Porsche Calipers

[phoenixv6quattro]

Hello All. I'm making some carriers so I can fit Porsche calipers to my 2.8.....Does ANYONE know the hole spacing on the hub where the caliper mounts?

Cheers Gents,

Ollie

 

[aragorn]

Which porsche calipers?

Most arent really suitable for a B5.

 

[GSB1]

What caliper? I have some carriers made for a 2.8 V6 B5 for a 4 pot Brembo from a Porsche 993 twin turbo.

 

[Talkwrench]

Carriers are disc & caliper specific, do you have S4 uprights? If so I have some B5 RS4 calipers that bolt straight on, you'll just need some discs.

 

[Broken Byzan]

^^ I have discs, just need some cheap calipers due to a mis communication and too much being machined off them. ( don't ask) LOL

120 mm std and 140 S4 IIRC rings a bell anyway, will check garage later

 

[phoenixv6quattro]

DAMN!!! I forgot about that!! Anything larger than stock calipers and I will need S4/RS4 uprights won't I!!! BOL*OX!! Tell me, is there any better caliper I can fit without the need for different uprights???

 

[aragorn]

Only the 312mm upgrade using the TT carriers.

What exactly are you trying to achieve?

Theres only two real benefits from upgrading brakes, better pad selection or better thermal mass. The pad selection on the A4 calipers is pretty decent, which leaves thermal mass. 312mm disks will improve that, simply by virtue of being larger, but if you need larger still then you'll need to go to S4 uprights.

 

[phoenixv6quattro]

Uhhh....Better braking Aragorn lol! Already done the 312mm upgrade and didn't really send me through windscreen so after something that will (if I wasn't wearing my seatbelt!lol). Looks like i will be investing in some uprights then!

 

[adamss24]

Uhhh....Better braking Aragorn lol! Already done the 312mm upgrade and didn't really send me through windscreen so after something that will (if I wasn't wearing my seatbelt!lol). Looks like i will be investing in some uprights then!

Ollie, be carefull if you decide to upgrade the brakes on the front of the b5 without upgrading the rears as you will end braking less than with the existing 312mm set-up ! I do not drive my a4 on wet tarmac since the cold spell as the ABS is buzzing on continuously ! Had a light prang a few weeks ago on wich i dented the bonnet ! I reckon the 312mm is more than adeqvate on the b5 platform and only if you're packing more than 200 bhp then i would think of upgrading...

 

[basssound]

312mm would be more than efficient in slowing the car but remember to couple the larger brakes with wider tyres
as you've still got the same coefficient of friction to the tarmac

All you would really gain from larger discs would be less heat fade on heavy track braking, on normal roads all you need to do is use a slightly wider tyre to increase the friction between the tyre and the tarmac.

 

[aragorn]

The braking of the car is limited by the tyres. Not only the size as mentioned above, but the compound as well.

The 312's should have been able to lock the brakes if the were working properly. Even the 288's would probably manage that. Once.

Fitting some huge 365mm 6piston beasters may give the impression of better braking, because for a given leg input the braking effect will be larger, you'll still get to the same total torque at the front wheels before the wheels lock.

As adam says, by upgrading the fronts, and leaving the rears, you end up altering the bias such that the total force is actually less.

If you imagine the point just before the brakes lock up, with the standard brakes you might be pushing 3000psi into the calipers, and all four brakes on the car will be just about to lock up. Then you fit your huge brakes on the front, and now the front brakes will lock with only 2500psi. Unfortuntely, the rear calipers are now also only recieving 2500psi at the point just before the fronts lock, so the rear brakes are doing less, and therefore the total braking effort transmitted to the road falls.

 

[ScottD3]

The braking of the car is limited by the tyres. Not only the size as mentioned above, but the compound as well.

The 312's should have been able to lock the brakes if the were working properly. Even the 288's would probably manage that. Once.

Fitting some huge 365mm 6piston beasters may give the impression of better braking, because for a given leg input the braking effect will be larger, you'll still get to the same total torque at the front wheels before the wheels lock.

As adam says, by upgrading the fronts, and leaving the rears, you end up altering the bias such that the total force is actually less.

If you imagine the point just before the brakes lock up, with the standard brakes you might be pushing 3000psi into the calipers, and all four brakes on the car will be just about to lock up. Then you fit your huge brakes on the front, and now the front brakes will lock with only 2500psi. Unfortuntely, the rear calipers are now also only recieving 2500psi at the point just before the fronts lock, so the rear brakes are doing less, and therefore the total braking effort transmitted to the road falls.

That is a very good point.
Never thought of brake upgrades like that before.

Thanks.

 

[aragorn]

No worries.

I'm not saying theres no improvements to be made, because the stock brakes while capable of locking the wheels will overheat pretty quickly if driven hard. The other advantage in larger brakes is better modulation. The more force your leg applies, the less able your body is to finely control that force. So larger brakes which require less "leg" to lock the wheels mean you can better modulate whats going on. Another advantage is that by running a bigger disk, you keep the temperatures lower, so can run a pad with a lower temperature range. IE you can run a standard road pad, and get nice cold performance, rather than having to upgrade to a more aggressive pad compound that feels wooden when cold.

I'm just saying the mods need thoroughly thought thru.

I've been looking at fitting 321mm S4 disks and Allroad/B7 calipers to mine along with 256mm vented rear disks from a facelift S4. That should provide a nice increase in effort over standard, and a worthwhile improvement in thermal mass, while keeping the bias in the right place.

The Next step after that, would be to use 345mm B6 S4 disks and calipers on the front, then the same facelift S4 calipers from above, either with S8 carriers and 280mm disks, or 300mm rear B6 S4 disks along with some brackets to space the caliper over.

 

[nwmlarge]

Uhhh....Better braking Aragorn lol! Already done the 312mm upgrade and didn't really send me through windscreen so after something that will (if I wasn't wearing my seatbelt!lol). Looks like i will be investing in some uprights then!

let me know when you are shifting the 312 brakes

 

[phoenixv6quattro]

Aragorn, I'm already running 225's and have even gone to 235's on my Audi when I had the monoblocks, so tyre width was/is never an issue. It's top quality dunlop rubber too. Just because I didn't mention the rears dosn't mean I wasn't going to even things out with the front. I think every one of my mods through..........Here's what I'm going to try instead (for the time being). My mrs has a 3 ltr B6 Avant. The brakes on that car are EXCELLENT, and its just the 312mm set-up. Why the hell it felt like dogsh*t on mine had me scratching my head. I'm doing the 312mm setup again but with new or reconned calipers, vented Brembo discs and maybe some Ferodo or Pagid pads. See if that makes the difference I'm looking for!

 

[phoenixv6quattro]

let me know when you are shifting the 312 brakes

Hello mate, there already gone! After the conversion I was less than impressed and swapped back to the 288mm setup. Sold the 312mm (that I got for the price of a pint of a friend modding his TT) for beer tokens! Sorry pal! Lovely Avant BTW mate!

 

[aragorn]

Ye, perhaps the B6 has a slightly larger servo or something, giving a bit more bite?

Or perhaps your servo is a bit tired, so while still giving assistance, not as much as it should be?

Another possibility, is slightly mal adjusted or siezed rear calipers, which gives the whole system a bit of sponge, not usually enough to think theres something wrong, but often enough to remove the sharpness from the brakes. Had this on the FWD, and after fixing it the missus kept trying to put us thru the windscreen when slowing for junctions they were that much sharper afterwards.

Last thing to consider is a tiny amount of air in the system, which again might not be enough to give a horrible pedal, but could be enough to take the edge off?

 

[nwmlarge]

Hello mate, there already gone! After the conversion I was less than impressed and swapped back to the 288mm setup. Sold the 312mm (that I got for the price of a pint of a friend modding his TT) for beer tokens! Sorry pal! Lovely Avant BTW mate!

ah they go so quickly!!
cheers dude.