Splitting Atoms

This is a timely thread on brakes. I need to replace my fronts soon.

himself

Wheel bearings are sealed. I would say they are not a user serviceable part. They can only be replaced. And, it's a PITA to reomve them. You need special tools and a press. It is possible on some variants to get bearings off without removing the wheel carrier, but in my experience, it's way easier to take the carrier off and use a 12/20-ton shop press. In terms of special tools for the suspension parts, I use a couple flare nut wrenches and flare nut crows feet, ratcheting box ends and a giant torque wrench to get the axle nut torqued down. For the bearing, you need a few adapters for pressing the hub and bearing out and some sort of jig or horseshoe to get things level on the press. Also need a 2-jaw puller or a dremel tool to get the bearing off the hub. Note, that when you remove the hub, the bearing comes apart - with half remaining on the hub. So that needs to be pulled off separately. AND, if you forget to install the bearing plate before you reassemble, you'll ruin the bearing getting the hub off. That is, every time you take the hub off, you need a new bearing. Do be sure you get it all together right the first time.

Personally, I wouldn't replace a wheel bearing until it starts to fail. And I don't actually believe they are a wear part on the Porsche recommended service bulletins.

In terms of cost, bearings are like 90 bucks. Hubs are around $250. Wheel carrier might be $500 or $1500, depending on your car model. You'll need new caliper bolts and a new wheel axle nut as well. Those are like 5 bucks each. If you take it to a mechanic, it'll be a couple hours labor per corner. And then possibly an alignment.

-td

Slakker

The Ferodo's were boiling your fluid because they are a more aggressive pad and are going to generate more heat. Not because there is something wrong with them.

As for the wheel bearings, I've had to replace 3 in the last year. You can tell by pushing on top and bottom side of the tire with it off the ground and seeing if there is any play. You can also check side to side but on the front that can also be a tie rod. I have a machine shop that charges me $60 if I take them the wheel carrier and a new bearing. I do not replace the caliper bolts with every use as I've probably had the calipers off 40+ times in the past year as well. There is also a video on how to replace the grease in the new bearings with Redline high temp grease. I think it's very good but I haven't tried it yet.

NYoutftr

I would not attempt the bearings at my home.
There is a brake / Suspension guy who has worked on our cars for 20 years, not a Porsche Indy, but great mechanic.
He put the Techart Suspension on my 996 2 years ago. Every bolt, nut and washer was replaced in the suspension. Drop links, sway bars, coil springs, struts, bushings,strut mount support.
Drive in, drive out $500.
I believe it was very fair priced.

dkraige

Going the exact same speeds and braking at the same points would not generate more heat just because of a different pad. Physics. The difference is the pad's ability to *dissipate* that heat, rather than holding onto it and making other things in the braking system get hot.

Anybody that wants to try them is free to do so, I'm just trying to help the community by saying that I tried them and had problems that I have never had with any other pad. Your mileage may vary.

targa996

I run textar pads also - including a couple of track days. Sebro rotors up front - and used ate at 1/2 the cost at the rear with good results. Ate2000 fluid. Better bang for the buck than oem and no issues - but if you are hard on the pads you might want to consider switching to pfc or cool carbon specifically for the track day and then back to the street pads ...

Palting

I thought I'd put in another of my .02c, this time regarding Ferodo pads.

I use the Ferodo DS1.11. They have a very strong initial bite, and have very good durability. Excellent for DE. They are high friction pads, so yes, they can and do generate more heat. Heat dissipation is a function of the rotors, not the pads. Specific driving techniques to help cool the rotors also help. With the increased heat generation from high friction performance pads, you'll need high heat brake fluid as well, and flush them regularly. The standard brake fluid you would use with street pads are more likely to boil when you use high heat high fraction racing pads. Ferodo DS1.11, like any other high heat high friction racing pads, do make a lot of noise when cold, you sound like a POS schoolbus on the streets, so I wouldn't recommend them for mostly street driving. Didn't want Ferodo to get a bad rep, so I thought I'd share my experience.

NYoutftr

This is what was explained to me at the track. The new high tech pads, not the pad but the steel plates, have costings or finishes that make disipating the heat more difficult.

Triple Black

I use Ferodo pads as well and have never had any problem with boiling fluid. They give me a lot more confidence with braking, much less fade than OEM pads. Some squeal on the street though.

JRitt@essex

Okay...lots of issues going on here!

When you step on your brakes, the kinetic energy from the spinning brake disc is turned into heat. The amount of heat generated is a function of how fast the disc is spinning (your car's speed) and the mass of the object in motion that is being slowed (your car's weight). The pad compound doesn't really play into that equation.

Where the pad comes into play is the transfer of the heat that is generated. Some pad materials are better conductors than other pads, and some are better insulators. Racing pads tend to have a higher metal content than organic street pads, which gives them a higher max operating temperature before they melt and fade. The pad with the higher metal content will conduct that heat back into its backing plate more readily, which puts more heat into your caliper pistons and fluid.

All Ferodo Racing pads actually use a special thermal underlayer near the backing plate on their pads to slow the transfer of heat into the pistons and fluid. That underlayer is essentially just an insulator to slow the transfer of heat and prevent fluid boil.

The bigger issue at hand is any given pad's maximum operating temperature (MOT). A brake dyno evaluates a pad's coefficient of friction (mu) across a temperature range. If you look at a brake dyno plot for a given brake pad, there is a temperature at which that pad compound shows a dramatic drop in its coefficient of friction. What that translates to in the real world is commonly referred to as pad fade. That means you step on the brakes, and the pedal feels hard, but the car doesn't slow as you would expect. The pad got so hot that the materials are physically breaking down, and it can no longer generate friction. What usually happens at that point is that the pad melts, smears, and sticks all over the disc creating uneven pad deposits, which lead to judder/vibration, and generally inconsistent performance from that point forward.

Race pads are designed specifically with a high MOT. They keep generating friction at track temps, and they don't break down and smear all over the discs. Many times they also don't generate much friction until they get some heat in them. Squeal, dust, etc. are not of concern. Street pads are the opposite however. They're designed to generate friction when cold and not make noise. They have a much lower MOT however, and will melt, smear, etc. far easier than race pads when taken on the track. When we run simulations on our brake dyno, we'll many times take pads up to the 1800F range before they start to fade. An OEM or OEM-style pad may only make it to 1100F before hitting their MOT however.

When shopping for a track pad, your primary concern should be MOT. Will the pads handle the conditions you're throwing at them without fading, melting, and potentially destroying your discs? On a Miata, one doesn't need a pad with an extremely high MOT, because the car/brakes don't generate much heat. The mass of the car is low, and the speeds from which it is stopping are low. The conversion of spinning disc energy to heat is therefore relatively low, and the pads don't need an extraordinarily high max operating temperature assuming the discs have enough thermal mass and airflow to work properly. A Porsche 911 is a different story however. It is heavier, but more importantly, it is carrying much higher speeds into a brake zone. As such, much more heat is being generated, and the pads need to be able to handle that heat. While I'd wholeheartedly recommend the Ferodo DS2500 for a miata under just about any conditions, we would NOT recommend them for a 911. The Ferodo DS1.11 would be a far better choice due to its higher MOT.

Also keep in mind that track layout, tire choice, engine power, braking style, etc. all impact the demands placed on the brakes. So what works for one person on Roebling Road or Willow Springs on street tires, may be destroyed very quickly on Watkins Glen or Road America on R Compound Tires...very different brake demands!

Here are a couple videos we did on brake upgrades. They discuss some of these issues and you may find them useful:

Jason @ Paragon Products

The Pagid Sport pad will certainly dust less than a race pad but it will dust. I'd still consider it to dust less than many pads available. I've used them on one of my early 911's with very good results. We can build and type of brake package you like...pads, rotors, sensors etc.

NYoutftr

Any ever try some of the Hawk street/performance pads?

dkraige

If you mean HP+, be ready for ear-piercing squeal on the street.
If you mean HPS, it's really not suited for track use and may fade towards the end of a session and wear pretty quickly.

This is based on my experience using them on a B5 Audi S4. Have not tried them on the 911.

NYoutftr

ty

Timlin

I just had these fitted. A tiny bit bigger than OEM too, as well as lighter.

I use PAGID pads too.

http://www.girodisc.com/Girodisc-Fro...de_p_6547.html