jangy

They are coated. VIC55s just pickin on me. They did not come out at all the way I wanted, but like i said they are growing on me. I will be getting forged rims, soon so I can handle them for now. i just wanted to get the offsets straight to be sure to fit 275s in the front and 295s in the rear before I spent the money. No rim company was willing to say it would work (and actually a few said it was IMPOSSIBLE), so i did the R&D myself.

france2112

I'm now on a quest for forged wheels. By the way your car looks amazing. I live in South Florida not too far from Renntech and I plan on also getting the lowering module. I need the wheels first then the module.

I read your posts to the "AI Design: Audio Install Debacle" and couldn't agree with you more!!!! The president of that company is a total A-- H---!!! You were right on the money with all your comments.

By the way, I still get nightmares about the Kreb Cycle!!!

jangy

I just tell it like it spills.

You don't need to wait on the rims for the module, as it is a dynamic thing. Change it according to mood swing (like me) or even when you get different rims. You do not want to miss out on the "intro" pricing. If you are getting it for more than $1150, let me know. I paid that installed.

dinko

Jangy, have you considered Evosport Rotors? Saves you 34 lbs on all 4 corners?

ChicagoX

I would be very careful of lighter rotors.

Lighter = less thermal mass. Not necessarily ideal for a heavier car.

Just my $.02, sorry for the OT.

jangy

Please explain. You saying they will heat up more?

jangy

Yes I have, just haven't gotten anyone to cut me a good enough deal. I'll be getting those or the RENN ones soon.

ChicagoX

Think of the Evosport cooling upgrade, which increases the volume of fluid in the cooling circuit. This helps with heatsoak.

Same principle with the brakes; less mass means less of a heatsink. Critical/max temps will be reached sooner, and the ability to absorb heat will be lessened.

For 1-2 quarter mile jaunts, you won't notice a difference. A canyon run or track day would be where the problem would occur. Heavy car + repeated braking will expose the failings of lighter rotors in short order.

W

CynCarvin32

Here is the theory with brakes:

You take Kinetic energy and slow the car down by converting it into thermal energy (heat in the brakes).

When you have a brake rotor you make it heat up every time you slow the car. Doing it over and over taxes it a great deal and it can eventually over heat.

To fix this issue you want to create a way to cool the rotor down between brake applications. You can cool the rotor with airflow and things like that but at some point you just do not have enough airflow.

The big benefit of the EVO rotors is that the 2-piece nature does not retain heat like the stock rotor. It is indeed lighter and that is the same reason it sheds heat more quickly. The heat stays in the rotor it self and it stays over an area that has a great deal of surface area (best for cooling) thereby it cools down very quickly between heat applications. A factory brake rotor has that massive center section (hat) which absorbs the heat and retains it where as the hat portion of a racing style evo rotor acts to shed the heat since it is connected to the rotor via pins and or bolts. The space between the rotor and the hat allows for added cooling before the heat is transferred to the hat and hub. Plus the hat and the rotor and made of different alloys and this also slows the rate at which the heat transfers to the hub because aluminum is a slower conductor of heat.

Finally, the 2 piece nature of the hat and rotor also allows for a slight increase in the rotor size (around the bolts) before that increased rotor size changes the position of the disc in relation to the caliper. That is is called radial float (I think) and it just allows the rotor to change size a slight bit with heat cycles and maintains brake feel under sever loads.

So when having the evo rotor, you do have less material to heat up but that is the best part of the upgrade since you have less mass to cool down. The rotor sheds the heat into the air quickly where as the factory rotor retains the heat in the hub section and the brakes slowly over heat and become useless. The evo rotor does weigh less but its ability to shed heat much more quickly allows it to stay cooler in canyons and at the track where the factory rotor just heats up and cracks (like mine just did!)

This theory also applies to doing a bigger brake upgrade vs. doing an upgrade to a 2 piece at and not going any larger. The larger brake will take longer to heat up to the point of fade or failure BUT it also takes longer to cool down. So once hot a bigger body takes longer to cool while the smaller body sheds that heat more quickly and stays in the operating temperature range.

You very often see race cars using 13 inch brake kits not massive 15 inch kits and that is due mostly to the fact that a 15 inch brake does not provide that much more stopping power and often just adds massive amounts of weight to each axle -- plus it takes forever to cool that big body of metal down once it gets to hot.

Anyone understand any of this? I doubt it... seems to be all jumbled but good luck!

ChicagoX

Strictly a cost/weight vs. diminishing returns issue.

Race cars change components after every event; sometimes more often during endurance racing. What works for max performance on the track for 2 hours won't necessarily be the best for a hi-po street app. There are trade-offs everywhere when going from street to track and vice-versa.

I'm not saying that there's nothing better than the stock offerings- far from it. I'm simply warning members to be cautious of the compromises (from experience.)

The reduced mass from the hat is far less crucial than removing mass from the hub. Removing mass from the hub reduces it's ability to absorb heat and forces it to heat cycle more often.

Sorry again for the OT content.

CynCarvin32

As for being better than stock thats simple to do since stock on the E55 is not that great. Trouble is I just ordered a set of new pads and rotors all around and it will cost me $650 to have everything purchased and installed. At that price even I can't justify going for the $1,999 EvoSport rotors (without pads and installation). So for 650 I will just melt and crack the stock parts once again!

Being that you cant jsut go around changing the hubs on these cars sticking to brake items makes the debate far easier. The 2 piece nature of the evosprot parts makes them more resistant to heat and they also were able to use a stronger rotor that is less prone to cracking (and which will wear less quickly).

As for the size of the brake kit I bet a 14.1 inch stop tech kit or a Brembo F40 caliper with Pagid Black pads would destroy the OEM 8 piston 14.1 inch brake kit. The big difference being pad compount and the stronger and lighter (better cooled) rotor.

ChicagoX

So you haven't used aftermarket rotors on these cars?

GTR Power

--OFF TOPIC--

The OEM brake system works fine.

If you want to increase heatsoak capacity in the braking system, install brake ducting and direct the air to the middle, behind the rotor. A nice bonus is that the calipers won't get heated up as much either, minimizing the color change.

The OEM pads are Pagid FYI. Using a Pagid 14 Black pad with any brake would increase the heat capacity.

The F40 is not "the end all/be all" of calipers- but it is very capable. The limiting factor in that caliper is the use of two separate castings that relies on several bolts to limit flex. A better caliper for high performance use would be the Brembo Indy- a one piece cast caliper.

Many race series limit the braking systems allowed by limiting wheel size. That is the reason why you don't see bigger rotors. Bigger rotors are definitely an advantage- increased torque and increase heat capacity- better feel and more consistent braking- which could allow for smaller, less abrasive pads and calipers.

Do the Evosport rotors use McLaren antirattle clips? Do they have sufficient clearance for heat expansion? (FYI StopTech rotors fail miserably on both- no McLaren antirattle clips, interference fit rotors and hats). Carroll Smith once wrote that aluminum was a poor choice in rotor hat material, but he also stated that in practice it didn't seem to hurt.

If I were to install two piece rotors I would stick with the OEM E63 fronts with the appropriate OEM pads, although I don't know if they would fit. E63 brakes use a 6 piston caliper whereas the E55 uses an 8 piston caliper according to the latest literature.

vader

ON OFF TOPIC

The more I read and learn on this site...the more I realize there are people here that REALLY know their stuff....in every aspect and every area.....cool ! Love reading this stuff. GTR...do you race or build race cars in some way ?

CynCarvin32

I can melt a whole lot of 71 buck rotors before I meet the cost of the EVO rotors.

I never drive the car all that hard and I just replaced the brakes to find that the rotors and pads were cracked.


OEM is junk but its priced low enough to make going aftermarket not an option unless you want to pay 2k for some rotors. 300 for 4 rotors is dirt cheap. I just cheaped out I think

I have done aftermarket brake kits on other cars but those cars I used for real track use. This car just go screaming down the freeway. So why the cracks?

Who knows!?!

CynCarvin32

I personaly would never put a pagid black into the E55 given the fact that I managed to crack the stock rotors with never once going to the track or taking a serious canyon drive. The real agressive pad would just make more heat and make the rotors crack more quickly.

For the average driver stock is fine but even a trip to 160 and back down for fun makes the stock brakes fade groan and rumble. I just wish the MB brakes were more along the lines of a 997 brake or M5 brake.

GTR Power

You don't need to put a Pagid Black pad in. That was just an example (a poor one on my part).

Just use some ducting if you have problems with the OEM system.

Most of the performance gain from aftermarket systems such as the Race Technologies Brembo kits (Race Tech is part of Brembo) or Stoptech are from removing the heatshield plate- to give the rotor more room, which also gives it more air circulation (allows more heat dissipation). The problem with that is you are also heat soaking parts that were designed with the heatshield in place- ball joints, traction control sensors, etc. Proper ducting (welding on a ring attactment on the rotor backing plate for silicone hosing that draws air from a high pressure point) will give you more than enough cooling on the rotors. However, you can choose to do whatever you want.

I race some stuff... I've built my fair share of track cars and have been involved with race prep, have too many friends racing various pro series... I currently road race karts in a national level series- too old to go pro, too young to drive something slow.

jangy

Don't forget that some of us are interested in replacing the OEM rotors for the EVO ones simply due to unsprung weight.

vraa

Seriously, I never knew that StopTechs were prone to cracking and they weren't designed with thermal expnasion in mind (meaning, they don't pass the interference test as parts expand due to heat, as far as design, I'm not sure.. it was just easier to type )

jangy - I think the initial argument started with the unsprung weight part. As stated (and I'm not sure refuted, still trying to comprehend the post) that the less mass = lower critical temperature meaning that the point of useless brakes temperature comes sooner. CynCarver said that the design of the rotor however refutes that because it's more able to cool effectively.

jangy

Especially since I am not planning on getting the cross drilled style as I see it as a simple eye candy attempt. i am going with the better cooling grooves.

ChicagoX

Cross-drilled *will* crack, eventually when pushed.

Slotted is a much better option for outgassing and pad scraping.

Cooling is a separate issue, based on ducting and internal pillar design. The better designs have a pillar-vane design or similar to aid in heat removal.