Rear Brake-Callipers – Design fault on pre 5th Jan 95 versions, self-destruct

Work-around – Short-lived, fix is rebuilt/new (Sumitomo redesigned).

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

The Problem

– Handbrake pivot pin seal of rear calliper

 

    • The handbrake cable links to a spring/pivot-arm which mechanically operates the piston/brake-pads against the rotor. The pivot pin pivots on a needle bearing, with the two sealed into the calliper body by a rubber seal.

 

    • Design failure is seal deterioration, allowing water in to cause corrosion, destroying the bearing and over time the handbrake pivot pin seizes. The handbrake will fail to release, or on repeated heavy brake-application the calliper will not release – causing intense heat to the rotor (orange) and distorting the calliper. The calliper must then be replaced with a new (redesigned) or rebuilt unit.

Some owners report regularly lubricating/operating the mechanism can release it and keep it operating for a time, but only as a short-term solution. Castrol CL grease is a waterproof sticky grease but once corroded it is too late (treating the effect and not the cause).

On both front & rear callipers, periodically lubricate the guides (chromed sections) with an antiseize waterproof high temperature grease is advisable.

Solutions

:

Short term:

    • Unhook the handbrake cable from the pivot arm, spray WD40/penetrant around the area and work the pivot pin through it’s entire range of movement. Then apply a grease (Castrol CL) to the area and work that in. It is possible on relatively new callipers 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. It is not possible to use the redesigned seal. Using a helper spring may also help in the short term.

Finding that lubrication is only a short-term resolution correlates with the cause being deteriorated pivot-pin 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 is too late as a long-term solution.

Longer-Term Solution:
Warranty: See Dealer.

Ex Gratia: Ford-UK & Mazda-UK have contributed towards the cost of replacing failed callipers, being well aware of the problem. Refunds are not total, usually the cost of the calliper but not extending to rear brake disc (UK: remarkably inflated £120 vs £22).
Ford UK stated that the revised level calliper has been fitted in production since Jan 5th 1995, and these parts can also be fitted to earlier vehicles. It would appear that this revised part is supplied as a matter of course, externally there are no changes – the seal/needle-bearing has been redesigned & the redesigned parts themselves are not retro-fittable.

Sourcing yourself: Calliper components may be rebuilt or new:
– Canada: Rebuilt Callipers from Fenco (Fenwick Automotive Company). Brake pads as Axxis/Repco Metal Master (dustless and 40% uprating favourite of BMW and Porsche), or Raybestos Semi-Metallic. Rotors from Roebuck Mazda are around 58$US for the front, so similar discounting for the rear.
– USA: New or Rebuilt callipers from Roebuck Mazda or elsewhere (rebuilt 80-125$US).
– UK: UK owners can get new callipers from Mazda/Ford-UK ex-gratia. Rebuilt callipers available from Roebuck Mazda (20$US shipping to the UK). Rotors for front & rear are available from Trans Auto Sports, UK, on +44-(0)-1772-454647 rear £21, front £37.

Roebuck Mazda www.roebuckmazda.com discount ALL mazda parts, so most are available 50% cheaper than in the UK even after shipping & other costs are included. Voice: 205-836-0600, 1-800-240-2121, Fax 205-836-0195.

Other cars (Nissan, VW) suffer similar problems, and the Miata/MX5 can suffer the problem having the same design, but it appears almost rare suggesting there is some wheel-arch/environmental factor.

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 not refunded 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 calliper-only costs (get rotors from Trans Auto Sports).