B8S4/B8S5 Brakes on a B5S4?

[ThirdStrike]

Im too lazy and too excited to search. I just picked up some B8s4 brakes for next to nothin.
Will they fit?
Custom carriers? The b8 chassis/suspension is almost exactly a B5S4 setup right?

[Capt. Obvious]

They'll bolt right up, but you'll need rotors from a B6/7 S4. The rotor offset on the B8s is different.

[*Blue-Angel*]

Not sure I would do it. I tried the whole B6/B7 Suspension on my B5 and it was a complete failure. The pedal feel was horrible. The newer cars use larger brakes which in turn are using larger master cylinders. Ie it feels like shit and they dont stop work anything.

[ThirdStrike]

Not sure I would do it. I tried the whole B6/B7 Suspension on my B5 and it was a complete failure. The pedal feel was horrible. The newer cars use larger brakes which in turn are using larger master cylinders. Ie it feels like shit and they dont stop work anything.

that doesnt make much since to me.
Are the b8 brakes the same as the b6/7?

[sherbet]

^From what Ive seen, no. My dad's got a B8 S5 and the brakes look entirely different than any b6/7 brakes I've seen. I'd love to see if they work on the B5 as they perform very well in the much heavier S5...

[Dorny1]

just a question of logic. If moving to bigger b6/7 brakes cause poor feel and such, then shouldn't bbk's cause the same problems. I'm just saying something doesn't line up to me. I hope you get an answer cause I got a few friends with Audi's of newer generations and they are looking to move up in the braking department.

[Capt. Obvious]

A few B6 A4 guys have done B8 S4/S5 swaps and are very happy with them.

Worst case scenario, try them out on your car and if you don't like them, a B6 guy will pick them up with the quickness.

[*Blue-Angel*]

just a question of logic. If moving to bigger b6/7 brakes cause poor feel and such, then shouldn't bbk's cause the same problems. I'm just saying something doesn't line up to me. I hope you get an answer cause I got a few friends with Audi's of newer generations and they are looking to move up in the braking department.

wrong way of approaching it. It all has to do with the piston sizes and fluid displacement so to answer you. No that is not true. Doesnt mean that these wont work. But several people here tried the B6/B7 Set up and did not like them at all. They were also just one very large piston vs two smaller ones. But I would be very curious how the B8 brakes work. They could be fantastic. Just be careful before dumping money into the project becasue you may not get the return your looking for thats all. Worst case scenario you sell em back to anohter member.

[034Motorsport]

B5 S4 uses basically the same master cylinder as a B6/B7 S4 and RS4 and R8, etc... Its more then powerful enough to run very large volume brakes, but multi piston brakes don't normally hold much more fluid volume then OEM single sided brakes.

The B6 S4 345mm front brake upgrade is pretty common amongst B5 S4 owners, it's just not really worth it in my opinion since it is still a single sided caliper (not opposing calipers like on aftermarket and Brembo brakes, etc) and all you are doing is moving up 25mm on rotor diameter (which is still significant), but...you are still limiting fade resistance with a single sided cast steel OEM caliper. Pedal feel is entirely dependent on the bleed and the lines, etc used.

You can install B7 8 piston RS4 brakes or R8 brakes or basically any other brake on your car, including rear 4 piston rear brakes, and still maintain a stiff and solid pedal feel; you just may not have as much clamping force as with a car that has a larger master cylinder.

B8 S4 brakes don't seem much different to me compared to B7, but the rotors have a different hub diameter and such.

[ThirdStrike]

The B6 S4 345mm front brake upgrade is pretty common amongst B5 S4 owners, it's just not really worth it in my opinion since it is still a single sided caliper (not opposing calipers like on aftermarket and Brembo brakes, etc) and all you are doing is moving up 25mm on rotor diameter (which is still significant), but...you are still limiting fade resistance with a single sided cast steel OEM caliper. Pedal feel is entirely dependent on the bleed and the lines, etc used.
.

I noticed faster brake fade on the track when I had a b6a4 with b6s4 brakes, as compared to my HP2 setup. Clamping force for around town seemed to be better than the HP2's but didnt last as long on the track.

B8 S4 brakes don't seem much different to me compared to B7, but the rotors have a different hub diameter and such.

The caliper looks bigger

I guess Ill give them a try with some b6/7 rotors and switch back to the HP2's if im not happy.

[034Motorsport]

I noticed faster brake fade on the track when I had a b6a4 with b6s4 brakes, as compared to my HP2 setup. Clamping force for around town seemed to be better than the HP2's but didnt last as long on the track.

The caliper looks bigger

I guess Ill give them a try with some b6/7 rotors and switch back to the HP2's if im not happy.

They use a larger rotor right? The S5 rotors I saw in our trash looked huge.

[ThirdStrike]

They use a larger rotor right? The S5 rotors I saw in our trash looked huge.

I think theyre all (b6/7/8 S4) 345mmx30
The caliper looks bigger on the B8 though... Im not sure though

[*Blue-Angel*]

You cant say its basically the same master cylinder because its not the same. The difference in piston size is quite a bit actually.

B5 S4 uses basically the same master cylinder as a B6/B7 S4 and RS4 and R8, etc... Its more then powerful enough to run very large volume brakes, but multi piston brakes don't normally hold much more fluid volume then OEM single sided brakes.

The B6 S4 345mm front brake upgrade is pretty common amongst B5 S4 owners, it's just not really worth it in my opinion since it is still a single sided caliper (not opposing calipers like on aftermarket and Brembo brakes, etc) and all you are doing is moving up 25mm on rotor diameter (which is still significant), but...you are still limiting fade resistance with a single sided cast steel OEM caliper. Pedal feel is entirely dependent on the bleed and the lines, etc used.

You can install B7 8 piston RS4 brakes or R8 brakes or basically any other brake on your car, including rear 4 piston rear brakes, and still maintain a stiff and solid pedal feel; you just may not have as much clamping force as with a car that has a larger master cylinder.

B8 S4 brakes don't seem much different to me compared to B7, but the rotors have a different hub diameter and such.

[ThirdStrike]

your logic doesnt make sense. people run cheyanne brakes on the b5. now we both know that monster vehicle has a bigger master cylinder. hydraulically it doesnt matter.

[*Blue-Angel*]

You obviously dont have a clue what your talking about. Those larger pistons displace more fluid vs the cayennes or the brembos. It will affect brake feel unlike what Max has said.

[ThirdStrike]

You obviously dont have a clue what your talking about. Those larger pistons displace more fluid vs the cayennes or the brembos. It will affect brake feel unlike what Max has said.

okay.
I didnt create this thread to ask about pedal feel, or whatever. I'm asking if B8S4/S5 brakes bolt up. I've gotten most of my answers. So you can go away now. k?thxbye

[S4 00 2.7]

Thats a shame, I had my eye on the b7 Rs4 brakes.

[jibberjive]

Its more then powerful enough to run very large volume brakes, but multi piston brakes don't normally hold much more fluid volume then OEM single sided brakes.

Volume doesn't matter, brake fluid is incompressible.

your logic doesnt make sense. people run cheyanne brakes on the b5. now we both know that monster vehicle has a bigger master cylinder. hydraulically it doesnt matter.

Hydraulically, it's all that matters

[fatezero]

You obviously dont have a clue what your talking about. Those larger pistons displace more fluid vs the cayennes or the brembos. It will affect brake feel unlike what Max has said.

The MC is exactly the same in all B5-B7 S4's including the RS6! I have run every single factory brake upgrade/Brembo/StopTech on my B5 and there has NEVER been an issue with peddle or MC. it's all about the fluid and lines you run.

It's just a non-issue. Plenty of people have run BBK for 10+ years on this platform

[zillarob]

Like fatezero says, youll be fine.

The ratio between mc piston size and caliper piston size will affect pedal pressure vs clamping force. Kinda like a leverage thing.

The only thing I might see as a prob would be pad knockback from loose wheel bearings or flexing components.
The larger calipers will increase the pedal travel required to get the pads back where they need to be. Dont think this will be a prob on the street with a well maintained car though.

[*Blue-Angel*]

The MC is exactly the same in all B5-B7 S4's including the RS6! I have run every single factory brake upgrade/Brembo/StopTech on my B5 and there has NEVER been an issue with peddle or MC. it's all about the fluid and lines you run.

It's just a non-issue. Plenty of people have run BBK for 10+ years on this platform

Exactly the same huh...

2007 S4


2000 S4


A greater pressure is generated by a smaller piston. However their is a lot of elasticity in a brake system and so the master cylinder piston diameters are sized according to pedal travel constraints as much as pressure requirements.

A small piston may give nice high pressure and thus reduced efforts, but at the expense of excessive pedal travel. Master cylinder bore sizes are always a balancing game between fluid pressures and pedal travel. Everything has to be balanced including front to rear.

Thats all Im trying to say. In the end I would like to know how the B8 S4 brakes work on this vehicle so please keep us updated. Thanks.

[Scotty@Advanced]

The MC is exactly the same in all B5-B7 S4's including the RS6! I have run every single factory brake upgrade/Brembo/StopTech on my B5 and there has NEVER been an issue with peddle or MC. it's all about the fluid and lines you run.

This is not true. The C5/B5 share various master cylinder part numbers across the models. The C5 RS6 MC is the same as the B6/B7 S4/RS4.

[fatezero]

I stand corrected. I knew the rs6 was the same as B6/b7 S4 but the 2mm difference in the B5 I would argue is basically the same size.

I don't what there is to argue? I have B7 rS4 8 piston brakes on a b5 right now and I track it routinely with no issues ever. What is the point of this discussion?

[*Blue-Angel*]

Very simple. I was just letting him know their is a minute chance that the pedal feel, travel may be slightly different thats all. :)

[Scotty@Advanced]

but the 2mm difference in the B5 I would argue is basically the same size.

I wasn't arguing with you just correcting you, 2mm is a large difference when it comes to high pressure hydraulics. I'd tend agree the usefulness of this thread died many posts ago.

[Capt. Obvious]

I stand corrected. I knew the rs6 was the same as B6/b7 S4 but the 2mm difference in the B5 I would argue is basically the same size.

That's a drastic difference in size, actually.

The total volume of the B6/7 master cylinder is 25.304cm^3

The total volume of the B5 master cylinder is 21.819cm^3, or 13.77% smaller.

[S4 00 2.7]

I stand corrected. I knew the rs6 was the same as B6/b7 S4 but the 2mm difference in the B5 I would argue is basically the same size.

I don't what there is to argue? I have B7 rS4 8 piston brakes on a b5 right now and I track it routinely with no issues ever. What is the point of this discussion?

How is pedal feel on your setup? No issues is good news.

If he has no issues and has good pedal feel, then that settles it for me.

[ThirdStrike]

So being that the rotors are the same size, does anyone know if the b8 calipers are larger than the b6/7 calipers?
Im wondering if theres a difference in the brake package besides the rotor offset.

[jibberjive]

That's a drastic difference in size, actually.

The total volume of the B6/7 master cylinder is 25.304cm^3

The total volume of the B5 master cylinder is 21.819cm^3, or 13.77% smaller.

I didn't try to see where your calculations came from, but are you really talking about volume, or are you talking about surface area? As I said before, volume doesn't matter, as brake fluid is, for all intents and purposes, incompressible. That is why hydraulics work. Piston diameter (or if there are multiple pistons, the sum of the surface areas of the pistons) is what matters for a given stroke.

[S4 00 2.7]

So it would be a good idea to use the b7 Rs4 MC to be on the safe side?

Ive heard of people using these calipers (B7 Rs4) on A3s, besides the B5.

[sherbet]

+1 for this thread. Its actually been quite informative. This info is good to know, esp. since I have been looking for a cost effective option surrounding my poor pedal feel. Good to know all I need is new lines and it should be much improved. Not BBK status, but better, still.

[fatezero]

So it would be a good idea to use the b7 Rs4 MC to be on the safe side?

Ive heard of people using these calipers (B7 Rs4) on A3s, besides the B5.

To be on the safe side of what? The mc works just fine with any BBK. I have had BBk's on all my 8 B5's and never had an issue.

But feel free to spend your $$ on what you like I guess

[S4 00 2.7]

If it worked for you then thats the info I needed. Thanks.

I was only bringing it up since the talk was more focused on the different MC volume and clamping force.