BNR34 Maximum disc size with standard wheels

[bigboss59400]

Hello,

I made quite some research but I couldn't find a kit or informations above 355mm size disc brake fitment on R34 GTR standard wheels ?

Like 370mm or 365mm for instance ?

I have the ability to make custom brackets but prefer not too.

Looking for brand such as Brembo, AP racing...

Thanks for your time.

[Duncan]

For looks or performance? Good 355mm rotors, pads and calipers will work up to and beyond 24 hour endurance racing.

Assuming it's for looks I'd check out R35 brakes, I know that 18" wheels can be used on an R35, so those brakes must fit under 18s

[bigboss59400]

THanks for your reply

For both

R35 brakes are 380mm (or 390 for latest model) so it will fit on Nismo wheels for instance but not on the standard one...

And I would like to use both and I want the biggest possible

Edited March 31, 2020 by bigboss59400

[GTSBoy]

It depends on the calipers you use too. Different calipers have different radial "height" over the outer edge of the disc.

[KiwiRS4T]

I think its unlikely that anyone running 390mm rotors will be running  stock 34 wheels so you probably won't get your answer from the internet. You will have to actually take one of your wheels and try it on cars with bigger brakes.

BTW the bigger the brakes the bigger the unsprung weight.

[bigboss59400]

  On 31/03/2020 at 11:35 PM, GTSBoy said:

It depends on the calipers you use too. Different calipers have different radial "height" over the outer edge of the disc.

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Yes you are right and I asked it implicitly, I should have precised this in my original request !

I'm looking for calipers with a small "height" thus will determined the maximum disc size

 

Thanks KiwiRS4T I guess I will have to make my own research...

 

I was just wondering if someone managed to use >355mm disc brake with standard wheels

[GTSBoy]

Just measure the diameter of the barrel and subtract 355mm from it to see what radial space is left. (and of course, divide that by 2 for the number you're really looking for). Then you can ponder which calipers will fit in that gap, and if perchance there was room for a 5 or 10mm larger disc as well. Oh, plus the running clearance you're happy to live with.

Edited April 1, 2020 by GTSBoy

[KiwiRS4T]

  On 01/04/2020 at 8:06 AM, bigboss59400 said:

Yes you are right and I asked it implicitly, I should have precised this in my original request !

I'm looking for calipers with a small "height" thus will determined the maximum disc size

 

Thanks KiwiRS4T I guess I will have to make my own research...

 

I was just wondering if someone managed to use >355mm disc brake with standard wheels

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355 is another story - I thought you wanted bigger.  Both Duncan (above) and I have used brakes variously known as  K Sport or D2 brakes but not with stock R34 wheels - mine were Rays TE37 . If you google 355 brake fitment you might get lucky.

[Duncan]

I've actually got 330mm ksports under r34 gtr wheels on my stagea. 

(rough) measurements are:

410mm inner diameter of the wheel (18x9" R34 GTR standard)

40mm clearance either side of the disc (330+40+40=410mm)

20mm clearance from the caliper to the inner wheel (or to say it another way, they hug the disc nicely, only 20mm proud)

Based on all that those 355s would fit fine - 12.5mm less clearance at the caliper still leaves 8.5mm clearance for a 355 kit.

Of course, different 355 kits will have difference sizes, but generally you would expect a 355 kit to fit under 18s.

[bigboss59400]

Thanks for all your reply !

 

I want to go bigger than 355mm and I know 355mm it will fit (cf calculation of Duncan)

In fact, I start this topic to know if someone has already done it so that he can point me out some low "height" caliper

 

I just measured one of my wheel and I got 412mm (I need to check the 3 others)

 

I should be able to fit 365mm disc or maybe 370mm

For instance if I go with this caliper

https://apracing.com/cdn/drawings/cp9560-1cd.pdf

 

This will give me 407mm for a 370mm so 2.5mm clearance that's not a lot I agree but still be faisable

With a disc of 365mm that will give me 397mm so 7.5mm that's better !

 

Thanks for your time

Edited April 1, 2020 by bigboss59400

[GTSBoy]

  On 01/04/2020 at 9:16 PM, bigboss59400 said:

so 2.5mm clearance that's not a lot I agree but still be faisable

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No. Not feasible. Go below 5mm at your peril. More is better.

[Duncan]

Well, required clearance comes down to your willingness to run unbalanced wheels and accept gouges in the wheels when rocks flick up....

For race use both are usually acceptable....but I'm not sure taking that chance is a good idea with post-US-25-years-rule prices on genuine skyline wheels...