C5 front brake calipers on all 4 corners.

[beeman]

Has anyone seen this modification? I don't recall it. My garage is littered with C5 calipers...C5 base and Z06 calipers are identical (other than the color) BTW...
I will preface this by mentioning that I will have ABS, but I've torn out the junk C5 EBCM/ABS for a motorsports grade ABS system, probably the BMW MK60.
With the mid-engine layout and rear weight bias, I don't like the idea of the small single piston C5 rear calipers.
Looked at options including big brake kits. But I don't think the 2600lb GTM needs a big brake kit. It just needs more rear brakes.
So I'm installing the C5 stock front calipers on all 4 corners. One benefit of this is retaining the parking brake, that you would lose if you don't keep the rear C5 or C6 rotors.
To run the C5 front caliper on the rear, you only need a C6 rear rotor from the z51 or j55 package (this is completely compatible with the C5 parking brake which is a drum brake inside the rotor!), plus the C6 j55/z51 front caliper bracket to position the caliper appropriately on the rotor.
If I find that I have too much rear bias, I'll start with a more aggressive pad up front.
Worst case, I go bigger up front.

[Power Surge]

It's not stock calipers but I just put Wilwood six Pistons all the way around on my GTM. I used C6 z51 front rotors and C6 ZO6 rear rotors. I did have to do a little Machining on the rear caliper mounts and the knuckles, as the offset is not correct using the C6 rotors. If you look at my build post I'm pretty sure I talked about it.

[beeman]

It's not stock calipers but I just put Wilwood six Pistons all the way around on my GTM. I used C6 z51 front rotors and C6 ZO6 rear rotors. I did have to do a little Machining on the rear caliper mounts and the knuckles, as the offset is not correct using the C6 rotors. If you look at my build post I'm pretty sure I talked about it

Sounds like a great setup. I'm guessing the kit included Wilwood rear caliper brackets?

[Power Surge]

Sounds like a great setup. I'm guessing the kit included Wilwood rear caliper brackets?

No... I just used two front kits. Will wood doesn't make a six piston setup for the rear on the Corvette. But they do make a four piston setup for the rear. I just wanted the big six piston calipers front and rear from a visual standpoint. So to make the front setup work with the offset on the rear rotors I had to machine a little bit off of the Wilwood caliper mounts and then also machine a little bit off of the rear knuckle until the calipers were centered.

[VRaptor SpeedWorks, LLC]

If I'm not mistaken, Crash was running that setup (stock C5 front calipers on the rear) on the original GTM race car?

[crash]

Yes we ran the C5 front calipers all the way around on the FFR PDG GTM race car for quite a few years.

Because the weight distribution is much closer to 50/50 with the mid engine setup of the GTM we ran much more rear brake and that worked well. On front engined cars it is really astonishing how small the rear brakes can be due to weight transfer during braking.

We moved from the C5 setup to a Stop Tech six piston setup with all four corners being the same caliper a few years ago. The issue was that we could run 1) wider rotors which allowed for more rotor cooling 2) a race specific pad that was easy to source in multiple compounds, and 3) the calipers held up to more heat than the stock C5 calipers. We were having issues with melting the dust boots and seals on the stock calipers, and more heat was being transferred to the brake fluid as well and we were dealing with boiled fluid. We ran a fluid recirculating system to deal with the fluid issues, but since going over to the Stop Techs and moving to the 660 degree brake fluid we have had no further issues.

You will probably not see any of the issues we experienced since they only showed up after HOURS of full fledged, non stop racing as we were/are running endurance races with a minimum duration of 3 hours. We run multiple cooling fans and fresh air brake ducting as well, and we have been able to manage the brake issues to the point that we have no more issues.

Happy to help others out with this, and may have some parts available from the NOS on the shelf. You should not be having to modify anything to fit the C5 fronts all the way around. The only issue I can think of that may show up is caliper clearance to rim. We adjusted this with the use of small spacers for fine tuning, but also ordered rims with the correct offset so that we did not need to run the FFR provided spacers. Yeah this can all of a sudden get more expensive if you choose to do it the right way.

BTW Beeman- The MK60 unit is the one we have experimented with and I have two units sitting here on the bench waiting for install on the race car. Had a couple glitches on the test car which was one of the FFR PDG GTM driver's street GTM. Lots of things on the list yet to work on before that install, but it did work on the test mule and is a solid system.

[doug_porsche]

Just offering a different option.

https://www.shredjesse.com/1999-c5-c...-track-testing

easy to update to Brembo 4 pot Cadillac ATS calipers

[beeman]

Just offering a different option.

https://www.shredjesse.com/1999-c5-c...-track-testing

easy to update to Brembo 4 pot Cadillac ATS calipers

I went through that page as well, great info. I do like the ctsv option but don't think I'm going to need it, as Crash's PDG GTM experience showed. It is on my radar as a front upgrade if balancing is required.

[doug_porsche]

I read Crash's write up before I did the Cadillac ATS brakes, but I did it anyway for two reasons:

1. I figure it will totally eliminate braking issues on my 99% streetcar. This includes the 1 - 2 open track days a year and, living in Denver, I can come down ANY mountain road without worrying. (Example: when you come down the Pikes Peak road, they actually stop you and measure brake temps about halfway down)
2. The biggest reason I did it.... It was a fairly cheap way to upgrade the looks of the brakes! The WOW factor.

I thought the stock C5 brakes looked like the stock LS-1 motor in my car. It just didnt look sexy.

[crash]

"2. The biggest reason I did it.... It was a fairly cheap way to upgrade the looks of the brakes! The WOW factor."

This is really the only reason to change anything having to do with brakes on a street driven GTM.

Just an observation...

"Example: when you come down the Pikes Peak road, they actually stop you and measure brake temps about halfway down"

That is absolutely ridiculous! What, exactly, do "they" think they are going to determine by looking at brake temperature? And who makes the call as to what is "too hot"? I can boil fluid and lose all braking ability at relatively low temps with bad fluid and crappy pad compound, or I can have a vehicle that will absolutely astonish "them" that my brakes are still working at a given temperature. Probably more of a way to force vehicles to stop and take a "brake".