1993 Quad4 GTZ: Project WTF

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Re: 1993 Quad4 GTZ: Project WTF

Postby themixer » Sat Jul 16, 2016 11:40 am

$1800 USD!!!! you can buy a house in canada for that much



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Re: 1993 Quad4 GTZ: Project WTF

Postby woody90gtz » Sat Jul 16, 2016 12:27 pm

Only a 12.8 rotor? F that! That's more than I have in a 13.4 setup at all four corners!


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Re: 1993 Quad4 GTZ: Project WTF

Postby DanteGTZ » Sat Jul 16, 2016 1:22 pm

Yeah, but 6 pistons on each caliper...... ;)


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Re: 1993 Quad4 GTZ: Project WTF

Postby woody90gtz » Sat Jul 16, 2016 4:37 pm

Which usually add up to less piston diameter than double or single big pistons...and reduced brake force...

Remember a six piston fixed would only be like a 3 piston floating. And they have to make the pistons smaller to fit them in the caliper.

Just for s&g I did the math on the stock Beretta single piston caliper vs the Wilwoods:
3.88" area - stock single piston 92 Beretta caliper
3.54" area - Wilwood 4-piston Cav/Beretta kit (9% reduction vs stock)
4.04" area - Wilwood 6-iston Camaro kit. (4% increase vs stock)

So you'd actually be better off with a stock caliper on a bigger rotor than the Wilwood kit. Which means the N-body calipers is probably even better...

4.37" area - Nbody single piston (12% increase over stock Beretta, 19% increase over Wilwood kit)

Hydraulics are all math, and the numbers don't lie. So the upgrade people feel when they swap to the Wilwood kit is the leverage on the bigger rotor (and/or pad friction). So a stock caliper with a bigger rotor would be an even better upgrade. Hmmmmm


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Re: 1993 Quad4 GTZ: Project WTF

Postby nocutt » Sat Jul 16, 2016 9:53 pm

woody90gtz wrote:Which usually add up to less piston diameter than double or single big pistons...and reduced brake force...

Remember a six piston fixed would only be like a 3 piston floating. And they have to make the pistons smaller to fit them in the caliper.

Just for s&g I did the math on the stock Beretta single piston caliper vs the Wilwoods:
3.88" area - stock single piston 92 Beretta caliper
3.54" area - Wilwood 4-piston Cav/Beretta kit (9% reduction vs stock)
4.04" area - Wilwood 6-iston Camaro kit. (4% increase vs stock)

So you'd actually be better off with a stock caliper on a bigger rotor than the Wilwood kit. Which means the N-body calipers is probably even better...

4.37" area - Nbody single piston (12% increase over stock Beretta, 19% increase over Wilwood kit)

Hydraulics are all math, and the numbers don't lie. So the upgrade people feel when they swap to the Wilwood kit is the leverage on the bigger rotor (and/or pad friction). So a stock caliper with a bigger rotor would be an even better upgrade. Hmmmmm


Hi Woody,
You are violating a simple rule; all else is simply not always equal. The math may be on point I don't doubt it actually, but many of the guys doing these swaps do they race? If they do then there is absolutely more to it than the math (...although I never had a Wilwood kit, so u may be on to something).

IMHO Tires, Tires, Tires...pads, pads, pads...did I mention tires? lol Often enough after doing a brake kit...you are more than likely getting tires...the feel is actually very quantitative imo, so is pad selection. If the Wilwood allows for better class of pads with enough surface area and good compound tires then I will have to disagree with the bolded statement above... :D

edit: hope no one is putting 6 piston calipers on their stock cars btw?



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Re: 1993 Quad4 GTZ: Project WTF

Postby Cliff8928 » Sat Jul 16, 2016 11:54 pm

DanteGTZ wrote:John, you need something like this -- http://wilwood.com/BrakeKits/BrakeKitsP ... Brake+Rear


You can't use that or most of the F-body kits because it uses brackets attached to the 4 hub mounting bolts.

Kore3 does make adapters to use any 97-13 Corvette setup on the N-Body spindle though. And I have drilling jigs to re-drill 5x120.67 rotors to 5x115. I also have a complete C6 front brake setup on the shelf :evil:


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Re: 1993 Quad4 GTZ: Project WTF

Postby DanteGTZ » Sun Jul 17, 2016 9:22 pm

woody90gtz wrote:Which usually add up to less piston diameter than double or single big pistons...and reduced brake force...

Remember a six piston fixed would only be like a 3 piston floating. And they have to make the pistons smaller to fit them in the caliper.

Just for s&g I did the math on the stock Beretta single piston caliper vs the Wilwoods:
3.88" area - stock single piston 92 Beretta caliper
3.54" area - Wilwood 4-piston Cav/Beretta kit (9% reduction vs stock)
4.04" area - Wilwood 6-iston Camaro kit. (4% increase vs stock)

So you'd actually be better off with a stock caliper on a bigger rotor than the Wilwood kit. Which means the N-body calipers is probably even better...

4.37" area - Nbody single piston (12% increase over stock Beretta, 19% increase over Wilwood kit)

Hydraulics are all math, and the numbers don't lie. So the upgrade people feel when they swap to the Wilwood kit is the leverage on the bigger rotor (and/or pad friction). So a stock caliper with a bigger rotor would be an even better upgrade. Hmmmmm


Another factor I'm not sure your considering entirely is the floating/fixed caliper. A fixed caliper has a much higher efficiency than that of a floating. That being said, I wonder if the 9% discrepancy in your figures can be made up in efficiency in the fixed caliper. Those calculations represent maximum potentials, which aren't directly translated to real world operation. Thoughts?

For my money, the Wilwoods feel and respond fantastically. When we drove the Cherohala Skyway in '14 my stock brakes were almost unable to stop the car on some of the longer downhills. Brake fade was horrible. I literally had to stand on the pedal to get only marginal performance. The same trip with my Wilwoods was a joy. Absolutely no brake fade and the harder I pushed, the harder the brakes clamped.

For the amount of fab/machine work you'd have to do to get a factory caliper mounted on a larger rotor, I'm not sure it's worth more than the Wilwood kit. Plus being able to keep a 5x100 pattern on all 4 corners is appealing to myself. Same thing with the axles - being able to run factory L-body axles with the Wilwood kit keeps things simple to those that don't need anything more stout. JMHO, but the rotor material, caliper construction, and overall detail given to the Wilwood kit gets my vote. Geoff has proven the kit can be had for sub $800.

Not dogging the N-body setup at all, I'm just extremely happy with my purchase.


1993 Quasar Quad4 GTZ - Project WTF
1993 Garnet Quad4 GTZ - GTZed-Eh? - SOLD
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Re: 1993 Quad4 GTZ: Project WTF

Postby 3X00-Modified » Mon Jul 18, 2016 10:54 am

Oh and btw, My Camaro caliper that bolts directly to the N-body Knuckle is the 2000 era caliper, so the 94 one is not compatable. They do have a few Willwood kits for the 2000 Camaro but they are HUGE and expensive. My desired result is to find a 12" Camaro rotor that is lighter than 20lbs that I can run, I say that because I know I can fit this setup behind my 15" drag wheels... Any larger of a caliper/rotor combo and it wont work.

Second to that I'm researching and trying to find a way to get a 1" bore master in my car vs the 24mm... Yeah i know not a huge difference but going from original of 22mm to the Lumina 24mm was a big change so I think going from 24mm to 25.5mm may be just that little bit I'm missing.

It would be a one and done if I deleted the ABS... But I'm not about to do that ;)



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Re: 1993 Quad4 GTZ: Project WTF

Postby 3X00-Modified » Mon Jul 18, 2016 11:26 am

if I did this the same as you did, the F-body caliper is 4.81 square inches per caliper... the pistons are 1.75 dia and there are two per.



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Re: 1993 Quad4 GTZ: Project WTF

Postby woody90gtz » Mon Jul 18, 2016 11:51 pm

nocutt wrote:IMHO Tires, Tires, Tires...pads, pads, pads...did I mention tires? lol Often enough after doing a brake kit...you are more than likely getting tires...the feel is actually very quantitative imo, so is pad selection. If the Wilwood allows for better class of pads with enough surface area and good compound tires then I will have to disagree with the bolded statement above... :D

Oh agreed on pads. I underestimated how much a friction change makes a difference. A friend on NastyZ game me a spreadsheet several years ago that lets you calculate actual brake torque. And pad CoF made a bigger difference than rotor diameter...

Here's the attachment with the inputs set up for my Beretta now: Stock 92+ front brakes, Neon rear brakes, Lumina master cylinder
(Ignore the pedal input force and the pedal specs - I just adjusted them until I got to 1400psi front line pressure, which I have measured myself twice. I also adjusted the rear mc diameter to show the bias I measured in the master)

Brakemath beretta.xls
(28.5 KiB) Downloaded 26 times


It shows the front capable of braking at appx 1-1.1/1.3-1.4 G-forces (16,432-21,127in-lb brake torque) with FF coded pads (.35/.45 CoF), and 1.3-1.4/1.5-1.6 (21,127-25,821tq) with GG coded pads (.45-.55 CoF)

Most pads are FF. I'm pretty sure the ones on my Beretta are. So given the DOT range of the FF pads on it, my car will brake between 1.0-1.4 negative g-forces...let's call it 1.2g. If my guess of about 58/42% front/rear weight bias is right, that's 84% front and 16% rear braking at 1.2g.

At the rear it shows with the crappiest FF pad possible (.35 CoF) the brake torque is 4,436...well above the maximum 3,870 required at 1g braking...past 1g the required rear brake required drops because of additional weight transfer.

DanteGTZ wrote:Another factor I'm not sure your considering entirely is the floating/fixed caliper. A fixed caliper has a much higher efficiency than that of a floating. That being said, I wonder if the 9% discrepancy in your figures can be made up in efficiency in the fixed caliper. Those calculations represent maximum potentials, which aren't directly translated to real world operation. Thoughts?

For my money, the Wilwoods feel and respond fantastically. When we drove the Cherohala Skyway in '14 my stock brakes were almost unable to stop the car on some of the longer downhills. Brake fade was horrible. I literally had to stand on the pedal to get only marginal performance. The same trip with my Wilwoods was a joy. Absolutely no brake fade and the harder I pushed, the harder the brakes clamped.

For the amount of fab/machine work you'd have to do to get a factory caliper mounted on a larger rotor, I'm not sure it's worth more than the Wilwood kit. Plus being able to keep a 5x100 pattern on all 4 corners is appealing to myself. Same thing with the axles - being able to run factory L-body axles with the Wilwood kit keeps things simple to those that don't need anything more stout. JMHO, but the rotor material, caliper construction, and overall detail given to the Wilwood kit gets my vote. Geoff has proven the kit can be had for sub $800.

Not dogging the N-body setup at all, I'm just extremely happy with my purchase.

I have also read fixed is more efficient than floating, but I've never seen numbers. I'd love to find out what it actually is. A good functioning sliding caliper loses very little compared to a fixed, but you have to keep it maintained. Most OEM calipers are sliding because of how they conform to flex (knockback). Fixed calipers have more of a problem with pad knockback on an axle that has any flex (ie spindle pin or sealed wheel bearing) because they flex pushes the pistons back in their bore and the next step on the pedal has to overcome that distance and then apply pressure, so you get a pedal that's a lot lower. Very common in autocross with heavy lateral-Gs.

I'm sure there is a huge difference in brake fade with the Wilwoods, that's where they will really shine. But the difference in fade is in the mass of the rotor. A bigger rotor with a stock caliper would do the same. A thicker rotor helps with fade, and a bigger diameter rotor helps with brake torque and fade. The trade off there is unsprung rotational weight.

I'm not dogging the Wilwood kit either. They are nice parts that work & look great. But I'm cheap and would go another route...mostly because to me half the fun is figuring stuff out. haha

3X00-Modified wrote:Oh and btw, My Camaro caliper that bolts directly to the N-body Knuckle is the 2000 era caliper, so the 94 one is not compatable. They do have a few Willwood kits for the 2000 Camaro but they are HUGE and expensive. My desired result is to find a 12" Camaro rotor that is lighter than 20lbs that I can run, I say that because I know I can fit this setup behind my 15" drag wheels... Any larger of a caliper/rotor combo and it wont work.

Second to that I'm researching and trying to find a way to get a 1" bore master in my car vs the 24mm... Yeah i know not a huge difference but going from original of 22mm to the Lumina 24mm was a big change so I think going from 24mm to 25.5mm may be just that little bit I'm missing.

It would be a one and done if I deleted the ABS... But I'm not about to do that ;)

Jon, you're talking about pedal travel vs master diameter I'm guessing? Because the extra stopping power of the Lumina 24mm vs the Beretta 22mm is not from the piston diameter, it's from the extra pressure out back. A bigger bore master actually reduces line pressure for a given input force. (PSI - Pounds per Square Inch). So 100lbs of force divided by less square inches (smaller bore) = more PSI. A bigger bore master will bring the pedal higher off the floor though if yours is really low due to bigger pistons.




So - long post, but I want to make sure everybody has this stuff right. Some of it is counter-intuitive. I've got a pretty good handle on it now though, because I did a ton of homework on the subject as I was fighting issues with my Camaro brake project in 2007. Download the excel file and play with different combinations in there.


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Re: 1993 Quad4 GTZ: Project WTF

Postby woody90gtz » Mon Jul 18, 2016 11:56 pm

Hey Jon, can we split this into a brake topic actually? Since I unintentionally kinda hijacked the build thread! haha


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Re: 1993 Quad4 GTZ: Project WTF

Postby 3X00-Modified » Tue Jul 19, 2016 6:00 am

I'll see what I can do at work with this topic... and I know that the bias is most of the reason you swapped masters but I also did it for the larger bore because of my increased piston area when using the F-body setup. I noticed less travel with this master vs a stock one so I can only assume increasing the bore size again will produce the same result and get me a higher pedal. I would probably use the same bias valves in whatever I end up with for a master cylinder.

Sent from my Nexus 5X using Tapatalk



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Re: 1993 Quad4 GTZ: Project WTF

Postby bonecrrusher » Tue Jul 19, 2016 10:47 am

woody90gtz wrote:I have also read fixed is more efficient than floating, but I've never seen numbers. I'd love to find out what it actually is. A good functioning sliding caliper loses very little compared to a fixed, but you have to keep it maintained. Most OEM calipers are sliding because of how they conform to flex (knockback). Fixed calipers have more of a problem with pad knockback on an axle that has any flex (ie spindle pin or sealed wheel bearing) because they flex pushes the pistons back in their bore and the next step on the pedal has to overcome that distance and then apply pressure, so you get a pedal that's a lot lower. Very common in autocross with heavy lateral-Gs.


I have seen people complaining about pad knockback in the Pro-Touring world.

Would the pad knockback with a solid rear axle be more noticeable then an IRS?

Reason I ask - is because with the Fixed C6Z brakes and IRS in the Vette - I have never noticed it while autocrossing, on the road course, or in the twisties.


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Re: 1993 Quad4 GTZ: Project WTF

Postby 1988GTU » Tue Jul 19, 2016 12:23 pm

Past run in with both fixed and floating, I've noted the following.


Fixed tends to make an irregular surface or compromised (warped rotor, debris in between pad and rotor) braking system give the infamous steering/brake system counterbalance receptivity, or at least make it more pronounced.
Floating usually only reveals those irregularities when the pedal is applied, wheel bearing/balljoint due for replacement making the brake system absorb the worn out driveline parts.



Again the feedback noticed is based on my own past dealings with both styles.

Just my .02 regarding fixed and floating from personal experiences.


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Re: 1993 Quad4 GTZ: Project WTF

Postby 1988GTU » Tue Jul 19, 2016 12:34 pm

bonecrrusher wrote:I have seen people complaining about pad knockback in the Pro-Touring world.

Would the pad knockback with a solid rear axle be more noticeable then an IRS?

Reason I ask - is because with the Fixed C6Z brakes and IRS in the Vette - I have never noticed it while autocrossing, on the road course, or in the twisties.



Would you be referring to using snub for a braking event? Usually the taller pads have that issue.


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