KoreaJon

Hello All,


I recently saw an old thread where a gentleman installed a pair of front calipers on the rear of his C5, and reported great results. That got me really thinking.....

I had previously installed a set of Z51 rotors on the rear of my car, along with a set of braided steel brake lines.

As part of THAT upgrade, I bought a set of Z51 caliper mount brackets, and used my original calipers. The Z51 caliper brackets spaced the calipers at the correct position to account for the increased diameter of the new rotors.

These rotors use the same emergency brake setup...I changed nothing there.

Well, I came across an excellent deal from a CF member on a set of standard front calipers and caliper brackets, here they are after a little cleaning:




The only modification that needs to be done to the caliper brackets is to shave off the two bosses where the mount bolts go to secure the brackets to the nuckles, seen in this picture:




Here's why the bosses need to be shaved down (once they're shaved off, the caliper will be centered on the rotor)




Here is one of the caliper brackets in the mill, about to be shaved:




Here's what they look like after milling. If I were to do it over, I'd leave the bosses about .010 tall.




As part of the "makeover," I installed new seals and dust boots in the caliper, and painted them with red VHT. I cured them in the oven at 200 deg. F for an hour, then lightly sanded the red off of the "Corvette" lettering.




The caliper brackets got another cleaning, then painted with silver VHT.




After I installed the "new" calipers, I bled the system with a "Mighty-Vac" hand-help pump until the air bubbles got really slow....then, I did the unthinkable (to some!)........
I've been following a couple of threads where the discussion was in regards to "exercising" the ABS pump. This got me thinking; first, I know that it works, because I've USED it recently, but second, I want to "pressure" bleed the brakes, but since there's only one of me, I can't push the brake pedal and open the bleeder at the same time......so what to do?

With the rear of the car still on jack stands, I installed the Might-Vac onto one of the bleeder screws. I pulled the maximum vacuum, then just ~ever so slightly~ cracked open the bleeder, just enough that the vacuum was pulling a bit of fluid out. Then, I started the car, put it in drive, and as soon as the rear wheels started turning, I heard and felt the ABS pump activate. Sure enough, when I looked at the reservoir on the Mighty-Vac, brake fluid was slowly being pumped out of the caliper. I did this for both rear wheels. I know, empirically, that the fluid THROUGH the ABS pump is new and clean, as well as the fluid in the lines is clean. The pedal is very firm.

Here's the "before" picture:




And here's the "after" picture:




You can see in this picture that the new calipers really fill up the empty space inside of the wheel:




When I was done, I took it for a little spin....the increased braking is remarkable. I've got much bigger brakes on the back, I still have my emergency brakes, and all the parts are inexpensive, stock parts. As a bonus, it's about an hour job if I ever wanted to swap back to the original rear brakes!
The only slight adjustment that I'll need to do is to very lightly chamfer the outer edges of the circumference of the rotors, as this is causing some "swishing" noises as they very slightly rub against the caliper bracket. This is a small thing, and I'm extremely happy with the results thus far.

I'll post more after I make the necessary adjustment, and do some road-testing.

I hope you enjoyed the read!

Regards,
KoreaJon

Cutlassmaster

Very nice! I did the same upgrade to mine about a year ago. I clearenced a little on bracket and caliper so that the rotor didnt rub. I also took an old brake pad and removed pad material so I could weld the plate to the new pads so it moved the pistons back in a little and prevented the pad from coming out of the brackets. Mine is a 99 so I also did the DMR spring upgrade on proportioning valve. Brakes work great and look great too. Enjoy!
Chris

Tommyxgun

Awesome write up! Wanting to fill the gap on my 20" rear wheel, without forking out huge bucks for a bbk. Thanks for this!

mrr23

Nice upgrade and get to retain the ebrake.

bjones7131

Nice job

NukeC5

Good work, funny how opposite some builds can be. I'm currently putting rear brakes up front for a 15" all around drag pack. If anyone's interested in my front brakes (calipers, brackets, drilled/slotted rotors, and pads) to put on their rear, PM me!

Caveboy

I am thinking about doing this! AP T1 Racing Brakes in the front and move my Z51 Caliper front brakes to the back! Any thoughts? Also, how would the e brake work on this setup?

neutron82

I thought about doing this before I decided to go with c6z brakes... good job on the install

KoreaJon

It's pretty simple. All you'll need to install the front calipers on the REAR of the car is:

2 front calipers
2 front caliper brackets (remove the mount bosses)
Replace the STOCK rear rotors with Z51 REAR rotors (this will allow you to retain the parking brake.)

That's it.

As I stated in my post, I will have to very slightly clearance the rotors / brackets due to some minor scuffing of the rotor to the caliper bracket. It's nothing major, just an adjustment.

Based on the threads I read on this same subject, and the fact that the ABS is pretty darn "smart," I'm not predicting any ill effects due to the increased braking ability on the rear. That being said, I still have to road test the car. There ~may~ be some adjustment required to the proportioning valve spring (on those cars equipped w/ a proportioning valve.


Regards,
KoreaJon

Caveboy

My car already comes with the Z51 Suspension. I didn't think it come with a different rotor than stock?

KoreaJon

You ~may~ be in luck! The rotors that were on my coupe were significantly smaller than the Z51 rotors....I don't remember the exact dimension, I THINK that the stock rear rotors are 12", and the Z51's are 12.9. The Z51 REAR rotors are just an RCH larger than the STOCK front rotors.

If the rotors currently on the rear of your car are the same size as the fronts that are currently on your car, you can do the switcharoo.


Regards,
KoreaJon

Uhhtaken

Im in the same boat as you caveboy, i know my car has the z51 package but have never looked at the brakes well enough to tell and if it was easy enough to do this big brake kit and have better stopping for such a low cost i would definitely do this mod. Does anyone know if the z51 package included slightly bigger rear brake rotors to enable use to just buy the bracket and caliper?

mrr23

What year z51?

Caveboy

99 c5 auto

Caveboy

How much of the brake bracket bosses did you need to grind off?

KoreaJon

The C6 Z51 rotors that I bought are ~slightly~ larger than the front brake rotors currently on the car.....I haven't measured them (yet) but I ~think~ that they're about .10 larger.




I ordered 2005 C6 Z51 rotors


If you're asking about the bosses on the caliper brackets where the brackets bolt to the spindle....I milled them off flush with the surrounding structure....see the pics above. For my application, I ~would~ have been OK to leave the bosses 0.10 tall.

My examination last night of the slight rubbing issue revealed that I had to clearance the inside of the caliper brackets to clear the rotor. This was easily done with a carbide burr mounted in the flex attachment on a Dremel tool. I pretty much just had to clean up the excess from the casting, I didn't have to get into the "structure" of the brackets. More pictures to follow.

As of this minute, I still don't know if I'll have to "adjust" the little stamped steel spring-thingies that squeeze into the caliper bracket....where the "ears" of the brake pads sit.... part of those is still sticking out and rubbing on the outer edge of the rotors. Small stuff, I'll get it figured out!


I hope this helps!
KoreaJon

XotiK ZO6

I really like this idea. A couple questions.

I know the rotors were from a C6 Z51.

What year are the calipers and brackets from?

KoreaJon

I THINK that all of the front calipers and brackets are the same for all years and models of C5's....at any rate, the calipers and brackets that I used were from a 2002 coupe.


Regards,
KoreaJon

KoreaJon

Update: I did some minor clearancing of the caliper brackets, and trimmed off most of the tabs on the little sheet metal spring-things (see the red arrows.) After that, I drove the car again....for the first 20 miles or so, all was well. Then, I started to hear a little scraping / whispering sound coming from the brakes. Off came the wheels again for an inspection of the brakes....I discovered that I needed to trim the tabs all the way back on the spring-things.




After I made that last adjustment, all scraping / whispering is gone.

I made 4 or 5 max-effort stops....all of them from speeds ranging from 50 to 80 mph....there was no pulling, no noises, nothing unusual. The ABS engaged just like it should. The most notable difference with the new rear brakes is that the car DOES NOT dive when doing a max-effort stop (like it used to,) it just.....STOPS! It stays very level. My passenger ~might~ have some slight bruising from the seat belts, though. It's his fault....he knew what we were going to do, but didn't expect the results!

After that second round of tests, I pulled into the garage to inspect everything....everything around the rotors, pads, and calipers looked good. When I popped the hood to inspect the master cylinder / engine area, I found some seepage originating at the junction between the master cylinder and brake booster. The seepage had actually wetted the frame area under the master cylinder...

Testing is stopped until the new master cylinder arrives. Oh well, this is the opportunity I was waiting on to install the line-lock on the front brakes!


Update! 02 Jan 15

I finally got the new master cylinder installed, and while I was at it, since the brake system was completely opened up, I installed the line-lock solenoid, as well.
Since I was in there, I also installed the braided steel lines on the front brakes, and the metal end links on the front sway bar.

I took the opportunity to disassemble the calipers, clean and paint them, replace the piston o-rings and dust seals, and install new brake pads. Initially, I had intended to install new pads on the old rotors, because I THOUGHT that the rotors were in good enough shape. When I actually started working on the brakes, I looked up the wear criteria and found that my rotors were near the end of their usable life. Soooo, I re-installed the old pads on the freshened / overhauled calipers, and planned to drive the car on the old rotors / pads until the new rotors arrived, but just as I got everything assembled, here came the new rotors!
So I also installed the drilled and slotted rotors. (I know, I know.....there are those that will immediately proclaim that the drilled and slotted rotors are inferior to the solid rotors, but really, I don't care! I'm not a road-racer or track star wannabe, I just like the way they look!!) and installed the new ceramic pads.

Here's how the fronts looked before the new rotors:



Here's how the fronts look now:


So! New brakes on the front, and a new master cylinder....I bled all four wheels, and off I went!

I followed the brake pad manufacturer's recommendations to bed in the pads on the front and rears, then got down to testing the brakes.

As it turned out, I needed to do a little more work on the rear caliper brackets. When I really heated up the back brakes, I could hear some more whispering / grinding coming from the back brakes. What it turned out to be was a couple of things:

In this picture, you can see the casting flash on the caliper brackets:



And you can see it in this picture, as well. I really should have seen this and corrected it while the brackets were in the mill, but I was able to dress it up with an angle head grinder. If I had done it while they were on the mill, though, it would have saved a LOT of frustration!




That casting flash was contacting the face / corner of the rotor. You can see the relationship of the two in this picture. I also dressed up the area (slightly) on the rotor, as well.


The other thing I did yesterday was to TIG weld another brake backing pad to the outside brake pad on the rear calipers. This is because with this mod, the outside pad sits much closer to the end of the rail in the caliper bracket, and I was concerned that when the pad gets very worn, it could "****" in the track. This can't happen now!






So now, when I want the car to stop, it ~really~ stops.
The pedal is a little softer than before...I attribute that to the increased bore / area of the pistons in the rear calipers from the stock calipers. I'm gonna do a little research on the proportioning valve, and see what I can see. Right now, though, its just a matter of preference; the brakes are working great.

I hope this helps,
KoreaJon

lionelhutz

Just be careful as the pads wear. The C6 Z51 rear rotor is thinner than the C5 front rotor so the ears of the pads could come out of the slots in the brackets if they wear down enough.

To the confused people - this uses C6 Z51 rear rotors and C5 front calipers and brackets. A C5 with the Z51 package won't have the correct rear rotors.