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Discussion Starter · #22 ·
Hooker06, I gotchu! This is what I wrote up for my friends. It's not in a spreadsheet, but only because all of these can be found with a quick rockauto.com search. Pretty easy, which is part of the appeal. I hope this helps.


"Welcome gentleman, to another addition of useless comparisons and car facts! Today we cover, OEM 4-piston calipers. Why? Well if you run 17/18" wheels, it becomes a real thing and it never hurts to know what "custom" applications can be created on the cheap. This is possible because almost all these calipers are sold as remans with plenty of rebuild parts available on the cheap, which creates the opportunity to provide the performance of a "BB kit" at a fraction of the cost (with perhaps some adapters from your friends with machining tools ;-)

The other reason? It goes without saying for us track folks that a 4-piston can often stop a car as well or better than a 6 or 8 piston caliper. Lots of tests, conjecture, opinion and locked-away OEM research on what is best resides in the ether here; but the consensus for the track is that at/under 14.5 " rotors, 4-piston is enough, which I'm guessing is why you see the massive calipers on late model stuff paired with 15-16" rotors (the new Porsche Cayenne comes to mind). But why you ask? Well, mainly because of heat and the amount of "coverage" a larger caliper like a 6-piston creates on a smaller 13-14" rotor.

At any rate, this evening I was sparked with the inspiration to finish a list I was working on during the early stages of my 944 LS build. I wondered, "what are the largest OEM 4-piston brakes I can get my hands on?" Since then I've learned that pad size can vary, and therefore piston size is not king-all in 4-piston performance, however, it's a good place to start. So without adieu, I give you what I've found so far. If you have any combos you think might make the list, send 'em to me and I'll research it. I had a hard time validating any BMW and late model Chevy truck piston diameters. So if you have that info, please share. Enjoy!

note these are all front caliper sizes
2018 Tacoma - 45.3/45.3 mm
1998 Supra - 43/43 mm
2004 LS430 - 43/43 mm
2008 WRX STI - 40/46 mm
2017 SS - 40/44 mm
2004 Evo - 40/40 mm
2004 CTS-V - 39.88/43.18 mm
1989 944 "Big Red" - 36/44 mm
2017 Camaro SS - 34.5/42 mm
2004 996TT - 36/40 mm

follow up notes

  • In theory the largest rotor one could fit along with any 4-piston caliper (if you insisted on 4-piston) would be ideal. I was thinking that could make the Supra 4-piston an interesting choice, since it had the largest piston size, but one of the smaller caliper bodies on the list.
  • It was also mentioned, however, if you sacrifice caliper size for rotor size, you may find even more performance out of a 2 or 1 piston setup; this has been argued by BMW and Jaguar, that I know of.
  • As Ben said "...the limit of braking force is dependent on the grip of the tires. So long as your setup is effectively dissipating heat, it's doing its job."
    • Caliper material, design (monobloc or two-piece), rotor size, pad size, all would effect that effective dissipation of heat I would imagine, but an important point to consider if we're splitting hairs "
 

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2015 Mystic Green Metallic (wife's car)
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Thanks brother--this is very interesting proposal that I've not thought about! Two questions if you have time. Call me slow but, I don't understand the size listing of x/y? Is one bore size and other caliber size? Second, any ideas on rear wheel calipers? Thanksl!!
 

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Discussion Starter · #24 ·
Thanks brother--this is very interesting proposal that I've not thought about! Two questions if you have time. Call me slow but, I don't understand the size listing of x/y? Is one bore size and other caliber size? Second, any ideas on rear wheel calipers? Thanksl!!
No problem, and that's not slow at all! I wasn't very clear in my email to my friends because we had been talking about it. The x/y numbers represent the bore sizes for the pistons, on each side of the caliper. Often times (like in 6-piston calipers), you'll notice the pistons are different sizes from top to bottom on each side of the caliper. It should be noted though that they will be mirrored exactly from side to side e.g. if on the left side of a 4-piston caliper the top bore is 40mm and the bottom is 38mm, so will it be on the right side.

I haven't done this work on rear caliper setups, simply because the type of vehicle and bias needed is so variable. Most of the time folks will go for the largest rotor and caliper in the front, simply because the hydraulic bias on most cars/trucks is considerably up front. My guess is with your setup, you could do well with an OEM-like single or dual piston, with a large rotor diameter for the rear. I would think in a truck the bias would be close to 75/25 front. Anyway, I hope this helps.
 

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2015 Mystic Green Metallic (wife's car)
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Thanks again Track Rat!! Very exciting for me as I never knew about the "split" bore size on calipers!! Most educational and helpful!! Thanks for this and Happy Thanksgiving!!
 

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Couple of notes on the Manual PDF List ..

Clutch, brake, accelerator pedal assembly .. part number 42344394 is for a Sonic ( plain black pedals, not aluminum racing pedals ) .. not sure if this is even an interchange part.

Differential assembly .. 92293118 is for the Automatic, 92283119 is the Manual 3.70 Differential assembly

Engine harness .. should be 92283228 ( typo )
 
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