E53 Front brake piston collar size

[R*I*C*H]

Hello everyone,

New member here, been browsing the site for a while after the purchase of my 2006 3.0d X5 but this is my first post.

I recently bought a caliper rebuild kit and some new front caliper pistons to sort my binding front brakes.
Upon reassembly I noticed I had been sent new pistons that had 9.6mm piston collars (I ordered the correct 6mm ones)
BMW changed the pistons to 6mm collar versions in Nov 2005 (as well as a different seal & dust cover).
Does anyone know if using the 9.6mm collar versions will cause a problem?
I know BMW must have changed the pistons to smaller collar versions for a reason, and i'm hoping someone can shed some light on why

Any help would be much appreciated, thank you in advance

Rich

[mashby]

Did you ever get an answer to your question about collar size, I just bought a kit with 9.6mm collar & mine are 6mm. I have an August 2005 E53 X5

Mark

[Alan Gunn]

I get my brake parts from biggred.co.uk never had a wrong part and good prices quick delivery as well.

[Themoog2]

By collar do you mean the area between the piston seal groove and the front of the piston?
I have a new set for mine from big red but never got round to fitting them.
I cured my sticking caliper by just pushing the piston in and out a few times.
Maybe I should fit them..