Rear BBK anyone?

jt2ma71

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I've only had about .25" all the way around machined and that's enough. The transition was also beveled to prevent any structural issues. I'm sure everything was done right :)

As jt2ma71 says here, the e-brake shoe has heaps of clearance - just pulled mine apart to check and there's 6mm to spare, so no need for machining there.



This is a good point, as the step goes the opposite way to what you'd expect...... who knows why its there? bloody Subaru....... :p I'd be wary of machining across the entire surface from the center to the outside edge of that face though, unless you also skimmed the wheel mounting face and both sides of the disc surface to ensure they all remain true - otherwise the runout could be a problem. I'm sure your machinist only took down that stepped section though to avoid this. Good info, thanks jt.

I've got some more pics and fitting points that i'll post up once they upload.
 

1jz-Rolla

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I've only had about .25" all the way around machined and that's enough. The transition was also beveled to prevent any structural issues. I'm sure everything was done right :)
I have no doubt it was done right in your case mate, the level of your build leaves no corners cut i'm sure!


So the handbrake shoe adjuster access is an easy one to resolve: Just line up the old rotor against the new to mark the position of the hole, then use a drill-press in two stages - all the way through at 11mm, then partially at 18mm diameter, so that you can refit the stock plug afterwards. Although its not identical because of the taper of the 18mm drill-bit, it makes no difference as the rubber plug still seats at the top of the taper (as opposed to on the flat surface of the stock disc).









Of course you could do it "properly" in a milling machine, but its hardly necessary or worth the effort.


Cheers
Phil
 

1jz-Rolla

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How did you find a set of 2nd hand evo calipers that don't have the clearcoat peeling off! Nice find ;)

Is that a stepped section inside the friction surface of those fancy looking black discs? Hopefully this setup doesn't have a different swept pad area to the STi that the rotors were designed for......
 

yhatzee89

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eBay bro lol.
And it's got a groove inside but it's even on both sides of it. What do you mean different swept pad area?
 

silverhornet

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What a masive read that was :eek:
Just so i can clear up as im a worrier.

I will need for this BBK;

EVo 5-9 Calipers (Rear)
New Bolts so 4 x m10 x 1.5 at least 36mm long?
4 x 2mm washer's to space the calipers outwards.
then the bit im stuck on, I need STI 05+ rotors? theres so many different verients in rotor, these thinner or thicker, vented and none. which type would i need?

Then to check all clearences, once ive got all the bits. install and done?
 

mytmk3

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I fit rx7 16x8's but I'm not sure the guy may have said something about clearancing them to fit over his mk4 2pots but that may have been some one else

Sent from my GT-I9300 using Tapatalk 2
 

Mo87NA

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I've got a set of Brembo EVO calipers and Centric power slotted rotors for sale is anyone is interested.
 

1jz-Rolla

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Before you go to the machine shop, double check that your rotors don't have a lip on the hub-face like this:





If they do, consider machining a corresponding step in your hubs, or getting the machinist to skim the rotor (hub would be preferable)
 

yhatzee89

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Is that a major concern? Also, why better to machine the actual hub vs just the rotor?

Yeah I haveit on mine :/

 

1jz-Rolla

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Machining the hub just means you'll never have to do it again when you replace rotors. I'd also prefer to not remove any structural material from the rotor, but it really isn't much in this case anyway.

If you do machine the rotor instead, just ensure they only machine from that point outwards, It's too likely to induce runout if they swept the entire radius.

This is what I did to mine:

 

1jz-Rolla

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More than needed, just to be sure in-case future rotor sets have a taller step (from other manufacturers). For the current RDA rotors, the step is less than 0.5mm

So a step 1.0mm deep and 5mm radius should be plenty on the hubs.


Cheers
 

Dan_Gyoba

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If you are milling material from your hubs, I would have to say that you'd need different hub centric adapter rings for your wheels as well, or else you'd have to depend on centering on the lugs, which isn't a great idea.
 

1jz-Rolla

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What? machining is only from the outer edge of the hub........ nothing at all to do with the center spigot that locates the wheel.


besides....... 90% of the guys on here seem to run aftermarket wheels in any case, which would require hub centric adapter rings to begin with, so i'm not sure what you are referring to?
 

Poboy69

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Is that a major concern? Also, why better to machine the actual hub vs just the rotor?

Yeah I haveit on mine :/

^^ This, what is the main concern here? It seems that if one or the other isnt machined then there will be a small gap between the mating surface toward the center of the rotor/hub. However, the outside edge will still make contact. Just trying to figure out how not doing anything in this area poses as a safety issue.
 

Poodles

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Yes, now bolt them down :) Warped rotor would be the least it would effect it, worst could be cracking...
 

Poboy69

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Yes, now bolt them down :) Warped rotor would be the least it would effect it, worst could be cracking...
Ahh, that makes sense! It would seem that one could kill 2, maybe even 3 birds with 1 stone by designing a 2mm spacer with a .5mm step outer lip that would sit in between the hub and rotor. I wonder if this would cause any interference?

Edit: Racist Germans at ECS only sell their 2mm spacers for use on the autobahn!!!

Dbl Edit: Thinest spacer I could find with 5x114.3 bolt pattern is 3mm, wonder if that would bring the rotor out 1mm too far from the caliper?
 
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1jz-Rolla

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I wouldn't chance it with a spacer under the rotor... apart from the fact that you'll need to increase your caliper spacer (washer) correspondingly, the chance of getting runout at the disc braking surface is not worth it, and also changing (moving) the contact surface for the internal drum e-brake, albeit probably not enough to matter.

It would however eliminate the need to clearance the backing plate where it touches the rotor.......

If you're gonna bother with machining a spacer, you may as well just machine the rotor or hub though yeah?


BTW: your spacer wouldn't need a step..... it only has to sit inside of the stepped section of the rotor, that's plenty enough contact for the hub (no less than the donor Subaru Impreza has in any case)
 

Poboy69

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I wouldn't chance it with a spacer under the rotor... apart from the fact that you'll need to increase your caliper spacer (washer) correspondingly, the chance of getting runout at the disc braking surface is not worth it, and also changing (moving) the contact surface for the internal drum e-brake, albeit probably not enough to matter.

It would however eliminate the need to clearance the backing plate where it touches the rotor.......

If you're gonna bother with machining a spacer, you may as well just machine the rotor or hub though yeah?


BTW: your spacer wouldn't need a step..... it only has to sit inside of the stepped section of the rotor, that's plenty enough contact for the hub (no less than the donor Subaru Impreza has in any case)
Hmm, I was under the impression that by bringing the rotor out 2mm it would do 3 things:
1) Eliminate the need to space the caliper outward by 2mm.
2) Eliminate the need to trim the backing plate
3) Eliminate the need to machine the step on rotor or the hub edge.

Explain the runout part as I'm unfamiliar with it.
EDIT: I figured out the run out. Basically the concern is if the spacer is a true 2mm all the way around, no more than .0002 of run out. BTW, I didn't realize they make rings to correct for run out that you stick in between the hub and rotor. I always assumed that you machine or replace the rotor.
http://youtu.be/SSxCNbjKi-0

I think the spacers are a good option pending any safety issues. You won't have to take the hub/bearings apart and you won't have to do extra machine work on every rotor replacement.

BTW, does anyone know the diameter inside of the step lip on the STi rotor?
 
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1jz-Rolla

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That's a cool flex-arm setup for the dial-guage in that video link, sure beats using the magnetic arm standard versions!

Sorry, didn't measure the diameter at the step in the rotor before mine went together.

I think you'll find that the caliper spacer thickness will have to be increased by the same amount as the thickness of your rotor spacer that you are planning to use, not the other way around.

I don't see any major issues with what you are planning to do, it makes some sense if you are not changing wheel bearings anyway (as I was) so saves extra dis-assembly.


Cheers
 

Poboy69

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That's a cool flex-arm setup for the dial-guage in that video link, sure beats using the magnetic arm standard versions!

Sorry, didn't measure the diameter at the step in the rotor before mine went together.

I think you'll find that the caliper spacer thickness will have to be increased by the same amount as the thickness of your rotor spacer that you are planning to use, not the other way around.

I don't see any major issues with what you are planning to do, it makes some sense if you are not changing wheel bearings anyway (as I was) so saves extra dis-assembly.


Cheers
You are correct, the caliper spacing would have to correspond with the rotor. I was thinking of it backwards!

BTW, has anyone determined if the evo rotors will/won't work and why?
UPDATE, just found out the Evo's use a 168mm parking brake drum, STi 190mm...

Also, has anyone attempted to use MK4 Supra rotors with these calipers? From my understanding all that is needed for the rotor to work on a mk4 rear brake conversion is a hub centric ring.

Interesting Info: Looks like there's a 10mm difference in thickness...

05-07 STi Rear Rotor Dimensions
http://jamalb.net/pictures/brakespecs/dba_2655_cat.jpg

SupraTT Rear Rotor Dimensions
http://www.r1concepts.com/PartImage/12044103.jpg

2010-2013 Hyundai Genesis R-Spec: possible option with hub centric rings
http://www.stockwiseauto.com/product_info.php/products_id/57588/fit_id/13358/Year/2010/Make/Hyundai/Model/Genesis/source/googleps?gclid=CNuVoKO52rYCFYHe4Aodf3kAzQ

BTW, EVO 8-9 rear rotor thockness is 22mm, hence the 2mm spacers needed for the STi rotors to work w/evo calipers...
 
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jnybbad

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If the STI hub hole is 58mm why are the hubcentric rings for thr same model 56.1mm?
 
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Poodles

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The hub is tapered, that's why the ID of the hub centric rings for wheels are smaller than the ID of the rotor. If it wasn't tapered, you'd never get the rotor off...
 

Poodles

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Well, it's either that or the simple thought that the hub centric rings are wrong...

I'm sure the measurement on the rotor is right though :)