[curtis73]

Picked up a 67 Lemans Convertible with 4 wheel manual drums. The long-term plan is a pretty serious build and I have a disc 9" for the back and will likely do a completely re-engineered front suspension.

That project is a while off. I would just like to drive it for now, but the manual drums suck. A lot. I think I'll do the LS1 front disc conversion or possibly an A-body disc setup. For the rear I could find the 4th gen Camaro rear discs, or I would likely be happy just converting the rears to power drums.

What would happen if I sent boosted brake pressure to the manual rear wheel cylinders? Is that a viable option, or do I need to convert the rears to power drum? I'm thinking of getting it on the road with decent brakes for as little money and knuckle-busting as possible. How would you folks do it?

[SteveGB21]

With the brakes, if you can find:

1969-1972 A-Body (Chevelle/SS/El Camino; GTO/Tempest/LeMans; Cutlass/F85/442; Skylark/Special/GS)
1969-1972 G-Body (Monte Carlo; Grand Prix; Cutlass Supreme)
1969-1974 X-Body (Nova; Omega; Ventura 2; Apollo N.O.V.A.)
1969-1970 (early or 1st Gen) F-Body (Camaro; Firebird)

This is the front. The rear, especially if you're going to swap to a 9" Ford, best to leave the GM differential.

[HWYSTR455]

Rear wheel cyl are the same for manual or power, the combo/prop valve is what's different. That you would have to change when you do the fronts anyway, so no biggie.

.

[curtis73]

Oh... I saw a 7/8" option and a 1-1/8 option for wheel cylinders. I assumed that was power/manual.

So I can just toss in a booster, swap front brakes, and prop valve?

[curtis73]

Originally Posted by SteveGB21

With the brakes, if you can find:

1969-1972 A-Body (Chevelle/SS/El Camino; GTO/Tempest/LeMans; Cutlass/F85/442; Skylark/Special/GS)
1969-1972 G-Body (Monte Carlo; Grand Prix; Cutlass Supreme)
1969-1974 X-Body (Nova; Omega; Ventura 2; Apollo N.O.V.A.)
1969-1970 (early or 1st Gen) F-Body (Camaro; Firebird)

This is the front. The rear, especially if you're going to swap to a 9" Ford, best to leave the GM differential.

Thanks for the list. Have you heard much about the LS1 disc swap? From what I understand you sand down the drum hubs a bit, slide on the F-body disc, buy a readily available bracket and use the F-body caliper. The attractive side to that is not having to change spindles.

I might have trouble sneaking them behind 14" wheels though.

[HWYSTR455]

Hm. Not familiar with diff size cyl bores, thought that was on master cyl, not wheel cyl?

Master cyl bores for manual brakes are 7/8, and 1 1/8 for power.

You can look at KORE3 about the spindles, or Wilwood, but honestly, if you plan on sticking with 14" wheels, you're better off swapping with OE spindles. They're readily available, and inexpensive. And parts are available at any auto parts store.

.

[SteveGB21]

I do know for sure if you use rear disc brakes (& front) off either 1993-1997 or 1998-2002, you will have to use 16" or 17" wheels. 1987-1992 F-body you can use 15". Depends what you want to do.

[curtis73]

Originally Posted by HWYSTR455

Hm. Not familiar with diff size cyl bores, thought that was on master cyl, not wheel cyl?

Master cyl bores for manual brakes are 7/8, and 1 1/8 for power.

.

You are correct... I was looking at wheel cylinders on Rock Auto and didn't realize it was including front wheel cylinders in the list. I thought it was showing two different sizes for rear, but it was showing 7/8" rear and 1.125" front. My mistake.

So I'll need booster, master, prop valve (I'll do an adjustable since this is a temporary combo), front disc setup.

I have a new master from a 95 Caprice. I'll check bore size and pushrod depth... might be an option. Are there preferences on boosters? Like for instance does everyone prefer the [insert GM car here] because it clears valve covers better, or provides more assist? Or should I just get any A-body booster?

[curtis73]

Originally Posted by SteveGB21

I do know for sure if you use rear disc brakes (& front) off either 1993-1997 or 1998-2002, you will have to use 16" or 17" wheels. 1987-1992 F-body you can use 15". Depends what you want to do.

Good to know. I was planning on 17s in the future, so I might just go ahead and pull that trigger since I need tires anyway.