XT6 Rear caliper piston size ?

[discopotato03]

Hi all , from the WSM's the XT6 rear disc caliper pistons appear to be smaller than those in RX Turbo L series sedans ie 30.23mm vs 33.96mm .

 

Can anyone confirm this as we didn't get XT6's in Australia only RX Turbo sedans and XT4 4WD and 2WD Turbos .

 

Cheers A .

[idosubaru]

that's news to me, i always thought they were the same.

[Numbchux]

I just hopped on rockauto.com, and all EA82 rear caliper repair kits are for a 1 3/16" (26.125mm) piston.....XT6, RX, XT turbo, GL-10 turbo, etc.

 

not a 100% reliable source, but pretty good....

[kingbobdole]

3rd'ed The calipers are the same size.

[discopotato03]

Righto , thanks all .

 

Cheers A .

[GeneralDisorder]

The piston sizes ARE different in some USDM models. There are three different (for each side - 6 total part #'s) rear calipers used, according to my parts manual, across the turbo/xt line, and a fourth type used for XT6's. There are only two types of pads - regular, and XT6.

 

There are three types because there was a change in 87. Up to 12/86 there is a single pair of part numbers for rear calipers. 1/87 and up have two different part numbers based on the vehicle.

 

The piston size is *largely* a product of the type of drivetrain - 2WD's had a smaller piston than 4WD's. BUT that's not true of non-RX Turbo 4WD Sedan's - they had the smaller pistons as well (all non-RX sedan's [1/87 and up] use the same smaller caliper)

 

The calipers DO interchange between 2WD's and 4WD's, so it's never easy to know what is on an older car without measureing the pistons.

 

XT6 is a different animal according to my parts book. None of the number match up.

 

This of course says little about the AUS market vehicles. You might have to ask some of your local soob nuts.

 

GD

[discopotato03]

My RX Sedan is 85/86 and the spare rear calipers I have are off an early XT4 that had the flap AFM and non Spider manifold EA82T .

I'll have to measure them both .

 

Can anyone tell or show the difference with XT6 calipers and pads ?

[discopotato03]

From the Australian 86 Subaru L Series FSM .

 

Before I quote figures it seems that Subaru speced the L series rear brake proportioning valve and caliper piston size according to the rear end mass of these cars . As is obvious the 4WD cars are heavier at the back than 2WD ones . The proportioning valves limit rear line pressure at either 569 or 640 psi and the rear caliper piston alternatives are 30.23 or 33.96mm .

 

Model ................................ Piston size in mm ... Rear line limited to in PSI .

 

4 Door Sedan 2WD ............... 30.23 .................. 569

4 Door Sedan 4WD ............... 30.23 .................. 640

4 Door Sedan 4WD Sweden .... 33.96 .................. 569

 

3 Door Coupe 2WD ............... 30.23 ................... 569

3 Door Coupe 4WD ............... 33.96 ................... 640

 

4 door wagon ALL ................ 33.96 ................... 640

 

2 Door XT4 .. 2WD ............... 30.23 ................... 569

2 Door XT4 .. 4WD ............... 30.23 ................... 640

 

 

So in theory my car being a 4WD RX sedan should have the smaller 30.23mm rear caliper pistons and the higher 640 psi rear line pressure limit .

If caliper mounting plates were made to mount the rear calipers out for a 266mm Liberty/Legacy rear disc then there's always the lower 569 psi proportioning valve to fall back to if it started locking the rear brakes .

 

A .