Brakes for 79 Z28

[zbadone]

I am trying to compile a Christmas wish list for my wife. Right now, my camaro has stock brakes front discs and rear drums. I have purchased C5 calipers, abutments, and rotors. I still need the rest of the kit(hub, brake lines......etc). I would like to eventually install either the LS-1 camaro rear disc set up or a WilWood rear set up. I am looking at the Wilwood master cylinder and was wondering if I should use a 1" or an 1 1/8" and also if I should use the stock brake booster or upgrade to a double diaphragm type. My vac on my car is marginal at 18. Would I be better off switching to manual brakes and going with a 7/8" master cylinder? Also, would I use the factory distribution block until I switch to rear disc? Then do I need to swap that out or can I use a proportioning valve? Thanks for any help

[Apogee]

You should be looking at the 1" bore Wilwood master cylinder with power, 7/8" with manual when running C5/LS1 brakes IMHO. If upgrading to a dual-9" diaphragm booster is in the budget, that will most closely mimic the pedal feel of the Corvette and/or LS1 F-body applications. If your engine vacuum levels at idle really are 18 inches Hg, that is exceptionally good in my experience and shouldn't pose any issues with running vacuum boosted brakes. As for the combination valve, you will need to replace it when you go disc/disc, so whether you replace it now or later doesn't really matter, however it doesn't usually make sense to wait if you're redoing the plumbing now. I prefer the adjustable proportioning valve for the flexibility that they add to the brake system. Just keep in mind that you'll want to add a 10 psi residual pressure valve to the rear circuit to maintain pressure on the cup seals inside the wheel cylinders so they don't leak.

Tobin
KORE3

[zbadone]

Thank you so much for the info. I was wrong on the vacuum. It is actually around 14 or 15hg. Is this a concern then for power? They are so so with this vac it seams. Also, when you said to add a 10 psi residual pressure valve to the rear circuit to maintain pressure on the cup seals inside the wheel cylinders, I assume that it is for the drum brakes?

[Apogee]

...I was wrong on the vacuum. It is actually around 14 or 15hg. Is this a concern then for power? They are so so with this vac it seams. Also, when you said to add a 10 psi residual pressure valve to the rear circuit to maintain pressure on the cup seals inside the wheel cylinders, I assume that it is for the drum brakes?

Your vacuum levels are still respectable for a built 383 with the camshaft you're running and should be workable for power brakes. You may want to add an accumulator if you find yourself getting inconsistent feedback at the pedal when really hammering it, but you may not feel the need. You would be correct that the 10 psi RPV is for the drum brakes only. It would need to be removed if/when you upgraded to rear discs.

Tobin
KORE3

[BOBBYA312]

good info

[Skip Fix]

FWIW my Trans Am with the stock 4WD dual diaphragm power booster would work fine down to about 10" iffy below that.

[zbadone]

Is that the booster on the 79 or 81 Trans Am that you are talking about?

[Skip Fix]

81 as it has the larger register aluminum master. I think other than that the 79-80 id about the same. I have it on my 78 I retrofitted with the factory rear discs back about 1988, and the DOT 5 silicone fluid in it has never felt spongy either:)