Converting over to manual brake question

[Yoda4561]

Finally got me a 2nd gen to work on, once the transmission is fixed this week I'll start on the brakes. I had been planning on switching to manual brakes as soon as I got it but in case I don't find them to my liking, can I just disconnect the vac line from the booster and bolt up the manual master cylinder? That way there's no need to rebend lines or buy a new pushrod and backing plate for the firewall.

[lucky13firebird]

been daily driving my 68 firebird on manual 4 wheel disc for years now, LOVE it. 13" corvette fronts and 12" ls1 camaro rears on my 12 bolt. don't see why not. i think the only real difference in manual master cyl is the bore diameter to help make it easier... someone else will hopefully chime in.

i'm using a 1 1/8" bore diameter master cyl.... most recomend a 7/8... the smaller the bore, the easier to push. just gotta make sure your lines and hoses are bleed and have no bubbles because the smaller the bore the less total fluid you can push through with the same amount of stroke...

[David LaBuda]

If it's anything like an A body, there are different positions on the brake pedal for manual and power brakes. The manual master cylinder has to be mounted directly to the firewall in order to line up with the correct spot on the pedal.

[Yoda4561]

I thought that too David, but when I checked my pedal, there's no second hole. The used auto brake pedals at firebird central don't mention anything about manual/power brake options either. I don't have a stick shift brake pedal to compare it too, maybe the automatics never had the option for manual brakes?

[Skip Fix]

Second gen you need to move the rod up to were the brake light tab is located for manual ratio.

Manual disc/drum Second gens used a 1" MC also. Most power MC do not have a hole deep enough for the manual rods. Rod is made onto the booster so you will need a clevis and rod to go manual.

[NOT A TA]

Good to see ya got a car Dan! The 2nd gen power disc/drum can work pretty well if you have good components, the right pads/shoes, and enough vacuum. Post up some pics of the car!

Skips got ya covered on the differences in his post above if you want to go manual.

[Yoda4561]

Thanks for the info skip, I'll start getting that stuff together then, I got some time before I get to that point anyways. The previous owner replaced the soft lines a couple years ago but the hard lines look like they're the ones that came with the car, so I want to get those replaced. Debating between getting the prebent oem steels or just bending my own in NiCopp tubing. Leaning towards the nickel copper right now, would make it easier to reposition later when I get to the manual conversion.

And hells yeah John, I've looked a few cars since we last chatted, even dropped a deposit on a white 75 T/A that I had to back out on later due to second thoughts about the condition of the body and motor rebuild. This car just sort of popped up 2 miles down the road from me, a bit rough around the edges but daily driverable other than the bad transmission. I'll get more pics of it once I get it back on the road this week. I plan on keeping the stock setup with some upgrades as I go along since I'm not going to track the car, first order is those new brake lines, then I'll switch to pfc street pads up front and semi-metallic shoes. The engine has good vacuum and the booster operates fine, I do need to bleed them though, there's a fair bit of pedal travel before the pedal firms up and they grab.

[Skip Fix]

One thing to look at also is the power booster rod just bolts to one side of the pedal, so it is offset from the center of the pedal. A Clevis straddles the pedal so the rod will then go into the MC at an angle-hard if the MC has a deep recessed hole for the rod. I cut off one side of the clevis and that offset the rod. A Heim would work but the hole in the bearing portion I think needed to be 7/16 and I could not find one with the correct threads for the rod that had that big a hole.

[68 TT]

been daily driving my 68 firebird on manual 4 wheel disc for years now, LOVE it. 13" corvette fronts and 12" ls1 camaro rears on my 12 bolt. don't see why not. i think the only real difference in manual master cyl is the bore diameter to help make it easier... someone else will hopefully chime in.

i'm using a 1 1/8" bore diameter master cyl.... most recomend a 7/8... the smaller the bore, the easier to push. just gotta make sure your lines and hoses are bleed and have no bubbles because the smaller the bore the less total fluid you can push through with the same amount of stroke...

I did the same thing. Ran the power disc sized MC in a manual brake setup. I switched from 1-1/8" to 7/8" by the suggestion of a fellow drag racer and it made a world of difference in pedal effort. Increased pedal travel a bit but made up for it in making the car feel lighter when bringing it down to a stop after a run.