Pad knock back?

[jlwdvm]

Is pad knock back mainly a problem with cars with c-clip axle retention systems? Currently looking at getting a Strange S60 for my 69 Trans Am clone track car with their S-Trac carrier. I already have Wilwood 6-piston brakes with 12.88" slotted rotors up front. I'm wondering if I could go with the matching 4-piston calipers for the rear, or if I should go with their D-52's. The car will eventually see a fair amount of road course time and the occasional auto cross. Thoughts?

[csouth]

The best solutions for you would be a full floater or floating calipers. A lot of the people here that are in the market for rear ends have chosen the full floater for that same reason.

[jlwdvm]

I thought about that, but was wondering if the floating calipers would give the same benefit.

[Apogee]

Not really...floating calipers are good at accommodating axial end play up to a point, however angular deflections pose the same issue with floating calipers as they do with fixed calipers, with the rotor essentially behaving like a prybar between the brake pads. The best way to address angular deflection is to stiffen up the system, hence the popularity of full-float setups, although certainly some brake setups work better than others given the pad size relative to the axis of deflection.

Tobin
KORE3

[eric1967]

Not really...floating calipers are good at accommodating axial end play up to a point, however angular deflections pose the same issue with floating calipers as they do with fixed calipers, with the rotor essentially behaving like a prybar between the brake pads. The best way to address angular deflection is to stiffen up the system, hence the popularity of full-float setups, although certainly some brake setups work better than others given the pad size relative to the axis of deflection.

Tobin
KORE3

Tobin do you have a brake set up for a full-float rear end?

[dontlifttoshift]

Virtually any caliper can be made to work with a floating rear hub.

[alocker]

I'm curious why nobody has come up with some machined c-clips to adjust the amount of axle movement?

[dontlifttoshift]

They exist, I don't remember from who, but I have seen them on here some where.

Tight c clips will help but won't solve the problem completely.

[rrelco]

I had my diff shop weld material to my axels to fill the gap, i then installed a 10 psi residual valve and pad knock back is gone....

[jlwdvm]

My Boss has a Torsen differential with the stock floating rear calipers and I haven't experienced any braking issues while on track. Is a full floater rear overkill for my application?

[dontlifttoshift]

Yep.....but I like overkill.

The axle endplay on an 8.8 rear end is ridiculous but the factory calipers soak it up just fine. I wouldn't change a thing on your boss, there are many guys going fast with basically stock rear brakes on the S197 platform.

Back to your original post, the S60 ships standard with 9" style ends _ I think_ so no c-clips required. With the tapered bearings and a floating caliper you will be fine as far as knockback is concerned. If the budget allows, a full floating axle is stronger in every way and will allow for a fixed caliper that offers better pedal feel, more choices in caliper sizing and the ability to match front and rear calipers and possibly brake pad sizes.

[AutoX_a_Truck?]

I'm curious why nobody has come up with some machined c-clips to adjust the amount of axle movement?

After searching for c-clips with various thicknesses but not quite finding the exact thickness I needed for my application (many thicker designs were intended for aftermarket style axles) I ended up using hardened valve spring shims machined to fit as shims. Factory end play was quite a bit and more on one side than the other. Now end play is basically zero. It helped with pad knock some, but it's not a 100% fix.

[Sparky65]

I'm curious why nobody has come up with some machined c-clips to adjust the amount of axle movement?

Tom's Differentials sells parallel ground c-clips in various thicknesses for GM 12-Bolt rears.