My "ACR-X style" rotor experience: street and track

Longdaddy

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I recently had a chance to try an alternative for Brembo’s “Wide Ring” ACR-X rotors, which provide larger friction surface, and accommodate “D1001” shape pad. As many of you know, Brembo caliper used as OEM on GenVI Vipers is able to fit both “D968” brake pad (SRT-10/ACR) as well as “D1001” shape pad, so ACR-X setup takes advantage of that by utilizing a wider pad with a differently proportioned ring/hat combo.

Brembo unit that is supplied with ACR-X, and can be purchased for non-X cars through vendors dealing in Brembo Motorsports part, is a good rotor that will stand up to heavy track use, as well as repeated high temperature cycles. It does, however, have some disadvantages, mostly centered around noise/vibration during low speed driving (see my post in the earlier thread here: http://forums.viperclub.org/threads/650977-ACR-X-Brakes?p=3177688&viewfull=1#post3177688), and somewhat abrupt initial torque when using “cold” pads/rotors at track speeds.

Ever since I got the ACR-X setup, I have been looking for an alternative that retains larger pad, can be used with the Brembo hat I had already, and is a little friendlier to street driving.
I am happy to report that the latest version of the rotor I tested appears to be a perfect fit for the Brembo Motorsports “ACR-X” hat (I believe an alternative hat is under development as well)

One thing I like about these rings, is that the hardware is much simpler. Neither a washer, nor locking compound are required for the assembly/rebuild, and you can use “normal” 8mm socket instead of 4mm hex bit. I have gone through many 4mm hex bits over the years of using 2 piece rotors, and it is pretty cool to not have to worry about not having one in my toolbox that has not been ruined.

I am looking forward to testing these rotors at the racetrack; I am hoping to get the car out within the next few weeks!

Here are the pictures:

Comparison with Brembo ACR-X rotor:
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Comparison of ACR-X/D1001 option with stock sized ring and D968 pad:
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Comparison of hardware (Brembo on the right)
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Ready to go!
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P.S. While I am aware of the policies regarding non-Sponsor product information, I hope this post is OK, as it answers questions I have heard many times regarding ACR-X “option” for street driven cars, and reflects my direct experience with driving (and developing) my Viper - rather than promotion of any specific product or business. Feel free to message me if you are interested in learning more.
 
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Longdaddy

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Unfortunately, Brembo Motorsports catalog only lists P/Ns for "assembley' ( which includes both hats and rings): 90.9303 and 90.9304. I do not believe the hats have any numbers on them, but I can double check tonight.
 

Viperless

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Brembo hat p/n:

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Longdaddy

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I've tried these out on the track (as well as XR5 pads from the same manufacturer) last Saturday, and they work as advertised. It was a cooler, damp day, so I cannot speak to rotor performance in "maximum stress" conditions. The rotors looked as expected at the end of the first day with a couple of hard cycles, and another couple of easy ones. Some material transfer from new pads, no heat checks/cracks, low wear on rotors, moderate wear on pads (I probably could have bedded in new pads a little better - I just drove on them to work and back prior to taking the car to the track)

In any case, the rotors had same predictable bite/modulation characteristics as earlier versions I tried in the summer, which was really nice on the track with braking zones that still had remains of a major "oil spill" from 2 weeks ago. Actually, braking zones were the only areas where I could really push the limits of the car - everywhere else I was basically tip-toeing around very slick track that already ate up a car earlier in the morning, and nearly bruised mine in the second session out!

So, all in all, I am happy with this product.

http://www.youtube.com/watch?v=unrMYq1ETTU

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