Need a bit of help please.

[Snydersmuncher93]

I have just replaced my brake booster and now have the following puzzle.

Front calipers are rebuilt with new pistons and seals. Work very smoothly.

Rear brakes work great and release fully, shoes completely retract and drums spin freely.

Front calipers don’t release. And pedal gets very firm.

Any ideas on what’s up?

Is there an airlock somewhere?

Could the new booster be duff and cause this? It seems to work fine, (pump till hard, turn car in and pedal sinks down).

Could the master cylinder have dirt in it now?

Is there a handy way of cleaning out the fluid return bit from the front calipers?

Thanks in advance. Tony.


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[Bordos]

Are you sure that the system is bled properly? (Including the ABS pump)?

The return of the calliper piston is forced by return of the piston inside the brake pump (there is a spring inside).
Is it happening when the calliper is not installed ? (Not on the rotor with pads inserted)?

 

[Catnip64]

Front calipers are rebuilt with new pistons and seals. Work very smoothly.

Front calipers don’t release. And pedal gets very firm.

Can you clarify the above, what doesn't release? Are the pistons stuck, is the caliper not moving or are the discs dragging when turned?

 

[audifan]

Have you done an ABS bleed using VCDS? Did you bleed each brake in turn?

 

[Snydersmuncher93]

Thanks for the steers everyone.

Turns out the new booster was also duff.

All good now with another one.


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[audifan]

Was the booster an OEM or a copy?