The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - 1970 GMC 2500 2WD 8 Lug disc brake conversion

k2rm · 09-19-2011, 04:07 PM

I have a Performance Online MC running 4 wheel discs on my 1970 C20 and the truck stops really well. This is even running the 77 el dorado rear calipers with parking brake which are known to require a lot of volume to engage. A 1" bore should be fine for front discs only. I am running the original 9" dual diaphram booster. If you do get a 1 1/8" bore, make sure you use a large booster like the dual 9". I tried a single 11" first, and braking was very poor. Once I slapped the original dual 9", it stopped really quick.

09-19-2011, 04:07 PM	#8
k2rm Registered User Join Date: Aug 2009 Location: Concord, CA Posts: 147	Re: 1970 GMC 2500 2WD 8 Lug disc brake conversion I have a Performance Online MC running 4 wheel discs on my 1970 C20 and the truck stops really well. This is even running the 77 el dorado rear calipers with parking brake which are known to require a lot of volume to engage. A 1" bore should be fine for front discs only. I am running the original 9" dual diaphram booster. If you do get a 1 1/8" bore, make sure you use a large booster like the dual 9". I tried a single 11" first, and braking was very poor. Once I slapped the original dual 9", it stopped really quick.