Had a discussion with a friend yesterday, whose opinion I value, and he seemed to think that having larger discs on the rear is a bit silly, and possibly illegal.

I planned to only use dman1k disc setup on the front but the plans a have now moved to R31 rear end now too. So now I will have little laser discs up front and larger skyline discs in the rear.

If I use a proportioning valve to control the front and rear, would this cause me any grief? other than the rear discs bieng overkill?

u should have about 65:35 front:rear bias on a rwd, even less like 80:20 on a fwd, so u might have a lot of trouble with the rears locking up.
Also u might have trouble getting a small master cylinder to match up with a good pedal feel, as the skyline calipers will take up a lot of fluid and require a longer push on the pedal.
But they will look good there under your back wheels tho.

i wouldnt really be calling r31 rear discs big

and as for a bigger disc on the back, i assume your friend is talking about diameter, 300xz's and r32 non gtr skylines have 280mm front and 297mm rear, r32 gtr and r33 have a 296mm front and 297mm rear, even the r31s have 250mm front and 260mm rear.....i think there is a trend
bigger calipers on the back would be silly, but cant see anything wrong with bigger discs

bias on the other hand is something completely different

and as for a master cylinder, 13/16th sunny master should be able to handle rear discs pretty easy and still have a user friendly pedal

would it be easier to put smaller brakes on the rear instead of the r31 or would it to hard to do that.

Neil AKA dattoman1000 is gonna do this... well wants too. And i probably will to when i get this rear diff organised!

So speak to him about it, he is the brake specialest afterall!

r31 rear setup is pretty easy to adapt, just a matter of redrilling the caliper bracket and then spacing the caliper to sit centered on the disc

I was kinda hoping that Neil would say something.. but his is busy i guess.

If neil waves his magic wand and makes a kit that would match up with his front brake conversion, then Ill be the first in line, but until then, I want to try and keep stuff as standard as possible so that parts are easy to get.

Ok so after re reading the posts, it seems that some cars come with a larger rear disk anyways.

Yes the disks are from a R31 rear so its the 297 you mention, and its the somewhat smaller laser disks up front.

I guess thats its gonna be a suck and see thing.

Neil, oooo Neil

Do you have any comments to add to this??
Seeing as you are the brake guru and all....

Oh yeah, Still have to some and collect those manifolds from you

r31 is 260mm, 297mm with laser front discs would be just a bit off

sorry i mis read you last post.... hmm yeah 297 would be just a tad silly looking.

yeah i wont be using anythign flashy, just the standard calipers and discs.

another thing...

The backing plates, the tin things, mine are all bent up, and you can only get them from Nissan is was told. I dont want to remorgage the house, so do I actually need them?

It seems that they are an asthetic part, but I have been wrong plenty of times before.