kwhiteside

Thinking about stiffening things up.

I've heard a couple guys rave about their Pfatty sways at the track.

The best handling C5 I've ever rode in (FredTurner) had T1 suspension with 315/18's on all 4.

I currently have Z06/ Bilstien sports shocks and am running 275/17f 335/17r and struggle with the understeer push.

I'm waiting for John Bergot to call back with a set of 315/18 R6 scrubs and then I'll order the 4 18X10.5 ZO6 wheels from another lead I was given. I'm guessing that the square tire wheel change will make my car go from slight understeer to very much oversteer loose rear end, and that the stiff sway bar is necessary to make the square setup just right. I'm stating this without experience, but from reading multiple articles that state the T1 sway upgrade will create more understeer due the big front bar.

Ken . . .

redtopz

I have T1 bars and usually have been running a slightly smaller front tire than rear tire. My car is pretty neutral right now. Based on what you are saying, I would go with the pfadt street bars or T1 bars. The street bars are adjustable front and rear but are not stiffer than T1 bars. The Pfadt comp bars are really stiff, I think double the T1 bars. You can adjust the T1 rear bar to adjust for understeer also.

Here is a link to a sway bar chart by Pfadt that is worth a thousand words:
http://www.pfadtracing.com/photos/da...ph_with_SS.jpg

wtknght1

You're going to have a push running 275s up front with 335s in back...especially on a C5...no question about it. The 315 square or 315/335 combo is much better.

The T1 kit as a whole is terrific and designed by John Heinricy...nuff said on his accomplishments.

Trust me though, no matter which kit you get, setting it up correctly is the key - correct ride height, shock settings, camber, cornerweighting, zeroing the sway bars, etc, etc all play a big part in how well the car handles. Take it to a pro shop and get it set up well and get some testing time to fine tune everything.

I've said this before and will say it again: A Corvette with a well set up T1 kit, and an experienced driver behind the wheel is a potent combination that does just about everything well...and balanced.

SIK02SS

315/17x4 on my T1 vette feels very neutral. I've ran 295/315 and i didn't care for it much, a bit more push then i wanted. But a lot of guys switch between the 295/315 fronts for different tracks

drivinhard

I run square for tires/wheels, the original non adjustable T1 rear bar the car was a tick loose off the corners under power. I've got Khoi's old adj rear T1 now, and with it on the outside (softest) setting, it's just about perfect on balance. My cross weights are nearly even.

Some of the Pfadt front bars will interfere with brake cooling ducts to, so check on that.

kwhiteside

Ok, so I'm thinking GM T1 Sways with these LG Links that are supposed to be adjustable and quiet. (my 2001 car still has the plastic end links )

http://www.lgmotorsports.com/catalog...c01dbbfc674bfc

Question for Mark and SIK02SS, are the 315 square R6 tires going to rub in the front?

I'm feeling a little paranoid of the change as I'm sure I've adapted my style to the push. My rear rarely comes out and I know it. Now I'm probably spoiled. I suppose I'll adapt and figure it out though.

What I really look forward to is how the stiffness puts your car on rails for turns like #12 and #1 at Road Atlanta, or Turn #2 at Roebling Road. Those high speed sweepers seem totally different when your car isn't leaning the whole time.

drivinhard

davidfarmer

both are very good. If you want to "set it and forget it", or don't like making adjustments, then T1 is the way to go. If you are up to constant tweaking, then the Pfadt bars offer a ton of adjustability (possibly too much for most of us) and may ultimately give you better performance. However, extremely adjustable parts (bars, 3-way shocks, etc) take lots of time to dial in, so unless you really want to spend several days experimenting, it is unlikely you'll ever dial in the Pfadts to their perfect setup for your car.

gkmccready

Just because something is adjustable doesn't mean you need to adjust it...

RAFTRACER

gkmccready

Am I the only one that likes a tick of understeer that I can balance with the throttle? :-)

6SPEEDZ

I run the T1 bars with a 275 square setup and it is easy to drive after getting used to it. I also had both Andy Pilgrim drive my car and he said it was very balanced. I have limited experiance driving the Pfadt bars on a friend's C6 and I believe that they have a great potential when adjusted properly.

fatbillybob

Just for another data point....When I bought my T1 bars they came with the monoball endlinks. The package was about 850 bucks new from a gm dealer about 2 years ago. Also, a hoosier rep said the 295 17 was designed to fit for the porkers who had to race with a spec wheel width. I guess that means that specific tire is cantalever design. Anyway, By luck that 295 17 is perfect for our C5Z stock wheels. So you can run a square 295 17 front and 295 18 rear. I have done this and it works perfectly. Even more amazingly as Chris said some T1 guys are running the 315 17 on the 17x10" wheel which is really too small a wheel per hoosier but seems to work OK on the track. I have done that too and surprisingly mounting that wide 315 on a 10" was easy even with my meager skills and cheap Hunter tire mount machine.

froggy47

A question for the guys that run 315 fronts.

I tried it once and had a small rub on the liner. I was full lowered (front) on stock adjusters.

But ride height was thrown way off, negative rake by maybe 1/2 inch.


So the question is what ride height are you guys running who have 315 all around?

I don't think I would do it again, a bit too much front grip.

sperkins

Personally I'd rather have a bit of oversteer. Ploughing through a corner just ticks me off.
I'm with Mark on the rear bar setting and I also run a square tire/wheel set up. I ran the center slot for a while, but with his advice I tried the softer setting and it made things much better - especially on scrubs.

I have 6 if you're interested.

wtknght1

If you're running your car lowered all the way, you have really screwed up the handling of your car. The suspension must travel on these vettes for it to work properly. I cannot stress just how important that is. Have your car professionally set up (ride height, cornerweighted, etc, etc, etc). Right now, all you're doing is riding on the shock bump stops and are essentially getting an infinite spring rate...not good for these cars.

wtknght1

Nope, there's nothing wrong with that at all. Driver comfort is a key element! If you're not comfortable with a loose car, you probably won't be fast for the whole race/session.

Some people can drive a really loose car fast for a lap or two (like in qualifying), but can't be consistent for a whole race. You have to weigh the risk(s), overall lap times, tire wear, and the transistions the car makes throughout the race.

My car, on a low fuel load is fairly loose, so I have my car set up to push a bit on a full tank. During the middle of the race, the car is nearly neutral; but at the end, if I need to hang it out there a little, it's loose enough for me to do that. I also zero my sway bars at half full tank...some prefer to use full, and others prefer empty. Testing, testing, testing...repeat.

kwhiteside

The attached data pretty much makes it clear that I will go from understeer to oversteer when you compare the tire patches. Seems like the T1 sway would be almost necessary for a square setup because it causes a little push. Without the T1 sway a sqaure setup would be very loose in the rear.

I'll be giving up

13.8" rears for 12.5"
11.4" fronts to 12.5"

Looking at the numbers, I'm wondering if a v710 295/17 will hit the full tread patch on a 9.5" wheel. If so, this seems to make more sense to me (all of these are the old rounded style).

295/17 front 12.2"
and either
315/17 rear 12.9"
315/18 rear 12.9"

froggy47

Thanks for the post.

With big bars and adjustments on the shocks I have not had much problem being on bump stops.

You may be familiar with putting a tie wrap on the shock shaft to show if it's travel is near the bump stop limit. I use those & check them.

Bullet camera(s) aimed at the suspension are even better but I can't justify 4 of those.

Check out the ride height on the SCCA solo ASP vettes. Probably an inch lower than I am.

Ride height is easy to change if the track/course is known to have any bad bump sections.

I prefer to do my own setup.

But thanks again, I'm always learning.

drivinhard

if just doing HPDE, take your wheels/wheel sets and just come up with 2 (if you have that many, or just 1 if you don't) square set ups.

ie, a set of 17x9.5's

set of 18x10.5's

put a set of 275/17's on the 9.5s
put a set of 295/18s or 305/18's on the 10.5's

have at it with either set as as square set up