Brake Caliper Piston Tool

If you do any maintenance on your modern MG (as in anything under 60 years old), chances are, at some stage you’ve changed the disc brake pads. It’s not a hard job and can be done in under ½ hour with just a pair pliers and a large screw driver or two if you know what you’re doing and the mechanical gods are smiling on you.

_{(Hmmm, he never comes out of that shed in under an hour!!….Editor)}

One of the hardest part of the job is forcing the caliper pistons back to their start position. Over the years I’ve done it many ways, usually with a very large screw driver. The problem with this method is that

a) you put a large amount of sideways pressure on the disc. It probably doesn’t matter but it feels wrong, and

b) the pistons are not pushed back square to the caliper. This can cause problems with the two rubber seals that keep the fluid from escaping.

Yes it can be done successfully and I did it this way for the first 45 years of ownership. Why, because I didn’t know better and I used the tools I had. Every time I did it I thought ‘there has to be a better way’. There is!

eBay has a tool that slots in when the worn pads come out and with either ½” socket drive, spanner, or by hand, the pistons are wound back evenly and square each time. It’s called quite originally a ‘brake caliper piston spreader’ (who would have thought of that name… chuck that in your eBay search and see) and I swear by it now, not at the job. eBay has them for $15 with free postage. I’ve even seen them at Gas Weld for $50.

It’s a tool that you’ll wish you had if you ever do that job, even if it’s once every few years. If you need a lesson with your new tool, let me know. I can be bought for a beer or two.

Steve Jones

On The Marque October 2017