Mopar Disk Brake Upgrade Advice

[LemonTwisted]

I'm looking to upgrade the brakes on my 70 Roadrunner from factory power front disks/rear drums to 4 wheel disks. The car will primarily be used for weekend cruising, some autocross and I may do a USCA event. I'm looking at the Wilwood Superlite 6R, 6 piston calipers with 12.88 rotors for the front and the D154 2 piston floating calipers with 12.19 rotors for the rear. The factory master cylinder has a 1.125 bore. Looking for feedback to see if this sounds like a good combo for what I plan to do and if I need to change out anything else on the factory brake system for this set up to work.

Thanks,

[Dave Pratt]

Steve...your car brought a tear to my eye.I sold my 70 RR about 1.5 years ago,383 factory air grabber,18-spline 4-spd,Dana-60...Hemi Orange/Black top.No advice unfortunately but I did want to say you have a great looking RR there sir.Treat her well...I went 69 Camaro after all these years

[Tomswheels]

Steve brakes sound good, probably will need a master cylinder that's set up for disc/disc, I think DR Diff sells them and he is a good guy to ask about the bore...

[mmosley]

I'm looking to upgrade the brakes on my 70 Roadrunner from factory power front disks/rear drums to 4 wheel disks. The car will primarily be used for weekend cruising, some autocross and I may do a USCA event. I'm looking at the Wilwood Superlite 6R, 6 piston calipers with 12.88 rotors for the front and the D154 2 piston floating calipers with 12.19 rotors for the rear. The factory master cylinder has a 1.125 bore. Looking for feedback to see if this sounds like a good combo for what I plan to do and if I need to change out anything else on the factory brake system for this set up to work.

Thanks,

Here is an option to consider: http://www.doctordiff.com/brakes/complete-kits/ If you do... call Cass (aka Dr Diff) and he will steer you in the right direction regarding the master cylinder.

[Apogee]

Given the Wilwood kits noted, you should be looking at a 15/16" to 1" bore MC for a vacuum assisted power brake application IMO. Vacuum level and booster size/configuration should also be taken into consideration when sizing the MC.

Tobin
KORE3

[Bigblue73]

Tobin are your guys (Kore3) doing anything for the Mopars? Always need another quality source that you can trust.

[mmosley]

Tobin are your guys (Kore3) doing anything for the Mopars? Always need another quality source that you can trust.

They make kits to fit your Corvette spindles and your Ford 9" rear axle just like everyone else. The farther you stray from the '69 Camaro, LS Engine, DSE front suspension with a 9" rear axle "Pro Touring" formula the harder it is for you to find suitable parts, especially bolt on kits.

[LemonTwisted]

Thanks for replies guys. Here's a little more info on the current brake system. I'm using a rebuilt factory Bendix dual diaphragm booster with an original brake system safety switch. The current system seems to work fine with the 10 - 12 inches of vacuum at idle. I'm planning on swapping the factory prop valve for an adjustable unit. Is there any reason to change out the factory safety switch?

Tobin - With the Bendix booster and 10 inches of vacuum, which size master cylinder do you think I should go with?

Thanks,

[Apogee]

Tobin are your guys (Kore3) doing anything for the Mopars? Always need another quality source that you can trust.

Not at this time, there just hasn't been enough interest to justify the development costs. Many of the Mopar guys who are going to the extent to upgrade their brakes are also upgrading their suspension as well, so while we've put brakes on more than a few Mopar applications, they were running Mustang II spindles and Ford 9" rear ends for the most part.

Tobin
KORE3

[Apogee]

Thanks for replies guys. Here's a little more info on the current brake system. I'm using a rebuilt factory Bendix dual diaphragm booster with an original brake system safety switch. The current system seems to work fine with the 10 - 12 inches of vacuum at idle. I'm planning on swapping the factory prop valve for an adjustable unit. Is there any reason to change out the factory safety switch?

Tobin - With the Bendix booster and 10 inches of vacuum, which size master cylinder do you think I should go with?

Thanks,

With only 10-12" Hg of vacuum, I wouldn't even consider vacuum boosted brakes without an auxiliary vacuum pump and possibly an accumulator. The reality is that with those levels, your booster is going to be marginal at best, so you're not really that much ahead of manual brakes at that point. If you had 16" Hg or better, then no worries with a properly sized booster and master cylinder, something like a single-11", dual-8" or dual-9" booster with 15-16" to 1" bore MC assuming a 4:1 pedal ratio or thereabouts. I start to notice pedal inconsistency and higher effort which vacuum levels in the 12-14" Hg range, and at lower levels it tends to be an uphill battle.

FWIW, I'm not a big fan of aux. vacuum pumps for a variety of reasons, cost and reliability being the two biggest. That said, you could go hydroboost if you wanted to divorce your brake performance from your camshaft specs, or you could go manual. Pad choice and how you intend to drive the vehicle should come into play as well.

Tobin
KORE3