Rear Brake-Callipers - Design fault on build pre 5-Jan-95

Frequency - Most Probe/626/MX6 rear callipers stick circa 55k miles.

The Problem - Handbrake pivot-pin seal defect on rear calliper

The handbrake cable moves a spring/pivot-arm which operates the piston/brake-pads against the rotor. The pivot-pin sits in a needle bearing sealed into the calliper body by a rubber seal.
Design failure is seal deterioration allowing water ingress & corrosion. The handbrake is usually found unreleased or the caliper will not release on repeated heavy brake-application. The caliper must then be replaced with a new (redesigned) or rebuilt unit.

Lubricating the mechanism can release it and keep it operating for a time, but only as a short-term solution. Both front & rear caliper's must have their caliper guide-bolts lubed regularly with a high temperature anti-seize grease or the caliper will only brake one side of the rotor.

Solutions:

Short term:
Unhook the handbrake cable from the pivot arm, spray WD40/penetrant around the area and work the pivot pin its entire range of movement. Then apply a waterproof grease (Castrol CL) to the area and work that in. It is possible on relatively new calipers to remove the pivot-pin & spring: in such cases replace the pivot-pin and seal, and thoroughly clean & lubricate the pivot-pin needle-bearing area.

Finding that lubrication is only a short-term resolution correlates with the cause being deteriorated rubber-seal & needle-bearing inside the calliper.


Regular use of the handbrake will help prevent the area seizing. Once the pivot-pin rubber seal and needle bearing inside have deteriorated, regular use/lubrication will not work in the long term.

Longer-Term Solution:
Warranty: See Dealer.

Ex Gratia: Ford-UK & Mazda-UK have contributed towards the cost of replacing failed calipers being aware of the problem. Refunds are not total, usually the cost of the caliper itself.
Ford UK statement: revised level caliper was fitted in production from 5-Jan-1995, and such parts may be fitted to earlier vehicles. This revised part is supplied as a matter of course now - since the seal/needle-bearing has been redesigned.

Trussville Mazda www.trussvillemazda.com supply remanufactured & new calipers are discounts to other Mazda dealers.

Symptoms:

Very hot rear wheel, speed falls back rapidly during gear-changes, deteriorating fuel mileage. If extreme, brake burning smell & glowing orange brake disc with the car being destabilised towards oversteer which the TTL suspension can't correct.

Complaints:

USA owners refused refunds should complain to the NHTSA (National Highway Transport Safety Association) at http://www.nhtsa.dot.gov/cars/problems/ with classification set to Brakes.
UK owners not refunded should complain to Ford/Mazda UK direct, who are aware of the problem and will instruct insomniac dealers to arrange refund of caliper-only costs.

Last Upload: 31st January, 2002. V1.50a
URL: http://homepage.ntlworld.com/dorothy.bradbury/probemx/p_p1.htm