A wanted thread on here last weekend for a pair of early 40mm mounting bracket Calipers reminded me I had a set in the garage that I’d been meaning to pop the pistons out of to see what condition they were in before offering them for sale as in need of refurbishment. I didn’t reply to the thread because I wanted to know what they were like internally first. I’d been putting off doing it because it’s a job I hate doing, mainly because in the past I’ve struggled with an array of bodged together tools to remove pistons, so thought I’d investigate a set of proper ones. I was lucky to find this used set on EBAY which I ‘Won’ for under £30 inc postage, and they arrived on Saturday. And to the point of this thread – Why the hell didn’t I get a set of these years ago? I’ve not used the slide hammer bit yet as the Calipers turned out to be in really good internal condition, and the pistons slid out really easily when gripped with the different sized tool inserts. I went from this: To this: In literally around 5 minutes. – Brilliant.
Rightly or otherwise I just put a bit of rag in the caliber and blow the pistons out with compressed air.
The trouble is I'm often working with Calipers and pistons that are properly stuck with corrosion, so I've found neither of the above method has worked. I had a pair of the pliers a while back, but found they don't give nearly as much grip as the tool I've brought. .
I have never found using air to work well…one pops and the other refuses. I’ve been lucky in that I’ve never had one totally stuck I use spanner’s to limit travel and had them all out till I can wiggle them out. but having a piston tool would be lovely
One of the funniest things I read when doing this is that the last they saw of the piston was it going over next doors roof
I had a professional overhaul a brake caliper that was well and truly stuck and he used a high-pressure fluid system to squeeze the caliper pistons out and then replaced the old corroded one, all for a very reasonable price.
I have considered getting some piston pullers myself but have done ok with compressed air so far. The worst one I had was an old 70's caravan caliper, a 50mm dia steel piston in a steel bore, ended up screwing a grease nipple into the bleeder port and used a grease gun to hydraulic it out.
My last stuck piston ordeal was on the Darmah brake calipers. And before that, the clutch piston on a 1989 900 Supersport. For both, compressed air was not strong enough. I use hydraulics in place (brake/clutch fluid) to get the pistons partially out before flushing and dismantling things. Then, in the vice with vice grips around the piston and they come out pretty easy. Obviously, you need new pistons after that…
I've got some piston pulling pliers that normally get them out easily enough, sometimes have needed compressed air to assist. Recently, refurbing some Landrover calipers I had to resort to other, more persuasive, means involving damaging the surface of the pistons with grips/vice but, when things get that far then I'm fitting new pistons anyway.
