Subaru 4 pot front callipers on the front and the rear?

[Bob_n_Cincy]

Thanks Bob, this is my math, but it needs to be checked

The 2006 wrx front calliper has a working piston area of 3.97 square inches (2 pistons at 1.591 inch diameter)
The 2006 wrx rear calliper has a working piston area of 1.77 square inches (1 piston at 1.5 inch diameter),
so for the same brake line pressure, putting front callipers on the rear disk will give (3.97/1.77) 2.25x more rear braking.
Then with the larger rear rotor (316mm vs the standard 290) that 2.25x clamping force acts on a 1.08 times longer arm, so I get the 2.4x (ish) increase in rear brake


Thanks Frank, I haven't checked to see if the front callipers will fit without major modifications
One big difference is the rotor width, the front calliper expects to see a 24 or 25mm thick rotor, but the standard rear rotor is only 18mm thick. This is one of the reasons I was looking to the DBA 42657 rotor, it is 20mm thick.

Hi Tim
To solve the 18mm to 25mm thick rotor, I welded an old backing plate (1/4") to the backing plate of the outside pad.

Here are some of the trimming I had to do to make things fit .
IMG_20141012_205029097s.jpg

IMG_20141012_205040000s.jpg
Bob

[DodgyTim]

Bob, if the pad surface wears down to very little thickness, do you think it could come out of the calliper housing? or does your welded on piece act to keep it anchored?

[Bob_n_Cincy]

Bob, if the pad surface wears down to very little thickness, do you think it could come out of the calliper housing? or does your welded on piece act to keep it anchored?

That is exactly why I did it. With the pad material gone. It cannot come out of the bracket.
Also without this mod, the piston may come to far out of the caliper.
Below, you can see why I put it on the outside pad.

I wish the rotor as about an inch bigger in diameter.
Bob

IMG_20141012_205309322s.jpg