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Wheels:
Enkei TX5
18x9.5
35mm offset
32mm adapter
Black Chrome finish by California Chrome Wheel, Valencia, CA.
Tires:
Goodyear Eagle GT
255/40ZR18.
NOS C5/C6 rear backing plates (modified to fit 3rdgen 9-bolt axle) support all C5/C6 and Cadillac XLR/XLR-V rear brake options (XLR = C6 platform + Cadillac skin):
C5/C6/XLR Base 12"
C5 Z06 12"
C6 Z51/XLR-V 13"
C6 Z06 13.4"
12" also supports a Wilwood lug mount caliper.
13" also supports a Wilwood radial mount caliper.
After you pull the axles for the initial installation of this rear conversion, as you would with any rear conversion, you won't have to pull them again if you want to change sizes later. Install the option of your choice (12", 13", 13.4"), then simply swap calipers and rotors to change to a different size. There's no such versatility with an LS1 rear brake conversion, which is what it is, 12", and doesn't bolt up to a 9-bolt anyway.
NOS C6 Z06 6-piston front calipers, 4-piston rear calipers. PBR, not Brembo. The painted CORVETTE graphics wipe off with graffiti remover. Z06-style FORMULA decals made by TGO member, Abubaca. Thanks, Chris!
The next three pictures show mock-ups of this conversion kit with the C6 Z51/XLR-V 13" option and a couple of C5/C6/XLR 12" configurations.
12" should fit 16" factory wheels. And all of these rear calipers are interchangeable: LS1 (good), C5 (better), C6 Z51/XLR (best). Use whichever you prefer, you can find, you might already have. C6 calipers fit inside my Formula's 16" wheels, but fitment with GTA wheels might require LS1 calipers, which aren't quite as tall as C5/C6 calipers, to get a little more clearance inside 16" wheels, and a 1/4" wheel spacer might be needed.
The next four pictures show my 98-02 4thgen hardlines, NOT necessary for this conversion, just my preference. The driver side hardline on my 87 (82-88 rear disc axles) has to be replaced for rear brake upgrades anyway. From the factory, that axle hardline runs all the way into the caliper, no soft line at all, so I changed both hardlines to late 4thgen hardlines. They're designed for 10-bolts, but they fit 9-bolts just as well. Most people would be more likely to replace the driver side with an 89-92 Performance Package 3rdgen hardline.
Supporting the ends of the hardlines are modified 4thgen mounting brackets, easy to find on late 4thgen axles in junkyards. They place the soft line connections on the front of the axle, which I preferred for my fore-mounted calipers.
Completing a clean installation, a 90* swivel fitting at the hardline, and a 6" stainless flex hose to the caliper.
Last edited by LAFireboyd; Mar 12, 2024 at 11:05 AM.
Reason: always fine tuning and updating the script and pictures
C6 Z06 Brakes w/BBU C6 Rear Brake Conversion for 9-Bolts/10-Bolts
Rather than bringing this thread ttt, I'm editing this post to include pictures of the modified 4thgen hardline/hose connection brackets. The picture in the above post shows the brackets unmodified, which won't fit with LCA relocation brackets. To use them with LCA relocation brackets, the back and side needs to be lopped off of each 4thgen bracket, as shown in the pictures below:
Notice that not only are the back and inner side of the brackets cut-off, but that provision for the parking brake cable is gone too, because the new kit has its own bracket for the parking brake cable.
Re: C6 Z06 Brakes; C6 Rear Brake Conversion, NEW from BBU: C6/C5 Std, C6 Z51, C6 Z06
Hi guys, I have a 87 ws6 gta 4 wheel disc and am looking to upgrade my brakes. I want to run the 17 inch rims from hawks and Scott from big brake upgrade said to use c6 base brakes in the front and 1le s in the back however I was wondering what would be involved in running c6 brakes all around, and if the c6 base rears would fit a 17 inch rim.
Re: C6 Z06 Brakes; C6 Rear Brake Conversion, NEW from BBU: C6/C5 Std, C6 Z51, C6 Z06
C6 base rear brakes are 12". When I did this, I test fit the 12" rotors with my factory 16" wheels, and they fit, so they'll fit with 17" wheels. However, I'm not sure whether or not they'll fit with GTA wheels, 16" or 17", because of the wheel's hub design. A spacer of like 1/4" might be required.
But I think C6 rear backing plates have long since been discontinued. And since Scott suggested 1LE rears, then he probably can't get C6 rears anymore, so you'll probably have to go with 1989 3rdgen Performance Package (1LE) rear brakes for your 9-bolt axle. They're 11.6" I believe.
Some people have modified/adapted 98-02 4thgen LS rear backing plates to 9-bolt axles, so that's an option. It's not something I would do, but people have done it, so if you feel so compelled, then go for it. Those are 12", and the backing plates aren't hard to find in junkyards, depending on where you're located, I suppose.
Re: C6 Z06 Brakes; C6 Rear Brake Conversion, NEW from BBU: C6/C5 Std, C6 Z51, C6 Z06
I see you have front calipers as well, what rotor type did you use there? Did i miss the thread? Was it C4 type but 14" like a lot of kits use or C6 rotors?
Re: C6 Z06 Brakes; C6 Rear Brake Conversion, NEW from BBU: C6/C5 Std, C6 Z51, C6 Z06
No kits. All new C6 parts that I shopped for.
I don't think the calipers are available anymore, new, but used and rebuilt seem easy to find.
The front rotors are C6 14" DBA, like the C6 13.4" DBA rear rotors seen in this thread. I had to wait 6 months for them because they weren't in stock in the US and had to be manufactured in Australia.
I didn't do a thread for the front, only for the rear because the 9-bolt lacked upgrade options, which was the point of having Scott modify C5/C6 rear backing plates for me and making the tread.
Front just uses standard spindle and hub mods that all 3rdgen front upgrades use. Nothing special there, so I didn't do a thread for them.
I'm currently refreshing all of the steering components, so when I eventually get everything back together I'll probably just add them to this thread rather than make a new thread.
Re: C6 Z06 Brakes; C6 Rear Brake Conversion, NEW from BBU: C6/C5 Std, C6 Z51, C6 Z06
Originally Posted by LAFireboyd
C6 base rear brakes are 12". When I did this, I test fit the 12" rotors with my factory 16" wheels, and they fit, so they'll fit with 17" wheels. However, I'm not sure whether or not they'll fit with GTA wheels, 16" or 17", because of the wheel's hub design. A spacer of like 1/4" might be required.
But I think C6 rear backing plates have long since been discontinued. And since Scott suggested 1LE rears, then he probably can't get C6 rears anymore, so you'll probably have to go with 1989 3rdgen Performance Package (1LE) rear brakes for your 9-bolt axle. They're 11.6" I believe.
Some people have modified/adapted 98-02 4thgen LS rear backing plates to 9-bolt axles, so that's an option. It's not something I would do, but people have done it, so if you feel so compelled, then go for it. Those are 12", and the backing plates aren't hard to find in junkyards, depending on where you're located, I suppose.
thank you for responding, I am a little confused to be honest. I can get all c6 brake parts from a shop just not the backing plates and that’s where I am confused. From my understanding prior to reading your response it was the same thing as the from just the hub and the spindle modification, however I seem to be wrong. I’m sorry to ask but may you please explain how the backing plate mod works and what I would need because I found AC Delco c6 backing plates online but don’t wanna buy anything yet.
Re: C6 Z06 Brakes; C6 Rear Brake Conversion, NEW from BBU: C6/C5 Std, C6 Z51, C6 Z06
The spindle/hub was a general statement about the front brake upgrade, not the rear.
The C6 rear backing plates will have to be modified to fit the axle, and Scott at BBU does that. They've been discontinued, so if he doesn't have any, and you've got a source, then he'd probably modify yours if you send them to him. Then you'd also need the parts for base brakes: calipers, abutment brackets and 12" rotors.
Re: C6 Z06 Brakes; C6 Rear Brake Conversion, NEW from BBU: C6/C5 Std, C6 Z51, C6 Z06
Originally Posted by LAFireboyd
No kits. All new C6 parts that I shopped for.
I don't think the calipers are available anymore, new, but used and rebuilt seem easy to find.
The front rotors are C6 14" DBA, like the C6 13.4" DBA rear rotors seen in this thread. I had to wait 6 months for them because they weren't in stock in the US and had to be manufactured in Australia.
I didn't do a thread for the front, only for the rear because the 9-bolt lacked upgrade options, which was the point of having Scott modify C5/C6 rear backing plates for me and making the tread.
Front just uses standard spindle and hub mods that all 3rdgen front upgrades use. Nothing special there, so I didn't do a thread for them.
I'm currently refreshing all of the steering components, so when I eventually get everything back together I'll probably just add them to this thread rather than make a new thread.
I have baer 13" setup on the car and new front silver C6 calipers id like to try out. Baer used a C4 rotor. Just need to order new 14" rings and make the bracket i guess
