Rear big brake swap - Maintenance and Repair Forum

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Rear big brake swap
Monday, August 07, 2017 11:35 AM
This is about swapping post 2002 9" rear brakes onto a pre 2003 7" J-body. Fooled ya hu?

Im not sure what years this will work on but I did this on an 02 to 03. Our 1997 Z/24 vert look similar to the 02 & my 05 look like the 03.

The reason I am bringing this up is I have a 2003 Cavalier 4 door parts car & my daughter has a 2002 coupe that needed some brake work. Nothing big just leaking wheel cylinder & a broken spring. Since the 03> are 9" drums as opposed to the 02< being 7" I figured since I had the bigger drums that would otherwise just sit around I would see if there was anything out there about this swap. As you can imaging all I found was the drum to disk swaps. I talked to a few friends & the best we came up with was if its pretty easy *go for it*. So I did. Note that if you do this you are probably not looking at a noticeable improvement in braking nor is there going to be any better parts availability that I know of. It was just that I had them.

It is an easy swap. Simple bolt-in. It took about 2 hours. I had to remove the parking brake cables as the ends are different at the shoes. The brake lines fit either wheel cylinder. Plus the 03's only have 4 parts other than the shoes & cylinder where the 02 is old school with about 15 parts.

So here is a quick rundown of how to do it.
Remove the 02 brake parts, put them in a box, label it & put it in the back of the garage or take it to the metal recycle & donate the shoes to your local auto parts store for relining.
Remove the ABS plug from the hub & get it out of the way so brake fluid does not get on it.
Loosen the hub/backing plate bolts & remove the hub. Leave a bolt holding the backing plate.
Remove the E-brake from each side under the rear of the car. There are probably special tools or a better way to remove the e-brake cables. If so chime in.
- I pried the tabs out from the connector that connects the front cable to the two back ones.
- Used vice grips to hold the spring that pushes the front cable to the left connector back so I could pull the front cable out. Removing the front cable gives you a little slack to get the wheel cables out.
- Work the left wheel cable out of the connector.
- Do the same for the right wheel cable.
Unbolt the packing plate & pull it & the wheel e-brake cable out. Note how the cable runs so you can put the new one under & over the other lines.

The nuts on the hub for 2002-2005 are 15mm. The bolts on my 2002 & 2003 were T-50 torqs (I think is what the video said. I did not look & mine.) On my 2005 the bolts are 13mm (I believe) hex not torqs.

I would suggest test fitting the brake lines to the new wheel cylinders as the post 02 are aluminum & I almost cross threaded it trying to line up the lines. There was a different angle between the 02 wheel cylinder & the aluminum 03.

To put on the 9" brakes
Clean the backing plate & hub mounting surfaces.
Run the cable back where it goes.
Put a bolt in the backing plate to hold it up.
Bend the tabs in just a little for the cables & put them back together. Note the routing so nothing rubs.
Bolt the backing plate on with 2 bolts & test fit the wheel cylinder brake line. I left the hub off to keep it out of the way & loosened the wheel cylinder to get things lined up.
Once the line is connected to the wheel cylinder put the hub & all four bolts back on
Tighten the wheel cylinder to the backing plate & tighten the line.
Plug the ABS plug back in & put on the rest of the brakes like normal.
Bleed the brakes
You may need to adjust the e-brake cable.

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