ilikemy944

Hey guys, have overheated twice now a pair of rotors at DEs where they start giving me a lovely steering wheel shake near the end of a hard session. The brakes are phenomenal until then. I will add that I am assuming that they are overheating as the first set turned blue. I am using DTC60 pads, Motul 660 fluid. Still have the original dust shields in place and using phone dials so I'm guessing I'm not getting much cool air at all to where it needs to be. I may also need to work on my braking techniques.

Anyway, I will be removing the shields, adding the 968 duct setup and swapping the wheel bearings.

I have been using the sebro rotors from Pelican, should I be looking at something else? PP also has Zimmerman rotors but they are drilled and I'm not sure that is ideal.

Any recommendations on rotors or should I be good with the sebro once I add some additional cooling?

Thanks

Droops83

Step 1: install a brake cooling setup with cooling hose ducts. Lindsey, Paragon, and others sell complete kits. This will make a huge difference.

I don't have any experience with Hawk pads, as I use Pagids. When I ran the old Pagid Orange pads, I would sometimes get vibration while braking towards the end of a long session due to pad deposits. I now run Pagid Blacks, and haven't had the issue.

I have used both Sebro and Zimmermann on my '86 without issues, so I would try a cooling setup first.

Dwane

Run the Hawk Blue pads(think they are the 9012) they will clean pad material off the rotors. Keep them on at the track and compare. I've run Blues ONLY for the last 7 years on a 964 and recently on a modded 944T. Saw(and helped) many people with pad transfer using Pagid's and PFC's. Loaned them my pads to clean up their rotors.Trying the PFC's now that I "know" how to brake properly. Problem may be your braking technique and not pad compound.

Good Luck

jasonlp

Agreed with you Dwane on technique.

PFC's are fantastic and as well you could use slotted http://www.frozenrotors.com

mikey_audiogeek

OE (gen-u-wine Porsche) rotors are better than the Sebro, Zimmermann etc.
Much better design of internal cooling vents, better material, even the way the rotors are balanced is designed to reduce the risk of rotor shudder.

968 cooling ducts are cheap and make a big difference, you'll like these.

Cheers,
Mike

Arominus

Get some cooling, the 968 cooling paddles help! i run them on my car. Rotor wise i just put a set of sebros on my S2 and like them so far. The OE is better in longevity but i'd say until you get the cooling and warping under control, you may be better served ruining the cheaper rotors vs the OE's.

mikey_audiogeek

Good advice.

Wheels might make a big difference too. Lots of things to try, sounds like you are on the right track!

Cheers, Mike

Thales

Make sure you "bed" the pads well (1) if the rotors or pads are new or (2) if you have been driving around town long enough to "scuff" the bedded friction material off the rotor.

I have skipped this step after a pad change at the track and gotten the vibration you are describing.

As others have mentioned, smooth braking with a different aggressive pad (Pagid RS-14 Blacks, possibly Hawk 9012 Blue, I use both) may fix your issue unless the rotors and pads were badly glazed, which they may have been if your rotor turned blue...

I've found that only changing one of the pad/rotor combo at a time works best and beds quickly (i.e. never put new rotors with new pads on at the track).

I have used both Frozen and Sebro rotors on my 951 DE car. Currently prefer Sebro due to cost and since they get swapped out so frequently

Good luck!

951kaos

From a tech session with PCA-PNWR at Giro disc; they said to make sure the surfaces between the rotor and disc are clean, no rust or oxide build up. Any bit of dirt between them will cause a very small run out on the rotor, not noticeable on the street. When rotors get hot on the track; the high points will heat up more and may cause the rotor to get hard spots which may result in a brake shudder.

Iridium

Your biggest problem is heat. Go directly to ducting, skip the reflectors. Its way more important to have proper ducting. Even great pads and rotors will just eat themselves unless you can shed the thermal load properly.

disasterman

Ducting is a good idea to control heat and the DTC60 is a good pad but consider;

1. How much time do you have on the track and how are you braking? Post some video if you can.
2. Consider putting Hawk DTC 70's on the rear to get more braking out of your rear tires. The 70's are a more aggressive compound that will be more effective when not as hot.
3. Even with an overheated brake you should not have a shudder in your wheel. Check all of the mechanical components.

Just my two cents.

jmj951

+1 on slotted Frozen Rotors and brake cooling (I installed a kit from Lindsey). The rotors are expensive, but they seem well worth it. I was interchangeably using Pagid Orange (for track) and stock Porsche pads (for street), and the rotors are wearing incredibly well. I don't notice any wear at all, and definitely no warping.

ilikemy944

Thanks for all of the feedback guys!

It is a definite possibility that I am causing it with my braking, I have video but I'm not sure if you will get a real idea of what my braking is like. I clamp pretty hard initially, don't 'slam' on the brakes but I push pretty good, then adjust if needed. Should I stick a gopro in the footwell at the next event? I have only done a few track weekends but they are at Road Atl and I am coming down the hill into 10a over 130mph or more on some occasions down to 50ish for the corner. Also the car is basically full weight, only weight reduction is seats (but added a rollbar) and removal of the spare/etc.

I do feel heat is an issue but there is also possibility for other issues. I don't have any play in the wheel bearings but I will be swapping those out before the next track day. I will also be checking/cleaning up the face of the hub as I read that as a potential issue as well.

Is there a good source for fog light ducts? It sounds like the $250 ducts from AIR are not the greatest...

Here is a video link from a trackday last year, it was the last session and I was taking it a bit easier down the straights but hopefully it will give you an idea. I have video on a gopro from this year somewhere I need to locate....

Oddjob

The shudder is just during braking, more noticeable at high speed?

Not sure I have ever seen a "blued" rotor from over heating before. Do you have pics?

Cracking is the common problem with track use. See below. This is about 5-6 events on a set of M030 fronts. Some tracks are harder on brakes than others, and the last two events at Road America did these in. Point is, rotors are a consumable with track use, they don't last that long. Already stated here, I have also found OE Porsche rotors do last longer than the aftermarket rotors. Have to compare pricing from some of the discount dealers (like Hennessy and Sunset) to see if the difference in price is worth the increased life. Id guess the aftermarket rotors last about 2/3rd as long as the porsche rotors. But hard to say for sure. I have never tried or compared frozen rotors, but that process should also extend the life of the rotors some amount.

You are using good track pads and a good fluid, which is often a mistake made by many (low temp fluid, or not a dedicated track pad). What are you using for tires, suspension? Any power upgrades? Street/DE cars with high straight speeds and slow corner speeds can be very hard on brakes.

If getting the rotors hot enough to discolor them, I would guess its possible that even the DTC60s might be transfering material onto rotors. As mentioned, the pagid orange are notorious for doing that even at lower temps. Hawks are not known to, but maybe can when getting up over 1500F+ (?), not sure.

This is on your '86T? So it does have the short factory ducts thru the lower part of the front bumper cover and wheel well tubs?

I might recommend to not remove the entire dust shields. The lower section does act as a heat shield to protect your tie rod and ball joint boots. I have cut the top half or so of the shields off and left bottom part in place on a couple cars for that reason.

The upper and lower 968 brake scoops do work well. If this is a street car, I would recommend using those vs a cool brake ducting kit. A cleaner, cheaper, lower maintenance install, compared to the ducting. But you will want the lower scoops too, which require a fabricated mounting bracket to install (I think these are still available from some sources, like Frozen Rotors/Diversified Cryo) on cars that don't have 968 control arms.

The AIR fog light scoops are not a great fit and may require your own fiberglassing for a good asthetic installation.

jasonlp

I did it once.