I am getting ready to purchase a set of Stoptech ST-60 / ST-40's for my C6. What is the best size to use in the front with stock C6 Z06 wheels? Will the 380's fit ? Or are the 355's the best size to use?

Thanks for the help,
Charley

 

If you use an aftermarket wheel like a Forgeline or CCW, you can use an 18" wheel with a 380 kit. I think with the stock wheels you would have to move up to a 19" wheel to clear the 380's.

 

This is comparing apples to oranges, but it may be a data point to help you.

I have the 355 front rear and C5Z rears for over both. The clearance is tight (Alcoa's provide about 0.180" and Speedlines provide about 0.080" clearance between inside of spoke and caliper). I bought my ST-60/ST-40 calipers used from JDillon. He can tell you what wheel setup he was running as he had a C6Z.

 

I ordered ST60/40 kit for C6 Z06 with 380mm fronts. I was told that it clears the cup wheels, which came with my '13 Z06 since it has F55 suspension. I am yet to receive the kit, but I'll definitely see if everything works out soon!

Another forum member, C6psi reported in another thread that he had to modify the A-arms for clearance in order for his (355mm) StopTech kit to fit. I sure hope this is not the case, and if it indeed is, I'll be very frustrated since no vendor who sell the kit even mention it!

 

Yes, the lower A arm needs to be modified on the outer lip of the ball joint. I had to shave off 0.060-0.090" of material (mostly casting seam material) to get the rotor to clear the A arm from lock to lock. I can tell you from experience that if you don't clearance it correctly the first time, you will hear an aweful noise on the first test drive followed by sanding the aluminum ring off the inner rotor surface and more grinding on the A arm.... That part is no fun.

 

Himm, do you think it would be needed for the 380mm kit, too? I am wondering if it would be any different since the calipers are further away from the hub. Since you're saying the clearance issue is with the hat, I'm guessing I'll still have to deal with it. Oh well, at least I have all the air tools for a clean job...

 

I do believe its because of the hat and where the friction ring sits relative to the hub/suspension components and not the caliper placement. I doubt there is any difference between the 355mm and 380mm kit in that respect. IIRC, the instructions say to grind off material until you get 0.125" clearance with the suspension fully unloaded to ensure there is enough room with the suspension at full compression. I did this and had no issues my first time on the track. Just makes me nervous taking some structural material off the housing to the lower ball joint. I will take a look for any material cracks/failures before hitting the track this weekend.

 

Is your car Z06? This is seriously messed up. Well, StopTech states "Fits stock wheels" for the 355mm kit; they never said it "Fits A-arms", so I suppose they are not lying :P

If I knew about this, I could reconsider my purchasing decision..

 

You do have to trim some of the lower A arm. It will show how much in the instructions.

 

I don't really see a need for a 380mm personally, the ST40/355 kit continues to be the setup I recommend for customers! 380 is just a lot of weight, and you don't really need that much thermal capacity

 

I tend to agree with the above posters comments. Use the lightest brake that will still get the job done. In your case that would seem to be the 355mm disc. As mentioned, the instructions that come with your Stoptech brakes show where and how much to "modify" your suspension. I found that it was a very small amount, just a "trim". I predict that you WILL LIKE your Stoptechs, however, if you intend to use them severely, like at Road America, you WILL still need cooling, not bigger discs. Also, considering the total rotating mass, please buy/use the lightest WHEEL that will work. Most who race or track their Corvettes use 4X18" wheels.

 

No, I am only a base C6. Don't know if C6Z is different.

 

If you look up the installation instructions on the StopTech web page you can see how much trimming is required...It doesn't look to be a very big job. The trimming requirement was something that I discovered in my prepurchase research. The new brakes will be worth the effort.

Charley

 

You have to remove about 1/2 of an inch. Put the wheels on the car on the ground and try to roll it. Turn the wheels right and left and make sure it rolls. The car has to be on the ground to check clearance. You can put the wheel on when the car is off the ground and the rotors will not rub the A arms. I know I have said the same thing over and over.

 

I think the latest round of instructions say to allow for 1/8" clearance with the car off the ground. This worked for me and I sued feeler gauges until I got the complete clearance from lock to lock.

 

380s will not clear 18" stock wheels. They will clear 18" CCWs One thing to keep in mind is that Stoptech uses 355s on the front and rear with there std ST60 and ST40 kits, this allows you to carry one right and one left rotor as spares and they fit front and rear. JD

Sorry For the typo,

 

The 355's won't fit the stock C6 Z06 wheels???

 

Don't sweat the small stuff. ST developed their T1 kit on my C5Z for SCCA T1 racing using ST40 front and 41 rear. When doing the testing and developing at the race track on my car the ST engineer simply used a scotch wheel to take off a very small amount of non-structural material in about 2 minutes! Like the other poster said it was mostly parting flash that was removed and does not add to the structure of the A-arm. The removal amount is very small like tenths of inches or even less.

Now I'm racing a C5Z in T1 or T2 for 2013 on 355's. I don't think you want the extra capacity or the extra weight or the extra limit on wheel choices which add to your costs. I say this because when I ran OEM rotors I cracked them on the 3rd day and wore out carbotech XP16's in 2 days. My ST floating rings last me longer than 2 years of racing! I change pads only twice a year! Our minimum weight in T1 was 3180lbs. So there is a real world datapoint. ST does have T1 race kit for C6's. Our 2012 SCCA T1 national champion won on them. By the way the reason for more pistons is to reduce pad taper which leads to more knock-back issues. I only have 4 pistons using ST40's on front and ST41 rear and have almost no taper. ST60's would be even less taper but it is not much to write home about if there is any significant cost difference.

 

Thanks for your input! My car comes with the 19"/20" cup wheels, and I have more clearance than I'd ever need. Sure, I could change the wheels to smaller ones, but then I could also ditch those heavy seats, and while at it, put some headers to lose even more weight, etc., but there is no end to this. The car is a very good performer as is, and I don't want to get into a **** fight with myself.

The reason why I am getting this BBK is that it is next to impossible to cruise around with the race pads on stock C6 Z06 brakes during the season. One of the side effects of using 20 padlets is that they squeal individually, making a big choir, and it is simply unbearable. With the Stoptech brakes, I hope to lower the maintenance cost in the long run with cheaper pads/(2-piece)rotors, and if the squeal is half of what it was with the padlets, I could manage that in summer time (I hate switching pads all the time!). Another possibility is that if the heat capacity is large enough (and they should be with the 380mm rotors), perhaps I could get away with using Stoptech's own standard pads at tracks that are not demanding on brakes, which have 1300 degrees F heat treshold before they fade. Those pads are about $100/set, and if their initial bite is enough and the downside is just a bit premature wear, they could be even more cost-effective than carrying separate pads.

Lots of possibilities to play with. 380mm kit's ring is 17.75lb vs. 355mm ring's 15.5lb. Granted, moment of inertia is also impacted by a bit due to increased radious, but I don't think the difference is that much at all. We'll see!

 

You can buy 1 piece pads for C6Z OEM calipers and some pads are alot quieter than others. You go with a ST BBK if you want bling, heat capacity, and make up for a deficiency in your oem brakes. If you are not running them to capacity all you are doing is wasting money buying anything else. When a brake kit is 3-6 grand that is alot of pads. For the C5 , DBA made 2 piece rotors that improve over OEM in all benchmarks but yet are cheap. You get a little bling and a little more performance out of the OEM calipers that way. You may want to see if they have C6 sizes. With ST there are 2 different sets of pins that connect the hats to the rings. Call them quiet or loud, not floating or floating. Racers want them loud and floating because they perform better. Street people want them quiet and look like real race rotors so go for quiet pins. The difference is about 020 of length that allows the play. ST gives you the option while DBA may not have that option as i think they are a 2 piece hat and ring but fixed solid non-floating. some dealers don't know the difference and call all 2 piece rotors "floating". Do you homework to make sure what you want and what you get. I can't say enough good things about ST. You tell them what you want and they will make it happen but you got to do your homework and speak their language.