Brake Maintenance

Every Race Weekend
Inspect the pads and pistons.  You will find that the pads have a tendency to “taper wear”.  That is the leading edge of the pad wears more than the trailing edge.  You need to have pads as square as possible to maximize the amount of friction area.   We reduce the effects of taper wear by regularly flipping the pads around.  That is, putting the inside pad on the outside and vise versa.  Doing this not only extends pad life but improves braking.
After you flip the pads, you will need a lap or two to get them operating correctly again.  Braking power won't be maximum until they fully seat, keep this in mind so you don't use someone else's car for brakes.

The pistons (and you should only be using phenolic pistons for reasons I'll explain later) develop a light colored, flaky texture over time.  This condition is exacerbated at tracks that have a high percentage of sustained braking (e.g. street circuits).  You want to replace pistons that are starting to get very light colored (white) or are starting to break away.

Also, it should go without saying that you bleed the brakes for every event.  I perform this task at the track (rather than at the shop) to provide the freshest (driest) fluid for use during the weekend.

Annually
You MUST rebuild the calipers each season.  There are several reasons.   Obviously you want to replace the rubber o-rings which seal the pistons to the caliper bores.  We don't run the rubber dust boots which cover the  pistons.   It's our experience that they just burn off within a race or two anyway.  When you are rebuilding the calipers, be sure to use a lubricant which is compatible with brake fluid to coat the caliper bores, pistons and o-rings.  You can't use regular grease, but brake fluid itself will work in a pinch.

Here's one of the real “secrets”.   Referring to the picture of the caliper below, it is essential that you remove the Teflon liner (“E”), the rubber grommet (“D”) and thoroughly clean the mounting pin bore (“C”).  The reason is that over time, rust and corrosion build up inside the mounting pin bore and start clamping down on the mounting pin (“F”).  This has the effect of limiting the ability of the caliper to float and will absolutely increase brake drag on the car.  As I'm sure you understand, brake drag is the same as less horsepower and is to be avoided.  I use a 3/4" steel wire “bottle brush” to clean out these bores.  In addition, when reassembling the calipers, I use a little grease to coat the bores to slow down the corrosion.

Brake Fluid
I use Wilwood 570 and have never boiled the brakes.  I also use moisture barriers on the master cylinders to keep the fluid as dry as possible.

Torque Brackets
This is the caliper mount and also the guide for the pads.

It's important to be sure that the "ears" of the torque bracket are clean and free of rust to allow the pads to move easily.  I wire brush the ears and coat them with oil.  In addition, when mounting the torque bracket to the hub, be sure to use red Locktite (#271) on the bolts and torque to 74 foot-pounds.  The socket required for these strange mounting bolts is a Snap-On #FLE140.  By the way, the proper torque for the caliper mounting pins is 25-27 foot-pounds.

Parts
Caliper Rebuild Kit: Chrysler 83 500 034 (Renault: 89 83 500 034)
Caliper Pins: Renault 89 32 000 314
Caliper - Left: Renault 89 32 000 367
Caliper - Right: Renault 89 32 000 366
Moisture Barriers: Girling 70-0009

Rev. 2/21/98

Barry