MikeFleischer

C6 Setup questions

OK I have had my C6 on track for the 1st time. I did not do much with it before hand other than tech it, brake flush, pads, and ducts...

My Impressions:

Engine: Ran up to 265 oil temps but it cooled down fast, Good power, but the Z06's and ZR1's just eat you alive on the straights (and in the turns too )

Trans: Very nice, smoother shifting than my C5Z

Tires:
GY EMT Runflats (non F1) are super sensitive to tire pressure. I ran too high all day Monday (cold 31 all around), and the tail just wanted to walk out all day. I lowered it to cold 28 and it was fine until some heat got into them and then it started to wiggle more. I think dropping down to 26 probably would have worked a bit better, but that is quite low. The EMT's are terrible on the track, my first purchase for track setup will be some wheels and decent tires!

Brakes:
Ran OEM Z51 pads, showed up with 85% pads all around, replaced the fronts Tuesday morning (thanks Jon for taking my student for a session and Thanks Short Throw for letting me borrow the tools that impact drill made all the difference, I am going to pick one of those babies up ASAP!) rears have ~70% still, new fronts still look new (2 sessions). OEM pads grip well, but it seems like my braking is much earlier, a faster input to the brakes really does not help them grab, and a slow steady approach worked much better... Need to work on my style there a lot, my M3 would let you get on the binders much more quickly and they grabbed right away. That also may be directly related to the tires sucking though so I need to sort that first I think before I try some DTC 70s or PFC 01's. Ducts saved the rotors, fronts showing barely any spiderwebs which is great for X-drilled! Rear rotors are fine.

Here are my questions:

1. What Alignment setup works best for occasional track/street driving? F/R toe? F/R Camber? F/R Castor (is that adjustable?)?

2. Brakes: Anything to be done to firm up the pedal feel and get a more solid threshold braking feel? On the street they are fine, on the track the pedal sinks quite a bit as you go deep into a turn? Anyone have tips? Would like a more solid pedal feel if possible.

3. Steering: A bit numb steering feel, anyone have advice on that? The steering is OK, but it could be better I think.

4. Tires: What size wheels/tires will fit a standard C6? Hw much upsizing can be done on the stock rims? EG Can I got to a 275 front, 295 rear? What sizes work. I think I will get something other than the GY EMT tires for the street and another set later for dedicated track use after I have some harnesses/bar or half cage... What tires work best? The ZR1's used Michelin Pilot Sport 2's and they seemed to stick really well, pricey but maybe the best street option?

OK awaiting the sage advice of the many very fast folks on this list

OCCOMSRAZOR

Though not one of the "very fast folks" I do have some experience with C6 track car.

I'll limit my comments to brakes.

For an occasional HPDE car, the Z51 brakes are quite adequate, however, there are three relatively easy (and inexpensive) things to improve brake "feel" and performance.

1. Upgrade your brakelines to braided stainless steel. This will improve brake pedal "feel" by eliminating the flexing and expansion that factory rubber lines experience when things get hot.

2. Change your brake fluid to a DOT 4, like Motul RBF 600 or other similar brand. This will significantly reduce the chance of your brake fluid "boiling" as things heat up.

3. Change your brake pads, or get a second set for track days. I think the best bang for the buck is to get some C5 Z06 factory pads. They fit the C6 calipers. These pads work very well in most HPDE applications and are relatively inexpensive.

If you feel you need more braking, you might consider a Cobalt GTS pad or another one of the many pads available that are made for HPDE or track use.

It is very easy to swap pads yourself. However, when you do, plan the swap so you can get the new pads properly bedded before you hit the track. If I am swapping pads, I do it the day before the event so I can properly bed them and then let them cool down sufficiently.

One note concerning safety:

Get in the habit of inspecting your rotors for small cracks that can develop between the drilled holes. If you see ANY cracking, don't run your car on the track until you get them replaced. Otherwise, you risk a catastrophic failure.

See you at the track!

MikeFleischer

Someone at RA mentioned high temp OEM brake line failures (Frank Gonalez maybe?) happening (the hose clamp heats up enough to cause a failure) it fortunately happened on the street at low speed, not on the track from what I recall so SS brake lines do make sense.

(fluid was changed to ATE Blue, if I boil it I will flush with Gold, and repeat, the color change is nice though the blue will stain the reservoir blue a bit!)

Great comments: Anyone want to chime in on Alignment?

Bulitt

Wow, you got the bug fast!
Put some Z51 swaybars on (183$ from Gene Culley) and Pfadt poly sway bushings for the Z51 sways @30 $

LS3FORME

Lose the factory pads, go to hawks hp plus or better, I have heard som guy go to pfc 01 not too rotor friendly, or dtc or ht-10s. I would go to the R888 in 295/30/19 rear and 255/35/18 front fit on stock rims. Add caster and someone from pfadt posted setup variations-street/agressive/track.

I tracked my new 08 z51 mn6 npp, and felt alot of the same, brake fad, tire gripp not that great, the f1s are a little better 220 tread wear. The bars should help but going to a z51 bar go to aftermarket. I think my next suspension upgrade would be the coilovers, or bilstein short body sports, hardbar lowr bolts if not coilovers, and a larger front bar. The car has some body roll.

MikeFleischer

OK the car is a Z51... And Sorry if I made it sound like that was my 1st track event, that was my first one in my C6... No idea how many DE's I have been to, in hindsight I should keep a log book...

So not getting the bug quickly, had it all along

I dropped the car to the stops at all 4 corners, before I screw around changing anything I want to go with a decent alignment, I found some notes from my old Vette (C5Z) (and a dyno sheet, that thing made 360 rwhp stock!) where I ran -1.5 and -1 camber F and R, and 1/8th toe out front and 1/8th toe in rear, with 2.5 of caster up front? Any of that sound like sane settings for a C6 also? The toe out up front has me perplexed a bit...

Also any shops in the North of Chicago area that can do a decent alignment?

C6400hp

I like my alignment at about -1.25 front camber 1/32" to 1/16" toe out any more and you will get a mid corner push. as much caster as you can get ~7.75 with the above settings.
-1 or so rear camber with 1/16" to 1/8" toe in. Definitely get some R888 or RA1. Check the manual on how low you can go before affecting the factory geometry, you are probably too low if you are all the way down on the stops. the service manual shows the proper points to measure from.

0Vector Vette

Mike,
1. Street/track alignment is a tricky issue, what is best for one is not so good for the other. More camber is great at the track but will wear out tires on the street. I would suggest a Pfadt camber kit and learning how to change it yourself. Same with toe, at the track you want a little toe out in front (3mm), toe in in rear (0 to 2mm). However, tow out in front will make your front end darty on the street. This is also something you can learn to do yourself.

2. Stainless steel brake lines a must. Racing brake fluid like Motul or comperable a must. No rotors with holes in them. Cobalt Friction brake pads are the best pads out there. Once you try them, you will never use anybody else's pads.

3. A little toe out will help the car turn in better but again, not what you want while cruising down the interstate.

4. I just put a set of Michelin Pilot sports on my C5 street car and am very pleased with them. I didn't get the emt's so will hope for no flats. If you are going the dedicated track wheel/tire route, Hoosier R6 are hard to beat.

I have SS brake lines, Cobalt Friction brake pads, 2 piece rotors, Pfadt camber kit and sway bars, brake fluid in stock. I can also setup your car and show you what you need to do to change it yourself if you want to go that route. My shop is in Aurora, give me a call at 630-844-0089.
Robert Finlayson
Performance AFX Motorsports

Bulitt

I also thought the body roll on my 08 Z51 was excessive. i went with the Pfadt poly sway bushings and replaced the rear spring with a Z06 spring bought from a supporting vendor for 135$ shipped. Put a set of bilstein sports on which I picked up on the forum for 250$ shipped. Also been adjusting the tire pressures and I can say the car handles night and day different. May not be ideal for drag racing but the cornering is awesome. Next step would be coilovers which I have seen on the forum selling for as low as 1200$ used. But I am happy with my 400$ improvement. I am not seeing oversteer some suggest would occur.

Seems to me the Z06 being the legacy car, that Chevy left much on the table with the Z51 so it would not compete with the Z06 intentionally. But the parts to upgrade are so frickin cheap on the forum- You gotta love this forum !

EvilBoffin

Agree totally with C6400HP. The settings he suggests are really close to what David Farmer applied to my '08 C6Z51, though I opted for the more aggressive side, including -2.0 camber in front.

David spends a lot of time getting the suspension symmetry, thrust angle, chassis rake and corner weighting correct first. Only then does he concentrate on the caster/camber/toe settings. He also warns that over-lowering a street-drivable C6 can indeed degrade it's suspension geometry and travel on the track.

The point is: a really thorough alignment can make a HUGE difference in the feel and handling of an otherwise stock car, before you throw a bunch of money & parts at the problem. But you probably already knew that...

I'm running :
- 275f / 305r RA1's on CCW wheels for DE's
- stock F1 Supercars on the street
- just ordered Hoosier A6's for autocross - 285 front/315 rear on stock wheels

Yes -the front 285's DO fit just fine - no rubbing or weird handling (at least with my -2.0 degrees of camber). I tried it, and have pics to prove it. When the 315's get here next week, I'll test-fit them and report back about fitment and any rubbing issues (if you'd like).

I intend to keep this alignment the same - even on the street (camber kits aren't allowed in my auto-x class). I realize this is a compromise setup for all these conditions, but the car is completely stable and drivable on the street. As this is my first Corvette, the setup will certainly need some tweaking over time, but it's served me well so far at several DE's and 7 autocrosses.

As for brakes, I experienced NO fade (neither pad fade or fluid fade) in 4 days at VIR. But that was using REAL track pads (Wilwood H's) and Motul 600 fluid. I did go through a pair of cheapie front rotors, but I was driving quite hard during most sessions, and the Wilwood's are not known as very rotor-friendly pads. So, I guess that's nothing new there.

However, these pads DO feel MUCH better on-track compared to stock pads. Much more initial bite and torque. Excellent modulation & release, too. I was amazed how great they feel, even when they're dead cold when driving to the events. That's what a real track pad can do for you. I've heard that the Cobalts feel very similar, though with even better linearity. I'd like to try a set of those when my Willie's wear out...

Hope that helps...

AU N EGL

and have fun

waktasz

They will definitely fit. In fact, the taller 295/40-17 and 315/35-18 Kumho v710 fit just fine too.

wtknght1

There's absolutely nothing wrong with running rotors with the stress/heat cracks between the holes. I've raced on mine all year long and they look like a spider web. You don't need to replace them until they crack all the way to the outer edge (you'll hear a "ting" when one of them cracks while they are cooling down). I will say that the C6 rotors last much longer than the C5 versions. I'm racing on the Z51 rotors with the cross drilling and they are doing really well so far. I've replaced my fronts every 2 events for optimum braking, but I'm still running on my original set of rears. None of them have ever cracked all the way thru yet, so i'm keeping them to run test days. Keep pounding on them baby!!!!!

tmak26b

Been there done that on my last car, just get into the habit of changing the brake lines often if you do want to stick with the stock one. http://www.youtube.com/watch?v=eneQcrYvMt4

I personally dont like SS lines because I lose feel to the pedal, also I have to run in stock class for autox. I now just change it once every 5 track days. I will change mine during the winter as i will have about 5 track days and 20 autox on it.

MikeFleischer

OK

Expect a call from me sometime next week

Mike