Silver Streakin'

<center><img src="http://pictureposter.audiworld.com/10901/stoptech_rotors_old_vs_new.jpg"></center><p>
Orange (RS 4-4) at short/technical/no-big brake zone tracks and Hawk HT10s at high speed/big brake zone tracks. I may give Pagid Blacks a try next. They HT10s only have 6 days on the them, so they're at about half. and I have found that the second half of pads goes quicker than the first half. heat issue, I guess.

fwiw, I run Hawk HP+ in stock rears. I have B5 S4 rear brakes sitting in my garage to go on when I get the time. I may bump up to Hawk Blues (9012) for the rears next. I would like some better rear bias.

Tomasz@Startup

I know, I know.

BremboGuy

<I>Semantics</I>, or actually understanding the difference between actually "floating" and "room for expansion"???

<B>Floating</B> means that the disc can move independently from the hat/bell portion of the assembly. When in motion, the disc can seek a true centerline with not restriction from the hardware or McLaren spring clips. This is a major benefit that <U>no other manufacture</U> has incorporated into their BBK's yet.

<B>Room for expansion</B> means that there is sufficient room for the disc to expand without restriction from the hat/bell as in increases in temperature. THIS IS NOT FLOAT. And too much spring tension can even restrict the ability for some assemblies to expand properly.

Everyone wants to claim that their systems are flaoting. It's a huge selling point. The truth is that most sytems are just not actually floating.

Tomasz@Startup

The idea of using this forum was to solicit input of others, and many have chimed in.

I told everyone in the first paragraph that I sell Brembo, and my conscience is clear. I still stand by all that I wrote.

Andrew C.

both systems only allow for float/expansion away from the rotor hat (futher inboard), meaning if the "true centerline" was slightly outboard, both systems would require shimming of the calipers?

also, how "off" from perfectly centered can the calipers vs. rotors be before issues arise? like if i was 2 mm off, would this just cause uneven pad wear or some other, more serious issues?

thanks.

Tomasz@Startup

I will add black, you are right. As to pads, yes, you are righ too, decent pads are $200 more.

Andrew C.

***** of rust (about 9 months old) so maybe they'll be issues even w/o salting . . .

Dan Barnes@StopTech

Tomasz,

First of all, thanks for inviting me to respond, and thanks for noting your overall satisfaction with your StopTech kit.

<i>Tomasz wrote:
NO WASHING. StopTech wants you to wash their rotors. Brembo does not require this. </i>

StopTech non-plated rotors are shipped with an anti-corrosion coating that must be washed off or it will interfere with brake pad function. StopTech zinc-plated rotors do not have this coating, and do not require washing. However, StopTech zinc-plated rotors should be driven gently until the zinc plating is abrasively worn from the friction surface prior to bedding the pads.

StopTech does not recommend zinc-plated rotors for immediate track use, as our experience with our products in service shows that the zinc diffuses into the pad material and interferes with proper pad function. This is not a safety concern, and will never be noticed on the street, but it is of concern when the last few percent of a pad's performance is required, as on the track. Driving gently so as to abrasively remove the zinc plating from the friction surface as noted above, or bedding race/track pads on rotors that have already been in service and had the zinc removed, will work fine.

On the other hand, zinc is strongly recommended to prevent corrosion when our brakes are going to be used in a road salt environment.

<i>Tomasz wrote:
StopTechs use a Belleville Inconel washer STaSIS uses two. The washers were originally just designed to be a high-heat lock washer. They have a very high spring rate so once they are torqued down they don't allow the disk to move. When a disk isn't allowed to expand the hat may crack around the bolt hole area. The Brembo hardware is more expensive because it was specifically designed for that application.
</i>

StopTech's Inconel washers are designed to yield during installation, ensuring a very precise spring preload that is consistent from pin to pin. The entire purpose of our floating hardware is to allow the disc to expand or contract radially relative to the hat as the two are heated and cooled at different rates, and with different coefficients of thermal expansion. What you suggest requires that the friction force between the contact ring of the washer and the iron rotor be greater than the strength of the aluminum hat itself. The low installation torque required to tighten the bolt through the yield zone of the washer (far below the final tightening torque, which is itself low) shows how far our assembly is from that situation.

I can't comment on the hardware used by Stasis, but StopTech's Inconel washers are not an off-the-shelf part that could be ordered from any industrial supply house. They have very particular specifications for material composition, heat treat and dimensions. In short, StopTech's conical washers are specifically designed and manufactured for this application.

<i>Tomasz wrote:
I am not aware of the Belleville Inconel washer to be acceptable when durability is of importance.
</i>

StopTech's washers last the life of discs in street use, and are replaced each time rotors are replaced because, as I mentioned earlier, they are designed to yield during installation and are thus a single-use part.

StopTech rotors and hardware have lasted through the 24 Hours of Daytona as well as the 25 Hours of Thunderhill many times, on many different vehicles. I could be wrong, but I've always considered such events to be good tests of durability.

<i>Tomasz wrote:
I also read a rumor (RUMOR) that StopTech is switching to McLaren type of hardware. If anyone connected can comment - please do.
</i>

I'd really like to know where you read your rumors. I'll leave it to Gary to comment on the probability of Brembo licensing any technology or hardware to StopTech. Or perhaps since you're clearly in contact with a Race Technologies sales rep as a Brembo authorized dealer, you could have saved us both time by asking them about this before posting that comment.

I can say that StopTech certainly has not asked to license any Brembo technology. In this particular case, our parts perform well and apparently cost less - why would we switch?

<i>Tomasz wrote:
Brembo supplied bracket, the clean black piece in the picture mounts with the two bolts toward the outside - unlike StopTech.
</i>

What this means in our world is that the Brembo bracket is mounted to the non-datum face of the upright. There is no requirement for the OE to make this a controlled surface, as the OE caliper is positioned relative to the rotor on its mounting surface, and the thickness of the bolts' through-hole can vary without affecting function. On many cars, the thickness does vary significantly. Audi may or may not control this thickness better than other manufacturers, but at StopTech, we assume it is not controlled, and mount the bracket to the same surface that the OE caliper mounts to.

<i>Tomasz wrote:
I forgot to mention. StopTechs install manual although not pretty - just some pages printed on a laser printer is specific to the Audi. It contains torque specs, etc. Brembos, although pretty bound booklet, is non car specific and it refers to Bentley for torque specs, etc. I recommend that you reference the StopTech one.
</i>

Thanks again for the props here. I recall when I supervised a Brembo kit installation on an S4 several years ago (before I worked at StopTech), my shop technician was initially confused because the "generic" Brembo instructions showed the bracket installed one way and the "correct" diagram showing the non-datum installation in that application was supplied on a separate sheet.

BTW, StopTech installation manuals can be downloaded here:

http://www.stoptech.com/tech_info/bbk_manuals.shtml

<i>Tomasz wrote:
StopTechs have least of pedal travel, but their modulation is worse as they feel grabbier.
</i>

You haven't mentioned which pads you were using in your StopTech kit. The Axxis ULT pads feature an unusual combination of characteristics relative to this point: they have good initial bite, excellent modulation and a clean release. Finding all of those in one pad is rare. Axxis ULT pads are also an outstanding financial value. Together, their overall characteristics make them highly satisfactory in most street-driven cars.

<i>Tomasz wrote:
I did not compare stopping distances as I can not understand how this is not a factor of the tire much more than the brake. All of these kits can easily lock the wheel.
</i>

You are completely missing the point of StopTech's Balanced Brake UpgradeĀ® message. To achieve the best braking performance, it's not enough to be able to lock just one or two tires. The shortest stopping distance is achieved when all four tires are brought to the maximum of their ability to do work (just below lockup) at the same time. For stability, we make the fronts reach lockup just before the rears. If the front or rear tires are being asked to do proportionally more work than ideal, the underworked tires will not be able to contribute their fair share before the overworked tires reach their limit. ABS-equipped cars will improve the situation somewhat, but even then, correctly-balanced brake systems will result in the least ABS intervention during a stop.

More in-depth explanations of these concepts can be found here:

http://www.stoptech.com/tech_info/tech_white_papers.shtml

StopTech didn't invent brake balance, and we didn't invent the laws of physics. But we did build a company around the simple philosophy that all cars must behave according to the laws of physics at all times, so we had better build brake systems that take those laws into account.

<img src="http://www.startupracing.com/images/Brakes/Brembo/8.jpg">

Notes regarding the chart above:

StopTech calipers are available in red and black as standard; silver is a no-cost special order option. Black is recommended for track use.

Cadmium is a heavy metal considered environmentally very unfriendly in the state of California.

Note that StopTech is a DOT-registered manufacturer of brake lines. All our lines are manufactured in-house and 100 percent tested to 4500 psi.

You seem pleased so far with the Ferodo-supplied pads in your Brembo kit (compound not specified). StopTech sells Ferodo DS2500 pads (a common street/track choice) to fit ST-40 calipers for $191.95. Adding zinc plating and DS2500 pads, a StopTech 332mm kit would still only be $2256.95, and you would have a set of ULT pads to sell to a BMW guy.

Also, because you need spacers to run stock wheels with the Brembo kit, a customer may be looking at anywhere from $15 for possibly scary hardware up to $49.95 plus about $3 per bolt for H&amp;R spacers, or a stud conversion as is on your car.

I hope this helps provide a balanced viewpoint on this thread, and thanks for reading!

-Dan

Dan Barnes@StopTech

This thread has included significant discussion of two-piece disc floating hardware designs and their relative merits in allowing radial float (which Gary Cogis called "room for expansion") and axial float.

The entire purpose of StopTech's floating hardware is to allow the disc to expand or contract radially relative to the hat as the two are heated and cooled at different rates and with different coefficients of thermal expansion. StopTech's Inconel washers are designed to yield during installation, ensuring a very precise spring preload that is consistent from pin to pin.

Axial float, the basis for most of Gary's and Tomasz' claims about the superiority of Brembo's "McLaren" floating hardware, is required in certain cases to combat pad knockback, which is caused by changes in the alignment of the rotor relative to the caliper as the vehicle is subjected to cornering forces. The extent to which this is a problem varies with vehicle platforms, and the particulars of the design and condition of wheel bearings and uprights or steering knuckles. Knockback is generally not considered a problem with any Audi platform. The current popular cars where it is typically an issue are the Nissan 350Z and Subaru WRX. I have previously invited Gary Cogis more than once to claim experience (without requiring proof) in which removing a StopTech kit and installing a Brembo kit on one of those cars reduced knockback, and he has not responded.

To learn more about knockback, please see our white paper:

http://www.stoptech.com/tech_info/wp_knockback.shtml

Again, thanks for reading!

-Dan

bhvrdr

Concise. Great having all these resources on the board!