Difference between 38 and 40mm cobra's?

[93silverbulletSH0]

Optional reading(I ordered some autospecialty remanufactured cobra calipers for a 2001 mustang b/c they were dirt cheap. What ended up coming was what looked like a mach 1 caliper. I took the pads out to see that they were PBR brand, as were the dust boots, and the pistons measured 38mm. All 38mm piston calipers from a mustang should have the cobra engraving right? What I think is these are new from PBR b/c autospecialty didn't have cores to rebuild to start, I have heard of that happening.)

Real question(What is the difference between 38mm and 40.5mm cobra calipers as far as performance and braking experience? Thanks)

 

[FoeSho]

optional answer PBR makes all of the dual piston and 4 pistons calipers for GM and Ford maybe others too , not sure. If they come from PBR directly, they will nto have the engraving. Also did you know those same calpiers you have will bolt right on to a 3rd gen firebird and camaro? Not too many people know that. Its an upgrade for the GM guys

 

[93silverbulletSH0]

I didn't know that, that's interesting. Do you have the "real answer"?

 

[yamahaSHO]

optional answer PBR makes all of the dual piston and 4 pistons calipers for GM and Ford maybe others too , not sure. If they come from PBR directly, they will nto have the engraving.

If you get the caliper directly from PBR, it will say Baer on it.

IIRC, the ones without any writing are the ones that come on the Mach 1's/Bullitt Mustangs.

Also did you know those same calpiers you have will bolt right on to a 3rd gen firebird and camaro? Not too many people know that. Its an upgrade for the GM guys

Bracket depending.... Those calipers work on just about any rotor out there. It is the bracket that provides proper mounting. These calipers are probably the MOST WIDELY USED caliper ever.

 

[93silverbulletSH0]

Well these have no writing but also 38mm pistons, meaning they are not Mach1's (38mm= before 98 and 40mm=99+). Why would calipers directly from PBR say baer on them? Just as Ford and etc. can specify what they say, so could Autospecialty. The PBR pads and PBR dust boots on a caliper in a box that is supposed to contain a caliper remanufactred by a company that also makes their own brand of pads and rebuild kits leads me to believe that they are new from PBR. Why wouldn't Autospecialty use their own stuff to rebuild it? I should have left that optional part out (or at least put it second ) b/c I have already drawn my conclusions about that part, it was just a background story leading up to what I really wanted to know... what difference would one experience between 38mm and 40mm cobra calipers. I hope I do not sould like a dick, just trying to get back on track, so to speak. Either way I do appreciate the previous input, and keep it coming.

 

[yamahaSHO]

I'm not going to lie, I didn't read that whole thing. Please use paragraphs...

 

[Shoaz]

Changing between 38mm and 40mm pistons will change the brake bias. Todd worked this all out at one point and as I recall one of them is very close to stock and the other moves the brake bias forward (so IIRC 38mm is close to stock, which is also the most common for the PBRs).