C5 conversion question

[73X]

I'm plannning a C5 or LS1 swap and would like to do it in stages. First, will my stock '73 Nova disc/drum master cylinder work with the new calipers? I know other parts will need to be changed. Second, will the 13" C5 rotors work with the LS1 calipers? Any suggestions are welcome and appreciated. Thanks,

[Tucks69]

It may work with the front conversion, but if you change the rear to disc you will need to change the master cylinder. I have C5 front and rear, I have a Corvette 4 wheel disc manual master cylinder. I also installed a proportioning valve in the rear brake line. This allows adjustment . My brake pedal is a little firm, but the brakes work great. I have ran three autox's and had no problems. You can check with touring classics and kore 3 they have alot of great info and products. Both were great help on the phone with tech questions.

[gort69]

I'm plannning a C5 or LS1 swap and would like to do it in stages. First, will my stock '73 Nova disc/drum master cylinder work with the new calipers? I know other parts will need to be changed. Second, will the 13" C5 rotors work with the LS1 calipers? Any suggestions are welcome and appreciated. Thanks,

The stock single piston discs have a greater piston area than the combined area of the twin pistons of the C5 or the LS1. You'll have a tough time generating enough line pressure to get the front brakes to work correctly with the stock (1 1/8) MC unless you go to something like hydroboost. A 1" bore MC might be a better idea in conjunction with an adjustable valve to your rear brakes, with the tradeoff being more pedal travel. All assuming vacuum assist.

My advice would be to "buy" the parts in stages, but install them all at once. Meaning front/rear discs and MC, adj prop valve.

I don't think the C5/LS1 discs are a particularly good match with stock rear drums. C5 and LS1 interchange with eachother very well.

[67rsssls]

I can answer the second question...the LS1 calipers will work with the C5 13" rotors but you will have to use Corvette abutments GM part #12455799. I used this combination on the front of my 69 Camaro convertible along with LS1 rear brakes and LS1 booster/master cylinder. Brakes work excellent. The toughest part of the project was mounting the booster. For the front conversion I think you need to start with drum brake spindles and hubs. For the front conversion brackets it would be tough to beat the quality of the Speed Tech brackets.

http://www.speedtechperformance.com/...prod/prd51.htm

[MonzaRacer]

Not sure which spindle the 73 runs but Kore3 has both short and tall GM spindle kits.
As for using LS calipers they are similar but use different casting techniques, The Corvette units are much stronger than the LS Camaro parts.
As for master cylinder choice, give Tobin over at Kore 3 a shout either email or pm or phone call, he can give you proper choice in master cylinder. Also if you like to drag race use the S10 rear disc set up as it will clear 15 in wheels(if you like to use drag slicks or might even remotely think of using them).
The brakes from S10 rear disc are plenty large for just about all but most severe uses from my gathering of information.
I have part numbers for s10 backing plates for disc parts, they can be had as complete part per side. then all you need are brackets, calipers and rotors. Finding and removing the stock pressure check for drums in some cars may be required, some disc cars may require 2 psi check in front lines.
And you should not need to switch spindles if using Kore 3 adapters.
My Caprice will use the Kore 3 adapter then i will source my own calipers and rotors.

[Apogee]

The '73 and '74 X-bodies are basically the same as the '68-'72 X-bodies with respect to the running gear, so they still use what we refer to as the modular GM short-spindle up front with the bolt-on steering arms and caliper brackets. The left and right hand spindles are the same part. Whether you have disc or drum spindles doesn't matter as you should be able to get brackets for either...ours are the same brackets and just differ in the mounting hardware that we supply with them.

As for master cylinders, neither your factory 1" (manual) or 1-1/8" (power) units will be optimal with a C5 or LS1 type of setup for the effective piston area differences mentioned above. Ideally, you'd go disc/disc at the same time as that tends to simplify your plumbing and MC requirements in the long run. It also helps to know what your primary uses are for the vehicle in question as we usually wouldn't set up a daily-driver the same way as a dedicated track car.

Doing things in stages can simplify things in some ways, particularly troubleshooting IMO since you're usually only changing one thing at a time, but can complicate them in others. Most people don't like buying parts twice or replumbing their brakes numerous times for MC changes, inline residual pressure valves, adjustable proportioning valves and the like. That said, we've got plenty of customers happily running C5/C6 front discs with factory drums in the rear since that's what their budgets allowed at the time...many have upgraded later while others have stuck with the disc/drum setups with good results.

Tobin
KORE3

[73X]

The '73 and '74 X-bodies are basically the same as the '68-'72 X-bodies with respect to the running gear, so they still use what we refer to as the modular GM short-spindle up front with the bolt-on steering arms and caliper brackets. The left and right hand spindles are the same part. Whether you have disc or drum spindles doesn't matter as you should be able to get brackets for either...ours are the same brackets and just differ in the mounting hardware that we supply with them.

As for master cylinders, neither your factory 1" (manual) or 1-1/8" (power) units will be optimal with a C5 or LS1 type of setup for the effective piston area differences mentioned above. Ideally, you'd go disc/disc at the same time as that tends to simplify your plumbing and MC requirements in the long run. It also helps to know what your primary uses are for the vehicle in question as we usually wouldn't set up a daily-driver the same way as a dedicated track car.

Doing things in stages can simplify things in some ways, particularly troubleshooting IMO since you're usually only changing one thing at a time, but can complicate them in others. Most people don't like buying parts twice or replumbing their brakes numerous times for MC changes, inline residual pressure valves, adjustable proportioning valves and the like. That said, we've got plenty of customers happily running C5/C6 front discs with factory drums in the rear since that's what their budgets allowed at the time...many have upgraded later while others have stuck with the disc/drum setups with good results.

Tobin
KORE3

Thanks for the info. So what size bore MC do I need for this application? I don't know what size a stock C5 is. I'm also interested in how some of your customers are getting the C5 front/rear factory drums to work together. Reason being is I drive the car on the street and maybe will attempt to auto-x it 4-5 times a year just for fun. I'm not breaking any records on a track, just want something affordable and somewhat better. I plan on the full C5 conversion eventually but a MC and front caliper change (I'm sure there's more to it), then a rear disc conversion 6 months to a year later sounds about right.

[Apogee]

With C5/C6 disc/disc setups, we normally suggest running a 7/8" to 15/16" bore MC's with manual brakes, 15/16" to 1" bore MC's with vacuum power brakes and 1-1/8" bore MC's with hydro-boost.



Since you're planning on sticking with drums in the rear for a while, I would just plan on running a disc/disc master cylinder and plumbing in a 10 psi residual pressure valve (RPV) for the rear brakes to be removed when you swap the rears to discs. The RPV is there to maintain some pressure on the rear cup seals inside the wheel cylinders so they don't suck air when the pistons/seals retract.

Tobin
KORE3

[73X]

Any suggestions for a master cylinder? Such as Camaro or Corvette? If I run the disc/disc master do I need to switch the prop valve to disc/disc as well?

[Apogee]

Any suggestions for a master cylinder? Such as Camaro or Corvette? If I run the disc/disc master do I need to switch the prop valve to disc/disc as well?

Manual, vacuum assist or hydro-boost? Then we can make more specific MC suggestions.

You can ditch the combination valve in favor of a stand alone adjustable proportioning valve and a tee fitting for the front brakes. Or, you can gut the prop valve from the combination block and use it as a distribution block if you prefer...that would maintain the dummy light functionality for the brake balance switch if that's important to you.

Tobin
KORE3

[73X]

Sorry, forgot to add that I have vaccuum assisted MC now and would like to stay with it. Also, what's it take to gut the stock prop valve?

[gort69]

Hey Tobin - Have you seen this item from SSBC? Looks to be a replacement for the stock prop block with a provision for the brake light on the dash as well as adjustable valve for the rears. Looks pretty cool. Scroll down to page 43. http://www.ssbrakes.com/content/imag..._web_small.pdf

[Apogee]

Hey Tobin - Have you seen this item from SSBC? Looks to be a replacement for the stock prop block with a provision for the brake light on the dash as well as adjustable valve for the rears. Looks pretty cool. Scroll down to page 43. http://www.ssbrakes.com/content/imag..._web_small.pdf

I have seen that and it's a slick little combination valve for the money. Some think it's a bit overpriced, but for what it contains it seems like a pretty good deal to me if you wanted to maintain a more factory plumbing scheme and dummy light functionality. Summit offers the same thing for a few bucks less (SUM-G3910) so it's probably just brand labeled from someone else, maybe SSBC, maybe not.

73X, if your '73 Nova is like ours was (drum/drum), then it doesn't have any proportioning valve, just a distribution block with a brake balance switch, so there's nothing to gut. As for master cylinders, I'd probably start with the 1" bore 67-76 C3 Corvette disc/disc or the 15/16" equivalent that CPP sells. Just make sure that you match the pushrod length on the booster with the depth of the pushrod hole in the MC piston...I believe the Nova was a long pushrod booster, but don't quote me on that as ours was manual.

Tobin
KORE3

[gort69]

Tobin -

The Summit unit you linked is different. It has a two prong switch and I beleve it is simply a brake light switch. The one I linked looks to be a direct replacement for the GM prop block (not sure size-wise) and has the brake system failure switch, which is why I thought it was so cool. Perhaps summit does sell the same thing - I haven't looked.

Take care.

[Tito]

Yeah, but they both have the same part number -- A0730.
Looks like the "early" design from SSBC had the single-terminal switch that looks like the brake pressure warning switch connector. The catalog you linked to is dated 2007 and this SEMA blurb is from 2005. All of the pictures I've ever seen (as well as the SSBC instructions for A0730) have the 2-pin brake pressure switch.

No way to tell if the original design actually had a differential pressure warning switch or if it was really a pressure switch with a different connector, but it seems like the "old" version is discontinued and the 2-pin pressure switch job is the only one available these days....

Bummer, as I like the idea of a "real" drop-in replacement that's adjustable.

[gort69]

Sigh..........

[73X]

73X, if your '73 Nova is like ours was (drum/drum), then it doesn't have any proportioning valve, just a distribution block with a brake balance switch, so there's nothing to gut. As for master cylinders, I'd probably start with the 1" bore 67-76 C3 Corvette disc/disc or the 15/16" equivalent that CPP sells. Just make sure that you match the pushrod length on the booster with the depth of the pushrod hole in the MC piston...I believe the Nova was a long pushrod booster, but don't quote me on that as ours was manual.

Tobin
KORE3

My car is a factory disc/drum car with vaccuum assist. Should I just try to find a drum brake car distribution block?
Thanks

[rickpaw]

Sigh..........

Al,
On 69TAPoser website, he mentioned using SSBC (under Summit brand) distribution block and prop valve unit.. Not sure if it's the same thing though.

http://www.69firebirdbuild.com/page/page/4543814.htm

Tu

[Apogee]

My car is a factory disc/drum car with vaccuum assist. Should I just try to find a drum brake car distribution block?
Thanks

You can, although it's not necessary, it just depends on what you prefer and how comfortable you are making your own brake lines. By using a factory distribution block or combination valve, you can use your factory hard lines and/or aftermarket replacements without too much hassle.

If you decide to replumb the car yourself, you don't need the distribution block unless you want to maintain the brake balance switch. If not, you can just run a Tee fitting to split the front line and go direct from the MC to the rear center hose with an adjustable proportioning valve in between.

Tobin
KORE3