precise size of front brake pistons

[HardTop]

Has anybody got the definitive dimensions for the front brake pistons primarily the diameter .
The tolerances on this dimension are also of interest

Thanks in advance for any info or sources

[mbell]

What car/calipers? Elan v +2 had different brake setups on the front.

[Billmack]

Id say plus or minus .0005 or 7 inches from the nominal size

[HardTop]

1970 elan s4
front caliper are I believe Girling 14LF

values so far
48.1 mm
OR 1 and 7/8 inches = 47.625 mm
real values and tolerances would be appreciated

[69S4]

I have 48.05mm on two pistons - one new, one used.

[rgh0]

I measured 6 original pistons in good condition with no significant wear with a calibrated quality micrometre with zero error at 50.00 mm

Measurements were 48.10 mm +/- 0.02mm

cheers
Rohan

[2cams70]

Any reason why this dimension is important to you?

[Craven]

As the originals are hard chrome plated I doubt the precise diameter is closely controlled. Surface finish more likely.

[HardTop]

Thanks for all the comments
I was interested because I suspected some new pistons I had were over size
It seems from the comments I was mistaken
Thanks again