Caliper pistons

[King_berald]

Hi guys, I've been trying to order some pistons for my front calipers (for my vx) and I seem to be a bit confused, I believe the part number is K272-020 (Diameter: 42mm / Height: 43.7mm), I've been supplied with part number K272-040(Diameter: 41.9mm / Height: 44.5mm) which I think is to suit BA Falcon. Seller has told me it is interchangeable. I have been told the same thing by another seller also. I'm not sure of the tolerances involved but being the brake system, I want to be sure its the right part. Does anybody have any info? Has anyone been through this?

 

[Lex]

Hi guys, I've been trying to order some pistons for my front calipers (for my vx) and I seem to be a bit confused, I believe the part number is K272-020 (Diameter: 42mm / Height: 43.7mm), I've been supplied with part number K272-040(Diameter: 41.9mm / Height: 44.5mm) which I think is to suit BA Falcon. Seller has told me it is interchangeable. I have been told the same thing by another seller also. I'm not sure of the tolerances involved but being the brake system, I want to be sure its the right part. Does anybody have any info? Has anyone been through this?

Have you pulled your old ones down yet?
I rebuilt my calipers in 2018. I bought new pistons (which where not needed), seals , pins. Also rebuilt the master cylinder.

Here's what the Ellery workshop manual says about the piston sizes.

Hre's the vt workshop manual specs.
FRONT CALIPER
Make PBR
Type Twin piston, sliding caliper
Bore diameter (nominal) 42.0 mm (each)
Disc pad material Organic, non-asbestos
REAR DISC
Type Solid
Diameter (nominal) 286 + 0.0 - 0.2 mm
Thickness 15.9 mm ± 0.2 mm
Lateral Runout (maximum)
(Rate of change 0.03 mm in 30O rotation max.) 0.05 mm
Minimum disc thickness, requiring replacement 13.9 mm
REAR CALIPER
Make PBR
Type Single piston, sliding caliper
Bore diameter (nominal) 40.5 mm
Disc pad material Organic, non-asbestos

 

[krusing]

Option 1 -
What's wrong with the existing ones ?,
Order caliper service kits,
Clean the old ones up and re-use them.

 

[krusing]

Option 2 -
Source a pair of calipers from a Wrecker, and strip them down, and use the pistons from them,
or
Service the s/hand units, and fit them.
Then you have spares on hand for future repairs.

Best of both worlds.

 

[King_berald]

Thanks for the replies, yeah i was going to use my old pistons as a last resort. The pistons came part of a kit.
i was just skeptical of the size difference between the 2 parts. Im wondering if anyone has used them before and if the part is interchangeable like they say

 

[King_berald]

Have you pulled your old ones down yet?
I rebuilt my calipers in 2018. I bought new pistons (which where not needed), seals , pins. Also rebuilt the master cylinder.

Here's what the Ellery workshop manual says about the piston sizes.
View attachment 261644
Hre's the vt workshop manual specs.
FRONT CALIPER
Make PBR
Type Twin piston, sliding caliper
Bore diameter (nominal) 42.0 mm (each)
Disc pad material Organic, non-asbestos
REAR DISC
Type Solid
Diameter (nominal) 286 + 0.0 - 0.2 mm
Thickness 15.9 mm ± 0.2 mm
Lateral Runout (maximum)
(Rate of change 0.03 mm in 30O rotation max.) 0.05 mm
Minimum disc thickness, requiring replacement 13.9 mm
REAR CALIPER
Make PBR
Type Single piston, sliding caliper
Bore diameter (nominal) 40.5 mm
Disc pad material Organic, non-asbestos

Havent pulled them down. I lost brakes on the way to work the other day so im just getting everything together for the job over xmas while i got the car off the road.