MC sizing and actual pressures

[Skip Fix]

So the first attempted drag track outing last month on the 500" Pontiac motor/Camaro the Strange /Mopar MC just would not get enough hold for the line lock to hold the car for a burn out. Crappy track we left after two 1/8 passes. Also brakes did not slow the car as much as I would have liked at the top end, 102 in the 1/8th with a SLOW 60 ft, but brakes probably not completely bedded in yet also.

It always took a lot of leg pressure to build pressure max pressure on front and rear gauges after master were maybe 700psi. The MC was a 1 1/8" I had bought years ago. Today swapped on a Mopar style 21mm(7/8"), stayed Mopar style as the pushrod and Heim I had set up for the first one would swap on. Wow it can make 1100psi with the same leg pressure! Heck 700 just with my arm. It does have a moderate amount of increased travel. I'm going to give this one a try next outing(if it ever stops raining have had 3 rain outs in the past 2 months and some rain today) if the travel is just too much there is a 24mm(about .94") I'll try.

Front brakes Wilwood Dynalite 4 1.75" pistons 10.75 rotor BP 10 pads. Rear setup-front GM metric D154 calipers single 2.5" piston rots I think is about 11" 79-81 Trans Am rear rotor. Skinny drag front tires 275-60-15 M/T drag radials.

[malibudave]

The 7/8" bore may be a little small to supply the amount of fluid volume needed for all for of those calipers. Might want to look for the 24mm version of the master cylinder you have. It will be a little less line pressure, but will be able to supply the fluid volume needed for the caliper setup you have on the first pedal stroke.

[GoodysGotaCuda]

I put a couple thousand miles on a 7/8" with 6piston front and 4 piston rear Wilwoods, it stopped fine..but the travel was quite a bit. For a drag car, I wouldn't worry about the travel, you'll get the line pressure just fine. I have a 15/16" now.

[Skip Fix]

Thanks guys. Another buddy said a swap to the lower hole might decrease the pedal travel. Also figure swapping on the D154 Wilwood small twin piston caliper could help. Was set for a outing Sat but already called because of rain in the forecast again-as well as the Bellville car show postponed to April.

One thing I did not like about the 21 and 24 are neither of the new ones I got(freaking Chinese stuff) have the small step for the rubber pushrod retainer sleeve and the recess was smaller (0.375 vs 0.430) and had to turn down my pushrod compared to my Strange and another 1 1/8 Mopar I have. Had to get the die grinder to get the holes for the GM spacing on the firewall but no big deal there.

Dave you need to put a second Gen F body kit together! You are local to me what part of town I'm on the west side.

Plum Crazy white top/interior 71 Cuda 383 auto in the storage space down from me where I have my 65 GTO and Late Model. Always liked those Cuda's and Challengers.

[malibudave]

Dave you need to put a second Gen F body kit together! You are local to me what part of town I'm on the west side.




I'm on the west side also, but in the Spring Branch area. I-10 and BW8.

I have a second Gen F body kit, but I haven't listed it yet. It will work with almost any master cylinder. Stock, strange, Wilwood, Baer, Mopar, Ford, etc

If interested, call me to discuss. Look forward to hearing from you.

[Skip Fix]

Not too far form my office Dairy Ashford and Memorial.