Brake caliper piston compressors: what they are for, which vehicles they fit and how to choose the r

A practical guide for selecting and correctly using SIXTOL brake piston compressors (MECHANIC BRAKE).

What a brake caliper piston compressor is and why you need one

A brake caliper piston compressor (sometimes also called a "tool for pushing back/screwing in the piston") is a tool that helps during replacement of brake pads and discs to safely and evenly return the brake piston into the caliper. On many vehicles – especially on the rear axle – the piston does not just push back but must also be rotated. The compressor ensures the correct direction, stable pressure and minimizes the risk of damaging the seal, piston or caliper.

When the piston needs only pushing and when it must be rotated as well

Piston only pushed (typically front disc brakes): a C-clamp is often sufficient, but a piston compressor is gentler – it pushes evenly and keeps the piston aligned.

Piston pushed and rotated at the same time (common on rear disc brakes): on calipers with an integrated parking brake mechanism the piston is screwed back. The piston face often has splines/holes into which an adapter engages.

Electronic parking brake (EPB): on some cars it is necessary to first put the parking brake into service mode (via diagnostics or manufacturer procedure). The compressor is then used for the actual piston return.

How to know which type of compressor your car needs

The quickest way is to observe how the piston behaves when returning. If it resists and "won't push in", it probably requires rotation as well. The piston face is also a good clue – it often has splines/holes that must match the adapter. If unsure, choose a universal kit with multiple adapters and both thread directions.

Right-hand vs. left-hand thread: why it matters

Some brake calipers use right-hand thread (piston is returned by turning clockwise), others use left-hand thread (turning counterclockwise). Therefore there are single-direction tools and kits that include both directions. If a kit contains only one direction, it may not fit some vehicles.

Single-direction SIXTOL compressors:

• MECHANIC BRAKE ONE R – right-hand: code SX1126
• MECHANIC BRAKE ONE L – left-hand: code SX1127

How to choose the correct SIXTOL kit (order codes)

SIXTOL offers mechanical kits (manual pushing) and pneumatic kits (for faster work with compressed air). There are also BLACK versions – functionally for the same use, differing by case finish (black case).

Quick choice based on how often you work on brakes:

• Basic for occasional replacement (12 pieces): MECHANIC BRAKE SET 12 (SX1101) or MECHANIC BRAKE SET BLACK 12 (SX1248).
• More universal choice for more brands (18 pieces, both thread directions): MECHANIC BRAKE SET 18 (SX1102) or MECHANIC BRAKE SET BLACK 18 (SX1249).
• The common "golden middle" (22 pieces, wide range of adapters): MECHANIC BRAKE SET 22 (SX1103) or MECHANIC BRAKE SET BLACK 22 (SX1250).
• For a workshop and regular service (35 pieces, more accessories): MECHANIC BRAKE SET 35 (SX1104) or MECHANIC BRAKE SET BLACK 35 (SX1251).
• Maximum universality (50 pieces, widest equipment): MECHANIC BRAKE SET 50 (SX1128) or MECHANIC BRAKE SET BLACK 50 (SX1252).

If you want to significantly speed up the work (e.g. in a shop):

• Pneumatic 16-piece kit: MECHANIC BRAKE SET PNEU 16 (SX1272).
• Pneumatic 23-piece kit: MECHANIC BRAKE SET PNEU 23 (SX1273).

What adapters do and why their compatibility is important

An adapter is a "plate" that bears on the piston face. It must fit correctly into the splines/holes of the piston so the piston rotates without slipping and is not pushed at an angle. The more adapters a kit contains, the higher the chance it will fit different types of calipers across makes and models.

How to use the brake piston compressor correctly

Below is a universal procedure. Always follow the vehicle manufacturer's instructions (especially for EPB and specific brake systems).

• Secure the car against movement, lift it and remove the wheel. Work on a level surface and use safety stands.
• Check the brake fluid level in the reservoir. When pushing the piston back the level rises – an overfilled reservoir may overflow.
• Before pushing the piston clean around the seal and the piston face. Dirt is a common cause of seal damage.
• Select the correct adapter – it must engage precisely into the piston splines/holes.
• Fit the compressor so it is in line with the piston and rests on a solid part of the caliper.
• Once the piston is returned, check the seal and proceed with installing new parts according to the manufacturer's procedure.

Tips for trouble-free work

• Do not force the piston – if it won't move it likely requires rotation or the EPB service mode.
• With a kit that includes both thread directions you have greater compatibility assurance.
• For regular servicing of many cars a larger kit pays off.

Common faults and when the compressor won't help

If the piston cannot be returned even with the correct adapter, there may be corrosion, contamination or a damaged caliper. In such cases inspection or refurbishment is necessary.

Summary: how to choose correctly

For common use a smaller kit is sufficient; for universal use we recommend kits with both thread directions and more adapters. For a workshop the largest kit or the pneumatic variant is ideal. For a specific thread direction you can also choose a single-direction compressor.