No brake pressure on 4 wheel disc conversion

[pandamarie]

Did wildwood 13" front 4 piston front and the GM.rear disc conversion on my Daytona project using a new factory booster and MC, also have a vacuum pump hooked to booster since engine doesn't pull more than 8" of vacuum.
Car stops but I need to put all my weight on the pedal and it's still not enough.
Anyone run into this problem? If so what was your cure?

[Charger4404spd]

From what I have read over the last few weeks (just installed Wilwoods on mine) it sounds like the bore in the master cylinder is too large. It was recommended to me to use one with a 15/16" bore, and it works well.

Sure someone with more knowledge will be along soon.

[pandamarie]

Have been doing a lot of reading on this since the post and 15/16-1" would give 1100-1300 psi line pressure with the pedal ratio of the charger.
So after looking around the dodge master cylinder with an Oreilly part # NMC1860 will work just about perfect, it has a bore of 1.031" and with the Mopar adaptor plate will work with no problems on my stock booster.
Hope this helps someone else here.

[John_Kunkel]

What's the diameter of your current MC? Changing from a 4-bolt to a 2-bolt on a booster using the adapter will need to have the pushrod in the booster lengthened.

A factory 15/16" needs no adapter.

http://www.jegs.com/i/Right+Stuff/965/DBMC15/10002/-1?CAWELAID=1710851736&CAGPSPN=pla&catargetid=230006180000849857&cadevice=c&gclid=CPnylv-e4sQCFRSEfgodioEA0Q

[pandamarie]

4 bolt MC was 1 1/8". Checked everything today after picking up the new 2 bolt MC and with the adaptor plate the pushrod did not have to be changed, had to make new lines down to distribution block, running a adjustable proportioning valve.
Haven't tested it yet except for just pushing pedal to check for leaks but it feels much better already.
Will test it once wife gets home.