I will be installing my restored M/C this week. 67 Power Brake car. I have read the archives and have a full understanding of the bench process, the gravity bleeding etc. I have two questions. First, can I bleed the M/C with the PDS installed. Second, when installing M/C to the booster, do I use the felt and a gasket, both, or neither. Archives makes no mention. Gary
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Re: 1967 Master Cylinder Bench Bleed
Gary I always bled without the PDS as I felt it hanging down would increase leaking on installation due to gravity.
Plus IMO it's harder to connect the hard lines under the PDS.
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Re: 1967 Master Cylinder Bench Bleed
Thanks Rich, I agree with your assessment and will follow your advice. I'll install the PDS to the brake lines loose, bench bleed the M/C, then install. it'll be easier, and quicker to install the PDS lines to the side of the M/C. In this scenario, losing less fluid in the process. Also, are there any gaskets installed between the booster and the M/C like on a non PB car which show a felt installed on the outer groove around the piston, and a gasket on the firewall. GaryComment
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Re: 1967 Master Cylinder Bench Bleed
Gary, Sorry I forgot you asked that too. I was at the Dr's office when I replied and he had just walked in so I hit reply immediately. Back home now.
So, you definitely do NOT want a gasket between the MC and the Booster. AIM J50 shows no gasket either. The reason for that is important.
The pushrod in the booster which drives the MC is a specific length. When you attach the MC to the booster the rod should just lightly touch, or just be off of the piston a few thousandths. If a gasket is added its thickness could alter that dimension and reduce piston travel in the bore.
Now, with that said, if you are rebuilding the MC yourself using new seals and piston, and using a reproduction booster, you'll want to take measurements of the supplied rod that came with the booster. One thing you definitely do NOT want, is the rod actually depressing the piston when the MC is bolted to the booster. If it does, it could block the return port in the MC and in some cases it could actually keep the brakes applied when the pedal is released.
It's tricky, but try to take some measurements of the pre-assembled parts to make sure you'll be in spec. If the rod is too long you can grind it a bit at a time to be within spec. Of course another alternative would be to add gasket thickness to extend the MC away from the booster, but not recommended.
RichComment
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Re: 1967 Master Cylinder Bench Bleed
Rich; Thanks for that important information. I'm using the booster and MC as supplied by Zip. I noticed in the archives, you used the same items for a PB installation you did. I'll pre-assemble the MC and booster tomorrow, check the tolerance between the piston and rod, and let you know how it worked out. thanks again for all your help. At some point I'll send out my original MC to be rebuilt. The one from Zip/CSSB looks like a quality part and I want to finish this up and move on without much of a delay. GaryComment
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Re: 1967 Master Cylinder Bench Bleed
Gary, Hopefully the rod length is properly designed to spec.
In my case I had the MC rebuild kit with a new piston, and that same booster from Zip. They didn't match.
There's a pin depth gauge tool on the market which helps taking the measurement, e.g. Here
Rich
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Re: 1967 Master Cylinder Bench Bleed
Rich, thanks for link for the depth gauge. And I thought this was going to be a simple re-install. Probably why a previous owner removed the booster and went to manual brakes. Anyhow, it'll be worth the effort, and back to how it originally left the factory. Gary
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Re: 1967 Master Cylinder Bench Bleed
Gary, if the car was originally J50 then changed back to manual brakes, was the long hard line from front to back changed to the stock manual brake shorter length length, or is it the original just re-bent to fit rearward?
That rear hard line was longer for J50 power brakes. It had to reach more forward due to the extended master cylinder placement. The shorter front line can be used for both but simply bent as needed to fit. Technically though, it was a different part#. Some AIM notes below.... Stock and J50.
AIM UPC 5 Sheet B1 Notes (Stock)
Item 6, long rear line 3904952
Item 17 short line 3904954
1967_UPC_5_B1.jpg
AIM UPC J50 Sheet A1 Notes(Power)
Item 4, long rear line 3904957
Item 5 short line 3904958
1967_UPC_J50_A1.jpg
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Re: 1967 Master Cylinder Bench Bleed
Rich; The original J50 rear line was retained, just bent back. I replaced the front line with a correct length line for J50 as the previous owner had installed a braided stainless line. Surprisingly, the original clip that holds the two was still on the rear line. I ordered the depth gauge. GaryComment
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