Upgrade Front Brakes - 2 to 4 pistons

[blind_elk]

I'm planning on upgrading the disks on the front of a '06 X-Trail. Currently they are 2-spot floating calipers. I have worked out that the disk diameter is the same as a R32 GTSt, but the current disks are a bit thinner, and slightly "less tall" (back of disk to front of hat). R32 GTSt rotors and 4-spot calipers should simply bolt up.

My question is - will this work, mostly in terms of pedal feel. Will I be able to get enough fluid pressure from the original MBC, or do I need to upgrade that as well.

TIA

[GTSBoy]

What size is the existing MC? R32 GTSt is BM44, which is just under 1". Like 15/16 or something.

[blind_elk]

MC bore = 25.4mm (1")

Caliper Piston bore = 44.4mm

[Ben C34]

I asse you have also measured how the calliper actually bolts up? Not just making wild assumptions based on disc diameter?

 

 

Just do it and drive it. It will work. If pedal feels spongy get bigger master. If feels too hard and wooden get smaller master.

[GTSBoy]

Is that caliper a 2-pot sliding caliper?

The R3X 4-pots are 40.44mm pistons. So with twice as many of those as a 2 pot, it is equivalent to 57.2mm pistons in a 2-pot.

R3X piston area = 4 x pi x 40.44^2 / 4. And the 4s cancel nicely, so it's just pi x d^2. = 5137.7 mm2

Entrail piston area (assuming 2 pot 44.4mm) = 2 x pi x 44.4^2 / 4 = 3096.6 mm2.

Seems like a substantial change. 165.9%.

BM50 MC over BM44 MC is 113.7%.

Pedal travel might increase a bit.

[blind_elk]

57 minutes ago, Ben C34 said:

I asse you have also measured how the calliper actually bolts up? Not just making wild assumptions based on disc diameter?

 

X-Trail is 28mm thickness (GTSt is 30mm), hat height is 49mm (GTSt is 54mm), mounting location is same spacing as GTSt, (although there is a possibility that the ears may be different ).

My problem now is that I used to have a set of R32 calipers, which I gave away after I upgraded to GT-R rotors / calipers on the front on my GTS4. Now, if you get change from $500 for a second hand set, you are doing well.

[niZmO_Man]

I'd be surprised if R32 brakes bolts up without mods. Let us know how it goes!

[morboost]

the ears being different is everything, once you need a bracket the disc being the same size goes out the window, attkd make a t31 kit, plenty of turbo xtrail half cuts around research if nissan upgraded them for the sr20