Speedtech AFX + Wilwood Discs = wheels not fitting

[Astro Blue]

Car is a 1970 Nova, I have the Speedtech stock subframe package with AFX spindles. I have the Wilwood SLC56 disc breaks. These are supposed to clear 17" wheels, but they are not clearing. Wheels are American Racing Torque Thrusts 17" x 8" with 5" backspacing. Anyone been through this before?

[JLMounce]

Not all ~13" rotor and caliper combinations will fit inside 17" TTII's. The problem is how the barrel is mated to the wheels spokes. If you look inside the wheel barrel you'll see there is a shelf where the spokes blend to the hoop. This causes the 17" wheel to act more like a 16" wheel, especially if the caliper is located forward in the wheel hoop, closer to the spokes.

I have the same wheels and have the same issue, which until I'm ready for a wheel change, keeps me stuck with factory type 11" rotors with D52 calipers. I've even tested the standard C5 kit from Kore3 and there's not enough hoop clearance with these wheels.

[Astro Blue]

Not all ~13" rotor and caliper combinations will fit inside 17" TTII's. The problem is how the barrel is mated to the wheels spokes. If you look inside the wheel barrel you'll see there is a shelf where the spokes blend to the hoop. This causes the 17" wheel to act more like a 16" wheel, especially if the caliper is located forward in the wheel hoop, closer to the spokes.

I have the same wheels and have the same issue, which until I'm ready for a wheel change, keeps me stuck with factory type 11" rotors with D52 calipers. I've even tested the standard C5 kit from Kore3 and there's not enough hoop clearance with these wheels.

So no amount of offset or backspacing can fix this with the TTII’s. So I either go to an 18” wheel, or change spindles.

[JLMounce]

That's correct, you'd have to space the wheels out something like 2" to get to the section of the wheel hoop that is more like a standard 17" hoop. At that point the wheel is likely never going to sit inside the wheel well. Not without changes to the hub to hub distances anyway.

You can see the shelf I'm talking about here.



I'm not incredibly familiar with the AFX knuckle, but my understanding is it has a hub mounting pad designed for a slip on rotor. That being the case, it's going to push the rotor face and the caliper closer to the spokes, right where that shelf is. In that configuration, my educated guess is that Wilwood's 12.19" rotor and 4 piston caliper combination is probably all you can fit.

I use the SC&C stage 2+ kit with factory spindles and integrated hub rotors. The integrated hub keeps the rotor face and caliper inboard and away from the spokes, gaining room as they sit behind that shelf.

So there are three total options. Downsize the rotor and caliper package, order different wheels, or change to a stock type knuckle. The last option obviously requires a brake package change as well.

[Astro Blue]

I cant downsize the rotor because there arent any other options with the Speedtech AFX spindle. What I am going to do is get a Wilwood AFX spindle that can work with a 11.75" disc that is said to clear 14" wheels.