R32 Gtr Brake Upgrade Advice

[LotusGTR]

No worries. OK. I've now got some R33 GTR 17 x 9's so can get some bigger rotors up front. Plan now is to get some R33 Brembo calipers for the front with some of those Stoptech slotted rotors from the mob in NSW. Does the collective wisdom think that they will balance well with std R32 rears? I think I can get a pair of front calipers in good nick for about $1,000. How's that sound?

Lastly, would the calipers 'Roy' is selling (should he choose to separate) fit under the R33 rims (he mentions them not fitting his street set) and bolt straight onto my steed?

Edited June 18, 2008 by LotusGTR

[Ronin 09]

i think you should be ok with Roy's calipers as the GTR offset and wheel design gives better 'face' clearance... i think his issue relates to the shallower offset of GTSt rims - basically how close the wheel is to the caliper.

There are heaps of people doing GTR brembo fronts with std sumitomo rear calipers - they should come up ok balance wise. They are a slightly bigger piston area, but it's fark all (don't have my specs on my home computer). Would be better if you get the rears too but they tend to go for around 500-600 bucks calipers alone...

front Brembo calipers I reckon should be around 1K mark, but really for an OK (not excellent) caliper should come with good life OEM rotors for that money. My opinion won't stop people advertising GTR brembos for 1400 with rotors though even though they're just an ok caliper.

if you want to, you could first try rebuilding your calipers (really little difference between them and the GTR brembos) with new seals, getting a caliper offset kit from nismo.com.au

make sure the brake lines are in good nick (if not throw on some newies, or braided if you want), good fluid.

this will be 95% of the way to the R33 brembos and you know that then you have basically a new brake setup - second hand brembos may require new seals etc etc so the exercise may be $$

if you're not happy with the 'basic' upgrade, sell the set to someone on nissansilvia.com, and save up for some proper big calipers like Roy's F50s or Alcons, or AP CP5555s.

i just don't think the GTR brembo is such a 'good value' 'upgrade' for the money people are asking - for $800 including rotors, it's a good deal for a marginally bigger caliper and rotor, but for $1400 I reckon they're not worth it.

my 2c - hopefully someone who knows something might chime in...

[LotusGTR]

Ronin, thank you. I was wondering what differences there were between R32 calipers and the Brembos and it sounds like not much. Given I've got 17s, I'm thinking of running 324 x 30 rotors (R33 GTR size) in favour of the 296 x 32 std R32 numbers. If I'm keeping my std calipers I presume they will run on this larger rotor but will need to be 'spaced out'. Is that what those brackets are for in the picture you posted from nismo.com.au and your reference to the caliper off set kit? I also presume the smaller thickness larger diameter rotor won't pose any problems for the std caliper.

Nick.

[Ronin 09]

i'll put up the piston sizes when i get to work...

GTR32 (Sumitomo)

Front Caliper Piston (diam x qty) - 40.4 × 4

area total caliper sq. cm - 51.28

Rear Caliper Piston(diam x qty) - 38.18 × 2

area total caliper sq. cm - 22.90

GTR33/34 (Brembo)

Front Caliper Piston(diam x qty) - (44+38) × 2

area total caliper sq. cm - 53.09

Rear Caliper Piston(diam x qty) - 40 × 2

area total caliper sq. cm - 25.13

Total volume front and rear (by one side only) sq. cm

GTR32 (Sumitomo) 74.17

GTR33/34 (Brembo) 78.23

% diff from GTR32 sumitomo to GTR33/34 brembo

Front 103.5%

Rear 109.8%

now my hydraulics brain is not working so well, but if F = P x A, then the brembos have a slightly greater rear bias.

so if you upgrade the front calipers only, you'll get a slightly greater increase in front bias. Note that this will increase even more because you're using a 324 rotor instead of a 297 rotor...

In answer to your question, the spaced R32 sumitomo caliper will work fine with the larger rotor, the swept area won't be outside it's working capacity. The brackets in the picture are the offset 'spacers' or dogbones as they're sometimes referred to. The 2mm narrower thickness rotor won't be a problem either - it will have the same effect as having ~1mm worn off each pad.

cheers

[djr81]

Good calcs but you need to include the rotor diameter in there somewhere.

Sumitomo front 296, rear 297.

Brembo front 324, rear 300

So the larger front rotor helps compensate on the Brembos.

Some random sizes for upgrades:

F40 area:53.09cm2

F50 area:55.50cm2

CP5555: 50.1cm2 (Same as 6 pot Endless)

CP5200: 49.59cm2 (Same as 4 pot Alcons)

All the vendors claim good balance but some are happy so sell you an F50 calliper on a 343 or 355 rotor for a GT-R whilst other will sell a CP5200 or equivalent on a 335 rotor. So who knows.

[LotusGTR]

Thank you thank you thank you. So, even the F50 caliper only offers a little over 8% more piston area than the std sumitomo? Does that translate to pad area? If so I guess the P part in your equation comes down in part to the rigidity of the caliper and how well the brake booster is matched to the cm2 of the pots? So the combination of larger swept area (say 10%) and greater rigidity (say 10% - an uneducated guess) gives an overall increase in F of 21%, which is not bad. Then if the greater force is applied further from the centre of the rotor, it multiplies again....Plus you have more mass to take the heat. I am on the right track? I guess ultimately the std caliper may not be strong enough for a large rotor due to the increased leverage.

Based on this it would seem that the spaced sumitomo would do a pretty good job. I guess if I get bigger rotors and the calipers do not do the job, I can upgrade them later?

If I'm 'spacing' sumotomo's then I guess I may as well find the largest rotor that'll fit in the rim right (343 or 355 - not likely)? Or do I / will I have to stop at 324? I've just thrown a tape over the rim where it bolts to the disk and the internal clearance seems to 390mm. So 324 would leave 66mm for caliper clearance and 343 47mm. Is this enough? Is this the limiting factor?

So much to know....

Edited June 19, 2008 by LotusGTR

[djr81]

So, even the F50 caliper only offers a little over 8% more piston area than the std sumitomo?

Yes. Bur for whatever reason the Brembo callipers actually have quite a large piston area relative to most other makes.

Does that translate to pad area?

In this case yes, but not necessarily. The CP5555 has a larger pad and a smaller piston area than an F50, for example.

If so I guess the P part in your equation comes down in part to the rigidity of the caliper and how well the brake booster is matched to the cm2 of the pots?

A badly matched master cylinder to piston area will give you either a very long pedal or a very hard pedal. Neither of which is any good.

So the combination of larger swept area (say 10%) and greater rigidity (say 10% - an uneducated guess) gives an overall increase in F of 21%, which is not bad. Then if the greater force is applied further from the centre of the rotor, it multiplies again....Plus you have more mass to take the heat. I am on the right track? I guess ultimately the std caliper may not be strong enough for a large rotor due to the increased leverage.

Remember that if you run too much front (or rear) bias you will reduce your braking capacity, not increase it. See the stoptech website for more info. Also calliper rigidity doesn’t compromise braking torque as you appear to have calculated, so you can’t include for it like that. A flexible calliper will be more prone to knock off and also give you a longer pedal.

Based on this it would seem that the spaced sumitomo would do a pretty good job. I guess if I get bigger rotors and the calipers do not do the job, I can upgrade them later?

Yes.

If I'm 'spacing' sumotomo's then I guess I may as well find the largest rotor that'll fit in the rim right (343 or 355)? Or do I stop at 324? I've just thrown a tape over the rim where it bolts to the disk and the internal clearance seems to 490mm. So 355 would leave 135mm for caliper clearance. Is this enough? Is this the limiting factor?

A 343 rotor would leave 74mm clearance for a calliper. But you need to leave a gap to prevent stones etc getting trapped in there. So you end up with no more than 68mm or thereabouts - this isn't a great deal of room.

Also 490? I think you mean 390mm. Which gives very little room for the calliper...

Edited June 19, 2008 by djr81

[Roy]

LOL...try now , buy later

From memory an AP CP5555 for instance needs about 22mm on top of your rotor radius to clear the wheel. So for a 324mm rotor, thats 162+22 = 184mm radially. So your measurement of 490mm ID is 245mm radially so will walk it in. Even if your ID is 390 still gives you 11mm, which is plenty. If you want to run a 343mm, can still do it but you need to make sure your 390mm measurement is accurate or at least conservative as its only leaving you with 1.5mm clearance

Oh, and will quickly add, the R32 V-Spec II BBS wheels are 17x8 +30, not 9", lol otherwise i woudl have bought some

And Ronins very nice AP CP5555-804s from memory , the pick of the litter. Means you can run endurance style thick rotors of 35.6mm etc all whilst running a std thickness pad which means the pad actually comes up to temp on the street, which with a caliper that runs an endurance style pad as well (ie twice as thick) there is talk that the racey pads never get up to temp meaning that they grind your rotors a new a55hole

[jenkies]

hey mate some food for thought. riantos rda group buy is awesome save a bit. i got fully slotted and dimpled rotors and ebc red stuff pads pulls up 30% better than before on r32gtr stock calipers. AND YOU CAN DO IT YOURSELF! paint is also a good option while your pulling it all appart. dont think rda rotors are as prone to crackin, just dba

Good Luck

[LotusGTR]

LOL...try now , buy later

From memory an AP CP5555 for instance needs about 22mm on top of your rotor radius to clear the wheel. So for a 324mm rotor, thats 162+22 = 184mm radially. So your measurement of 490mm ID is 245mm radially so will walk it in. Even if your ID is 390 still gives you 11mm, which is plenty. If you want to run a 343mm, can still do it but you need to make sure your 390mm measurement is accurate or at least conservative as its only leaving you with 1.5mm clearance

Yeah, 490 is a bogus domension. It's 390, and 1.5mm of clearance sounds like it may as well be zero, so I think 324s are the practical limit, especially given the stone / dust guards would be coming off...

Oh, and will quickly add, the R32 V-Spec II BBS wheels are 17x8 +30, not 9", lol otherwise i woudl have bought some

Yep, got that one too.....I've picked up the R33 GTR rim and got 9" and saved about $1,000 and got tyres thrown in too!

And Ronins very nice AP CP5555-804s from memory , the pick of the litter. Means you can run endurance style thick rotors of 35.6mm etc all whilst running a std thickness pad which means the pad actually comes up to temp on the street, which with a caliper that runs an endurance style pad as well (ie twice as thick) there is talk that the racey pads never get up to temp meaning that they grind your rotors a new a55hole

I'm guessing this caliper doesn't qualify in the budget upgrade category!

Thanks for the chat last night. Most helpful. I'll be in touch.

[LotusGTR]

Can anyone recommend a good brake shop to fit any gear I might buy? Someone with specific experience with GTRs. I work in Dandenong, so God knows there's got to be someone down that neck of the woods right? Any recommendations for the Dandy area?

Also, I've got my new R33 rims lined up next to the 16s on my car and they're big looking. The 16s are 225/55/16 and the newies are 245/45/17 (that's the std tyre size right?) and they look like a very tight squeeze. I'm running some kind of coil overs and its a little low but not too much so. I'm wondering if it is too low......I'll try them tomorrow and see how I go, but if anyone has experience of putting R33 GTR rims on R32s I'd be grateful to hear from you.

Cheers.

[Rowdyr32]

You undo the wheel nuts take the wheel off and put the r33 ones on. As for needing experience on gtr's to fit brakes there are only about 5 bolts to undo and retighten. Stop stressing mate.

As for ebc reds I melted a set in a 280rwkw gtr at the track. Go the ebc yellows in you want ebc and don't listen to the guy in the shop if he tries to sell you reds for the track. They would be fine for the street though. Just put different pads back in when you get home from the track. Its worth it. Maybe $700 all up for my setup. R33 brembo are the same pad length but extend about 5mm further down so most people are gaining more by going the larger disk than the caliper in my opinion.

All I have is ebc yellows with spaced out calipers and slotted 324mm $90 rda rotors with big castor rod air deflectors and cut the backing plate from behind the front and rear disks. No need to spend massive $ and my disks have never warped. Most people who are spending massive dollars on brakes in gtr's with under 300kw most likely need to learn to drive and get their cars to handle better and carry more corner speed so their not relying on the brakes so much.

Put the money into suspension if you want to go faster.

I'm in Seaford and can fit them if needed. Pm me.

Set your car to 355mm front and rear from centre of wheel to guard to begin with.

[Ronin 09]

fark gareth you're a hard man lol!!

[LotusGTR]

With my dexterous hands, opposing thumbs, and clever tools I will try and overcome the wheel nuts and will report back once they are fitted.

[LotusGTR]

and here are the rims on the car. Test drive and full steering lock test complete. Nothing has fallen off and no bad noises. Tramlines a little cf the 16s. No dramas so far, which I think is what I should have expected.

I think I'll drive with them for a while before committing to larger rotors and not being able to go back to the 16s. Make sure the car still handles well and the look of the rims settles well on me.

[Roy]

Talk to Scotsman on the forum, he is over your way and paints wheels for agood price and has a real nice daek grey simialr to the R34 wheel colour that looks great on the R33 wheels

[LotusGTR]

Talk to Scotsman on the forum, he is over your way and paints wheels for agood price and has a real nice daek grey simialr to the R34 wheel colour that looks great on the R33 wheels

Will do Troy. Thanks.

[Ronin 09]

have always liked the look of 33gtr rims.

if they fit over my front brakes i'd likely have a set.

what's the aspect ratio of those tyres - they look a bit tall...

edit - 245/45/17 sounds about right...

[LotusGTR]

Yeah, 245/45/17. I agree they look tall. I guess I could go a 40 series that is slightly narrower which would sort that out, but then they would look too small in the guards and then I gotta look at the suspension, which I kind of like for the driving I do, so am reluctant to mess with it.

I think I'll investigate what road legal track rubber is available for these rims and take it from there. The profile of those tyres with the stiffer sidewalls always looks slightly different anyway.

Anyhow, I've got to bottom the brake thing out now, which is where this all started.

[LotusGTR]

Anyone know if dogbones are ADR compliant / legal / roadworthy?

Also, the RDA rotors. There is a group buy on soon. Any thoughts on how there stack up against the Stoptech items. The RDAs are cheap.