Chassis stiffeners

[JusticePete]

Originally Posted by White_SS/RS

you'll quickly find out that the looseness you feel on the street is not there on the track with the tires warm. Car definitely needs Pedders 1le permagrin kit with a good aggressive alignment.

Hey Pete, what tire pressure shoud i start out with? I ran 44psi cold. any lower and it started chewing up the outside edge. I'm running stock suspension at the moment.

Road course or autocross?

[White_SS/RS]

Originally Posted by JusticePete

Road course or autocross?

Road course.

[JusticePete]

Originally Posted by White_SS/RS

Road course.

What are your pressures when you come off the track?

[White_SS/RS]

Originally Posted by JusticePete

What are your pressures when you come off the track?

If I remember correctly they were about 47psi. Honestly they were all over the place since the track works the right side much harder then the left but I'd say 47 is about average.

[JusticePete]

Originally Posted by White_SS/RS

If I remember correctly they were about 47psi. Honestly they were all over the place since the track works the right side much harder then the left but I'd say 47 is about average.

Typically we start out at 32 to 34 pounds cold and keep them at 40 to 42 pounds hot. It sounds like you don't have enough negative camber. Do you know what your alignment specs are?

[White_SS/RS]

Originally Posted by JusticePete

Typically we start out at 32 to 34 pounds cold and keep them at 40 to 42 pounds hot. It sounds like you don't have enough negative camber. Do you know what your alignment specs are?

Not specifically,.. whatever the factory set them toThis is the first time I had the new car on the track. Mostly wanted to get a baseline on the car and didn't have much time to do anything but change the fluids before the end of the season. The tire pressure/wear was one of the few things I need to address along with a rear sway upgrade and 5 point seat belts. I do have plans on getting a good alignment done, probably the aggressive street alignment that you mentioned above. Maybe with a little more camber if I can make the tires survive on the street.

[Fraxum]

In my humble opinion why would you want to add more weight to an already heavy car? Part of this weight is due to chassis stiffness already there. Get the most out of the existing chassis with bushings, sway bars and coil overs. If you want to build a 1,000 HP monster then yea, some frame strengtheners might help hold the car together. But at sane HP levels what do you want to do? Run 10s in the drags or challenge Z06s on a road course? Neither of these goals will require a stronger frame.

I did full bushings on my '11 and it felt light years better over stock, even tighter then my 1LE. Do I want my '11 back? No way, the 1LE is my dream car. But will I be doing full bushings on my 1lE? For sure, but maybe after paying for all my other mods already on the car.

I have only done 2 bushings so far on my 1LE, Radius rod (Inserts) and Trailing Arm bushings. The wheel hop is almost gone and my steering responsiveness is much improved. All of the vendors say do bushings first and see how that goes. I think that is the best plan.

But the hard part about doing full bushings is that it is probably more than most DIYers want to tackle, me included. So you need someone to do it for you. Most speed shops are much more interested in tunes, FI, and cams. And once you find someone to do it they will charge you an arm and a leg because the job is a PIA. But it can be done and once you do it you will understand what all the vendors are talking about. They are almost all happy to sell you what you want, but they are all giving you good advice about where to start. Listen to the experts.

[Dropspeed]

Originally Posted by White_SS/RS

you'll quickly find out that the looseness you feel on the street is not there on the track with the tires warm. Car definitely needs Pedders 1le permagrin kit with a good aggressive alignment.

Hey Pete, what tire pressure shoud i start out with? I ran 44psi cold. any lower and it started chewing up the outside edge. I'm running stock suspension at the moment.

Not saying is doesn't, but how can you say the car needs anything before you properly align it and adjust your tire pressure correctly?

It depends on track/air temps but I start at 32 usually. My last event I started at 30 as it was a warm/hot day. I found that anything above 40 is like driving on ice. (Not really, but you get the point) I ran my fastest laps last time out at about 38psi.

A 4000 lb car is going to wreck havoc on the tires. I just replaced mine with 4 events and 6800 miles. I am running -1.6 front and -1.3 rr camber. The right side tires were slick on the outside edges but also worn evenly across. Unfortunately you have to pay to play with 4000lbs of track car.

Matt

[Exigent]

If you are just starting out on road courses there are 3 important items:
1. Alignment as many have already pointed out. A proper alignment will allow the car to handle better and will help with tire wear .
2. Tire pressures, monitor them before and after each session - it matters.
3. Driver training is where you should invest your $, that's where the gains are made.

[White_SS/RS]

Originally Posted by Dropspeed

Not saying is doesn't, but how can you say the car needs anything before you properly align it and adjust your tire pressure correctly?

It depends on track/air temps but I start at 32 usually. My last event I started at 30 as it was a warm/hot day. I found that anything above 40 is like driving on ice. (Not really, but you get the point) I ran my fastest laps last time out at about 38psi.

A 4000 lb car is going to wreck havoc on the tires. I just replaced mine with 4 events and 6800 miles. I am running -1.6 front and -1.3 rr camber. The right side tires were slick on the outside edges but also worn evenly across. Unfortunately you have to pay to play with 4000lbs of track car.

Matt

Originally Posted by Exigent

If you are just starting out on road courses there are 3 important items:
1. Alignment as many have already pointed out. A proper alignment will allow the car to handle better and will help with tire wear .
2. Tire pressures, monitor them before and after each session - it matters.
3. Driver training is where you should invest your $, that's where the gains are made.

I appreciate your guys' imput and i agree with you. Ive been racing for many years,and this is my 2nd gen 5 so i have a pretty good idea of where to start. My first ss i did the alignment and yeah it helps but it desperatly needed sways.the best alignment in the world wouldn't get rid of the understeer. With my 1le i wanted to see how much better gm made it over the ss and i found out. In fact i started with 44psi because it was 50* that day. I dropped my pressures down to eventually run about 40 when hot and thats when it really started chewing the tire up. My lap times stayed consistant with either pressure and was getting petes insight for a starting point.

So 1.6 front and 1.3 works good? How is the street wear?

[JusticePete]

Originally Posted by White_SS/RS

I appreciate your guys' imput and i agree with you. Ive been racing for many years,and this is my 2nd gen 5 so i have a pretty good idea of where to start. My first ss i did the alignment and yeah it helps but it desperatly needed sways.the best alignment in the world wouldn't get rid of the understeer. With my 1le i wanted to see how much better gm made it over the ss and i found out. In fact i started with 44psi because it was 50* that day. I dropped my pressures down to eventually run about 40 when hot and thats when it really started chewing the tire up. My lap times stayed consistant with either pressure and was getting petes insight for a starting point.

So 1.6 front and 1.3 works good? How is the street wear?

The difference between -1.6 and -1 is probably 10 to 15% more inside shoulder wear up front and marginal in the rear. However, depending on how often you track the answer may be no difference. A couple of track days a year should even out the wear patterns.

Look for a deal on a pyrometer. When you come off the track get tep for the outside shoulder, center and insider shoulders along with tire pressures. With that data logged by track we can adjust TPs and alignments

[White_SS/RS]

Originally Posted by JusticePete

The difference between -1.6 and -1 is probably 10 to 15% more inside shoulder wear up front and marginal in the rear. However, depending on how often you track the answer may be no difference. A couple of track days a year should even out the wear patterns.

Look for a deal on a pyrometer. When you come off the track get tep for the outside shoulder, center and insider shoulders along with tire pressures. With that data logged by track we can adjust TPs and alignments

Thanks i have a pyrometer. I'll start with 1.6 front and see what im looking at. Wont be back to the track until spring.

[b4z]

Back in the '90s GM used to advertise the stiffness of its vehicles by using a Hz rating. I guess at what frequency the structure starting vibrating. The higher the Hz the stiffer it was. I wish GM still did this. I had 4 third gens and my 87 IROC was wet noodle rolling down the hwy. shit drove me crazy.

[JusticePete]

Originally Posted by b4z

Back in the '90s GM used to advertise the stiffness of its vehicles by using a Hz rating. I guess at what frequency the structure starting vibrating. The higher the Hz the stiffer it was. I wish GM still did this. I had 4 third gens and my 87 IROC was wet noodle rolling down the hwy. shit drove me crazy.

That is a standard measurement for all MFGs and still in use. You'll see it pop up occasionally when a new vehicle is released. When the 5th Gen was introduced the CTS was the highest rated sedan in the GM line up and in the rare air industry wide. The 5th Gen ranked with the CTS.