356mm Rear brake upgrade

**PeteJ** · 04-22-2018 04:02 PM

I finally had a chance to install the 356mm rotors and all I can say is do it! From 70 I hit the brakes as hard as possible and there was zero front end dive, braking performance and feel is significantly better...I guess going from a 12.2" to a 14" rotor will do that

The other plus is that the rotor sits away from the backing plate and will have much better airflow and cooling, a big benefit for track use.

I'll be posting all the pictures later today.

The only downside is that you are stuck running 19" wheels because there is only about 5mm clearance between the wheel and caliper due to the size of the rear calipers. I did check my S4 peelers (I run those as winter wheels) and they also cleared as well.

As far as the parts, I ordered the adapters here:

https://www.vagbremtechnic.com/rear-...golf-r-di0019/

and I used these rotors

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

You do not need to order the RS7 rotors unless you want the look. The S6/S8/A8 356mm rotor is a direct swap and it's about $300 cheaper per rotor.

**robertsonsylee** · 04-22-2018 04:19 PM

I run 18” Neuspeed for winter. Does that mean it won’t fit anymore if I go big brake for the rear?

How much clearance do you have compared to the big calipers at the front?

**will13k7** · 04-22-2018 04:24 PM

I did that upgrade on the s3, it did balance out the braking some, but it looks soo much better too!

went wavy to match:

**PeteJ** · 04-22-2018 05:19 PM

Here are thhe pics....

Bracket

Mounted on Stock Caliper Bracket

Stock Rotor with Backing plate

Wheel Clearance

New Rotor with extra clearance to backing plate

Rotor Installed

**OE2** · 04-22-2018 05:36 PM

looks great, i need to know if they will clear the 18s that clear the RS3 front calipers before i hop on board

**PeteJ** · 04-22-2018 05:44 PM

Originally Posted by OE2

looks great, i need to know if they will clear the 18s that clear the RS3 front calipers before i hop on board

Being that the rotor is almost 2" larger than stock do you have an inch of clearance to your rear caliper. I'd be shocked if 18's fit....

**iceman302** · 04-22-2018 06:22 PM

How is braking improved if you’re running the stock sized pads? Am I missing something?

**PeteJ** · 04-22-2018 06:31 PM

Originally Posted by iceman302

How is braking improved if you’re running the stock sized pads? Am I missing something?

All things staying the same installing a larger diameter rotor you will have more leverage. Just like using a longer handle on a ratchet.

Direct from the Stoptech web page:

"Only increasing the effective radius of the disc, the caliper piston area, the line pressure, or the coefficient of friction can increase brake torque. Increasing the pad area will decrease pad wear and improve the fade characteristics of the pads but it will not increase the brake torque."

That said, the larger rotor has a similar to going to a more aggressive pad or a bigger caliper.

**iceman302** · 04-22-2018 06:38 PM

Originally Posted by PeteJ

All things staying the same installing a larger diameter rotor you will have more leverage. Just like using a longer handle on a ratchet.

Direct from the Stoptech web page:

"Only increasing the effective radius of the disc, the caliper piston area, the line pressure, or the coefficient of friction can increase brake torque. Increasing the pad area will decrease pad wear and improve the fade characteristics of the pads but it will not increase the brake torque."

That said, the larger rotor has a similar to going to a more aggressive pad or a bigger caliper.

That makes sense... if the caliper and pad are now being applied to the outside edge of the larger rotor. Is that the case here? It looks to me like the caliper and pad are still applying pressure towards the inside diameter of the larger rotor... in the same sweep/diameter as the stock rotor. Maybe the picture is deceiving.

Sent from my iPhone using Audizine

**PeteJ** · 04-22-2018 06:47 PM

Originally Posted by iceman302

That makes sense... if the caliper and pad are now being applied to the outside edge of the larger rotor. Is that the case here? It looks to me like the caliper and pad are still applying pressure towards the inside diameter of the larger rotor... in the same sweep/diameter as the stock rotor. Maybe the picture is deceiving.

Sent from my iPhone using Audizine

Look at the stock rotor and installed pictures as well as the bracket. The pads are moved out almost a full inch. This equates to going from a 6" to a 7" lever arm or roughly a 16% increase in torque.

**iceman302** · 04-22-2018 06:51 PM

Originally Posted by PeteJ

Look at the stock rotor and installed pictures as well as the bracket. The pads are moved out almost a full inch. This equates to going from a 6" to a 7" lever arm or roughly a 16% increase in torque.

I stand corrected. For some reason, the stock pictures weren’t loading on my phone.

**Blue Smoke** · 04-22-2018 10:00 PM

Originally Posted by PeteJ

I finally had a chance to install the 356mm rotors and all I can say is do it! From 70 I hit the brakes as hard as possible and there was zero front end dive, braking performance and feel is significantly better...I guess going from a 12.2" to a 14" rotor will do that

The other plus is that the rotor sits away from the backing plate and will have much better airflow and cooling, a big benefit for track use.

I'll be posting all the pictures later today.

The only downside is that you are stuck running 19" wheels because there is only about 5mm clearance between the wheel and caliper due to the size of the rear calipers. I did check my S4 peelers (I run those as winter wheels) and they also cleared as well.

As far as the parts, I ordered the adapters here:

https://www.vagbremtechnic.com/rear-...golf-r-di0019/

and I used these rotors

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

You do not need to order the RS7 rotors unless you want the look. The S6/S8/A8 356mm rotor is a direct swap and it's about $300 cheaper per rotor.

Pretty slick. How long did the install take you? Did you have to re-bleed the brake lines?

**PeteJ** · 04-23-2018 05:40 AM

Originally Posted by Blue Smoke

Pretty slick. How long did the install take you? Did you have to re-bleed the brake lines?

About an hour for the install, no need to bleed the lines. Depending on how much wear you have on the pads you may need a tool to retract the piston. My Hex-Can won't work on the RS3

**S1RC** · 04-23-2018 07:25 AM

This looks interesting!

Is there a matching rear rotor to the OEM fronts? (without having to go RS7)

**Akediord** · 04-23-2018 09:29 AM

don't you need a taller caliper (and appropriate pad) to take advantage of the increased surface area? unless I'm missing something, it looks like you've got at least 5/16ths of rotor on the inside diameter not making contact with the pad. Have you not now shifted the clamping force (and all thermal properties of friction) to the outside diameter of the rotor instead of centered where it is on the stock, smaller rotor? Seems to me that the heat will be unevenly distributed across the rotor surface (outside to inside) and that these would be prone to warping under heavy track use.

**PeteJ** · 04-23-2018 11:04 AM

Originally Posted by S1RC

This looks interesting!

Is there a matching rear rotor to the OEM fronts? (without having to go RS7)

No, the RS7 rotor is the "matching" rotor

**robertsonsylee** · 04-23-2018 11:05 AM

@PeteJ, did you have to use any hub centric ring? I believe these discs have bigger bore holes?

Sent from my iPhone using Tapatalk

**S1RC** · 04-23-2018 11:07 AM

Originally Posted by will13k7

I did that upgrade on the s3, it did balance out the braking some, but it looks soo much better too!

went wavy to match:

Do you have the part numbers? I found these, are they correct:
Front: 4G0615301EKT
Rear: 4G8615601KT

**PeteJ** · 04-23-2018 11:16 AM

Originally Posted by Akediord

don't you need a taller caliper (and appropriate pad) to take advantage of the increased surface area? unless I'm missing something, it looks like you've got at least 5/16ths of rotor on the inside diameter not making contact with the pad. Have you not now shifted the clamping force (and all thermal properties of friction) to the outside diameter of the rotor instead of centered where it is on the stock, smaller rotor? Seems to me that the heat will be unevenly distributed across the rotor surface (outside to inside) and that these would be prone to warping under heavy track use.

The area you are talking about is about 1/4" but you are over analyzing, the small gap is not going to cause a problem. This is a proven and tested upgrade that has been done overseas, now that the 8V RS3 is in North America it's our torn. The only difference is that I'm using the S6 rotor, not the RS7 rotor.

One another thing regarding rotor warping...that ship has sailed years ago; rotors hardly. if ever. warp. What most people think is a "warped rotor" is actually pulsation due to pad deposits from overheating and/or not using a suitable pad. Being that this rotor is larger it also has more thermal mass, that in addition to the improved airflow around the rotor will only help this upgrade survive under serious track abuse.

**Akediord** · 04-23-2018 11:56 AM

Originally Posted by PeteJ

The area you are talking about is about 1/4" but you are over analyzing, the small gap is not going to cause a problem. This is a proven and tested upgrade that has been done overseas, now that the 8V RS3 is in North America it's our torn. The only difference is that I'm using the S6 rotor, not the RS7 rotor.

One another thing regarding rotor warping...that ship has sailed years ago; rotors hardly. if ever. warp. What most people think is a "warped rotor" is actually pulsation due to pad deposits from overheating and/or not using a suitable pad. Being that this rotor is larger it also has more thermal mass, that in addition to the improved airflow around the rotor will only help this upgrade survive under serious track abuse.

Call it overanalyzing, I wouldn't do it unless I could also get the appropriately-sized caliper and pad. That piston force is not optimally placed in the center of the rotor face any longer.

I'm well familiar with deposition and used to use hawk blues on the street for a couple of days after a track weekend to clean the deposition off of my rotors. Those rotors may be larger, but they're not any thicker and a true upgrade would have been a larger and thicker rotor with an appropriate fixed caliper which I guess doesn't exist.

For the record, I think the stock rears are horrible and my car squirms under heavy, high-speed braking as well. I'm not totally sold on this, but if it works for you, great and good luck with it.

**PeteJ** · 04-23-2018 03:20 PM

Originally Posted by Akediord

Call it overanalyzing, I wouldn't do it unless I could also get the appropriately-sized caliper and pad. That piston force is not optimally placed in the center of the rotor face any longer.

I'm well familiar with deposition and used to use hawk blues on the street for a couple of days after a track weekend to clean the deposition off of my rotors. Those rotors may be larger, but they're not any thicker and a true upgrade would have been a larger and thicker rotor with an appropriate fixed caliper which I guess doesn't exist.

For the record, I think the stock rears are horrible and my car squirms under heavy, high-speed braking as well. I'm not totally sold on this, but if it works for you, great and good luck with it.

Maybe the pictures don't show it properly. The piston is offset to the outer edge by about 1/8" which I have a hard time believing will cause an issue.

To your last point from my testing and what others have reported this upgrade eliminates the squirming and dive you are describing. As I posted in other threads when I had my RS3 out at Road America it was unnerving coming into turns one and five, it felt like the back end was going to come around under hard braking it was getting so light.

**Akediord** · 04-23-2018 03:48 PM

Originally Posted by PeteJ

Maybe the pictures don't show it properly. The piston is offset to the outer edge by about 1/8" which I have a hard time believing will cause an issue.

To your last point from my testing and what others have reported this upgrade eliminates the squirming and dive you are describing. As I posted in other threads when I had my RS3 out at Road America it was unnerving coming into turns one and five, it felt like the back end was going to come around under hard braking it was getting so light.

Ok. So I agree about a 1/8th in. offset. I wouldn't sweat that and the pics aren't telling the story for overthinkers like myself. I've made some costly mod decisions in the past that force me to be more careful in my consideration.

I'm still not happy that the pad coverage falls a little short of laying down material on more of the rotor surface, but I'm very curious to hear of your longer term impressions after you put a couple of Ks on them. Nice work regardless.

**will13k7** · 04-23-2018 10:38 PM

Originally Posted by S1RC

Do you have the part numbers?

s3 or rs3? rears will be the same, front's are different since the rs3's front track is a little wider (learned that one the hard way, I have a set of wavy front rs3 discs as garage ornaments

). check out killerbrakes.com for part numbers.

**S1RC** · 04-24-2018 08:46 AM

Originally Posted by will13k7

s3 or rs3? rears will be the same, front's are different since the rs3's front track is a little wider (learned that one the hard way, I have a set of wavy front rs3 discs as garage ornaments

). check out killerbrakes.com for part numbers.

RS3. Yeah I saw that website before, not much aside from carbon kits for the FL RS3 sedan.

I too am noticing a lot of squirlyness in the rear under heavy braking. I'm surprised there's not a larger caliper replacement for the rears as well as the option in this thread.

**shivaswrath** · 04-24-2018 10:58 AM

Originally Posted by PeteJ

Maybe the pictures don't show it properly. The piston is offset to the outer edge by about 1/8" which I have a hard time believing will cause an issue.

To your last point from my testing and what others have reported this upgrade eliminates the squirming and dive you are describing. As I posted in other threads when I had my RS3 out at Road America it was unnerving coming into turns one and five, it felt like the back end was going to come around under hard braking it was getting so light.

Pete, which option matches the Girodisc front discs best? I'd rather not spend $1400 for the Alcon J hook ones....IMG_6634.jpg

**will13k7** · 04-24-2018 04:10 PM

Originally Posted by S1RC

RS3. Yeah I saw that website before, not much aside from carbon kits for the FL RS3 sedan.

not as much stuff on that site as before.

The wavy pre-facelift 8v rs3 front's (which were noisy for some) are 8V0.615.301.C (the one on the right, the one on the left is the RSQ3 that fit my s3

):

Rear RS7's: 4G8.615.601.E

**hilltop804** · 04-24-2018 08:21 PM

Probably a stupid question...If the stock front discs are 370mm and 18s fit, wouldn't they almost certainly fit over these since they're only 356mm?

**PeteJ** · 04-24-2018 08:33 PM

Originally Posted by hilltop804

Probably a stupid question...If the stock front discs are 370mm and 18s fit, wouldn't they almost certainly fit over these since they're only 356mm?

Rotor size isn't important if the caliper sticks out as far as does..... Look at the pictures and tell me if you think an 18" wheel will work.

Originally Posted by shivaswrath

Pete, which option matches the Girodisc front discs best? I'd rather not spend $1400 for the Alcon J hook ones....IMG_6634.jpg

Girodisc does not make a matching rear. The first post had a link to the Raybestos rotor I used for the rear. It is a factory replacement for the S6/S7/A8 with the 356mm rear rotor.

**sean_entrust** · 04-24-2018 09:05 PM

but what do we do about the ugly rear calipers?!

**FuzzyHat** · 04-25-2018 05:48 AM

Originally Posted by sean_entrust

but what do we do about the ugly rear calipers?!

This is what I’m in for. I would love to get bigger calipers in the rear as well for form & function.

Sent from my iPhone using Audizine

**theskunk** · 04-25-2018 12:39 PM

Originally Posted by sean_entrust

but what do we do about the ugly rear calipers?!

Based on Pete’s review - I don’t think we actually need new rear calipers - if you want the look to be better, you may be better off with caliper covers <shudders>...

That said - I’m definitely doing this...

PeteJ - Can you sell your car and sell me your parts? Kthxbai... ;)

Sent from my iPad using Audizine

**PeteJ** · 04-25-2018 02:40 PM

Originally Posted by theskunk

Based on Pete’s review - I don’t think we actually need new rear calipers - if you want the look to be better, you may be better off with caliper covers <shudders>...

That said - I’m definitely doing this...

PeteJ - Can you sell your car and sell me your parts? Kthxbai... ;)

Sent from my iPad using Audizine

Ha! I was about to grab some steel and make my own brackets before I purchased the ones from the UK (I have a mill in my shop) but I have too much going on with trying to get my Cutlass ready for drag week this year... It should be a low 8 second street car.

**theskunk** · 04-25-2018 08:20 PM

Brackets are ordered...!

Sent from my iPhone using Audizine

**15DGR V6** · 04-26-2018 01:51 AM

Does anyone know if this will work on an 8S TTRS? I didn't see it listed on their website for the TTRS, but that doesn't mean it wouldn't work.

**PeteJ** · 04-26-2018 10:41 AM

Originally Posted by 15DGR V6

Does anyone know if this will work on an 8S TTRS? I didn't see it listed on their website for the TTRS, but that doesn't mean it wouldn't work.

I'd go to Audipartsusa.com and pull the rear caliper/caliper brackets and rotor part numbers for the RS3 and TTRS to see if they are the same. If they are I'd think you are good.

A quick update, yesterday I got my car out on the highway and was able to see how it did from some higher speed stops (luckily it was empty). Hitting the brakes hard at just under 90 I got a slight bit of dive but nothing unsettling like before. I'm hoping to hit a an upcoming track day next Thursday to give it a go https://www.tracknightinamerica.com/...-chicago-may-3. The plan will be to use the Giridisc front rotors and a set of Carbotech XP10 pads all the way around.

**zcspec** · 04-26-2018 12:08 PM

Hey PeteJ, I was really excited to read your thread as I recently upgraded my front S3 OEM setup to TT-RSs. The main question and concern I have which another member asked...isn't the rear hub size different? My OEM is 57.1 and I believe the A8/S8 chassis is 66.67?

**PeteJ** · 04-26-2018 05:07 PM

Originally Posted by zcspec

Hey PeteJ, I was really excited to read your thread as I recently upgraded my front S3 OEM setup to TT-RSs. The main question and concern I have which another member asked...isn't the rear hub size different? My OEM is 57.1 and I believe the A8/S8 chassis is 66.67?

The kit I got includes a spacer ring for the rotors.