Inline Tube - Caliper Rebuild

Inline Tube - Brake Caliper Rebuild
One of the largest problems with classic car brakes is that your brake fluid is to be changed every few years. Brake fluid collects moisture over time, this moisture has water in it and over long periods of time it creates rust. This means the inside of your components are slowly corroding causing your system to loose effectiveness. This happens with anything that has fluid in it. This includes brake lines, master cylinders, wheel cylinders, and calipers. If your car has been restored in the last few years keep up on the maintenance and change your fluid every 5 years. If your car has never been restored and you are wondering how you can improve the brakes, the first step is changing the fluid. By getting the old fluid out and replacing it with new fluid you eliminate all the moisture which will dramatically increase the effectiveness of the fluid increasing hydraulic pressure by as much as 20 percent. Next you can replace the old metal brake lines which can rust from the outside from being exposed to the elements and can also rust from the inside from trapped moisture. Before rebuilding any component you should consider the cost and labor factor. If the component has never been replaced and it is the correct date coded part for the car it is priceless, if the component has already been replaced with an after market piece, the time in rebuilding may not be worth the cost of a replacement. An original is always worth rebuilding. Most components have only a few rubber seals that need to be replaced and they will be a good as new. Rebuild kits are a small fraction of the component cost but take some labor time to install. If you are working on a driver, seals are quickly replaced in a few minutes, for a show car a more complete rebuild may be desired. All calipers, wheel cylinders, and masters have manufacture markings and date codes specific to that year make and model. Replacements have the same shape and function but do not have date codes or manufacture markings. For a concourse restoration these markings add value and detail to the final restoration. By following the steps below you can rebuild you components just like an experienced mechanic. Inline Tube offers all the pieces of the rebuild from the rubber seals to complete caliper ready to bolt onto your classic.

These are original Delco Calipers and feature the Delco logo, part number and date code, so they are very desirable for concourse correct restorations. Inspect the caliper for any markings, tags, or details that may want to be reproduced. The third picture shows a blue ring which is all that is left of the original bleeder cap. Also note the color of the plating of the parts. The calipers are cast, the caliper pins and sleeves are silver and the bleeder was gold. These calipers seem to be cast but many calipers were painted black before the machining process which makes all the machined surfaces bare metal or silver.

Drain the caliper of as much fluid as possible. In order to get the piston out of the caliper, leave the bleeder in place and take a air hose at low pressure (25lbs) and insert the end in the banjo bolt hole. When applying pressure make sure your hands are clear of the piston that is making its way out of the cylinder. When the piston reaches the end of the cylinder wall you will hear a pop of air pressure and the piston will be out.

In order to get the dust boot out apply a screw driver under the seal metal ring and twist until the seal pops out. The inner seal must also be removed in the same fashion. Once the two seals are out clean the rest of the fluid out with a rag. The caliper pins also ride on rubber seals that are rarely bad and not usually included in any rebuild kit. Inspection of the seals is all that is required.

Now that the caliper is completely taken apart, take a look at the cylinder wall, the wall may have small pits, as long as pits do not run under the inner seal, the caliper will be fine to rebuild. The seal is what holds the fluid in so this area must be clean. Next inspect the piston, they are chrome plated to be very durable and smooth. This piston will ride on the inner seal so it must be smooth and pit free. Since brake fluid collects moisture the caliper housing usually has a few pits but nothing that will affect the rebuild.

In this rebuild fine glass bead is used to clean the caliper, piston, and any other hardware that will be reused. When cleaning the pistons under low pressure, lightly dust them so the chrome finish is preserved. Do not sand blast the piston.

Once the calipers and parts are cleaned it is time to phosphate the caliper. A solution from Palmetto Enterprises is used. On a propane portable stove get a stainless pot big enough for the parts. Follow the mixing instructions for the solution, heat to 175 degrees and drop the clean parts into the solution and once they stop bubbling remove the parts from the pot and spray down with WD-40. The WD-40 heats up and turns to a heavy oil that will soak in and protect the finish. Only use a stainless pot, other materials react with the solution causing pot failure in minutes.

The cleaned piston is masked off and the back is painted cast. Plating the piston may destroy the chrome finish. The new rebuild kits are now ready to go back in the caliper. If you choose to paint the caliper do not paint the piston cylinder wall, the brake fluid will eat it. You may want to wait to paint until the piston and seals are protecting the cylinder wall.

First install the inner seal, this seal simply seats into the groove of the caliper wall. This seal needs to be lubricated with either brake fluid or WD-40 so the piston can be inserted. Again the piston rides on this seal not the wall of the cylinder.

This seal must be installed in the proper direction, the edge of the seal has a rounded edge and a sharp edge, the sharp edge goes down as shown. Spray the seal so it easily slides on the piston. Slip the seal over the piston and slide it down until the edge of the seal sits in the outer piston groove.

Now that the seal is sitting in the groove, pull the seal up to the top of the piston so it is flush, the seal will ride over its self. Now that the seal is folded over its self make sure the seal is still sitting in the piston groove,smooth and flush. This serves as the outer seal and the piston dust boot. Make sure to spray the piston with WD-40 or apply brake fluid to the piston so it will be lubricated to ride over the inner seal.

Place the piston in the caliper, it will be a snug fit. Once the piston reaches the first seal it will become much harder to push in, once past this seal it will become a bit easier again. Then the piston reaches the second seal that is on the outside of the piston and part of the dust boot. Again it will be hard to get the piston past this seal, but push down by hand as much as possible. The assembly has 2 seals, one in the cylinder wall and one on the piston.

Again for the outer seal to work properly it must be installed in the right direction. Once you have pushed the piston in by hand, you may need a c clamp to finish the job. The outer seal is at the end of the piston travel and requires a bit of pressure to get in place. The outer seal has a metal ring that will fit into the caliper housing. This ring may be pushed in by hand but in some cases may need a tap since it is a tight fit. Tap in place but do not hammer on.

Now all the hardware may be installed. The caliper pins, pin sleeves, banjo bolts, and bleeder are silver zinc. The hardware installs in a few minutes and your caliper rebuild is done. The rebuild kit and all the hardware is available from Inline Tube. Inline Tube also carries a complete new caliper.

Sources:

Inline Tube - Brake & Fuel Lines, Caliper Rebuild Kits, Brake Hardware, Disc Brake Conversions

15066 Technology Drive
Shelby Twp, MI 48315
(586) 532-1338

www.Inlinetube.com

Palmetto Enterprises - Grey Phosphate Plating

2311 A Old Parker Road
Greenville, SC 29609
(864) 246-3836 ph

Bob’s Boosters - Silver, Gold, Black Zinc Plating

Eastpointe, MI
(586) 774-8883