A4/S4 B7 Rear BBK

[xRenesis]

Going to start fresh to keep it simple and upgrade this post as time goes. I'll use this thread to gauge interest and post drawings for individual use and needed parts. Since we lost Voshmods, here is what my replacement is going to look like. Any questions, LMK or DM me.

This is to upgrade our rears to B8 S4 330x22 rotors with Cayenne/Touareg 4 piston Brembo and Wilwood MC4. This will be a two-piece setup, so no hub removal.
I also have the option to use the B7 S4 caliper in place of the Wilwood (would need to send some 3D prints for someone to test).


7/27/23 - Should have pricing request sent and prototype ordered before moving forward with group options.
8/24/23 - Order in for A4 B7 proto, should have around Labor day
9/14/23 - Add bracket proto that fits A4 and S4 (similar orientation to Vosh, 1 last 3D print should confirm)
9/21/23 - First version completely installed.
10/23/23 - Installed A4/S4 version. Removed old files.
2/19/24 - Add DXF files.
4/10/24 - Added Wilwood Lever to work with B7 cable

Group Buy/Interest
1.



B7 A4 & S4 4 Piston + Wilwood Bracket
2x Universal Brackets (Verified Drawing)
4x Main Caliper Spacer (Verified Drawing)
2x Wilwood Spacer (Verified Drawing)
2x Wilwood Levers - optional (More/Less Verified Drawing)
B8 S4 Rear 330x22mm Rotors (my pick 126.33137SLKT)
Cayenne/Touareg Calipers 7L6615423L & 7L6615424L
4x M14-1.50 x 45 Flange Bolts (or preference)
6x M6-1.00 x 20 Flange Bolts (or preference)
2x M10-1.25 x 55 Flange Bolts (or preference, stock caliper bolts)
2x M10-1.25 x 65 Flange Bolts (or preference, stock caliper bolts)
Rear Brake Lines 950.33005 (B7 RS4 Fronts)
1x Wilwood 120-12070
1x Wilwood 120-12069
4x 5/16-18 x 3.5 SHCS (Can re-use Wilwood bolts, these accommodate for spacer)

STEP FILES
Main Bracket
Brembo Spacer
Wilwood Spacer
Wilwood Lever

DXF FILES
Main Bracket
Brembo Spacer
Wilwood Spacer
Wilwood Lever

[james12lucy]

I ran a group buy for one-piece brackets that use the Brembo Super/Hypercar parking brake.

I literally have the drawings still and can create another group buy, if we get enough interested parties. The challenge is getting interest with the platform.

Scratch that. Don’t want to step on your toes, I didn’t realize you have a prototype built. I thought you were looking for someone to do that for you.

Good luck on the group buy!

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[xRenesis]

If anything, you helped me find your post. I was looking for those Brembo parking brake part numbers :). Don't seem to be many up for sale at the moment though. And the ebrake cable for the Wilwoods I'll need to figure out (pin vs ball)

[Jayz691]

This is def a nice option. The only issues with that previous kit, was the need to remove the hubs to install, and the price and availability of those "supercar" calipers. I feel this will gain MUCH more interest, depending on cost. Very interested to see how this works out, cuz I need new rear rotors soon. Currently running b7 S4 rears, these would be nice.
And since I already have s4 rears, I could do that option for now..

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[xRenesis]

I do have a mock up for B7 S4 rear calipers I'm going to be sending out to someone for testing as well. Trying to maintain everything the same, so if you'd want to swap for Wilwoods later, just change the 1 bracket out for the Willwood bracket.
Of course, I didn't account for S4 rear knuckles, which kind of upsets the dimensions..

[Jayz691]

I do have a mock up for B7 S4 rear calipers I'm going to be sending out to someone for testing as well. Trying to maintain everything the same, so if you'd want to swap for Wilwoods later, just change the 1 bracket out for the Willwood bracket.

Thats absolutely genius. Being able to swap the ebrake bracket separately is great.

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[james12lucy]

I do have a mock up for B7 S4 rear calipers I'm going to be sending out to someone for testing as well. Trying to maintain everything the same, so if you'd want to swap for Wilwoods later, just change the 1 bracket out for the Willwood bracket.
Of course, I didn't account for S4 rear knuckles, which kind of upsets the dimensions..

Great ideas.

And yeah, the aluminum knuckles are hell to build around. I had the same challenge.


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[xRenesis]

Picked up the brackets, have everything else here now. I should have time this weekend to get them (hopefully) installed with no issues.

[Jayz691]

And hopefully ill get the other ones test fitted this weekend.

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[ArizonaB7S4]

I am interested!! I have a B7 S4 and started buying all parts for the voshmod kit and voshmod closed. I have everything but the bracket and Willwood MC4. PM me for a group buy please.

[xRenesis]

Test fit with the actual brackets. Made some changes to the bolt lengths for mounting. Couple dimensions I should/could clean up for a finished version. For those already with 18z (maybe 17z), if youre running spacers to clear the fronts, it will be the same spacers to clear the backs now.

1x Wilwood bolt needs to be moved out a hair. Brembos spacers could be increased to next plate thickness.

[xRenesis]

I am interested!! I have a B7 S4 and started buying all parts for the voshmod kit and voshmod closed. I have everything but the bracket and Willwood MC4. PM me for a group buy please.

Saw your thread in the S4 section. Should have something solid for the S4 folks fairly quick now that I have a set of knuckles and some better reference from my first set for the A4. In my ideal world, I'll try to make the A4 and S4 brackets the same, so hopefully just a quick revision.

[ArizonaB7S4]

Bump👍🏼

[xRenesis]

Small update while I wait on new seals for the Brembos. I think I have a 1 piece design, need to confirm a few things, but so far it slips over the hub. Has holes for both A4 and S4 knuckle. Will have to bring the thickness down since the Wilwoods can only accept so much, but 3 dust shield bolts and the 2 main bolts are used.

*welp, brembo didnt fit S4, back at it

[BeefyA4]

Very interested for my b7 a4. I've been looking for this for a while actually.

[xRenesis]

Jay was able to check the Brembo + S4 carrier version and looks to check out. I'll get the Brembo + Wilwood version cleaned up on the 1 dimension and posted.

Then if people want to use the drawings and have them made locally or work towards a group buy option.

As for the S4 version, pretty close with a design that should work (looking at Vosh's) since the knuckle takes up all of the space, there is really only 1 spot for the Brembo available. Still fits A4 and S4, slides over the hub face just perfectly to clear as a 1 piece. Will do some FEA to make sure since the Vosh one had a chance of breaking.

[Jayz691]

Yup, all looks good for S4 calipers, on A4 knuckles0910231905.jpg0910231904.jpg
On a side note, something I realized while doing this test fitting. You know how on the A4 rears you don't have to remove the caliper carrier, to change the rotors. But on the S4 rears you do, since they are thicker vented rotors. Well you can just crack the bottom loose, and remove the upper one which is much easier to get to. That allows the carrier to swing out just enough(a few mm's) to slide the rotor out and in.
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[ArizonaB7S4]

I am open for a group buy or use the drawings for the S4. The rendering look awesome. 👊

[xRenesis]

Added the A4/S4 combined bracket to first post + drawing. Going to 3D print what should be my last iteration for it tonight. Last nights iteration needed a few mm more clearance to slide over the hub. From the FEA I ran, it should be a 3SF at any 'weak' point doing a 3kN load on the Brembo holes.

[xRenesis]

Drawing updated, slides over A4 hub nicely now. If someone had access to scrap steel or wanted to give it a shot on the A4/S4 combined bracket, that would be great. Otherwise I could likely try and get a set ordered next month to try myself. Already having the first set (waiting on new bleeders since I lost one during rebuild )

All drawings are 1:1 scale if printed in actual size. The larger ones are just on 11x17 (B) paper.

[xRenesis]

Managed to get some install done now that I have my bleeders. Test fit the other version, fits over studs as well. I do need to have a better solution for the ebrake cable attaching to the wilwood, may try drilling a hole in the ball end?

[Jayz691]

With that big, one piece bracket, theres more than the 3 dust shield bolts holding it on, correct? Are ya able to use the 2 factory bracket bolts?

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[xRenesis]

Yup, the 2 larger factory bolts M10 and 2 (A4) or 3 (S4) M6 bolts. Would be 3 and 3, but one of M6 dust shield bolts is on the corner for where the S4 wheel bearing is, so instead of creating a weak point it was deleted.

Fixed at only the 2x M10 locations. The 1SF minimum were more or less the points touch the bolts/interference.

[xRenesis]

Finally have both sides installed. Speed bleeders made for some quick work. Might buy some cable clevis ends at some point to look more professional, make shift way works though.

As for spacers, I currently need 5mm front for the 18z and 10mm back for the 4pistons on my ET32 summers (18x8.5 TSW Bathurst). Will need 15mm F/20mm R for my ET45 winters (18x8.5 Alzor MB8)

[BeefyA4]

Btw is there any way I could use my stock rear a4 caliper as the e brake caliper?

[xRenesis]

Unfortunately not. S4 caliper on A4 knuckles is as close as you can get. The A4 caliper only accepts about 20mm of rotor without pads.

[D.oxendine01]

I need these brackets please

[xRenesis]

I need these brackets please

If you have access to a local shop, the "A4 B7 Steel Knuckle - 4 Piston Parts Needed" are good to go, been running for ~3 weeks now. 1x full set in A572 g50 cost me about $300.

I should have the "A4/S4" version of the bracket I worked up last in the next 2-3 weeks for testing.

*edit* also, if anyone ever wants models (STEP, STL, whatever) or like dxf drawings, just let me know

[xRenesis]

Picked up and installed the new version of the brackets this morning. Not the most elegant for the ebrake cable but it'll work and shouldn't rub (ziptied to wheel speed).

Do fit over hub and studs as a 1 piece

[86turbodsl]

If you have access to a local shop, the "A4 B7 Steel Knuckle - 4 Piston Parts Needed" are good to go, been running for ~3 weeks now. 1x full set in A572 g50 cost me about $300.

I should have the "A4/S4" version of the bracket I worked up last in the next 2-3 weeks for testing.

*edit* also, if anyone ever wants models (STEP, STL, whatever) or like dxf drawings, just let me know

I have access to a CNC plasma. I'd like the files if you're willing. Saves me making a new design.

Thank you!

[xRenesis]

I have access to a CNC plasma. I'd like the files if you're willing. Saves me making a new design.

Thank you!

I added these to the bottom of the first post for you.

[86turbodsl]

I added these to the bottom of the first post for you.

Awesome! Thanks!

[maxum101]

Any tried using the s4 caliper as the E brake

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[maxum101]

Also... is there going to be a group buy for this,?

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[xRenesis]

I made a version that Jayz tried for using the B7 S4 as ebrake (above). Still have the drawings if you're interested.

Probably not an actual group buy unless enough people want, but all drawings and parts required are in the first post if you have people local or want to use send cut send. I also might have a bracket for the wilwood cable lever but haven't made it yet.

[BeefyA4]

How's the testing going?

[xRenesis]

Almost 4 months so far, some mild/hard braking no issues so far. I've been waiting for it to warm up to make my piece for the e-brake cable and see how everything looks.

[BeefyA4]

Awesome man, been keeping an eye on this thread :D
Great work.

[Jayz691]

I just picked up some calipers, so need the thick washers, and I can install the brembos(once painted, decals, etc). Then ill work on getting the brackets made for the S4 caliper PB, and get some solid feedback on that setup. A "this summer" job..

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[Matthewest91]

Bump for an awesome dude!

More people should see this !


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