Adding a Bolt-On Rear Disc Brake Kit to Your Ride
When building a Performance Car, a lot of time we get so focused on making it go fast, we don't think about the other side of the coin - stopping!! Well, Speedway Motors has you cover on both sides of that coin. The 1976 Chevrolet Laguna S3 I'm building has the Factory GM 8.5” 10-Bolt Rear End, and the Stock Drum Brakes just aren't up to the task of slowing down that big, old car down, especially with a Big Block under the hood. I chose Speedway Motors GM 10 & 12 Bolt Bolt-On Rear Disc Brake Kit.
This kit comes with everything you need to install it on your GM 8.5” 10-Bolt Rear End. The only additional items you'll need is a short brake hose to get you from the calipers down to the housing.
Safety Note:
You should always use a brake hose from the caliper to the housing. Using a hard brake line will result in a crack in the line over time and a leak, and eventually loss of brakes.
The kit comes with the following parts:
- 91031045-L Metric Brake Caliper (left)
- 91031045-R Metric Brake Caliper (right)
- 91031039 11 1/4" Bake Rotors (Qt. 2)
- 91031983 Bolt-on Caliper Brackets
- 91031983-2 Caliper Bracket Bolt Kit
- 9191562 Metric Disc Brake Pads (Qt. 2)
- 8352300542 Caliper Slide Bolts (Qt. 4)
The nice thing about this kit is, it is possible to substitute different calipers if you choose, as long as they have a 5-1/2” center to center metric mounting spacing for the bolts. I chose to substitute in the Speedway 2-3/4” Big Bore 1978-88 GM Metric Brake Caliper . This gave me more clamping power than the smaller 2.38” caliper does.
Installation is very easy, the first step you'll need to do after getting the car supported safely on a hard, level surface using jack stands. Drain the rear end fluid, on a rear end with a rear cover, loosen all the bolts, and loosen the lower six bolts more, and gently pry the cover loose, and this will allow the fluid to drain.
Safety Note:
NEVER, EVER, work under any vehicle for any reason using a jack of any kind, serious injury and/or death can occur.
After the fluid has completely drained, remove the rest of the bolts and the cover. This is a good time for you to look over the condition of the gears, and check for any metal shavings in the fluid. The rear end in my Laguna was in the need of new axles, so my housing was needing to be completely gone through due to the many years of Oval Track Racing it had been through, so there's no need to go through all those steps.
Once you have the fluid all drained, and the Cover removed, you'll need to rotate the inner Case until you see the end of the Spider Gear Pin. There are two ends to this Pin, so you will need to rotate it around until you get to the end that has the Retaining Screw. This Screw will be just to the right of the Pin and goes through the inner Case. Remove the Screw and inspect it for wear, if it is worn replace it. If it isn't worn set it aside, as you will reusing it. Once the Screw is removed, you can push the Pin out, you may need to rotate the inner Case to be able to remove the Pin completely, and then you'll be ready to remove the C-Clips, and remove the Axles.
This style of axle is a C-Clip Design and uses C-Clips to hold the Axles in. These are easily removed by pushing the axles in and using an extendable magnet to pull the C-Clips out, then the axles can be slid out of the housing, and set to the side
The next step is to unbolt and and remove the backing plates, there are 4-Bolts on each side and once they're removed you can take the backing plates off as an assembly without having to take the brake shoes or and of the hardware off.
Once the backing plates have been removed, you can install the bolt on caliper brackets using the caliper bracket bolt kit. You'll want to position the caliper brackets on the front side of the axle housing centerline.
The axles can now be slid back into the housing and reinstall the C-Clips, and it's a good time to replace the axle seal while you're at it. The rotor can now be installed, I always take a stock lug nut and turn it around with the flat side towards the rotor, then snug it down and it will hold the rotor tight against the axle, and this will make it easier to install the calipers.
The brake pads have an anti-rattle clip that snaps in to the caliper piston, and once the pads are in installed in the calipers, the calipers can now be slid over the rotor, and install the brake caliper slide bolts.
Tighten the caliper slide bolts down using a 3/8” hex key or socket.
NOTE: If the calipers have a metal sleeve in them, you WILL need to remove the sleeve. Factory slide bolts do not have the sleeve built on to them, our Speedway Motors Slide Bolts have the sleeve made on to the bolt.
This is what the finished product should look like, and you've not only increased the braking power of your car, but you've also increase the look factor a lot.
You can go from a worn, old drum brake rear end...
To a nice looking more modern disc brake rear end, with awesome performance and looks as well.
