Steveo369

Firstly, this is not a rant against or for ECS, I'm simply passing on some information which I recently sorted out regarding the "new" two piece rotors that ECS sells. I know there was a recent group buy on these rotors/kits, and wanted to pass word on to others so hopefully they can avoid my installation mistake.

I recently purchased the ECS A8 Big Brake kit with the new two piece Tru Float slotted rotors and TT carriers. The rotors were not stamped right/left, nor were any instructions provided, and there doesn't appear to be a good set of installed photos of the new rotors on ECS's website.

I scratched my head for about 2 seconds on which way the rotors were to mount, and figured the slots must face the same way as almost all other BBK's, like this:
(If you stop reading right here, please note, the following picture is <b>WRONG</b> for installation of these slotted rotors)
<img src="http://www.steveo369.com/gallery/albums/brakes/wrong2.jpg">

About two weeks later, I read this <a href="http://www.stoptech.com/faq/data/faq16.html">FAQ</a> from Stoptech. Note the last line:
<i>"The only correct way to determine what side a directional rotor goes on is the internal vane direction."</i>
Also note: <b>The ECS rotors have slotting that is OPPOSITE of Stoptechs.</b>

I soon suspected that I'd installed my rotors incorrectly, as I'd noted the internal vaning when I installed them. I had installed my kit per other pics of BBK installs I'd seen here on Audiworld, based on the external slotting. I contacted ECS via their live AIM support, and they were helpful, acknowledging that the slotting on their rotors was cut opposite of Stoptech's and other's rotors.

Hopefully they'll get some instructions, pictures, or other FAQ's added to their website, as it's nearly impossible to tell which way the vaning is set compared to the slotting from their website. FWIW, the slotting on the combo slotted/x-drilled rotors may be different than the plain slotted; I haven't seen these rotors firsthand.

So in picture summary:
Wrong installation (Passenger side shown, you can kind of see the internal vane angle)
<img src="http://www.steveo369.com/gallery/albums/brakes/wrong1.jpg">

Correct installation (Passenger side again, note the different vane angle, as the rotors have been swapped.
<img src="http://www.steveo369.com/gallery/albums/brakes/right1.jpg">

Wrong installation
<img src="http://www.steveo369.com/gallery/albums/brakes/wrong2.jpg">

Correct installation
<img src="http://www.steveo369.com/gallery/albums/brakes/right2.jpg">

I hope this helps others out there who might not have closely checked out the vaning, or realized that it matters more than the slotting. It also goes to show that every BBK is slightly different in design, and that you can't assume that because one setup has slots a certain direction, the others must as well.

BTW, so far, I've been happy with the new rotors, even if they were on backwards for a month and a track event. :-P

simply J

if you weren't sure, why didn't you call ECS and ask?

Steveo369

of course, if the dealer/distributor/manufacturer included clear instructions, I wouldn't have made the mistake now, would I have?

2001AWDFUN

I've always known how the slots are supposed to face. I'm sure if you had taken some time, you could have searched the internet for other cars that have the same kind of rotor installation and seen how the grooves are supposed to be facing.

Steveo369

so finding "same kind of rotor installation " isn't as easy as it sounds. Ultimately, if I'd read Stoptech's FAQ, I would have known. I suspect there are others in the same boat. I'm sure glad you know which way the slots are supposed to face, but it's not the slots which actually matter, it's the internal vanes.

I did run a search here on AW, and came up with nada. There actually was at least one other person who had asked the question about the ECS rotors (and also grumbled about ECS not outlining it in instructions or their website), but no one was able to definitively answer the question.

I've been around this board four years now, I've seen plenty of BBK install posts. I've seen people get chewed on by others for installing ST's with the slots/vanes backwards, but I'd never realized that the internal vaning was the important part of the rotor direction. You don't usually see the vane direction in install pics, just the slot direction, and that doesn't really matter.

Audi4orce

How does the abs sensor read the Trufloat rotors?
I know the OEM or the A8 rotors have the vain/ridges indide/back of the rotor for the ABS sensors to read...
How do the trufloat work???? any pics of the back side?

Thanks

Steveo369

the ABS sensor attaches to a bung in the knuckle behind the rotor and reads info from the halfshaft where it goes through the hub. (at least that's how it is in my '00 quattro)

The rotor doesn't send any info, nor does it have any ridges for mating to the ABS system. If this were the case, all other BBK's would have to have something similar, and they don't.

There might be something like that on the Frontraks since you have to pull the hub to replace the rear rotors, but I'm not sure.

Audi4orce

Don't know what car i was thinking about.
I just ran out to my garage and checked out my old oem rotors(don't ask why i still have them sitting in my garage, lazy) and they don't have anything behind them.
Thanks
DG

RKA

I would think the reverse orientation would have killed brake cooling and warped your rotors to hell!?

Steveo369

Seriously, it was a rainy day, low 50's at the track, cooling wasn't that much of an issue.

I can't imagine that reversing the vanes would make a *huge* difference, they wouldn't be much worse than the stock (non angled) vanes. Air is still gonna flow through the rotor, just not as well....

The whole premise/advantage of the two piece rotors is to allow expansion of the outer ring separate from the inner hub. Warping rotors usually is caused by the difference in thermal expansion of single piece rotors, the hub stays cool, the wearing surface overheats and tries to expand, and warping happens.