JRUTS

Nowhere Man

The dash or I/C does not need to be removed. For the booster you need a nut plate that was originally rivited to the firewall. But you do not need to rivet it as the booster will hold it in place with the trough bolts. If you have your AIM it will show how the factory did it

68hemi

I thought all 1965’s came from the factory with dual master cylinder?

Nowhere Man

No. Only power brake cars. Duel M/C became standard in EVERY GM car for 67 production

JRUTS

I'm looking to purchase a conversion kit from a number of Corvette suppliers but can you suggest a supplier to go to. that would would include the nut plate or where to get it? I'm just getting this car back on the road took off the 40 year old belt tires and got some new radials. Got it home and to test the brakes in my garage really laid on the brake petal then the 3/16". front crossover brake line blew out. So I think its time to replace all the brake lines and hoses as well. It looks like in late 1965 and defintely in 1967 they went to 1/4". lines. So when I talk to some of the Corvette supply houses, (not sure if I should mention them in this forum (I'm a new member in this) so just trying to figure out how to communicate etc. Many don't know the answers to all my questions. Such as if I convert to 1/4" do I have to change the rear junction blocks to 1/4" and what is the hose connection size that goes to these blocks (looking at replacement brake line #' the rubber lines seem to be all the same from 1963 - 67s so I have to assume the rear brake line junction block deals with some standard hose size?) then does the rubber brake line match the short steel 3/16 rear brake lines that feed the rear calipers or do I have to switch these to 1/4". If you can recommend a supplier?
I can call you sometime if your available to talk.

Tampa Jerry

As long as you are changing out all of your brake lines, why not get 1/4" lines, booster and master made for a a 67? I did that on my 66 and it all fit together without problems. Make sure you get the correct master cylinder for power brakes. They are different for power vs standard. Jerry

JRUTS

I'm going to go with 1/4 inch lines my question is does the 1967 dual master cylinder require the proportioning valves as shown with some of the conversion kits verses ordering a 1965-1966 master cylinder conversion kit which does not ? So is there something different about the 1967 version?

smuggler85

I did a 67 power disc brake conversion on my C2 and was abe to source all the parts from one vendor (Florida). Package contained the dual master, booster, brackets, SS lines, hoses, fittings and fasteners. You can certainly add the prop valve if you like - but it's not necessary on a street car. Great project and no longer need both feet to stop !!

Tampa Jerry

There is no proportion valve in the brake system. The C-2 and C-3 systems address the bias between the front and rear brakes by changing the size of the pistons. The rears are smaller then the fronts. In a system that utilizes both disc and drum, you need to add a proportion valve for even braking. You may be confusing the distribution block under the master cylinder as a proportioning valve. You do need the distribution block. Hope this helps. Jerry

Nowhere Man

for 67+ that is just a pressure switch to make the light in the dash work

JRUTS

Jerry, Thanks for confirming I don't need the proportioning valve. I wasn't confused about the difference between that and the distribution block.
My question came from looking at a couple of Corvette supplier retrofit kits. The up grade Kits that went from 65-66 models to a dual brake system with vacuum booster did not have a Proportioning valve but if I was to go to a 1967 upgrade some showed a proportioning valve, which I thought very strange and confusing. So needed to go to the experts. Appreciate your input. Jeff .

Nowhere Man

look up Lone Star Calipers. talk to them and they will send all the stuff you need

JRUTS

I just received my vacuum booster and adapter plate. I have a couple of questions, (1) The backing plate came with 2 rivets, which I see no way to back up to flair out. Any suggestions?
(2) Does the backing plate go inside the car on the back side of the firewall? You have to be a contortionist to just get up behind the dash let alone try to mount the plate back there or does the plate mount on the firewall side Held in place by the rivets? . I'm just worried that there is firewall insulation inside and I guess you try to move it before drilling the holes. I assume no wiring is up behind the dash to worry about.
(3) the booster came with the main mounting bolts pressed into the firewall mounting bracket. My car has the old master cylinder bolts already coming from inside the car through to the firewall engine side. They looked to either be pressed in or welded into the inside bracket under the dash do I pound them out then use the new bolts already pressed into the booster plate. Now the nuts are inside
the car much harder to reach.
Final question, any issues witht he oil dipstick looks like it will be right up against the dual master cyclinder when all this get back together.
Thanks for any help.

Nowhere Man

the nut plate goes on the upper most part of the firewall. you remove the wiper grille to get to it. there have been some factory installed PB booster nut plates that were not riveted to the firewall. it was only riveted to hold it in place until you bolt it in place.
the lower mounting part of the booster goes into the existing holes used by the master cylinder

davekp78

Remove the vent grill under the left windshield wiper to install the backing plate. Yes, you pound out the old MC bolts. The dipstick is close but works OK.

JRUTS

Thank you for the info. on removing the wiper grill. Much easier access once I get the grill out. I'm assuming the nut plate goes inside the wiper
grill housing just to help support the PB booster. Probably paint it to match the car paint. Just have to pound out the lower mounting studs
so the new PB bracket studs will work.

JRUTS

Thanks for letting me know I have to pound out those old MC studs.

Nowhere Man

The nut plate was installed before blackout. So no body color