Member Since: 10 Mar 2017
Location: Gloucestershire
Posts: 1072
Should caliper pistons come out at the same time?
Hi all
When testing calipers, (pads out and pressing the pedal) should both pistons come out at the same time, or does one come out then the other?
Cheers for any help.
Phil
27th Jun 2017 4:03 pm
rrhool
Member Since: 28 Aug 2014
Location: Norfolk
Posts: 4399
'In Theory' both should move together, as the pressure is equal on both, the pistons are the same, etc. etc.
In reality, one will always move before the other (when there is no restriction on their position) because all mechanical components are different, even if they look the same. ie. the two pistons will be different within their tolerance, the seals will be slightly different etc.
Perfectly normal for one piston to move before the other.
Edit:
To test both pistons are free, put a G clamp or similar around the caliper to restrict the movement of one piston, then you can test the other.
Dont let a piston come out too far, or you'll end up with brake fluid all over the drive, and a brake bleeding job!Richard
D3 SE 2007. Triumph 2.5Pi 1973. Ferguson TEA20 1948.
Discovery 2 4.0 ES 2001- Gone
Discovery 1 300Tdi ES '95 - Gone
Range Rover Classic '79 - Gone
27th Jun 2017 4:45 pm
Philip1972
Member Since: 10 Mar 2017
Location: Gloucestershire
Posts: 1072
Thanks!
One piston stayed put until the other was pretty much fully extended and was stiff winding back.
I was actuall fitting new ones, but wanted to see if that was the problem.
As it happens, the new Ines were the wrong ones, so I ended up putting the old ones back on until I get the right Ines in Thursday!
27th Jun 2017 7:40 pm
lynalldiscovery
Member Since: 22 Dec 2009
Location: Maidstone
Posts: 7274
If its stiff going back in its had it, little trick to get you out of a bind is to use a needle and syringe full of brake fluid and inject the fluid through the rubber gaiter to lubricate the rubber seal, the needle is so fien the rubber self heals.
I actually did the same but with anti sieze fluid on my old D2
I used to work the pistons Every couple of months untill I had a lightbulb moment and injected the dust seals
Yes it should have had a new caliper fitted but it lasted a year doing this before I part exchanged it
Lack of use didn't help
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