ATS (C7 Base) brakes on a 91 Z28 - My Experience
 

Hi All!

I started autcrossing this year, and decided that my factory brakes, even with hawk pads and front slotted rotors, just weren't up to the task, and they took so much pedal pressure to slow the car. I also upgraded to 17"x9.5" wheels, so the factory brakes just looked ridiculous in there with the 10.5 rotors.
https://cimg2.ibsrv.net/gimg/www.thi...97a7418d0a.jpg

The new setup is a Brembro 4 piston caliper on a 12.6" rotor.
https://cimg3.ibsrv.net/gimg/www.thi...825b0eaef6.jpg

I plan to post a bunch of pictures and tips I am finding out along the way, but I have one somewhat urgent question I hope people can chime in on...

At this point I packed one of the new hubs and packed it using the Lucas Red N' Tacky grease I had on hand, now trying to set the retaining bolt tension, it may be in my head, but I swear the tackiness is making more resistance as I try to spin it. Is it just in my head?

Has anyone ever used the Lucas Red N' Tacky grease for their front wheels bearings? Any feedback? I am making myself worried where I may not need to be, but now I am contemplating going to get new grease, and totally flushing all the old grease out of my bearings and repacking them with something else, if this stuff is going to give me any problems...

Re: ATS (C7 Base) brakes on a 91 Z28 - My Experience
 

The label and various sites say the red and tacky is at least acceptable for wheel bearings so I'm going for it... it is a NLGI CG-LB.

Re: ATS (C7 Base) brakes on a 91 Z28 - My Experience
 

Hear is a sneak preview, the wheel is only on as a mock up, haven't actually torqued or hooked up the calipers yet...

https://cimg0.ibsrv.net/gimg/www.thi...1f395919e4.jpg

Re: ATS (C7 Base) brakes on a 91 Z28 - My Experience
 

So for some finings, tips, and questions: (Sorry if this gets long winded... read it... look at the pictures... skip over it... If it even helps one person in the future it will be worth my word vomit, lol! Also, I am not a professional, Just been working on my car, for the last 20 years, and I am a design engineer professionally, so I cant help the way my brain works...)

As may be evident, I don't think I took any unreasonable shortcuts, but I did make the conversion as simple as I could. With this in mind, I did complete it with the the steering/suspension fully assembled. This means I did not remove the spindles and do all cutting, grinding, drilling and tapping on a bench, vice, or drill press. I understood there was some risk, and if you attempt, you should consider the same risk! That said, I think it worked out pretty well this way. I bought Cobalt drill bits for all the final hole diameters to get as clean of a bore as I could, and to minimize of snapping a bit off anywhere. I did use a cutting lube intended for ferric metals on the drill bit, tap and in the hole. I admit, for some reason the drill bits were grabbing pretty badly on the first side I did, so I would frequently stop, reverse to clear any chips, and carefully try again for a little more depth. On the second side, I think I figured out the level of pressure so it wouldn't grab, and it turned out to be VERY LITTLE, you really had to be gentle with the drill bit. It didn't seem like it was cutting at first, but then chips started coming out of the hole. I also took a smaller drill bit wrapped it in a little masking tape and stuck it in the last shield hole, so I could use that and the spindle to have visual reverence for the direction my drill bit had to be in.

As tar as I tore things down:
https://cimg4.ibsrv.net/gimg/www.thi...b5c4b2cebd.jpg

The tap I used I believe was a pipe tap style which means it had a medium taper. For the blind hole at the top, I drilled the hole to a depth of 1.10" before going back and tapping it only about 2-3 mm more than I had to. I cannot screw a screw in flush without the bracket in place, but that's ok. Make sure you really clean out and blow out all the holes of chips before you run any fasteners in, I used brake clean and compressed air. I tried running in one screw before this, and the threads got a little funkey, not terrible, but I learned from my mistake! I tapped with a proper two sided tap holder only going a quarter turn at a time until I was in about 4-6 full threads, then I started going 3/4 of a turn at a time using an adjustable wrench. Again because I did it in place, I had a little less space to work with, but it was not terrible.

I wasn't sure of the amount of spindle that really needs to be cut away. I've seen all the pictures, but again doing it in place, I didn't want to have to remove the strut bolts and cause myself to need an alignment. Turns out the top wing doesn't have to be cut back far at all. I fond a thin point on it and cut parallel to the strut bolts, then cleaned it up with an angle grinder. I used a full length 18 (I think) TPI blade for this. For the bottom wing, a simple vertical cut within 1-2mm of the mounting lug seemed to be enough, I rounded it a little bit which gave a little additional clearance. The tricky cut was the steering stop. You basically need to cut almost as high as you can. You also need to cut down your Sawzall Blade so that it does not contact the steering stop. Even at full opposite lock, I needed to cut about 1.5-2" off. ALSO, AND MOST IMPORTANTLY, only cut with your Sawzall on the steering stop in the direction from the front of the vehicle, to the rear!!! I had that in mind at first, but needed to take a little more off, and stupidly ignored my own warning. I didn't lighten up my pressure enough at the end of the cut and I nicked the boot on my ball joint! Now I need to figure out how to replace that, and I'm pissed, save yourself the frustration... only cut away from it. Any tips on changing the boot? I bought another ball joint, but I don't think I damaged the joint itself, can I use a pickle fork to separate it and just put the boot from the new one on the old one, put it back together, and re-grease it? Once everything is cut, test fit everything. I also took a socket for the bottom caliper bolt, put the bolt through the hole, pulled it and pushed it up as high as it would go, and found I could not fit the socket in there, so I used the angle grinder to relieve the bottom a little more until I could fit the socket with a little clearance. I shielded the spindle itself, and hit the cut surfaces with a little black spray paint.

https://cimg6.ibsrv.net/gimg/www.thi...96cac46ea8.jpg

So I have read how many people just do not replace the shield, others modify it cutting away everything except the hub grease guard at the center. Looking at it, I thought it looked like the design was also intended to scoop more air towards the rotor to improve brake cooling, so I experimented with various designs, cutting a little away at a time, until it fit, but I felt it could still fulfill some of its original purpose. I understand it is much smaller than the new rotor, but I don't think it can hurt anything, and should help pull a little extra air into the center of the rotor, which is the intake for the cooling veins. Since the piece was a little larger that just the center grease catch, I bent it slightly to give it tension against the spindle when tightened. I also cleaned and treated the rubber rings behind it with some rubber cleaner and conditioner. I then centered it and zipped the one screw back in with some blue Loctite.

Thoughts? Well see if it gives me any trouble.
https://cimg4.ibsrv.net/gimg/www.thi...67fa057bc0.jpg
https://cimg9.ibsrv.net/gimg/www.thi...6e453e12db.jpg
https://cimg2.ibsrv.net/gimg/www.thi...80cb4a8e7f.jpg

I was worried about cutting off the steering stops, and having to come up with a solution to make up for it, but it turns out on my specific car, the steering stop on the A-Arm is tall enough that even after cutting off the leg on the bottom of the spindle, it still contacts it well enough, and it contacts inside of where the caliper mounting bolt is so there is no interference, or contact on anything I don't want there to be! So nice when something just goes your way isn't it???
https://cimg4.ibsrv.net/gimg/www.thi...564f04354f.jpg
https://cimg6.ibsrv.net/gimg/www.thi...7c0104d7f5.jpg

I take LOTS of pictures as I work thought projects so if there is anything in particular you want to see, ask!
https://cimg1.ibsrv.net/gimg/www.thi...c5548344e1.jpg
https://cimg3.ibsrv.net/gimg/www.thi...50b629c67b.jpg
About an inch of spoke clearance with my wheels and 2\" spacers
https://cimg5.ibsrv.net/gimg/www.thi...7320ed88ec.jpg

Tonight I hope to hook up the new stainless hoses and torque the calipers, but it is supposed to be about 100 deg F this afternoon in the Chicagoland area, so, we'll see how much I want to sweat. I do have an autocross even Saturday, so I has to get done!!!

Re: ATS (C7 Base) brakes on a 91 Z28 - My Experience
 

Which Rims are you using, OEM or Aftermarket, 16 or 17?

Looks great, new brakes are always fun to break in!

Re: ATS (C7 Base) brakes on a 91 Z28 - My Experience
 

They're the OE Wheels, aftermarket company, 17 x 9.5" size wearing 275's all around.

Most of the other details for the recent projects are on this thread:
https://www.thirdgen.org/forums/orga...e-minimum.html

Re: ATS (C7 Base) brakes on a 91 Z28 - My Experience
 

Oh... baby!!!

Finished install and just finished bedding the new brakes. The difference from stock, even with hawk HPS pads and slotted rotors, is staggering! More to come tomorrow.

https://cimg4.ibsrv.net/gimg/www.thi...0d4b12763a.jpg
https://cimg8.ibsrv.net/gimg/www.thi...3a086fc417.jpg

Re: ATS (C7 Base) brakes on a 91 Z28 - My Experience
 

Yea, so the improvement in braking performance is pretty EPIC! Last night when going to start my bedding process, I started applying the brake for a firm stop as I would have with my old stock brakes, and I instantly LOCKED both front wheels! From there it took a little getting used to the new feel of the brake pedal, but this decrease in needed pressure is exactly what I was hoping for! With my old brakes I had to press the pedal literally as hard as I could, and brace myself in the car to do it, and only then would I lock the front tires.

The drastic increase in front braking makes me glad I had previously put in one of the 1NCR5 springs in the stock proportioning valve to add additional pressure to my rear brakes. Without it the rear brakes would have been doing even less. With this configuration they still generated some heat during the bedding process, so they are working still.

I should also note, I used a good amount of the Permatex Orange Silicone Extreme with Ceramic Solids brake grease on the back and sides of the pads as well as on the pins, but so far there is absolutely no squeaking, squealing, grinding or anything! I don't recall if I mentioned it in this thread but I saw the note about autox in the description and went with the Hawk HP+ pads, then quickly got nervous they were going to be really annoying on the street, but so far so good. They do seem QUITE dusty though...

Re: ATS (C7 Base) brakes on a 91 Z28 - My Experience
 

I almost forgot, I need to give a huge shout out to Scott at bigbrakeupgrade.com. He answered more email questions than I care to admit before and after I placed my order with him. I bought my brackets, hubs, and hoses from him, the kit also included instructions on how to do this all. He was very responsive with communications, and once orders were placed, I got the parts really quick! He even completed the machining on my calipers and got them turned around to me really quick! Once I had all the information, and parts, the install really went pretty smoothly. First time mounting up the caliper, the rotor fit just about perfectly centered in it!.
https://cimg7.ibsrv.net/gimg/www.thi...c5560977b7.jpg

I should clarify that he has brackets for to different install methods. The way I did it used the standard hubs, not the 1LE ones which would have increased the track width by 0.35" according to Scott. I also used flat brackets, that required the calipers to be sent in to Scott to machine them for clearance with the brackets all the way up against them. This all results in the brake assembly sitting in closer to the car. The reason I went this route was that I was already using 2" wheel spacers, along with an additional 0.25 in flat spacer, so I was able to just remove the 0.25" spacer, and put the rotor in its place (hats measured 0.333" thick) so my track width only increased by 0.166" (0.083" on each side). The other method uses the 1LE hubs and a bracket with raised mounting bosses or washers, cant tell from the pictures, between the bracket and the caliper. This results in the disk and caliper being further out, hence the increase in track width, but does not require the caliper to be machined.

Resulting wheel stick out with my 275's on 17x9.5" wheels, 56 offset, and 2" spacers, front and rear:
https://cimg6.ibsrv.net/gimg/www.thi...dd862dd9e1.jpg
https://cimg9.ibsrv.net/gimg/www.thi...5d3530be20.jpg


I bought from Scott:
This hub and bracket kit - Gen V, VI Camaro SS, ZL-1 CTS-V2, C7 Z51 & Z06 Hubs and Brackets (bigbrakeupgrade.com)
These SS braided hose kit - GenV,GenVI Camaro, C5,C6,C7 JL9,Z51, ATS & XTS Stainless Braided Hose Kit FRONT (bigbrakeupgrade.com)
And this machining service to make clearance on the calipers for the brackets - Caliper Service (bigbrakeupgrade.com) (note this one is only a service, so you just need to contact Scott and let him know you want to have it done, and he will send you and invoice and give you instructions for sending in your calipers)

He also offers this "Partial Kit" That includes everything except the calipers and rotors, if you do not want to have to cut on your spindles and source the rest of the small parts - C7 JL9, Cadillac ATS Partial Kit (bigbrakeupgrade.com)

To round out the conversion, I got most of the rest of the parts actually off amazon:
Right Caliper - Left Caliper - Pads - Hardware - (You need 2)
Rotors - (The picture is wrong, but the PN is right, and you do need 2)

Small parts like bearings, seals, and dust caps I got from RockAuto, but there is not much to explain there... Just make sure you get the right bearings depending on the hub style you go with...

By shopping around, and a little finagling with Amazon after they made some mistakes, which resulted in them covering a couple of things, I was able to keep this project right around $900 (before tax), which seems pretty decent to me!

Re: ATS (C7 Base) brakes on a 91 Z28 - My Experience
 

So I did some more driving last night. Need to get used to the very different braking feel before my autox event Saturday! I admit, I did now notice some fain squeaks here and there, but noting bad, I also noticed what I would call the faintest growl under heavy breaking. I'm not worried about it, I just attribute both of these noises to a very aggressive pad and the unique slots on my rotors, neither of which bother me.

Another thing I did notice, is that the braking feel is actually similar to my old brakes up to maybe 10% of breaking pressure, then as you increase pressure, it doesn't continue in a shallow linear way, its like the slope of the braking force becomes steeper after a certain point. Again, I think it is something I just have to get used to, but I am a little curious about. I wonder if it takes that first little heat getting into the brakes, then they start really grabbing.

Gotta love it thought how every time you make a change to a car you find another change you need... This upgrade makes very heavy braking so effortless, that I'm now finding myself being thrown forward in my seat, since I'm not having to put so much force against the pedal which used to brace my body, and press me back into my seat.... So, now I may need to consider some either some sort of racing harness, or even a complete seat swap... Anyone still have one of those CG Lock seatbelt clamp devices they used to sell for racing, that they may be willing to part with??? I looked a while ago, and they haven't been in production for years, and surprisingly no one came in and started offering something equivalent... Maybe I need to design one and start marketing it! Everyone needs a side Hussle right!?

Never shared proper before and after pics:

https://cimg4.ibsrv.net/gimg/www.thi...9be5e9eeda.jpg
Before
https://cimg6.ibsrv.net/gimg/www.thi...632a325bdd.jpg
After

Re: ATS (C7 Base) brakes on a 91 Z28 - My Experience
 

Thank you for documenting your install experience, the detail of the work, pics, part numbers,your reasoning for your methods and sharing your experience with the tooling really gives someone looking to do this great insight. Even with the smallest Brembo upgrade you can do, the impact is great, dividing the piston area in to 4 just makes for a faster reacting apply and higher pressure at each piston. Really impressed with your dust shield, and I agree it is there to funnel some air in to the rotor. One thing you could do if it does not stay in place is to use an Rtv sealant around the center portion in place of the rubber gasket, effectively gluing it down. I would add that there are several versions of this caliper with many different cosmetics than the ATS logo, you have several"Camaro" logo calipers in grey, red, orange and neon yellow even, you also have the C7 JL9 calipers, these run more because they say corvette but they are two staged painted in silver red yellow and black. I can link pics of these if anyone is interested in seeing.
You struck on a point in the beginning of this thread about the grease and setting bearing preload. We have been working with several road racers using pin type spindles and I can almost guarantee your bearings are over packed, this actually creates more heat- ever notice how much grease is in a bearing when you remove it ? I have a few tricks we have begun offering to road racers and I we can get you some gains but first I want to hear about your track results !! - good luck

Re: ATS (C7 Base) brakes on a 91 Z28 - My Experience
 

The smallest brembros are fine with me! And they were all I could fit in my 17" wheels without things getting really tight or maybe not fitting... In my searching the ATS calipers, since they're not painted, I think just black anodized (aluminum) they were the cheapest I could find, especially brand new. With my budget, that made sense. I'm more about function than form anyway.

Today's event (parking lot autox) is interesting.... it was pouring this morning and everything is soaking, puddles everywhere. Getting a LOT of understear. Still trying to feel out pedal pressure, to keep from locking up in the wet... we're on lunch now, fingers crossed for this afternoon...
https://cimg4.ibsrv.net/gimg/www.thi...a038a5dea0.jpg


Scott mentioned to me these bearing spacers, and while I'm annoyed that I now have to spend more money, I think they are genius! They totally elaminate the whole castle nut tightening debate. You actively set endplay, or tension of your bearings, then just torque down the nut!
https://cimg2.ibsrv.net/gimg/www.thi...fb343e10c3.jpg

Re: ATS (C7 Base) brakes on a 91 Z28 - My Experience
 

Just wanted to post a quick update after my first autox event, and about a week of driving this included about 7 runs in heavy rain, so that could have an effect on the grease initially applied to the brake pads. The brakes started making a slight squeak here and there, hardly noticeable, but there. If it stays this way, I will have no problem with it, certainly no major squealing or screeching. Another thing I notice is that under moderate to heavy breaking you do actually feel the grooves in the rotors, that may be compounded with the aggressive HP+ pads. You can slightly hear, but more so feel through the pedal a 'grrrrr' as you brake. Again it is not a big deal to me, but it is noticeable...

All in all, still breaks great! Also, maybe it was a result of flushing some more old fluid through the system, or doing a good old fashion two person bleeding job on the new front brakes, but my pedal while driving at least feels much firmer, and applies more braking pressure with the pedal in a higher position than before the upgrade. I still cant quite understand though that while stilling still, I am still able to push the pedal to the floor with the engine running. With the engine off, the pedal is hard as a rock. Is that how it is supposed to be???

Quick shot after the do it yourself wash... Maybe it was the combination with the rain, but this brake dust was hard to get off, missed a bunch and I went at it with the wheel brush for a little while...
https://cimg1.ibsrv.net/gimg/www.thi...ac73289e3f.jpg
https://cimg2.ibsrv.net/gimg/www.thi...1606471809.jpg

Re: ATS (C7 Base) brakes on a 91 Z28 - My Experience
 

Im very grateful you made this thread. I just may upgrade from my c4 baer brakes to this. Thanks for the info.

Re: ATS (C7 Base) brakes on a 91 Z28 - My Experience
 

Glad to hear it! The only thing I may have done differently was get the camaro calipers instead of the Cadillac ones. Just for the badging... there is no mechanical difference. I think they are a bit more expensive though, but it may have been worth it...
https://cimg7.ibsrv.net/gimg/www.thi...18401bcbd5.jpg

Re: ATS (C7 Base) brakes on a 91 Z28 - My Experience
 

Same basic stuff I been running up front for a few years now. I have had zero brake noise so thats probably coming from your more aggressive pads. IMO this is the perfect rotor and caliper size for are cars giving great autox and street driving performance with a nice touch of sex appeal.

https://cimg1.ibsrv.net/gimg/www.thi...7c61b8f30.jpeg

Re: ATS (C7 Base) brakes on a 91 Z28 - My Experience
 

Nice caliper color choice! There is a good example of how things can turn out if you do prioritize the looks a little more, but still with all the performance to back it up!

What size are those wheels?

Re: ATS (C7 Base) brakes on a 91 Z28 - My Experience
 

18x9.5 for the fronts.

Re: ATS (C7 Base) brakes on a 91 Z28 - My Experience
 

Have you used these hub spacers? it go's in between the inner and our hub bearings, this is new to me.

Re: ATS (C7 Base) brakes on a 91 Z28 - My Experience
 

I have ordered and recieved the spacers, but have not yet had a chance to install them. I hope to in the next few weeks. Once I do I'll be sure to update on this thread, or I'll link here if I create a new thread. A special grease was suggested to me to use with them that had a long lead time. That grease is supposed to be showing up today actually.

Mobil Mobilith SHC PM 220 (1- Pack) https://a.co/d/fepJBPK
This is the wrong one. I ordered it by accident, it's actually the variant for Paper Machines... (PM)

The right one is this one, but there is currently only one left, and strangely it was not searchable...
Mobilith SHC 220, Synth Grease, 13.7 oz. https://amzn.to/3S2em1n
(This amazon seller was also very helpful and communicative)

Re: ATS (C7 Base) brakes on a 91 Z28 - My Experience
 

Yes please do share I’m curious how they work out.

Re: ATS (C7 Base) brakes on a 91 Z28 - My Experience
 

I decided the bearing spacers need their own thread: Front Wheel Bearing Spacers - Third Generation F-Body Message Boards

Re: ATS (C7 Base) brakes on a 91 Z28 - My Experience
 

Quick update on these two topics:

The Hawk HP+ pad and rotor combo I'm using DOES eventually begin to squeak/squeal at low speeds with light braking, basically when they're cold. Nothing at high brake loads or higher speeds where you get a little heat into them. I think it comes with the territory, so I'm just ignoring it. You can adjusts your braking style to minimize it for street driving. I almost treat it like a badge of honor for having racy brakes...

While I'm not advising against it necessarily, I just want to share a word of warning to those using or considering the 1NCR5 springs in the stock proportioning valve. It really does seem to increase rear braking. I was driving spiritedly yesterday, and hit the brakes pretty hard on a highway off ramp from about 70 mph, and for the first time I actually noticed the rear end loosen up and start to step out on me. Luckily I was able to just release the brakes to get the rear wheels spinning full speed again then engage the brakes softer with no problem, but its something you have to have in the back of your mind, and be prepared for. I think it also allows me to get a little more rotation when trail braking at autox events which is helpful, when I get it right, since my car tends to understeer tight turns.

Re: ATS (C7 Base) brakes on a 91 Z28 - My Experience
 

Sorry if I missed it, but where did you get the 1NCR5 springs for the valve? Also, you running disc or drums on your rear?


thx!

Re: ATS (C7 Base) brakes on a 91 Z28 - My Experience
 

I got my springs from Zoro.com. it's like a grainger or McMaster kind of place, but they have a warehouse really close to me. They also frequently have good discpunt coupon codes!

https://www.zoro.com/zoro-select-com...23/?q=G0463723

Also, I'm running factory style PBR rear disk brakes, with ss lines and Hawk hp+ pads.

Re: ATS (C7 Base) brakes on a 91 Z28 - My Experience
 

ahhh good to know! thank you!

Re: ATS (C7 Base) brakes on a 91 Z28 - My Experience
 

Very true. I drove around for quite some time with a 1NCF2 spring on my old 87 iroc with an Ls1 brake swap. I never had an issue with that spring and never spun out, but i decided to swap it out for a Wilwood adjustible prop valve before selling it. Those springs are not for rookies, or a daily driver. By the way; your ride looks wicked!

Re: ATS (C7 Base) brakes on a 91 Z28 - My Experience
 

I don't recall if the spring you mention results in more or less rear brake bias, but I'd say you can safely drive a car on the street with the spring I'm using, you just have to drive the car and brake correctly. I was just playing around and braking very hard when I felt the wiggle I mentioned. I have been street driving the car all summer with the spring, and I don't think it causes any significant to normal street driving, you just have to have the thought in the back of your head.

Thanks by the way! Aside from pretty badly needing some rust repair, and new paint, I really love the way the car looks with this weel combo and the lowering springs! I've always loved this variant of thirdgens best, with the real low and angled front facia and rear Ferrari F40 style wing. It's really making me question if I should dump a bunch more money into this car, or save up and upgrade to something else in a couple years... It's an especially tough decision since this was my first car, bought when I was 15 back in 2001 or so... Hasn't been a daily driver for a long time.

Re: ATS (C7 Base) brakes on a 91 Z28 - My Experience
 

Word to those out there considering playing with their proportioning valve springs. In my setup at least it was brought to my attention that at a recent track event, when I braked heavy into one of the turns, I was locking up my rear brakes, telling me I got the bias too far to the back. The 1NCR5 spring is 1.5" long with a 30.82 lb/in spring rate. I need to try to find a spring with a slightly lower spring rate... based on my calculations the factory one is somewhere around 18 lb/in.