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Discussion Starter #1
Hi
I am putting discs on the front of a 67 that I just bought. The car currently has manual drums all around, and a nom 396. It does not stop. For now I will leave the drums on the back. The front rotors will be C4 13". The calipers will be twin 40.5mm piston. So, a little bigger than the C4 pistons. I am looking for a booster to fit, will probably use something from the junk yard and make up an angle bracket.

Should I use the 1 1/8 disc/drum mc from the 67? I have read a few C4 HD upgrades where people were using late model 1" mc. I plan on adding an adjustable prop valve to limit pressure to the drums.

Thanks!
 

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If you retain the rear drums you will need a residual pressure valve to keep 10 psi on the rear drum wheel cylinders. A prop valve really isn’t needed imho.

Don
 

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Discussion Starter #3
That's what I like about the 67 disc/drum mc. I'm not all that knowledgeable on drum brakes, but I figure it probably will be ok without the prop valve. The original had a prop valve but it also had 4 48mm pistons on an 11" rotor? My understanding is I will not need as much pedal travel to build pressure in the calipers, so the rear cylinders shouldn't have as much pressure, less chance of locking them first. But again, I'm no mc or drum guru so I'm not entirely sure.

Any thoughts on the mc size?
 

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I installed C5 front discs on my '69 retaining the rear drums and used a 1" MC. I installed a 10 psi residual pressure valve as Don suggests. I also replaced the non-adjustable proportioning valve with an adjustable one on the subframe.
 

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Discussion Starter #5
Thanks Chris. I assume you used the C5 calipers, which are functionally identical to the Mustang calipers I have with 2*40.5mm pistons and 13" rotors.

Did you use a booster angled up like the stock 67 unit and the bottom hole on the pedal?

Thanks for your help!!
 

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I know this is an older thread. I am looking for a 8” dual diaphram brake booster in black for my 67 camaro. I do not want a ugly brass or chrome one. If i cant find i may be forced to go with hydroboost. Any suggestions?
 

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Thanks Chris. I assume you used the C5 calipers, which are functionally identical to the Mustang calipers I have with 2*40.5mm pistons and 13" rotors.

Did you use a booster angled up like the stock 67 unit and the bottom hole on the pedal?

Thanks for your help!!

Yes, I used C5 calipers with the 13" rotors. Since I had power front discs originally, I just swapped out the MC for (as I recall) a 1" manual MC (had to make a push rod extension for between the booster and the MC). I kept my original booster. The original configuration is angled up and I did not change this. As for what hole in the pedal, I did not change it when I swapped the MC's, I believe the push rod is connected to the pedal in the bottom hole.
 
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