[Peter Serio]

On a car with power brakes that spring I do not think is needed. There is an internal spring inside of the vacuum booster that returns the pedal to the top of it's travel.

If you have modified a car from a non-power brake to power brake the bracket that holds the stop lamp switch is either 1), mounted in a different set of holes or 2), a power brake car takes a different stop lamp switch bracket. And/or a different switch (perhaps a longer switch).


The brake pedal has 2 sets of holes: the top hole is for a manual brake car (push-rod) with spring and the lower hole lines up with the push-rod from a vacuum booster (no spring). This causes the power brake car to have a slightly "lower pedal" at the fully released top of travel. There should be a drawing in the shop manual or the parts book (either one) that shows the 2 holes and how the push-rod attaches for manual vs. power.

[wbnapier]

I think you are right on the use of the spring with / without power brakes.

In any case, it doesn't hurt to have it, and it did take up most of the slack.

Is the internal spring inside the vacuum booster easy to access and adjust?

[Peter Serio]

The spring inside of the vacuum booster is not adjustable as far as I can remember. You would have to take the booster off of the firewall and then take it all the way apart to get to that spring which would be a lot of work. Plus there are a few special tools (Kent Moore) you'll need to take the booster's gold plated metal outer shell apart.

[rohrt]

Interesting topic. I have a power drum 64 setup that I changed over to dual reservoir MC. My pedal is intermittently not returning all the way. Already changed the MC and will swap out the Booster in the spring. I have to keep pulling up the peddle with my foot. I guess if the booster doesn't fix it I may just try that spring.

[wbnapier]

The spring would definitely help.

Yesterday, I removed the tape from the pedal that I had used to build up and push the brake light switch plunger that 1/2 millimeter more.

I removed the switch, disassembled it, and drilled a small hole in the end of the plunger and put a small screw in. This effectively increases the length of the plunger by 2mm.

I think this was a good solution.

[ramair455ca]

Originally Posted by pfilean

Maybe this will help.

Just wondering what book this set of pics might be from? Thats great info!

[tempest1964]

"Just wondering what book this set of pics might be from? Thats great info!"

Looks like the 1966 Master Parts Catalog or MPC. Usually available on Amazon and others.

[JAKE 64]

Originally Posted by tempest1964

"Just wondering what book this set of pics might be from? Thats great info!"

Looks like the 1966 Master Parts Catalog or MPC. Usually available on Amazon and others.

For 1964

Yes, either the '66 or '67 Master Parts Catalog (MPC).
Interestingly, this set-up is not shown in the 1964 MPC illustration, and first appears in an illustration in the 1965 MPC. Although not shown in the ''64 illustration, the parts are listed in both MPC's (Group 4.639). An illustration showing this set-up is also shown in the 1964 Tempest Chassis Shop Manual in Section 5-1, figure 5-1. The shop manual is dated August, 1963.

[ramair455ca]

Originally Posted by JAKE 64

For 1964

Yes, either the '66 or '67 Master Parts Catalog (MPC).
Interestingly, this set-up is not shown in the 1964 MPC illustration, and first appears in an illustration in the 1965 MPC. Although not shown in the ''64 illustration, the parts are listed in both MPC's (Group 4.639). An illustration showing this set-up is also shown in the 1964 Tempest Chassis Shop Manual in Section 5-1, figure 5-1. The shop manual is dated August, 1963.

So does that mean there is actually an MPC for 1965? Is this considered the same and as assembly manual? I would really like to find one for my 65 but have not had any luck.

[JAKE 64]

Originally Posted by ramair455ca

So does that mean there is actually an MPC for 1965? Is this considered the same and as assembly manual? I would really like to find one for my 65 but have not had any luck.

For 1964

No, each year received their own Master Parts Catalog (MPC), Assembly Manual, Inspector's Guide, Pontiac and Tempest Body Manual, Chassis and Shop Manual, Pontiac Flat Rate Manual, Molding and Clip Catalog, Air Conditioning Manual, Pontiac Service Information bulletins, Pontiac Colors-Interiors-Accessories booklet, Pontiac Sales Manual, and a myriad of other publications pertinent to that specific model year. The MPC included information for both the Pontiac and Tempest models that were combined, as well as for Vauxall, which was in its own separate packet. The '64 MPC was dated 10/1/63, and the '65 was dated 9/15/64. These catalogs would be updated periodically during the production year.

[Skip Fix]

Been messing with my 65 and it is manual brakes and definitely has one. Swapping on a 67 dual MC so been under it. Started to remove the clevis pin form the pedal now the spring is pulling it so it is a pain to get it back through.

My thread in 67 has gone unanswered but pushrod retainer in 65 GTO is under the piston spring for the MC the 67 cup fits over the end of the MC and is sandwiched between the firewall and MC.