Rear Caliper Rebuild, "How-To Thread" Options

[Eric_Shea]

In an earlier thread I was asked to write a “How-To” thread on the rear caliper rebuild. I had to get some pictures together before this made sense.

I’m starting this thinking you’ve already gotten them off the car and you understand how to reinstall them and bleed your brakes. This is all about the caliper rebuild. This is also about a “top-end” caliper rebuild. If your caliper is leaking through the handbrake lever I would consider getting a new core at least. Why? Rebuild kits are around $22.00. Handbrake rebuild kits are around $50.00. Now you’re in it for close to $80.00 with shipping etc. A rebuildable core should go for $20-$40 bucks… as these get scarce you may want to reconsider but currently they’re not too scarce.

This job is not fun and it’s not all that easy. It’s not too tough either, it just requires some mechanical ability, patience, special tools and some “tricks of the trade”. Yes, I rebuild these so I’m either loosing customers or gaining customers by writing this (I’m obviously not too concerned). Follow the thread. If it’s something you want to tackle then dive in. If not, you know where to go.

Here are some of the tools you’ll need:

 Dental Pick
 T27 Torx Driver (early single bleeder style)
 Torque Wrench
 4mm Hex key
 Small and Large Locking Pliers
 Brake Grease
 Brake Cleaner
 Large Screwdriver
 Small Wire Brush
 13mm Socket
 11mm Deep Well Socket (to press the spring and cover into the inner caliper half)
 11mm Socket
 MAP Torch
 Air Wrench
 Pistol Grip Clamp
 Brake Caliper Hone
 Hand Drill
 Two Rear Caliper Rebuild Kits from Your Favorite Vendor (they must include all seals)
 7mm Wrench (for the bleeder valve. I prefer to use a small pair if locking pliers though…)

Here’s the “How-To”

1. Drain it. You’ll want to get all the fluid out of these before you dig into the task at hand. As mentioned above, take a pair of locking pliers and snug them down on the bleeders. Most are stuck and this is the only way to go. The 7mm wrench will rarely do the trick. Once you get them off, try to blow some air through them.

2. I like to mount these in a vise before I start the dismantling process. Next I start with the caliper half bolts. These are 11mm bolts on the later style (dual bleeder) or T27 Torx bolts on the early calipers (single bleeder). The early calipers have 11mm nuts on them. These will seem impossible to remove. Here’s where the MAP torch comes into play. Don’t worry too much about heating these puppies up. First of all, brakes get hot. Second, you have new seals in your rebuild kits. You just don’t want to heat up the parking brake area because as discussed earlier, that’s another $50.00 in parts and another rebuild. Heat the bolts and use your air wrench to hammer these off. Split the caliper and remove the inner seals. While you’re at it, remove the dust boots and clamps using the dental pick.

[Eric_Shea]

3. Turn out the pistons. The heat you used on the caliper half bolts may have helped you on the piston side. Many have complained about stuck pistons that have the internals “spinning” (you’ll see what that means when you get one out). I’ve found “heat” to be a “major” factor in getting out these types of pistons. Keep your MAP torch handy. I mention “Inner” and “Outer” caliper halves; The inner halves have the parking brake arm attached. For the “Inner” piston you need to spin the adjuster “CLOCKWISE”. “Outer” pistons turn COUNTER CLOCKWISE. For the outer adjuster you’ll need to loosen the 13mm lock nut and spin the adjuster with a 4mm hex wrench. For the inner adjuster you’ll need to use the 4mm hex wrench to remove the adjuster cover. Many times this is stuck and the 4mm slot is stripped (has something to do with thread surface area and wrech surface area). If this is the case you’ll need to slot the cover and pop it with a large screwdriver or chisel (see picture) Turning out the pistons is the part that I feel is “easier” than any other caliper rebuild. If your calipers are in decent shape the pistons should simply spin right out to the edge. Once you get the adjuster screws turned out to their limit (you’ll feel it and the piston will stop moving), you’ll need to pull the piston out the rest of the way. Do this by placing a shop rag over the piston and use a large pair of locking pliers to grab the top edge. Don’t dig into it and destroy the lip. Just snug. Now “rock” the piston back and forth while pulling. It only has about 1/8th of an inch to go.

Here's a picture of the "inner" adjuster cover and the modification discussed above that is "usually" needed to get them off