need master cylinder help

[gen3bu]

this is for my street driven 1993 sonoma 2wd with 355 and n2o.

currently using a 1995 c1500 master, with 2000 camaro (ls1) rear disc brake swap. i will soon be upgrading to 1992 1le front rotors and willwood billet forged dynalite 4 piston calipers. i would like some help selecting the appropriate m/c.

thanks
kevin

[BluEyes]

What size pistons on the dynalites? Also what is the piston bore on the LS1 rear discs?

I presume your current front calipers are the GM "metric" calipers with the 2.5" piston?

[andrewb70]

I bet the piston area is very similar between the Wilwood calipers and th eones that you are using now. If that is the case, then your current MC will work fine.

Andrew

[gen3bu]

the willwoods i am looking at are the 4 - 1.75" piston calipers. the stock calipers are 2.5" metrics.

i think the ls1 rears are 44mm.

i got the ls1 rears on with the stock s-10 fronts and it stops ok but not as good as i was hoping (it isn't much different than the drums).

i am thinking about a stock 98-02 f-body m/c.

btw- the c1500 m/c has a 1-1/8" bore.

[BluEyes]

Andrew was right, the Wilwoods have just a tiny bit less piston area: 4.81 in^2 vs 4.91 in^2 for the metrics. So 2% less piston area.

The stock MC for your truck was a 15/16" bore, so I'd say the full size truck master is probably too large and not giving you enough hydraulic advantage (although a very firm pedal I am sure). The F-body MC definately looks like a good choice at a 1" bore. Of course, make sure the outlets are on the correct side of the MC and the right flare type, or be prepared to do some brake line work.
Another option to consider would be to keep your current MC and switch to hydroboost for more power assist.

Unless you are set on the 4-piston calipers or are really going to go crazy on a roadcourse, I'd see if there isn't any way to put the 1LE rotors on with stock calipers. Being in college, I'm pretty budget minded and the extra 1.5" of rotor is what will be giving you more braking force, not fancy calipers (nothing against Wilwood). Replacement parts for the stock calipers are also cheaper and easier to get.

If you can swap to the uprights off a fullsize car that used 12" brakes like I did on my Camaro, that is likely to cost a load less than the Wilwood setup. These uprights would use the GM fullsize caliper with a 2 15/16" piston and in that case I would keep the current MC, because the larger caliper piston would bring the hydraulic advantage more in line.