Rear W8 rotor

the rear brakes are the same as the 4mo's or atleast the V6 4mo's before the crazy 1.8t 4mo came out

our brake sizes are
front: 321mm X 30mm
rear: 269 mm X 22 mm

not sure about in inches, sorry

i would assume that any upgrade kit for any other 4mo would work, however i am not 100% sure, but why would you want bigger rear brakes and not bigger fronts, this will only mess up the braking distobution causing the rears to lock up before the fronts, which is dangerous (that is without abs, like spinning, flipping burning kinda dangerous)

importrp.com sells a part number # 8D0 615 601 A

this will fit the W8, or that is what the rep at importrp told me, and is made by ATE, $30 for a set of W8 rotors instead of hundreds or something like that

why do you want even brake distibution

when the car stops it pitches forward causing more weight to move to the front, also our cars our very nose heavy, this causes the largest and best contact patch between the tires and the road to be in the front, therefore the front wheels can have more braking force applied to them before locking up.

if there is too much braking force in the rear your abs will not work properly, your car wont stop properly, or nosedive properly allowing you to stop quicker.

if you read the zechenhusen (sp?) articles about making and testing a big brake kit you will see what i am talking about explained better.

i would strongly sugest not upgrading the rears without upgrading the fronts, and doing so proprtionally, or properly so that you stop correctly

i agree with slotted rotors to wipe the water off the pads for better wet stopping, i think slotted are worth it, as long as you know they will go through pads quicker, and could be a little more noisy.

but again, slotted all the way around it better, than just rear, or slotted fronts only

jeffsu350 said:

the rear brakes are the same as the 4mo's or atleast the V6 4mo's before the crazy 1.8t 4mo came out

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NEGATIVE!!!

Will (Swami) -- help me out here. V6 4MO's use a solid 9.6" rotor (like the FWD Passats), the W8 runs a similar rotor to the S4, which is a 10.6" vented rotor. I have no idea about the offset of the hats, however.

Check with ECS Tuning, they should have the correct aftermarket rotors for your W8. However, you're not going to "even out" the brake distribution just by going with slotted rotors, the improvement in performance is nowhere near the increase in performance you'd get with the larger rotors up front. You'd probably need to run a higher-performance pad in the rear (i.e., run Mintex Red Box up front and maybe Mintex C-Techs in the rear) if you really wanted to try and even the brake distribution. Unless you know what you're doing, I'd stay away -- just run the bigger brakes up front and not worry too much about the rears.

If you have the funds, run a StopTech BBK up front -- you get the advantages of the larger rotors (primarily better heat soaking, as well as better better braking power due to the larger lever), but they supposedly build their kits such that the braking bias isn't affected.

Andy

I<3myW8 said:

I wanted to upgrade the rears because IF I get a rather large, 13 inch, slotted brake kit with Porsche calipers, I'd be a bit power-heavy on the front end. And then, I'd even it out with slotted rear rotors. :thumbup:

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This statement is laden with assumptions. I'd suggest asking someone who works with these calipers what the effects will be before continuing. Some things you should know before you grab an off the shelf Porsche caliper and assume it's right for you, if performance and not looks is really a primary goal:

What's the piston displacement on the Porsche units compared to your stock calipers?
What's the swept area on the Porsche unit's pads compared to your stock caliper?
What makes you think that changing to "slotted rear rotors" is going to "even it out" ?
What type of activities am I engaging in that are coming anywhere even remotely close to taxing the stock brakes?

It's perfectly plausible that the Porsche switch could move your bias rearwards. It's also plausible that this would be beneficial. Cars usually have too much static bias to the front in stock form, for the same reason they're setup to understeer.

Mac, are you saying that an upgraded front kit woul move the bais rearwards? What? Or would adding uprgraded rear brakes help the car, as you said that stock cars are setup with too much understeer?


I am looking forward to tracking and Auto-X'ing my car, also, I feel that although the W8 brakes are big, they aren't sufficient enough to haul a two-ton car down uh, sufficiently. Enter the ECS BBK and the slotted/upgraded rears. Better power in the wet, better power for tracking, altogether better braking.I'd like to upgrade the contact patch and have a bigger rotor to slow it down better. Then I'd slightly upgrade the rear braskes, because an uneven brake bais could affect the 4Mo and ABS crap.


The Porsche calipers are four piston. I recently found out that the W8 calipers are simply two piston that 'function' like a four piston. Not sure how that works, but, I'd like a bigger rotor to say the least.

I'm saying that a different front kit could absolutely move the bias rearwards depending on the piston displacement, pad area and materials, rotor size, etc. Since we don't have any specs on the W8 calipers (we probably do have them for the Porsche units), there's no way to know other than testing. It's a complicated subject. Slotted brakes don't give you more brake "power." If anything, the reduced rotor surface area will slightly reduce the brake torque available. I suspect a 12.3" rotor is plenty big for your car especially if you're not on r-compounds and with some good track pads. Playing with the brake bias can be counter-productive unless you know what you have and know what you want. Go to the track with good pads and good fluid and see how it goes, my two cents say you'll have no problems. Those two things are waaay more important than the boutique BBK's. If you still feel that it's insufficient, then upgrade and pay the rotating/unsprung mass penalty (and wallet penalty).