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Upgrading rear 265mm rotors to 296mm

Hazzel255
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Hazzel255 Newbie

Hazzel255

Posted
Posted

Hi guys,

I'm wondering if anyone on here as changed their rear standard rotors from 265mm to 296mm? My 34 has r33 calipers adjusted to the 265mm rotors. Im wondering what i need to completely upgrade to the 296mm rotors as its cheaper than having the standard setup. 

Also will braking have issues as I have 280mm rotors on the front and then when i upgrade, the rear will be bigger? What are you running?

GTSBoy Grand Master

GTSBoy

Posted
Posted

It is hard to understand how your R33 calipers could be "adjusted" to fit smaller rotors.  It is often possible to make a new bracket to space a caliper out further to make it fit on a larger rotor, but the opposite is typically quite impossible.

I personally have no knowledge of whether the caliper mounts on the rear uprights of these NA cars are any different (ie smaller radius) than on the turbo cars, but I can't imagine that they would be.  As far as I can see though, they would have to be smaller to permit a 296mm caliper fit onto a 265mm rotor.

In order to achieve your goal, I would have just said that all you need is the rotors and calipers from the donor R34 whose brakes you want to upgrade to (and probably the hoses too).  But I would not bother doing it unless you are going to upgrade the front.  You DO NOT want to increase rear braking torque without doing the same at the front.  It does not matter that the rears would be 296 vs 280 at the front**.  What matters is that the car is currently hydraulically set up to run 265mm at the rear (vs 280 at the front).  Increasing the rear without increasing the front could make it much more able to lock up the rears (which is the fastest way to spin your car imaginable).

 

**as an example of this, stock R32 GTSt is exactly that.

KiwiRS4T Grand Master

KiwiRS4T

Posted
Posted

As far as I know the n/a R33 had 265mm rotors and presumably the calipers to suit. Why on earth would someone fit them to an R34? I presume your car is n/a so as above...just leave them alone - get some better pads if you want. If on the other hand you have a turbo car you should look for a full set of GTT brakes which might cost a bit but would be well worth it.

DatsunBanana Enthusiast

DatsunBanana

Posted
Posted

If you've got an R34 non-turbo then you can fit brakes from other models but you have to do caliper and discs together unless you have some sort of bracket to change the distance of the caliper from the disc. I would also be inclined to do a full set not just rears as mentioned above. I swapped out the smaller discs and slider style calipers on my R34 GT for a full set from an R32 GTR. Most (maybe all) R34 non-turbo models will have a 14mm bolt and therefore a 14mm hole in the mounting. If you swap for brakes from an R32 or R33 they'll have a 12mm bolt you'll and will have a 12mm thread in the caliper. You keep the 12mm bolt and just put a stainless steel sleeve in the mounting hole (14mm outside diameter with a 1mm wall thickness). The mounting hole centres line up perfectly. Braided lines would be sensible too. I haven't had any braking problems or hydraulic imbalance but some say to change the master cylinder as well to match the bias needed for the brakes you use. You also have to cut the lip off the backplate/dust-shield or change them for bigger ones to match the discs you use. I cut mine. If you use brake lines with banjos then you may need to cut the banjo bolt a little shorter.

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