C4/C5 Brake Adaptors

[69importkilla]

I was digging thru my garage and came across some Speed Tech made aluminum brake adapters I purchased long ago for my 69 Camaro. So I started doing some research and discovered Speed Tech doesn't sell them anymore.

Now the back of the adapters say C4 rotor on them, but the instructions mention the C5 set-up. Can this bracket be used for both?



Can anyone chime in who has some experience or knowledge with these? By my reading it sounds like the C5 route is the way to go.

[Amatouring]

They use 13" C4 rotors with C5 calipers. More 17" wheels will fit that combo than all C5 components.

[69importkilla]

So can I use all C5 stuff if it will fit?

[Amatouring]

No- those brackets are for the c4 c5 combo.

[Apogee]

The C4 rotors measures a true 13" diamter, versus only 12.79" [325mm] for the C5, and the axial offsets are different, as well as the disc thickness, so you must use those brackets with the 1988-1996 13" C4 rotor and either C5 or C6 2-piston caliper with the JL9 pad abutment brackets. The pads should match the abutments, so D731 C5/C6 spec.

Tobin
KORE3

[69importkilla]

So thanks for the information everyone.

Now the real question. Obviously I would like to continue on this route. I have everything else done, now I just have to purchase the rotors and calipers. Are there any pros/cons to using this set-up?

Please correct me if I'm wrong but dont the KORE3 versions use all C5 equipment? If so why would someone do it that way versus the C4/C5 hybrid set-up?

[gort69]

I have that exact setup on mine. I'd be willing to bet it was designed to clear AR TTII wheels, which is what I have.

Pro - It works great and provides better wheel spoke clearance than the full C5 setup, elimantes the need for wheel spacers

Con - The C4 13" rotor is 1.10" thick vs. the C5 rotor at 1.25"
The C5 pads and abutments are designed to be used with a 1.25" rotor so you shouldn't
let your pads wear down to the nub.

I'm sure Tobin has some other thoughts.

[Apogee]

I have that exact setup on mine. I'd be willing to bet it was designed to clear AR TTII wheels, which is what I have.

Pro - It works great and provides better wheel spoke clearance than the full C5 setup, elimantes the need for wheel spacers

Con - The C4 13" rotor is 1.10" thick vs. the C5 rotor at 1.25"
The C5 pads and abutments are designed to be used with a 1.25" rotor so you shouldn't
let your pads wear down to the nub.

I'm sure Tobin has some other thoughts.

Al has the gist of it...better wheel clearance with the deeper offset rotor. While 28mm [1.1"] thick rotors are at the limits of what the C5/C6 calipers can be safely run at, there are plenty of guys running that exact combination with no known failures due to the thickness as far as I know. The KORE3 kits are pure C5/C6 kits to maximize thermal capacity, maintain interchangeability between the smaller and larger kits, and leverage the excellent aftermarket support offered the C5 and C6 applications. The down side is the shallower rotors and larger associated caliper overhang dimensions.

Tobin
KORE3

[jpgolf14]

The C4 HD rotor is actually a heavier rotor than the C5/C6. It has more thermal mass. The friction surfaces are thicker. However, as a result the surface area of the cooling vanes is smaller, at least on a relative basis. It also has a strangely shaped entrance into the vanes from the hat area. It does not seem as efficient as the C5/C6 rotor, but that is not something you can usually eyeball. It would be very interesting to do a real test of the heat rejection of both rotors. I suspect they are pretty darn similar with all factors considered.

Its really a shame they are only 1.1" thick which screws up fitments on modern calipers. However I will suggest one possible solution. You can get titanium shims to go in between the pad and caliper. This will get rid of the 1.25" caliper on a 1.1" rotor issue as well as providing a side benefit of being a thermal break between the pad and caliper. You might be surprised that these shims are not as expensive as you may think.

John

[69importkilla]

Again, thanks guys for the information. Thats what I like so much about this site. You dont just get yes or no answers, you get some theory behind it as well.

@ John, where can I source these shims from?

Also while we are at it, any sources for these C5 calipers? Should I get them out of a wrecking yard or new/rebuilt?

[jpgolf14]

@ John, where can I source these shims from?

Also while we are at it, any sources for these C5 calipers? Should I get them out of a wrecking yard or new/rebuilt?

I have never used them personally, but Hard Brakes gets good reviews.

They are available in stainless or titanium.

http://hardbrakes.com/index.php?main...th=6_7_140_624

The stainless are 3.2mm and the titanium is 1mm.

Now ideally a 2mm thick shim would be best for your situation. Maybe contact them to see about making a custom shim.

John

[gort69]

Also while we are at it, any sources for these C5 calipers? Should I get them out of a wrecking yard or new/rebuilt?

Depends if you want new or used. Kore3 has very reasonable prices for new.http://www.kore3.com/products.php?cat=25 You can find them used on ebay all of the time, you could buy rebuilts from your auto parts store (core charge likely) or you could check corvette forum classifieds. I prefer new.

[srh3trinity]

I would consider new calipers. I bought some second hand for a really nice deal that were C6 Z51's. They are powdercoated red and it is going to take a lot of time and work to get all of the flaked and beat up powdercoat off. Kore3 has some nice ones that have their logo and a nice clean color that they sell. I would rather have those than mine that say "Corvette"