The 75 and ZT Owners Club Forums - View Single Post - How do I refurbish front nearside caliper?

SD1too · 20th April 2021, 10:49

Hello Ian,

What you're proposing to do is not an easy job by any means. You'll appreciate that the seal between piston and housing will be very tight indeed in order to prevent any leakage of brake fluid. Sorry if I'm asking the obvious but have you definitely established that the piston is the problem?

The weak point with sliding calipers is friction on the pins and/or the external cast iron moving parts. A good session with a wire brush and some suitable lubricant has always been successful for me.

I'd recommend asking an assistant to apply the brakes in a slow and controlled fashion whilst you observe the piston movement and check for any surface corrosion which can usually be cleaned off. If the piston travel is limited, don't overlook the possibility of air bubbles in the brake lines. Otherwise, try repeated manual back and forth movement of the piston.

If, after all this, you conclude that the piston is seized, there are people who specialise in the restoration of brake calipers and that solution would save you a lot of grief.

Simon

20th April 2021, 10:49	#5
SD1too Doesn't do things by halves Rover 75 2.5 Connoisseur Auto (1999) Dealer launch model. Join Date: Mar 2007 Location: Former Middlesex Posts: 20,386 Thanks: 1,587 Thanked 3,749 Times in 3,181 Posts	Hello Ian, What you're proposing to do is not an easy job by any means. You'll appreciate that the seal between piston and housing will be very tight indeed in order to prevent any leakage of brake fluid. Sorry if I'm asking the obvious but have you definitely established that the piston is the problem? The weak point with sliding calipers is friction on the pins and/or the external cast iron moving parts. A good session with a wire brush and some suitable lubricant has always been successful for me. I'd recommend asking an assistant to apply the brakes in a slow and controlled fashion whilst you observe the piston movement and check for any surface corrosion which can usually be cleaned off. If the piston travel is limited, don't overlook the possibility of air bubbles in the brake lines. Otherwise, try repeated manual back and forth movement of the piston. If, after all this, you conclude that the piston is seized, there are people who specialise in the restoration of brake calipers and that solution would save you a lot of grief. Simon __________________ "Whatever is rightly done, however humble, is noble." Sir Henry Royce.