AO

At my last DE, the front rotors on the coke car were clearly warped, discolored, and all around crappy. I'm very careful to avoid pad transfer after a heat, so I don't think that's the issue. Pretty sure they are either warped or are poorly constructed.

Frankly I have no idea what kind of rotors are on there. They are solid discs, but they appear to be made from cheaper steel - hence the discoloration, and the warping.

I'm currently running Pagid R29 pads, and this is a 1986.5 car, so basically S4 front brake calipers.

What have you guys found to be a good, solid, economical rotor for track applications?

The Forgotten On

I would go with solid Zimmerman rotors. They are what came on the car stock and aren't too pricey to buy new. They are also well made and very few people have issues with them.

That would be my decision and opinion. I'm sure one of the racing experience people will chime in soon.

Black Sea RD

When I had the car I used cryo treated solid rotors, forgot the manufacturer, and had no issues using Pagid orange pads.

I also changed out the front calipers to a 1990 S4 set which has larger pistons.

Have fun,

AO

Thanks Constantine. Didn't know you had updated the calipers.

Currently, I am considering Zimmerman or Sebro solid rotors, but am open to other suggestions.

BC

Better rotors (and sometimes cryo treated ones) do last longer - but at what cost?

What is the goal? To have fun, right? Corvette owners (C5) just buy many sets of rotors and change at the track. 25-40 bucks a pop. If it stops the car properly, then you are good.

Of course our rotor costs are not that low. But how much more are the "really good" ones?

GregBBRD

What brake pads and rotors to use is a "generalized direction" question that is tough to answer.....much like how much negative camber to use (the "negative camber" question is virtually useless.)

Pads and rotors are dependent on the driver and the track. What works for one person at one track, will probably not work for a different person at the same track.....in the same car. Different braking techniques require different pieces. A trail braking individual will have different needs than someone who does hard thresh-hold braking and is done. An "entry coaster" needs something entirely different. Change tracks and the requirements will be completely different. A course that keeps the brake temperatures up will require something completely different than a track that allows the rotors to cool more, between braking events. Outside temperatures also affect the brakes in a huge way.

Pick something and try it. As Brendon said, "stock replacement" rotors are cheap and a good place to start. (Zimmerman is not the maker of the OE rotors, BTW.) Buy rotor temperature paint.....use it. Monitor the results and keep notes. "Street rotors" (stock replacements) do not have the higher temperature tolerance than real race rotors do, but if you can "get away" with them, the cost is much less. Different "street rotors" also have different characteristics. Zimmerman rotors, for instance, have less initial "bite" than a factory rotor, however, with the "increased bite" of the R29 pads, this might work OK.

Depending on the track (and temperature), you may have to "play" with the ducting. A cold damp morning at Laguna Seca (which has a relatively long area for the brakes to cool, before subsequent hard braking zones) requires different "ducting techniques" than a summer day at Willow Springs.

If you end up "potato chipping" stock replacement rotors (almost anyone with average ability will), you may have to step up and buy some of the higher performance rotors with replaceable hats.

Be sure to also "paint" the rear rotors. Do whatever you need to do to get the rear brakes "involved" in the equation. More rear bias, softer pads, etc. Four wheels stopping always works better (and takes "work load" off of the front brakes) than two wheel stopping. As a "general rule of thumb" if you are not using one set of rear pads to two sets of front pads....there is something very wrong....especially if you are using a softer rear compound pad.

GlenL

FWIW... On my S, I had Sebro slotted rotors and they always felt uneven or "warped" from installation. As they neared the wear limit they developed serious cracks from the edge to almost the hub. I probably had 30 to 40 tracks days on them. Now going with Zimmermann rotors.

Black Sea RD

Greg's post reminded me that I also changed the rear brake bias valve to one with a higher number, IIRC 33, to get the rear brakes more involved.

Don't know if it was changed again after my ownership.

Drewster67

Go with Zimmerman and stay away from Sebro... You just want a solid / non dimpled / non slotted and especially non drilled rotors. They are directional so make sure you buy the correct replacements.

Good pads and Good brake fluid - Motul 600.

AO

Thanks everyone. All very good points.

I wasn't necessarily looking for the most expensive or best rotors - just good solid reliable rotors. Sounds like Zimmermans might be it. I'll probably get the ones that are on the car turned so at least I can use them as backups.

Funny thing, the Corvette guys are always complaining about cracking rotors, but you don't hear about that so much with the p-car guys. Might be the difference between a $40 rotor and a $140.

Speedtoys

No such thing, IMHO.

Solid, and cheap.

Ive sold 10s of 1000s of pairs of rotors in my last business, I'm not convinced rotors warm..I an convinced that poor pad selection deposits material not easily seen, that creates sticky spots on a rotor, and over time allows other areas of the rotor to wear faster however.

We dont have many choices..just..don't spend $ on gimmicky add-ons..they're expendable at the track.

Speedtoys

As a former Z06 class racer...

Speeds...and the ability to brake a lot deeper with the larger tire and lower weights. Just so much more heat load and shock.

$25/rotor back in the day..and they were good rotors, but remember that every 5mph is another 2x more energy you have to manage with brakes.

The Forgotten On

Oops

mark kibort

warping rotors is a inconsistant lug tighting issue, or a meterlurgy issue.

all rotors work near the same for DE applications. Ive never seen a problem with warping rotors unless there has been a problem with mechanical set up.

rear brakes.... Greg.... really? almost 75-80% of the brakiing is done by the front brakes.... proportioning valves dont allow any additional brake force even with more front pressure (which makes sense, because if you are using the brakes properly, they are in the "hot" zone of their Coef of friction.) so, you need even more pressure to stop..... you dont want more force on the rear brakes in this case. but the bottom line is with weigiht transfer during a hard track slow down, there is very little effect of the rear brakes. the majority of rear braking set ups , hurt the drivers performance. engine brakiing ALONE is almost at the threshold of what the rear tires can achieve as far as road to tire friction. 3rd gear lift at 6000rpm will achive this.. 2nd, might even be slightly higher than the tires ability to grip the road..... (i.e. engine braking for a 240hp stock 84 is near 150hp (negative) with just lifting off the throttle at 6000rpm. multipy that engine torque via the gear box and you get the answer.

I help drivers at the track CONSTANTLy with this common misconception and problem. i cant tell you of how many racer friends and competitors ive seen with too much rear brakes. you CANT save the fronts with the rears anyway.. YOU should always be at the limits of the fronts. the amount of braking force that the rears can provide , in a best case seanero , can only shorten braking time by a fraction of a second anyway. (remember rate of KE change)

as far as rotors and pads.... using a proper temp pad for the application is fine... for DE, most any performance pad will work. as far as rotors.. get a good quality rotor .. zimmerman is a good one.. OE Porsche is even better. solid is fine. hole'd willl look better but crack at the holes if you track a lot. racing, they might last 3 weekends if you are quick.

vibration in the brakes can be causes by out of round centering of the rotor. cracked spindle or a warped rotor... usually caused by street driving where folks will heat up the brakes coming down a hill , or off ramp at 100mph, and then leave the brakes pressed at a stoplight for a few mins.... over days, months and sometimes years, it can warp the rotor.

and no.... there is no "bite" difference in a rotor. a flat surface is a flat surface. racing, street, it doesnt matter. the differnce is the venting, thickness and meterlurgy of how they handle temp. fortunately the 928 rotor is a big heavy massive rotor. hard to find a problem with any off brand copy.

rs 29s are a endurance pad, designed to work at higher temps and are a hard compound. for DE, most cant see a difference. heck, ive driven my race car on the street for 20 years and cant tell the differnce between a mitex performance pad and a ST41 full out NASCAR racing pad. they all stop fine when cold and work in DE applications..... but the racing pad willl squeak when finally bedded , and the street pad will not grip when at track temps.

mark kibort

i did a very controlled test of this modification.... bad idea. any trail braking activities at the limit of some really big tires up front and in the rear, caused massive instability in the rear. straightline was fine,, but think about it... what are you trying to achieve? again,, there is very little braking potential of the rear at throttle lift at near redliine. ...... and in a 1g slow down, only 25% of the weight of the car is on the rear tires..... on a 4000lb car, thats 1000lbs on the rear tire, and only 500lbs per tire on the road. with a friction coefficient of 1, thats only 500ft-lbs of force than can be applied before lock up. take a turn, and that can go down by half on the inside rear tire!!!
unless you REALLY know what you are doing and what you want to do, dont mess with adding more rear brake bias.