Posted by Paul (in NY) on Saturday, December 23, 2006 at 21:33:15 :
In Reply to: Helitool brakes posted by Scott on Saturday, December 23, 2006 at 20:55:18 :
On my PW's with Helitool Disks, I use the 1979 Chevy C30, 1 Ton MC with JD-8 Option.
The JD-8 option is for use with Hydroboost and features a 1 & 5/16" bore MC.
The JD-7 option was for Vacuum assist boosters and features a 1 & 1/4" bore MC.
When I did the disk conversion on my Bumblebee (with a vacuum booster) I used the JD-7 option. The brakes worked well but I had no reserve pedal. On a hard stop the pedal was near the floor. The 1 & 1/4 " MC did not have a large enough bore to apply the brakes and still have a high pedal. I switched to the JD-8 option and immediately had full brakes and a high pedal.
By going with the JD-8 option you have 15-20% fluid moving to the disks, thus higher pedal when brakes are applied.
When I built my Carryall, the disks powered by Hydroboost booster pushed the JD-8 option MC and works great. Full brakes with a high pedal. I am using the same, Hydroboost, JD-8 on my Cummins M37
The Bendix part number for the Booster is 11584 (JD-8 option), The NAPA number is 39017
As a side note; I tried using the JD-8 option MC with 4 wheel disk brakes without booster on my Carryall. It was a failure. I knew In an emergency, I would never stop her in time. I added the hydroboost and have brakes equal to a modern 3/4-1 ton pickup with out ABS. The hydroboost are much smoother and more powerful in operation than a vacuum booster.
If you need the NAPA PN's for the calipers, rotors, pads, caliper pins, I have them and prices as of mid summer 2006.
I buy my bearings and seals at NAPA.
Paul