Lumina V6-191 3.1L VIN T MFI (1993)
Brake Caliper: Service and Repair
Front
Caliper Removal
1.
Siphon enough brake fluid out of the master cylinder to bring fluid level to 1/3 full to avoid fluid overflow when the caliper pistons are pushed
back into bores.
2.
Raise vehicle and remove front wheels.
3.
Mark relationship between wheel to hub and bearing assembly. Remove tire and wheel assembly.
4.
Using a suitable C-clamp and block of wood, push pistons back together into caliper bores.
5.
If caliper assembly is to be serviced, remove inlet fitting attaching bolt, copper washer, and inlet fitting from caliper housing. Plug opening in inlet
fitting to prevent fluid loss and contamination. Do not crimp brake hose, as this may damage internal structure of hose. If only shoe and
lining assemblies are to be replaced, do not disconnect brake line fitting from caliper.
6.
Remove two mounting bolts, then remove caliper. If only shoe and lining assemblies are to be replaced, suspend caliper from chassis using
suitable hanger. Do not allow caliper to hang by brake hose.
Caliper Disassembly
1.
Remove caliper assembly as outlined previously, then drain brake fluid from caliper.
2.
Position shop towel in interior part of caliper, then slowly apply compressed air to inlet port and remove pistons. It is imperative that one piston
be partially installed to facilitate removal of second piston from bore. A pad or wooden spacer may be used to prevent complete removal
of first piston.
3.
Remove piston boots from caliper bores, then using suitable wooden or plastic tool, pry piston seals from caliper bore grooves. Do not use a
metal tool of any kind to remove seal as it may damage bore.
4.
Remove bleeder valve from caliper.
5.
Inspect piston for scoring, nicks, corrosion, and wear and replace as needed.
6.
Inspect caliper housing and seal grooves for corrosion, nicks, scoring and excessive wear, and use crocus cloth to polish away corrosion from
housing bore. Replace caliper housing if corrosion in and around seal grooves will not clean up with crocus cloth.
7.
Clean all parts with denatured alcohol. Dry with unlubricated compressed air. Blow out all passages in housing and bleeder valve.
Caliper Assembly
1.
Install bleeder valve.
2.
Lubricate piston seals with clean brake fluid, then carefully install seals into caliper bore grooves. Ensure seals are not twisted.
3.
Lubricate boots and install onto pistons, then push pistons fully into caliper bores.
4.
Seat boots into caliper bores using boot seal installer tool No. J-36349 or equivalent.
Caliper Installation
1.
Position caliper over rotor and onto mounting bracket.
2.
Lubricate entire length of mounting bolts with silicone based grease, then install bolts and tighten to specifications.
3.
If inlet fitting was removed, install fitting using new copper washer.
4.
Install front wheels, fill master cylinder to proper level, then bleed brake system as required. Before moving vehicle, pump brake pedal several
times to be sure it is firm. Do not move vehicle until a firm pedal is obtained.
Mounting Bracket Service
Removal
1.
Remove caliper as outlined previously.
2.
Using suitable Torx bit, remove mounting bracket attaching bolts and the mounting bracket.
