FREQUENTLY ASKED QUESTIONS ABOUT POWER BRAKE BOOSTERS:
Q) Are the Brake Doctors familiar with all boosters?
A) Yes we are. This includes Mastervacs, Hydrovacs, Treadlevacs and remote boosters. We've
been in the brake business since 1956 and we have seen them all.
Here's a list of the makes you may find:
Aisin; ATE; Bendix; Clayton Dewandre; Delco; Girling; Girlock; JKC; Knorr; Lockheed; Midlands
and PBR just to name a few.
Q) Can brake booster bodies be sleeved?
A) If needed corroded brake booster bodies can be restored to better than new by sleeving.
Q) Are all boosters repairable?
A) We can restore most boosters, even some sealed units that come crimped together and which
were never intended to be serviced.
We keep a comprehensive range of brake booster parts that are sourced worldwide to ensure the
overhauling of as many boosters as possible. This includes boosters for American vehicles such
as Cadillac's, GM's, Mustangs and Galaxies; English vehicles including Jaguar, Aston Martin
and Bristol; and European vehicles like BMW, Alfa Romeo and Mercedes.
Q) Are all boosters tested after restoration?
A) Yes they are all tested on a dedicated test rig for output, vacuum and hydraulic performance.
Q) What is the likely cost of restoration?
A) Age and condition of model influence cost. A quick phone call to us on
(08) 82610888 will help answer that one.
Q) Can you suppy repair kits so I can overhaul my own booster?
A) In most cases we can, but for everybody's safety we prefer not to.
Q) Why is that?
A) The four main reasons are:
1) Some boosters or power brakes were designed as a sealed unit, never to come apart.
Special tools and equipment are needed to dismantle them.
2) New seals will fail prematurely if fitted to corroded or scored slave and control cylinders in
need of sleeving.
3) Kits only cover major components. You may not recognise other critical worn, damaged or
4) Your best efforts may be in vain if you can't test the unit for vacuum and hydraulic leaks, and
overall performance, before refitting to your vehicle.
For these reasons, we suggest you send your unit to us for a professional tested outcome.
Q) I'm not sure if my booster is working properly. How can I test it?
A) Here's a simple test. With the motor not running, pump the brake pedal 5 times, then apply the
brakes as normal holding your foot on the pedal. Now start the engine. If the booster is working
properly, the brake pedal will sink a little as the booster applies extra pressure. Now turn the
engine off. Your brake pedal should stay down. If your pedal slowly comes back, you have a
Q) What are the most common faults with brake boosters?
A) Fault 1...Ruptured Diaphragms. Result...Engine will idle faster and may stop when applying the
Fault 2...Seal failure causing an internal fluid leak. Result...Fluid will be sucked out of the booster
and into the motor and will burn and cause eventual brake failure once the master cylinder is
empty of brake fluid.
Fault 3...Reduction, or loss, of vacuum supply. Result...Hard pedal and poor braking. All modern
car boosters utilise vacuum generated by the suction of the pistons or by a vacuum pump. This
creates a partial vacuum inside the booster. Applying the brakes admits air at atmospheric
(higher) pressure to one chamber of the booster. The resultant pressure imbalance
actuates the booster. Therefore a good vacuum supply is vital.
To test, remove the vacuum hose from the booster and start the engine. A vacuum gauge should
read 20Hg on the overrun. Just putting a finger over the hose end is not conclusive.
Depending on age and condition, the hose may be heat and fuel affected and could collapse
when the air gets sucked out of it. If you have any doubts, replace the vacuum hose and examine
the external check valve. You should be able to suck air in through the valve, but not out.
Power Brakes facilities and collective experience are available to identify and correct all these
Q) Do you offer a guarantee on Power Brakes products and brake boosters?
A) Yes we do...just click on the "Your Guarantee" button for details.