Best disks that fit under the OEM 15” Rally ?

[Luke87gt]

Hi guys, I’m about to place an order for the CPP front disk brake kit (drop spindles, rotors, calipers)

Before I do, I’d like to check if there’s anything else out there with improved braking performance that will fit under the 15” truck rally?

Anything out there I should consider before placing the CPP order? Thanks

[70STOVEBOLT]

12" rotor is about as big as will fit. You could get drilled/slotted for better cooling if you need it.

[Luke87gt]

What about calipers?

[Steeveedee]

Don't know about with dropped spindles, but single-piston calipers will fit. Multi-piston calipers can interfere with stock wheels.

[SCOTI]

Nothing wrong w/the OE standard single piston calipers from the 73-87 trucks.

'Dual piston' calipers that fit within the confines of a stock 15" barrel are not going to offer much benefit. There would be a slight increase of the contact area for the pad but it would be minimal vs the cost vs the stock D52 caliper/pad. Wilwood makes a 'replacement' D52 caliper if you want the bling but again cost vs. functional output is a wash.

As far as drilled & slotted rotors? They're lust a look @ me thing so the 15" wheels used would need to have a large enough 'window' area to see through. The D/S rotors will actually have reduced surface contact area (which helps braking) vs a stock/solid surface rotor; can't be serviced (turned down), + are known to form stress cracks.

A good set of brake pads, flex lines, proper master cylinder, properly adjusted rear brakes, & an adjustable valve plumbed inline to the rears to help dial in bias if necessary is a solid brake package. The OE type set-up also has the benefit of easier to source parts when on the road if something were to need repair.

[weq92f]

Originally Posted by SCOTI

...<snip>...
As far as drilled & slotted rotors? They're lust a look @ me thing so the 15" wheels used would need to have a large enough 'window' area to see through. The D/S rotors will actually have reduced surface contact area (which helps braking) vs a stock/solid surface rotor; can't be serviced (turned down), + are known to form stress cracks.
...<snip>...

.

I put D/S rotors on my DD once years ago: 5 series sport. Will not do it again. Be aware that during the rotor seasoning and pad break-in, these things make a very odd sound which was quite concerning at first for me. Not to worry, sound diminishes quickly. I got the stress cracks near end of pad life and these rotors I purchased were a higher end brand.

-Kevin

[leftybass209]

I couldn't recommend drilled or slotted rotors... you just lose braking surface area. The braking system on these trucks remains largely unchanged from 71-96. I daily drive a 72 long bed with truck rallies and drop spindles in a densely populated area, and braking has never once made me nervous in modern traffic or left me wanting "more" stopping power. That said, its a relatively stock truck. If I increase power, i might look at some different brake options.

Side note: I originally had 2 inch CPP drop springs with the spindles and the truck could not be aligned and chewed tires fast. Some guys say these trucks can be aligned with 2 inch springs but not without longer A arms in my case. I decided to use Moog brand stock length springs on this build and the ride difference was immediately noticeable. I don't know what the spring rates are, but the CPP coils were softer and the CPP shocks didn't feel quality at all.