91_5.7_TPI

iTrader: (2)

Has anyone tested their car on the skid pad? And if so, what results have you gotten? I plan to test mine this weekend. I'll post when I know.

blyth18md

I believe dean has tested his car at just over 1 G on street tires. I dont know if any other here will have actual data.

Dewey316

In the skid pad, tires are going to be a HUGE part of what you pull. Dean did something like 1.07g, I don't know what tires he was on though. I would guess that was with Goodyear GSD3's.

I would love to get mine out and test it. What size skid pad are you testing on?

blyth18md

I just pulled up his cardomain. Correct tires and number.

91_5.7_TPI

iTrader: (2)

DAYUM..... 1.07. That is pretty awesome. What mods does he have?
I am thinking about running a 200 ft circle. I have the mods in my sig, and I riding on BGF g-Force Sports. Any idea what I may get?

Dewey316

Since you have pretty descent tires, I would guess you will be in the .94-.96 range.

200ft is pretty much the norm for most skid pad testing.

91_5.7_TPI

iTrader: (2)

I was telling people I was expecting .93s, but I would take .96s. I didn't want to over-state in and have to eat my words later. What would I need to do to my car to get over a 1.0? What tires should I go for?
My Uncle had some GS-D3s on his 96 LT4 Vette. Nice tires. Too pricey for a daily like mine, though.

blyth18md

car pictures and photos at CarDomain.com

91_5.7_TPI

iTrader: (2)

He has alot in there. Those 250 lbs max rear springs...wow. My car needs alot of work.
As for the V6 being lighter than the V8s, would a LS1 (being all aluminum) and a completely tubular front end (k-member and a-arms) get my nose weight down close to the V6? I know it won't be as light, but how much can I expect to loose compared to the stock?

blyth18md

That my friend might be a topic for the engine swap board.

91_5.7_TPI

iTrader: (2)

Sorry. I meant it as suspension related. I am looking for ways to drop my sprung weight without loosing A/C, seats, etc.

blyth18md

Understood, but you might be a more complete answer from the engine swap board, someone with actual data, who has swapped to an LSx might already have numbers for you.

You'll recieve more attention about this topic there

91_5.7_TPI

iTrader: (2)

Ok. I'll try it there. Which would be more heloful in getting me closer to 1.00? SFCs or a set of LCAs and relocation brackets?

Dewey316

The SFCs would. Neither of those are persay "handling" options, as in skid pad numbers. If you really wanted to wow the skid pad, you would slap a set of GOOD tires on for the test, something like a auto-x compound tire.

To maximize the handling, make sure to check tire pressure, and temps, and adjust your alignment, and tire pressure accordingly, to make sure you are taking max. advantage of the handling available in your current combo. Really the skid pad is not a good indication of handling performance, since there is no transition from one direction to the other, or is there the need to accellerate out of the corner. The key to doing well on the skid pad, is driving very smooth, with very small throttle input. And having sticky tires.

91_5.7_TPI

iTrader: (2)

I want a hard G, but slalom speed is more important...isn't it? What would be a good mod to improve my slalom speed...which I plan on testing as well.
Thanks for the skidpad advice, BTW.

Dewey316

Slalom takes a bit more work. You have to balance grip, with transastional stability, along with the balance of the car. Besides of course tires. This is were good shocks (The koni's are good choice, so you have that already), I am not a fan of the pro-kit for something like this, as I do not prefer progressive springs. I like linier springs, I think they are more predictable, and easier to drive at the limit.

Geomitry plays a major part in this. You need to car to be predictable, and easy to transition. For the most part, the key to handling is not in the parts at all. It is in the setup. The reason that guys with tons of parts, make their cars handle well, is because they have the adjustability to make the needed adjustments to balance the car out, and make it easy to drive. I see so many posts asking about what parts... It drives me crazy. Throughing parts at the car, isn't the answer. All the parts in the world, on a poor setup will not handle. Where as a properly set up car, even with many OEM parts, will do very well.

91_5.7_TPI

iTrader: (2)

I like the Pro-Kits over the stockers, but once I started reading on up on springs, I realized (like you said) linear springs are the way to go. Can you recomend a good set? I will probably replace them this spring, if I get the extra cash.
As for setting that car up, what do I need to look at? I know some of things involved are making sure that the springs and shocks/struts are balanced( or matched) and the geometry of the LCAs and the tq arm, etc, but what else should I focus on?

Dewey316

Well, I use the ground-control weight jack kit on my car, then I can use standard 5" race springs. That gives me a lot of flexability in spring rates, and also gives the the adjustability to corner-weight the car.

My best advice, is start reading. Eventualy, you need to learn to tweak and tune the suspension. Read the theory, then start driving, and tweaking. Knowledge really is power when it comes to tweaking suspensions. Small changes can go a long ways. But you need to understand the underlying dynamics of the car, so you know what to tweak, and what it effects.

Souseless

The focus is on improving the driver. Parts are the diversion. For improved corner exit acceleration look into changing the diff. A T2R is the diff of choice for many people me included. Dewey hit most of the highlights but I would like to restate the need for spring balance and Koni's. Also when considering transitional grip a not so common mod is to lower the rear PHB. I will be lowering mine soon so I do not yet have first hand info but it is supposed to be an excellent mod.

Dewey316

When you do this though, you really need to raise the spring rate, and likely look into some sort of revalved shock. When you lower the roll center, you have to raise the spring rate to compensate.

I do agree, it is a good mod.

91_5.7_TPI

iTrader: (2)

You mean with something like this?





I do alot of driving on roads that aren't exactly top notch finishes. Mountain roads, etc. I'm afraid that if I get the springs and shocks/struts too stiff, then the rough, uneven surface will cause me to loose contract pressure on the road. Is this an issue?

Found a page on the T2R. Reading up on those. I didn't realize that differentials were so complex.

blyth18md

http://www.unbalancedengineering.com/Camaro/

Right under the PHR, are the brackets, no photo though. UE's has both a body and a chasis side bracket from what I recall.

Jegs also makes a bracket which Dean runs and seems to be happy with. I also have this bracket, but I wont be able to instal it for a while. I will post feedback once the weather gets to a point where I can start working on the car again.

Dewey316

I am talking something like this...



The thing is, the spring rate you need with the lowered roll-center, will likely be more than even off the shelf koni's can properly handle. When you start talking about this type of geomitry change, you really need to look into a set of custom valved shocks.

You also need to take into account where the front roll center is located. To help determine where your rear should be located. This is all a goal to try to get the car to react more equaly front/rear.

blyth18md

Those are the UE brackets he's running.

Aluminum PHB

91_5.7_TPI

iTrader: (2)

Wow. In that case, I think I will leave it alone for now. I don't have the money to replace the Konis I just installed. Maybe when I am out of college and have some serious money coming in.
How does one go about determining where the roll center is? That sounds painfull

Dewey316

The rear roll center, is the point where the PHB, crosses the axle centerline.

The front is a little more dificult. It is basicly the intersection of the front Instant Centers. Here is a really crappy picture sort of showing it (my MS Paint skills are horrible.) You basicly, the the 90* percidiculare to the upper shock point, and also draw a line following the A-arm. The point where those two lines cross, are the Instant Center for the side of the front supsension. You draw a line from each of those points, back to the center of the contact patch of the tire. Where that line, from each side crosses is the front instant center.



Before you go modifing your roll centers, and geomitry. I really suggest reading about suspension dynamics, so you can understand what modifing these will effect.

91_5.7_TPI

iTrader: (2)

I understand that now. The diagram coupled with the explaination makes perfect sense. I am definatly gonig to do alot of research before I start looking to modifying anything. The goal is to get the front and rear centers lower, but as close to each other as possible??
Where could I find some info on the suspension dynamics so I can start learning this stuff....other than go to tech school. lol Could I find books that would be revelant in a book store or library?
How about the LCA angle? I know it supposed to be close to parrellel to the ground when it is level, or have a slight upwards angle from the back to the front. If I got LCAs and brackets to fix that, would it mess anything else up?
That seems to be something I could do to improve cornering without throwing anything off.

Dewey316

Your local book store should have several. If not amazon has any book you can image.

Here is a very extensive list. The Herb Adams, and Puhn books are probably a good place to start for someone just starting out.

The Milliken Books are like the bible, but it takes a good bit of knowledge to even start to understand all of the data included.

• Race Car Vehicle Dynamics (R146) - William & Douglas Milliken
• Race Car Vehicle Dynamics Workbook (R146) - William & Douglas Milliken, L. Daniel Metz
• An Introduction to the Design and Behavior of Bolted Joints (Mechanical Engineering) - John Bickford
• The Shock Absorber Handbook - John C. Dixon
• Going Faster: Mastering the Art of Race Driving - Carl Lopez
• Tune to Win - Carroll Smith
• Engineer to Win - Carroll Smith
• Nuts, Bolts, and Fasteners and Plumbing Handbook - Carroll Smith
• Drive to Win - Carroll Smith
• Secrets of Solo Racing - Henry A. Watts
• Winning Autocross Solo II Competition - **** Turner and J.B. Miles
• Race Car Chassis: Design and Construction - Forbes Aird
• Aerodynamics for Racing and Performance Cars - Forbes Aird
• Race Car Engineering and Mechanics - Paul Van Valkenburg
• Bob Bondurant on High Performance Driving - Bob Bondurant
• Bob Bondurant on Police and Pursuit Driving - Bob Bondurant
• Chassis Engineering/Chassis Design, Building and Tuning for High Performance Handling - Herb Adams
• Performance Handling/How to Make Your Car Handle: Techniques for the 1990's - Don Alexander
• Think to Win: The New Approach to Fast Driving - Don Alexander
• How to Make Your Car Handle - Fred Puhn
• Fundamentals of Vehicle Dynamics (R114) - Thomas D. Gillespie
• The Unfair Advantage - Mark Donohue with Paul Van Valkenburgh

91_5.7_TPI

iTrader: (2)

for the info and books tittles. Should help tremendously. I'll post up again when I get my skidpad numbers.

Souseless

What needs to increase is wheel rate. Increasing spring rate is one way to get it done, but you can also increase swaybar size. If you max out the swaybar size and keep the front springs around 800# then you can use rear springs around 225# (from Jason at UE). Off the shelf Koni's (yellows) will be fine for that. If you go stiffer it may become necessary to buy revalves. Also It depends on how low you set the bar. The above was for the bar at the lowest setting. You can use one of the other settings and feel some improvement. I guess I better order the brackets and start to prove out the setup that I think I will use.

CheezX

I also hit 1.07G's +/- 0.03 on 285 GS-D3's. It's a great tire, especially compared to the Kumho Ecsta 712's I had. All I have is cut WS6 springs, WS6 swaybars and subframe connectors. The car is about 3250 lbs.

Need to do some real suspension mods and dial it in, the we can really get going.

Hey Dewey, do you have all those books?!?!? I only have 5 of them.

91_5.7_TPI

iTrader: (2)

Well, I used a G-tech today. I think that the numbers are high. An EVO Lancer pulled like a high .9, a 2002 WS6 pulled a 1.00-1.01 and I pulled a 1.05
May not be the correct numbers, but it does show that I can pull harder than them, and that makes me happy. On anonther note, EVOs look freak pulling hard Gs. Their *** end lifts the computer is transfering all the power to the out side wheels. I had the least body roll of all.

Dewey316

Heck no, that is a lot of money into books. I need money to mod the car!

Are you coming down to Brandons in June?

Guest

I was searching around for something and came accross this old post on skid pads and g #'s using a hand held g-tech reader. The hand helds can and usually do spike higher numbers all becuase it relates to where the hand held is positioned in the car up higher in the cockpit. Real g computations are at the tire contact patch.

I had done my test on a skid pad and a stop watch. I do not recall but I ran a 200 ft skidpad in something like 10-11 seconds range and it was computed from there. I would have to search back for my actual results, I had posted them on here a few years ago under some name or another. All the bannings- I just can't keep up with all my old info.

But yes, it was 1.07g's on a left hand run, and 102 ft 60 mph to zero braking test. 0 to 60 mph in 15 mins though.

racing geek

iTrader: (5)

I have a program on my Ipod that measures g-forces and it continuously peaks at ~1.02 lateral g's during the autocross runs. I have it setup on the center counsel between the storage compartment and the power window switches so it is much lower then the window mounted G-tech most use. This would mean my numbers are slightly more accurate correct? I'm still hoping to someday get my car on a skid pad to get real numbers.

For your 1.07 number... aren't you supposed to use an average of the g readings (going clockwise and counterclockwise)?

Anyway, with a car that turns as well as yours did, 0-60 times don't mean much on an autocross course. Just keep the rpm's higher and you'll be fine. A road course or on the street is obviously a completely different scenario.

Guest

I do not know how people officially record g #'s, whether it is the best if one way or a combined. I have never seen info like that posted- I would speculate its the best run achieved. anyways, mine was 1.03 to the right.

As for power in autox/ Don't fool yourself into thinking power doesn't matter. If I had a nickel for every time someone tried to yell me that I would be rich. It does matter! My Camaro out handles my Vette, but my Vette will clean my Camaro's *** on any autox track by generally at least 8 seconds. In other words if I ran the Camaro at 63 seconds, my Vette would be at 55 seconds. I have proof compared to cars I have the same days in comparison to each of my cars on a few different occasions. One in particular is Brain Chemelewski's Vette.

i have run my '68 Vette against his 94 Guldstand coilover Vette as well as my Camaro. I beat him in my Vette, I did not come close in my Camaro. Yet, my camaro out handles and out brakes the Vette. I was however on street tires on the Camaro, but that would only give me about 3-4 second better times. Camaro=135rwhp...Vette=540rwhp(trust me when I say I have to have major pedal skills with the Vette, the camaro I just flat foot the throttle and bob back & forth in the seat going,"Common' baby, go!". The Vette burns rubber at 70mph.

Almo the Pirate

you have a 68 vette????? dude 68 and 69 are my favorite years!!!!!! im so epically jealous. you dont even know.

and i do apologize for being completely off topic.