Correct Master Cylinder for Manual GM Disc [D52 Calipers] and S10 Rear Disc app

[BBO Omega]

I am just finishing up the installation on the S10 Rear Disc Brakes on the 12 bolt in my Omega. I have the stock front calipers with Hawk HPS pads [front and rear]. This is a manual brake application, and I need to know which Master Cylinder to use. I would prefer one of the newer OEM Aluminum units if possible. Anyone have a good part number for this application? This is my first post on this forum. I tried searching, but no one seems to have as basic of set-up as I do.

[BBO Omega]

Bunch of veiws with no answers. It seems most of you guys have much more capable brake systems than mine, but I have to work within my budget. I guess I should probably save for a 7/8" Wilwood MC. That seems to be the popular unit for Manual 4 Disk set-ups. I was hoping for a less expensive OEM option.

[Randy67]

I would talk with Tobin at Kore3. The issue is the difference in piston sizes (very large front, good bit smaller rear) which makes master cylinder sizing tricky. Some of the guys on NastyZ28 have used the 1" bore with no complaints.

[BBO Omega]

I think that I have found a good comprimise in a 15/16" C3 Corvette style MC from CPP brakes. They offer a "Small Fitting" and "Large Fitting " version, with no explaination of what that means. I will give them a call. It is much less expensive than the Wilwood MC.

[woody80z28]

I've played "musical master cylinders" trying to get the same setup to work...and I'm still not there yet. I have a soft pedal that I'm not happy with. I even swapped in some 2.38 piston Wilwood GMIIIs in front to try and solve it. The pedal is soft with quite a bit of travel...feels like air but I've been down that road 10 times and even had a shop pressure bleed the system with no change in feel. I do plan to re-bench bleed my master this spring just for s&g.

I've tried a 1"bore 70 Vette manual master and a 1.125"bore 79 Vette power master and the 1.125" felt better, but the stopping power was reduced and the shallow piston divot made me nervous the brake pushrod could fall out. I also have an alum/plastic Dodge master I'm going to try and see how it works. If that doesn't work I'll try a tried & true Wilwood at 1" bore that everyone seems to like for manual brakes. People tell me the cheap Napa masters I'm buying are the problem, but I'm skeptical as to how much different they would perform when the pistons are the same size and their function really isn't that complicated.

I feel kind of defeated about the whole situation because I've done a lot of homework and still haven't come up with a solution yet. How's that for encouragement for ya?!

[Apogee]

I think that I have found a good comprimise in a 15/16" C3 Corvette style MC from CPP brakes. They offer a "Small Fitting" and "Large Fitting " version, with no explaination of what that means. I will give them a call. It is much less expensive than the Wilwood MC.

I think you would be happy with a 1" bore MC given your setup, but there's only about a 12% difference in area between the 15/16 and 1 inch bore units, so either should work. You have more master cylinder options in the 1" size, but all you need is one.

The CPP "Large" versus "Small" indicates the thread sizes on the outlet ports, where the "Large" units use the OE GM 1/2-20 and 9/16-18 SAE inverted flare tube nuts and the "Small" units are threaded for the semi-universal 3/8-24 SAE inverted flare tube nuts.

Tobin
KORE3

[BBO Omega]

Thanks Tobin. I figure that if I go with the CPP unit, I know it is a new casting as well. I used to sell auto parts and have seen some terrible items labled "Remanufactured". They seem to offer some decent looking prebent bracket / line kits for the distribution block as well.