Brake Caliper Rebuild
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Perform all these installs at your own risk. Know how to use all of your shop equipment and take necessary safety precautions when performing ANY modifications and or maintenance items to your vehicle. Seek the advice of a paid professional and do not substitute this publication for the advice of a paid professional. This product is how we accomplished our installs and is not meant to be carved in stone. We are not responsible for a mistake, misprint, or any other error found in this guide. This guide is intended as a supplement and not to be your only source of information.
Purpose: After lots of hard brakeing, usually from having too much fun on a road coarse, your brake calipers will be in dier need of attention. Ride along with Mitch and see just how simple a rebuild is.
Preface: Before you start into this install be sure you know how to use all of your shop equipment. Take your time and be careful.
Caution: Brake fluid will drain from the caliper and from the brake line.
This fluid will damage the paint on your car, so be careful.
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1. Using the 13mm line wrench, locate the banjo fitting bolt that attaches the brake line to the front caliper. Have a 3/8” x 1” bolt and nut ready. Remove the banjo bolt. There will be 2 crush seals on either side of the banjo fitting. Re-use these seals, along with the bolt and nut to seal the brakes system. (Figure 1)
If you don’t seal the system, you will drain your master cylinder and then a really bad day has just begun.
2. Next follow the directions outlined in brake pad removal to remove the brake caliper.
3. Place the caliper in some sort of container, as fluid will still be draining. The trick here is to remove BOTH pistons from the caliper. If you notice, 1 piston is behind the port where the banjo fitting attaches. I place a 1x2 block across both pistons and then insert another 2x4 block over the piston directly behind the piston that aligns with the port. (Figure 2)
You can see the port better here (Figure 3)
4. Using shop air, place a rubber tipped blowgun into the port. Rubber tipped so that you don’t gall the threads, which will lead to leaks when attempting to seal the system back. (Figure 4)
It doesn’t take much air pressure to force the piston out. Please note the piston blown out of the caliper and against the wooden 1x2 block. The wood “cushions” the impact and doesn’t damage the caliper ear. (Figure 5)
The 2x4 block keeps the other piston from coming out of the caliper.
Remove Piston #1
5. Remove all the wooden blocks and stand the caliper on it’s edge (Figure 6)
Using a long thin punch, insert it in the fluid port and using light taps, drive the remaining piston out of the caliper. Be careful not to touch the threads with the punch to prevent galling.
Here is the reason why calipers are rebuilt. (Figure 7)
Once the dust boot is breached, fine particles of brake dust and dirt from the road as well as water if you drive in the rain, find their way onto the piston and can cause an inner seal failure and system contamination. Once the remaining piston is out, clean, clean, clean, clean the caliper and pistons
6. Once cleaned and dry, put the caliper in a vice. (Figure 8)
Notice 2 sets of grooves in the caliper …. An inner and an outer. The inner is for the system seal and the outer is for a protective dust boot. (Figure 9)
7. Using fresh and clean brake fluid lubricate ALL caliper internal surfaces, the piston outer surface and all rubber seals (Figures 10, 11 and 12).
Figure 10 - Fresh Fluid
Figure 11 - Seal lubrication
Figure 12 - Caliper lube
8. Now insert the inner seal into the inner most caliper groove. (Figure 13)
9. Now come the tricky and fun part….Put the dust boot on the piston. Slide the boot down close to the bottom of the piston, the opposite end from where the boot seats in the groove in the piston. Now, the portion of the boot that seals in the caliper itself should be hanging BELOW the bottom of the piston. (Figure 14)
This part that is below the piston, seats it into the upper groove of the caliper housing. Twist the piston and boot back and forth. This twisting motion will help seat the dust boot in the caliper's groove. (Figure 15)
Then, align the piston into the caliper cylinder and press the piston into place over the inner seal. (Figure 16)
Sometimes it takes a lot of pressure to get beyond that inner seal. Just keep equal pressure. It has to be absolutely square. I can typically do it with my hands. If it doesn’t go with hand pressure something isn’t aligned correctly. You just have to working the piston searching for the “sweet spot”. Once you find it, the piston goes in really easily. Once past that inner seal, the piston should slide in easily and the dust boot can then be seated into the groove in the piston. (Figure 17)
With practice and experience, this is about an hour's job.