Need help updating brakes

[1965gp]

New guy here and could use any advice on a brake system... Here is my situation:

car is a 69 Trans Am clone that currently has manual disc/drums that are in sad shape. Going to try to update the car over the holidays and am looking for a nice complete bolt on kit that will provide consistent performance. The car isn't going to see a road course- more likely to see a spirited drive to the local cruise.

I've never considered an aftermarket kit but since this car isn't stock I think it's the way to go. Looked at Right Stuff, CPP, Wilwood, etc.

i need a kit that will fit behind a stock 15" Rallye II wheel and the car has a 455 with stout cam (no idea on specs- was in the moor when I got it) so vacuum could be an issue

so I guess my questions are- do I do a two wheel or four wheel disc set up?
I want a factory appearance booster- what is the advantage to a 8" or 9" booster?
I was only thinking of power brakes- should I look into manual brakes?
who has an entry level kit for a driver that they like?

Thanks in advance for the help- here is a pic of the car:

https://static1.pt-content.com/images/pt/2013/12/c9246b3b-1.jpg

[Apogee]

Regardless of the brakes that you choose to go with, the vacuum levels from the engine are going to potentially be your biggest hurdle to vacuum assist brakes. Caliper piston area, MC bore size, booster size/configuration,, vacuum levels, pad compound, etc will all play a role in determining the overall brake torque for a given pedal effort, not to mention the subjective nature of pedal feel.

A factory single-10.75" diaphragm booster has about 10% less effective diaphragm area than a dual-8" unit, and 35% less than a dual-9" unit IIRC. More area means proportionally more boost for a given vacuum level. That said, if you have less than 12 inches of vacuum at idle, you're typically fighting an uphill battle at that point. Without more info it's tough to say, however you may be better off considering manual or hydroboost assuming you have power steering.

Front discs are a must, however rear drums can be made to do pretty well in normal performance street application and provide a solid parking brake solution for very little cost. If it were mine and I was limiting myself to 15 inch wheels, I would probably spend the money up front first with the best brake kit that I could squeeze inside the wheels and then upgrade the rears later when funds allow.

Tobin
KORE3

[Ron Sutton]

That said, if you have less than 12 inches of vacuum at idle, you're typically fighting an uphill battle at that point. Without more info it's tough to say, however you may be better off considering manual or hydroboost assuming you have power steering.

Tobin
KORE3


Tobin, is the 12" of minimum vacuum idle a good rule of thumb, or specific to his application?

Thanks !

[Apogee]

Tobin, is the 12" of minimum vacuum idle a good rule of thumb, or specific to his application?

Thanks !



That's just what we've found to be a good general guideline, not a hard and fast rule...12-14 inches Hg is what we would consider marginal, with 15+ being pretty safe. We've seen people get away with less, typically in applications with large effective piston areas which require substantially less pressure than most of the aftermarket upgrade kits with less piston area which like more pressure to operate properly. Regardless, cam and engine design will ultimately influence whether or not an engine can or should support vacuum accessories, and not all will be the same. Low or marginal vacuum levels generally result in low brake torque and many times inconsistency at the pedal. There are band-aids to offset this in the form of vacuum accumulators to make up for low volume of vacuum and auxiliary vacuum pumps to offset low vacuum levels, however it's usually better to consider other options before you get to that point IMHO.

Tobin
KORE3

[Ron Sutton]

That's just what we've found to be a good general guideline, not a hard and fast rule...12-14 inches Hg is what we would consider marginal, with 15+ being pretty safe. We've seen people get away with less, typically in applications with large effective piston areas which require substantially less pressure than most of the aftermarket upgrade kits with less piston area which like more pressure to operate properly. Regardless, cam and engine design will ultimately influence whether or not an engine can or should support vacuum accessories, and not all will be the same. Low or marginal vacuum levels generally result in low brake torque and many times inconsistency at the pedal. There are band-aids to offset this in the form of vacuum accumulators to make up for low volume of vacuum and auxiliary vacuum pumps to offset low vacuum levels, however it's usually better to consider other options before you get to that point IMHO.

Tobin
KORE3

Super clear. Thanks for the all of your insight and expertise as usual.

[1965gp]

Thanks for the input- the car does not have power steering and manual brakes are certainly an option.

What would you suggest for the fronts? Looking at what your site shows I don't know that any of them will fit behind a 15" wheel?

[Apogee]

Thanks for the input- the car does not have power steering and manual brakes are certainly an option.

What would you suggest for the fronts? Looking at what your site shows I don't know that any of them will fit behind a 15" wheel?

Sorry, nothing from a C5 (1997-2004) or C6 (2005-2013) Corvette is going to fit inside anything less than a 17" wheel at minimum. That said, the vintage guys who must run period-correct brakes would generally run a C3 Corvette kit (JL8 upgrade) which uses a 4-piston caliper with a relatively heavy-duty 11.75" x 1.25" rotor. Wilwood offers an aftermarket C3 caliper that uses a more conventional piston seal configuration than the Delco-Moraine units and weighs substantially less, however by the time you're all said and done, you've spent a pretty penny to make it all happen.

Up front, you could do a Wilwood Dynapro 6-piston kit (140-10510 (http://www.wilwood.com/Search/PartNoSearch.aspx?itemno=140-10510&itempdf=140-10510)) instead with a 12.19" x .81" rotor for significantly less and have a perfectly capable setup that will still fit inside many 15" wheels, but you would need to verify fitment since you already have wheels. You could either rebuild your rear drums or convert to discs, and that's mostly a budget deal. Discs will do a better job of shedding heat than drums, but that's only an issue if you drive hard for extended periods of time.

Tobin
KORE3

[1966longroof]

Wilwood D52's

[1965gp]

Thanks for the input guys!