help with next mods to buy for auto x

[Kaldar142]

^ i LOVED my DTC70s...

 

[Vapour Trails]

With regard to hiding errors with sticky tires; I asked some of the best drivers at my local club what I should run now that I have more power and their response was R-comps, anything less would be nothing short of extremely frustrating.

 

[Sam Strano]

Coil-overs have 3 uses.

1. Pick your own ride height
2. Pick your own rates
3. Corner balance the car

Most folks opt for coil-overs for reason #1 unless they are hardcore racers. I am one of those, not sure the OP is. That said, if a set of springs offers good working rates and heights and the car has good corner balance--a set of "springs" will work very, very, very well indeed.

If someone is inclined or has the need to change rates, that's great and they should have some sort of coil-over. But if they opt for one without a useful damping adjustment they are leaving a huge amount on the table. Personally I feel the damping adjustment is much more critical to how the car works than tweaking 25 pounds of rate here or there. And if any big change in rate is made the dampers have to be able to compensate for the added spring rate which non-adjustables cannot do.

When I setup cars I don't make many changes for sites. In fact I am kind of known for my stuff working everywhere. Where many others change springs, bars, height etc, for this site or that, I don't have too--and win on all those various surfaces. We run on surfaces as diverse as glass smooth race-track asphalt to completely pock-marked, have to patch is with quick drying patch concrete and everything between. Sealed asphalt. New concrete ramps @ International airports, parking lots @ NFL stadiums, you name it we run on it.

Some are tweakers, some aren't. I haven't found a car yet I haven't been able to make work well on all surfaces with a basis singular setup. That could be why I'm not as hell-bent on coil-overs in all cases (even maybe my own).

Rotors: 2 piece rotors aren't cheap. 1 pieces are, but 2 pieces are much less prone to warping because they ring is not integral with the hub. We all know that you shouldn't overtorque wheels because it can warp rotors, well that gets worse when you add a lot of heat. Having a aluminum hat sort of separate (they are bolted together, so not entirely so) is helpful in reducing warping because stresses that go into the hub/hat aren't transferred to the rotor ring like on a 1-piece rotor.

I recommend HT-10 front/HP Plus rear are a starting track setup. Then we move to what you have DTC60/HT-10, and ultimately to DTC70/60 front and rear. FWIW, I carry all those, so when you need some--let me know.

 

[RedMosesSC]

There are a lot of heavy hitters chiming in and giving advice, all of it is good but some might be a lot to chew. I am no AutoX expert but i have been doing it for 2 seasons since i got my S197, much like Sam Strano i dont like to tweak things too much but rather learn to drive your car on different coarses with the same set up, as you become more advanced you can get the "hard core" parts and tweak but its most important to get seat time and learn your car, every time you add something to your set up, you have to learn how to drive your car again.

My latest addition to the car had the biggest impact on my Autox driving, i got a great deal on some Brembo GT500 brakes, can be purchased used for well under a $1,000 and the difference is HUGE over stock brakes. Auto cross heats tend to be short, so spending 3 grand on brakes that are made to resist open track heat fatigue is an over kill at this point. The Brembo kit will almsot double your stopping power and allow you to brake way later and give you more confidence going into the turn to get the lines you want. When i 1st put on the brakes, my opening run for the day was 65 sec by the end of the day i got it down to 58 seconds, some of it was me correcting mistakes but a lot of it was the brakes allowing me to point the car in the right direction.

In regards to Tires, i like to run the tires i drive on the street with(All Season Micheline XGT 4), as much as R comps would help, street tires are less forgiving and force you to drive the car with correct grammer, they are easier to throw of balance but as stated earlier they allow alot more feedback audibly so you can tell where your tires are at in regards to their point of faliure. Keeping your car in balance and poised is difficult to learn as the tendency it to turn abruptly, R Comps tires will mask poor technique. I started out with stock tires, moving to wider 275-40's made a big difference, the lower profile in particular as well as the width and just better tire quality.

I swapped all my suspension parts at one time but i did run an entire season on stock suspension and the difference is huge! most notable is the reduction of "brake dive", i went with Steeda Sport springs and i am very happy with them. Although many "hard core" guys knock on Tokico D-Specs i find them to be very usefull, since every surface id different they will allow you a small amount of tweaking to keep you car balanced depending on your driving style. Yeah you dont have "True" compression and rebound setting but i think they are good enough to get the job done without breaking the bank on a griggs set up.

Hope that helps, keep us posted as to what parts you have chosen and how they feel on the track!

 

[SoundGuyDave]

Sam: Beautiful writeup! Everything said was 100% on the money, and cogently described. I still think that the 2-piece rotors bear some serious thinking about prior to committing, though. How many friction rings do you go through during a season? That expense adds up quite a bit.

RedMoses: I agree that the Brembo GT500 package is a significant upgrade in the braking department, HOWEVER, I have to take technical issue with you on one point... Assuming all other things being equal, tires are the limiting factor on braking performance. The larger rotor diameter of the GT500 kit allows for a larger radiating mass, which results in less net heat uptake, but that only means that you can brake hard longer prior to heat-soaking the brakes.

The stock OE brakes, even with OE pads, are perfectly capable of getting into the ABS in the dry. The Brembo package also gets you there, so there is no appreciable net reduction in braking distance. That said, however, there IS a significant difference in pedal feel, and longevity. Coupled with serious track pads, the Brembo kit will be able to be driven harder for more laps before the heat does them in than the stock kit, and as a result, that will have an impact on driver confidence. You can't actually brake later with the Brembos, or any harder, but the perception of "reserve" left in the braking package lets you THINK that you can, and as a result, you do. Right now, I brake hard enough on road courses that the back end starts to wiggle from being light. I know that it's a spring rate issue, but that still implies significant braking forces to generate that much transfer. That's on stock brakes. Next season will be on the Brembos up front.

I'm also one of those that has no problem with the D-Specs. They're fine for what they are, and they served me well for a couple of solid seasons before I broke one... Since I want to go to coilovers (for all three reasons Sam mentioned!) anyway, that puts me right into the Koni adjustables, which should be just fine for what I want them to do.

Going to be a busy winter!!

 

[Random Asshole]

LOL
Nah not drag slicks, were can I find the rotorpros?

look up the ebay store

Brakes: Powerslots, Rotorpros, whatever is all good, but to be honest, I run very aggressive race compound pads, and the best bang-for-the-buck out there is a set of take-off rotors from Newtakeoff.com. They cost me less, delivered, than it costs to get a set of rotors machined... You'll be surprised at how fast you go through brakes. I'm averageing between two and three sets of rotors and pads up front, and one to two in the rear, each season... Our cars are pig-heavy, and it takes a LOT of work to get them to slow down. As for ducts, I honestly don't know how much effect you'll get in an autocross setting, but if you're on the road-course, they REALLY do offer significant benefit to brake longevity. I would budget to have them on the car for your second event, if not your first...

Where are you getting your rotors cut? I pay 20 bucks

..rotors aren't the issue, but if you were going to upgrade I'd have skipped the rears, and gone to 2 piece fronts to save a lot of unsprung and rotational mass, and upgraded the pads as well. To what depends on the use. Hawk HPS and HP Plus are NOT track pads. Fine for autox, but this is one place the two are very different.

+

I go through three sets of rotors a season, at least, and the cost differential there would make it less than attractive to go to the two-piece rotor.

I'm totally with you with the keeping things priced low, but I was cutting my stockers after EVERY event. That shit gets old. The only time I even touched my front brakes the entire season was when I finally cracked a front during the 5th out of sixth time attack + three HPDE events as well. Newtakeoff rotors are 39 bucks plus 27 for shipping to me. Multiply that by 3 sets and it comes to 200 bucks.

Wouldn't you guys rather just pay 280 bucks for a FULL set of rotorpros and not have to switch out rotors all the time?

 

[SoundGuyDave]

I pay about the same to have them cleaned up, but it wasn't long before I figured out that I'm not getting pad deposits or warping the hub section, I'm heat-checking the rotors which alters the hardness in random areas, resulting in uneven pad deposits, not to mention compromised integrity. I finally just scheduled the replacement every four or five track days, and ordered the rotors in bulk. I paid no additional shipping, since I had several sets delivered with my trans, which came on a pallet.

For 2010, I'm going to be running Brembo fronts, so we'll see how that pans out.

Got nothing against Rotorpros, just the deal on the stockers was too good for me. I bleed my brakes daily at the track, flush twice a season (when I replace pads), and swap rotors every time I do an oil change. Since I started that program, with the Hawk pads, I've had no brake drama at all, excepting one Napa rear rotor that I cracked all the way through.

 

[Sleeper_08]

..............Right now, I brake hard enough on road courses that the back end starts to wiggle from being light.

Ths is the first mention I've seen from anyone else of this issue. I have the same problem at Mosport pulling down from 135 + to about 90 for turn 8. I'm running the Brembo kit on the front and HP Plus pads front and rear. At these speeds do you think it is partly due to aero lift?

Next season I'm thinking of going HT-10 on the fronts and HP Plus on the rear to see if this helps. What are your thoughts.

 

[SoundGuyDave]

Ths is the first mention I've seen from anyone else of this issue. I have the same problem at Mosport pulling down from 135 + to about 90 for turn 8. I'm running the Brembo kit on the front and HP Plus pads front and rear. At these speeds do you think it is partly due to aero lift?

Nope, too soft a spring rate. Speeds vary, but usually I can find this in the 85+MPH braking zones into slower corners, where you really start to transfer weight around. With stiffer springs, it would help combat some of the nose-dive that I get under heavy braking. The easier braking zones, either out of slow straights, or into fast corners, won't cause as much transfer, and thus more rear weight. I'll admit, it does get a bit disconcerting at times. I'll try to post a vid clip of what I'm talking about.

Next season I'm thinking of going HT-10 on the fronts and HP Plus on the rear to see if this helps. What are your thoughts.

Honestly, I would step up the brake pads quite a bit. I usually recommend HT10/HP+ for novice drivers out on their first weekend or two. I wouldn't hesitate to recommend any of the following three packages: Carbotech XP12/XP10, Hawk DTC-60/HT-10 or DTC-70/DTC-60. It'll take a few corners for the heat to come in, but after that, you'll be braking like a fiend. They will offer a HUGE improvement over the HP+ in terms of fade resistance, particularly if coupled with some "real" fluid, like Motul RBF600, ATE Super-Gold (blue stains the plastic reservoir), or the Castrol XRF. Also, if you don't have cooling ducts, order them tomorrow. The difference is really that big with and without.

 

[SoundGuyDave]

Here's a quick vid of what I'm experiencing with my FAR too soft springs...



For sense of scale, the shift to fourth gear around the flag stand is about 102MPH. Hoosier R6 tires, DTC-60 front (ducted) and HT-10 rears.

 

[Sam Strano]

Respectfully disagree it's a spring issue. More shock rebound would slow the dive (which is actually more lift in the rear). And if you watch say a Nextel Cup car, which is most similar in size and weight to our cars, you'll see they do the same thing on short tracks or road courses when braking hard.

The other thing that matters is the rear suspension setup. I doesn't have a lot of anti-lift in it, so it wants to come up when hard on the brakes.

Bottom line, is while springs might help a little, the car will still be wiggly on the brakes because you are standing on the brakes, and it just gets light from the geometry of the rear suspension. If you play around with rear arm angles you can change the anti-squat/anti-lift of the rear suspension.

But from what I see in Dave's video--I'd try more rebound damping in the back to slow the transfer to the front.

And fwiw, if you guys look at pictures of cars stopping hard, you will see exactly what I'm talking about. The front is not slammed down so much as the rear is hiked way up in the air (just look at the wheel well gaps, that'll make the case).

 

[Jaylee]

Anyone know of a way to upgrade to 4 piston calipers without increasing rotor size? I am limited on brake upgrades by my wheels. I would like 4 pistons on all 4 corners.

 

[SoundGuyDave]

Griggs 4-on-4 kit is the only one that I think will fit your requirements. That said, unless you have a set of Jongbloed wheels or something like that, it may be cheaper to change out the wheels to clear a "standard" BBK...

 

[Jaylee]

That is what I am afraid of. Thanks for your help.