iceback

Hey guys,

I'm taking my C32 to a Drivers Edge class at Texas World Speedway in a couple of weekends. Any recommendations as to what inflation pressures have given you the best results on the track.

Cheers.

nukblazi

What tires?

And can I make recommendation? Call porterfield and ask for pads with either the Raybestos ST-41 or Hawk DTC-70 friction material. Race pads. Here's what a sport pad (porterfield R4S) leaves on a rotor when it over heats and fades, and any non-race pad is going to fade.

rrf

and to convince you further:
You can change out the C32 pads in 5 min per wheel, once you have the wheels off.
...So this is something you can do before and after racing rather than trying to find one pad for all uses.

iceback

Thanks for the thoughts on the brake pads - I'll check into that today.

Right now I have Pilot Sports up front and Yoko ES-100's on the rear (my car was a CPO and the stealership put cheap rubber on the rear - I foresee a set of PS2's in my future). Anyhow, with that said, do you like your pressures somewhere between 35-40 psi? Do you stagger the pressures F/R?

nukblazi

I have a brand new set of PS2s I could sell you cheapish. The 235s wouldn't clear my front strut so I couldn't use them. They're mounted now, but never rolled, never bolted on, brand new from TireRack. 235/40/17 Front and 255/40/17 Rear. I am going to replace them with a new set of shaved Toyo RA-1s

That being said, you need 4 consistant tires types. Period. Tire pressures have a big roll in fine turning your handling. You do not want the tire to roll over on the side wall, nor do you want it too high and to not deflect at all. For PS2 I would start at 32/34psi the lower pressure in the rear gives more grip exiting turns, the higher in the front BUT NOT too high reduces deflection and rollover in the turns. Most importantly, this will also counteract the tendency of your car to understeer. You want some on a track, but not a lot at all.

Immediately after your first run, check the tire pressure on all four tires and get a real gauge, not a pen thing, over 34-35psi they are INSANELY inaccurate. Also, take a good look at the tires and the wear marks. You really want to get it to roll right to the edge of the threads. Definately read the first three links rel "Tire Pressure" at http://www.tirerack.com/tires/tiretech/tiretech.jsp. Please also read this http://www.tirerack.com/tires/tirete...n/racepres.jsp. I think the page says it but here are the rules. Do not change front and rear pressures at the same time. Either both front, or both rear. Also, keep your changes between .5 - 2 psi in either direction. Not more than 2 psi up or down.

An important thing to remember is that you need to give your tires time to warm up. If you start whipping around cold, you will heat the treadblocks, which will end up happily removing themselves from your tire. Chunking. Take at least one lap to heat them up before you start to tear in.

smgC32

General rule of thumb for street tires at the track. Hot pressures around 45psi +or-. Race tires 5-10psi lower. A tire pyrometer will also give you accurate temps which should be around 160 - 200 degrees. Without the ability to adjust camber, you need to play around with the pressures a bit front and rear to find the balance you are looking for.

Nukblazi, your rotors seem to look fine. The R4-S's don't do well at all under extreme braking found at the race track. I gave up on them after the first set. The R4-R's and E's are much better suited for this type of driving, as well as a host of other race only pads. The material on the rotor's surface is pad deposit, which is a good thing. The more even the deposit, the better. It is this material that exists on both the pad and the rotor that interact with each other and provide better braking. A properly bedded in set of pads and seasoned rotor will have almost continuous pad deposit material. The fade you experienced at the track was due to the lower operating temperature of the R4-S's and the possible boiling of the brake fluid. I forgot the specs on the Porterfields, but they are designed as a street pad and work best at temps within those conditions. Exceeding 750 degrees and above with these pads will produce pad fade.

BTW, how did my spacers work out for you? Tell more about why the SSR's did not work. And what wheel did you run the the PS2's on? Maybe the KW's fit the description I wrote earlier about wheel clearance and offset in another recent thread. What is the diameter of the KW strut? 53mm?

As rrf pointed out, pad changes are quick and easy. Just remember to re-bed the pads at each switch.

steve s

max pressure is 51 for ur front pilot sport and 44 for ur rear es100... i think u might find the front a little grippier than the rear with ur current setup.. do that chalk thing on ur tire sidewall and check to see how much scrub'n u get.. like nuk said, don't want to roll over on tires..but also don't want a balloon'd tire. gl & hf

nukblazi

I have StopTech SS lines and Motul MT600 fluid in the car... great pedal feel, no stoppie. I just overheated the pads.

Maybe it's the angle of the pics, and when the rotors were hot, track hot, the pad material was ok. At street temps and normal braking, the material deposits are horrifically uneven and right now there is the most GOD AWEFUL pulsing during braking... Moving to BBK and building cooling ducts.

I put the PS2s on 17x8.5 SSR Competition wheels 15.8 lbs each.

I will measure the H&R and KW front struts later tonight and get back to you. I have a caliper for just such an occasion!

smgC32

As long as the pads and rotors continue to operate at high temps, the deposit material stays mostly constant. Once you begin to drive on the street for extended time, the pads don't come up to proper temp and start to wear away the good pad deposit material through friction and the material becomes uneven, causing pulsation and the "warped rotor" syndrome, which really isn't a warped rotor in almost all cases, but pad deposit distributed unevenly. The visiable deposit will eventually wear completely off with casual street driving and the shudder will go away. You must however re-bed the pads again before your next track session to prevent uneven pad deposit at the higher temps. I do this on the way to the track in the morning.

Thinking about rotor backing plates?! Have Jeff make those too! I'm in. Already though of how to route them.

nukblazi

Since it's just sheet metal I could tig or mig up the hose mount to the backing plate. I am looking at a bunch of the designs used on BMWs, then going to draft a template. I've looked at a couple complicated designs which "cup" the center of the rotor to prevent airflow blow-off from the rotor back, I don't think I am getting that fancy though. I already mapped out the routing of the plumbing too

I know it's not a warpped rotor. I just overheated the "sport" pad which lead to the uneven deposits according to both porterfield and stoptech. The shudder is decreasing. Stoptech warned me of driving on them and fusing the soft material to the rotor permenantly damaging the rotor. Raybestos pad material next time. :p

I kept the pressure in my P-Zero M+S tires at 35 cold, after a run they were at 41/42, I wasn't rolling over onto the sideway, and not rolling to the edge of the shoulder block either. The tires performed 10x my expectations, and I was easily hanging with that Civic and other cars on R-Compounds. I call out the Civic because the driver and I were comparable in skill level.

smgC32

You can use a very aggressive race pad to "clean" off the deposits made, but only use these pads for that purpose and change them out right away for the pad you will be using. Check out BMP Design's offerings for backing plates and ducts.

steve s

http://www.stoptech.com/whitepapers/bedincontents.htm

Zeppelin

The Coupe must have a smaller wheel well opening than the Sedan. I can run a 245 tire in the front with -2.5 degrees of camber with no rubbing. Can't wait to go down to 235's so I can increase the camber to -4

nukblazi

I am beginning to think the problem is that I have H&R coilovers designed for the Sedan on my coupe... I have KW v2 which have a different part number from the V2 for the sedan on my living room floor.

When I had the stock strut in there, I fit a 245 as well. After the V2s are in and the camber/caster plates finished, I am going to try to get 255s RA-1s @ all four corners...

RapidG

Deposits are actually the brake pad freezing to the rotor when the rotor is hot from racing. This isn't a function of the pad material. You can avoid this with any pads by keeping your foot off the brake after you pull off the track and stop, otherwise the pad welds to the hot rotor, and pieces pull off when you release the brake. It's a hard habit to break. Stop the car and immediately release the brake pressure.

The standard brake pads are very good for track use. I race quite a bit, and always use OE pads. Never had fade.

Tire pressure? 40 front, 38 rear, and check them each time you come off the track. Pressures will rise 10-12 psi from heat. More with soft racing tires.

dsC32

Zeppelin how are you getting that much negative camber on a C32?????

nukblazi

I have NO IDEA what OE pad you could be using or where you're racing. I could fade my OE set up in rush hour traffic. Two hot laps on the 3.27 mile course at VIR faded my R4S pads, good pedal feel, no stoppie with slotted rotors.

I know not to keep the brakes on, and we did one full cool down lap. According to the professionals, this was a direct result of overheating a street compound pad.

smgC32

[QUOTE=RapidG]Deposits are actually the brake pad freezing to the rotor when the rotor is hot from racing. This isn't a function of the pad material. You can avoid this with any pads by keeping your foot off the brake after you pull off the track and stop, otherwise the pad welds to the hot rotor, and pieces pull off when you release the brake. It's a hard habit to break. Stop the car and immediately release the brake pressure.

The tracks you are driving at are either easy on brakes or you are not driving fast enough and your lap times could be better

Your pad deposit statement is not true in most racing situations. Pad deposits are beneficial if they are consistant and the pads and rotors are bedded in properly, which produce such a deposit condition. My pads loose most material during street driving. I re-bed them each track event and get a good layer on the rotor. After a day at the track there is consistant pad material on the rotor. I don't have any fade or shudder under heavy braking and the brakes work as they are supposed to. The hotter they get, the better they brake.

Pads don't "freeze". What you are referring to IS a transfer of pad material on the rotors surface. And yes, it is very important that you don't keep your foot on the pedal when the car is not in motion when the pads/rotors are hot. This is why you don't keep your foot on the brakes when back in the pits, and why you don't apply the emergency brake in the pits after returning from a track session. If you do, as you described, the pad material will "melt" onto the rotor in the area in which the pads come in contact with its surface. You can see this quite visably by a distinct outline of the pad on the rotor. This will cause an uneven deposit of material on the rotor, causing vibration and shudder, and will cause possible warping of the rotor if it is quite thin and under specification for thickness, which will also cause shudder. Deposits are the culprit 99% of the time for this shudder.

Zeppelin

A couple of 10 cent washers per side

nukblazi

Oldest trick in the book!

Zeppelin

Cheapest too My whole car is put together with washers and duct tape

nukblazi

I was going to do if I found no other means but speedybenz is going to be working on some camber/caster plates for w203. I am sending him measurements and info once the snow clears here and I get the chance to install my KW V2s.