Rear break discs
 

I am trying to buy the replacement break disc for my v70 the front one was 286mm. I am looking online for a 286mm for my rear ones but i found one now 288mm. Does any one know if this is same disc or these 2mm difference can be a problem. thanks

The rear discs on my V70 were different from the front. They were solid unvented discs . Vented discs are fitted on some models. Any decent supplier will be able to supply the correct size etc if you give Vin no or reg number.

Rear discs are different.... always smaller.

When I recently baught for my xc70 mintex discs were £57 a pair compared to Volvo's £60 each.
Local factor gave reg number stipulated mintex from the ones he had available and paid my money.
You may need caliper mounting bolts as they are supposed to be single use and factor disks often do not have them in the box, £2.40 each from volvo.
Mine are vented disks
Paul.

that doesn't make sense. I got new front ones volvo original which is 286mm but everywhere where I search for the rear ones when I give my registration number it shows me 288mm diameter discs.
I bought the front one online and I am wondering if the seller has done a typing mistake.

Ive got a 54 plate v70, my rear discs are listed 288mm too.
Though theres 1mm difference in the radius, its basically effectively the same size as front, brake rotors can be equal, its the smaller caliper and pad size at the rear which keeps the balance in check.

Did you also search everywhere for your front discs ?

Did you get the same diameter as the disc you replaced ?

How do you know the disc you replaced was the correct diameter ?

He'd have noticed if the disc he replaced was the wrong diameter! It wouldnt meet pads enough, or itd not fit in the caliper (a real unobservant numpty could potentially fit too small a disc, but you'd have to be a total plum!)
Mine are 286 front 288 rear. Rear pads and calipers are half the size of front.

I might have been a bit too generic with my statement.... I should have said lower braking capacity or something like that.

I believe the 288mm disc is a SOLID disk whereas the 286mm at the front is VENTED. So slightly smaller in size at the front but much higher heat/braking capacity.

FYI strangely the pad size makes no difference to the braking effort - the friction created when braking is a multiplication if the size of the pad and the pressure (i.e. kg/m2) being excerted - if you halve the pad size, the pressure doubles etc. It's the piston size in the caliper that matters (or more specifically the ratio of the rear pistons to the fronts).

When my last Mini Cooper S had its front discs and pads changed by my local mechanic, he found that standard cooper pads had been fitted in the past and worn a groove in the discs.
It had been maintained by BMW under a service agreement!