UrS6 - New Brake Cylinder needed for 17z or 18z Calipers ?

[macspring]

If one was contemplating upgrading the front brakes on a UrS6 from oem to either Brembo 17z or 18z calipers and one wants to avoid any longer brake pedal travel than oem, does one need to change the brake master cylinder to a bigger brake master cylinder ?

If one does which car has the bigger brake master cylinder ?

The above assumes that the pedal travel cannot be adjusted to be longer or shorter ?

Thanks for any assistance.

[UrS4boy]

If one was contemplating upgrading the front brakes on a UrS6 from oem to either Brembo 17z or 18z calipers and one wants to avoid any longer brake pedal travel than oem, does one need to change the brake master cylinder to a bigger brake master cylinder ? If one does which car has the bigger brake master cylinder ?

I would say that no upgrades are needed. I am running old school "Big Blacks" (928 GTS) front calipers with 323 x 30 A8/S8 rotors and RS2 brackets like many UrS owners on this side of the pond and I do not recall anybody needing to upsize the master cylinder. The UrSs already got the larger C4 25.4 mm brake master cylinder (BMC), the same one that Audi used on the S6plus (326 hp V8) and the RS2 (315 hp, B4 chassis). No one (to the best of my memory/knowledge) has ever had to upgrade their BMC in order to use Porsche (Brembo) calipers on a C4 UrS.

So imagine that the 17z or 18z calipers don't need a bigger brake master cylinder either. I stand to be corrected.

[Error404]

Can be done but you need to convert to a dual diaphragm vac booster then you can use the 27mm BMC from the B6/B7 S4/RS4. Pretty easy swap on the URS6

[RichLV]

Can be done but you need to convert to a dual diaphragm vac booster then you can use the 27mm BMC from the B6/B7 S4/RS4. Pretty easy swap on the URS6

Requires fabrication. In particular the mounting bracket and the actuator rod which connects to the pedal. That is if we talk about dual diaphragm booster from A8. I suppose you don't speak russian, but here's a DIY. Pictures kinda tell the story though.

http://contik.narod.ru/S4/Vacuum/

Sorry for a little hijack of the thread, but how to tell which calipers are 17z and which are 18z? I'm going for an upgrade soon too. For example I have spare parts from mostly 4.5l Cayennes (Cayenne S/Turbo 4.5, Cayenne Turbo 4.8). Which calipers would those have (2004-2008 cars)?

[A1QSHIP]

Sorry for a little hijack of the thread, but how to tell which calipers are 17z and which are 18z? I'm going for an upgrade soon too. For example I have spare parts from mostly 4.5l Cayennes (Cayenne S 4.5, Cayenne Turbo, Cayenne Turbo 4.8). Which calipers would those have (2004-2008 cars)?

The 18Z/17Z will be cast in to the body of the caliper. The mounting "legs" of the 18Z caliper are longer than the 17Z caliper.
HTH, Chris

[popdemonic]

UrS6 got 1" master cylinder and more than enough even with Panamera Calipers which has the more total pistons area.

[UrS4boy]

UrS6 got 1" master cylinder and more than enough even with Panamera Calipers which has the more total pistons area.

Thank you Pop.

[Macchris]

i'll follow your mod with interest as i have bought 15 days ago a ZR/ZL 18 brakes too (however i think it's too big, i'll buy ZR/ZL17)

[popdemonic]

Differences between 17 & 18 ZR
- 17 clamping on 32mm disc,18 on 34mm(i lost my
Book which i have measured any bits of these calipers
Which i can tell you the largest disc in any aspects you could be using
On these calipers)
-18zr has longer brackert arms.
-18zr has wider brake pad sliding surface
72mm IIRC VS 65mm on 17ZR and yes
They are interchangeable.i have 17ZR pads
on 18ZR.
Unbelievable i spend over 15mins typing this on running machine lol.

[Error404]

17Z has larger pistons, so is a more powerful caliper

[Macchris]

& if i remember correctly, ZR/ZL18 fit under wheels 18" Mini, ZR/ZL17 under wheels of 17" mini

more powerful caliper

yes 17 Z more powerful but it seems less resistance on track (but i guess everyone dont run his car on track all the day ;-) )
tof

[Thuppu]

Brake force won't be an issue with either of them, 17Z or 18Z. They sure are enough for anything with these cars. UrS and 18Z no need for main cylinder change. Don't know about 17Z , as Alex says, they have bigger pistons so the pedal travel will be greater.

[macspring]

Thanks to all that took the time to share their experience.

Much appreciated.

[Wrath]

run 18z on 360mm discs with oem brake cylinder with no problem, you just snap on the brake and the car will flip or maybe brake the struts only thing I would consider is vac brake servo to get a more modern feel to the brakes, but it works good as it sits...

[Cordoba16vt]

I used 330x28 mm Mercedes CLK Sport discs with 17z to keep unsprung weight down. Car stops very well.

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