ate' cylinder. :smile2: My cylinder also uses the 'extra' rubber seal that came in your kit.

IMAG0366.jpg

So the seal Carl asked about, is for an Ate' 22mm brake cylinder. Sorry for not photographing this part but I did not remove it from inside of the master cylinder. It is inside the bore, just under the sliding aluminum piston (separated by a thin brass washer with several tiny holes), the flat part of the seal faces the piston, while the cup shaped part faces the other way. Originally my rubber bellows came with a 'spring clip' at each end. I could only make the large clip work but apparently they are no longer used...based on photos of newer master cylinders that are available.




Mark
 
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