Wildcat1

Wondering what the best mods I can do to my 94 LT-1 vette to make it handle somewhere near a Z06. My dad has one and it's night and day difference. My car pushes real bad sometimes and then swings around other times. His is on rails.

I've got alignment specs that I'm ready to use, but I want to get other stuff taken care of first. I could get away with maybe lowering it no more than one inch, what's the best way to do that?

Please state the mod list from best to worst.

I've looked at DRM camber brackets, R-D cross frame, R-D cross bar (those are different?), sway bars, beam plates?, smart camber rods, rear camber struts, and shocks. Maybe I'd be better off buying only a coil-over setup? What's the best bang for the buck suspension mods?

Thanks for any input!

65Z01

I just installed ES poly graphite sway bar bushings and there is a noticible improvement in flatness in corners.

The effect is about the same as going up one size in sway bar diameter and keeping the stock bushings.

Gary04Z06

Coil overs would be great, but kinda $$

Camber Brace would be a great help, ties the upper A-Arms together for better conoring, the Cross Frame (goes under the car to strenthen the chassis) is a great help also, can't go wrong with either or any of R-Ds products.
Of course, poly busings would help, better shocks Vette Brake Products Extreme, better tires (wider 11" all around)
Its almost endless the improbments you can do.
Might try a driving school like the Evo, best mod I did was learn to control what I had before adding products, you'd be surprised how much faster you can co when you really know what you are doing.

Roscoe's 85

One of the best things to do is change out the stock bushings with an entire set of poly bushings. This will stiffen up everything. All of these joints flex with old bushings and when compounded makes for a very unpredictable suspension. By changing out and putting in poly you make the suspension (any mods you make) do all the work. I saw huge improvements with this and my autocross performance.

The next best thing is tires. If you want to stay stock I would recommend something like Kumho's just because they are nice and grippy but still fairly cheap in price. If you are autocrossing a lot you don't want to be replacing $300 tires twice a year.

These 2 things will give you the biggest difference from the factory set up. After that I would go with a race/semi race alignment. Don't go crazy if you still plan to run on the street. I played around with the shims on the upper front and it helped out alot. Easy in and out so I just took them out just for racing and them put them back in.

luvmy92

You haven't mentioned anything about what suspension you have (FE1, Z51, FX3, etc). That will tell us what springs you have, sway bars and shocks.

Mike

Strick

Scan through this thread and you'll find lots of ideas:

http://forums.corvetteforum.com/show...66&forum_id=23

For me it was tires. I went with 11" on the rear and stayed with 9.5" on the front and played with tire pressures. The R&D Racing camber brace and cross bar stiffened my vert up as tight or tighter than any coupe. The biggest gain comes from good ole fashion seat time.

Wildcat1

Thanks for all the help. I've got the FE1. I am currently running 5yr old hand me down 275-40-17 comp t/a up front (borrowed bigger wheels from my dad) and the same size nitto drag radials on back. It's the best I have to work with right now. I know I could put on new autox tires all the way around and probably beat everyone on the course. I got FSTD when I was 15 in my dad's 91 vette. This is my 13th year, although, this w/e was the last time I've run in the past 8 months. I ran in only 3 events last yr. Before that, I hadn't run in probably at least 3 yrs. When I was 15, I ran every event. These days, I'm rusty.

Like I said though, my car is sloppy....no matter the skill of the driver...compared to a Z06. You have to admit there is a huge difference in the handling of the z06 and a C4. My dad's has been lowered, it's 3.5 inches off the ground. He has to drive on to wooden blocks to get a jack under the car. He's running Hoosiers, he races at Barber and such these days. His car has also had the weight distributed evenly from corner to corner. My car is 7.5 inches off the ground at the jack point.

I know it will never handle as good as his car does now, but anything close to what a stock Z06 does would be great. I can run door to door with a stock z06 at the drag strip, but I want the secure feeling it provides when turning too.

Tires and alignment will be the last things I do after changing parts, even though they are the most important. I want to fix the main problems first. My car is also a daily driver for the most part. I have a beater for rainy days.

Keep 'em coming! Help me put these new RX-8s and 350Zs in their place.

USAsOnlyWay

Well first off, the mods to the Z06 make a huge difference.

First of all the GY F1s that come on the stock z06 have a great stick to em. Not to mention your dad's has Hooisers on it!
Also the lowering of the car and the weight distribution are big changes from just stock.

You want awesome handling, I would go:
-DRM/ExoticMuscle Coilovers w/ adjustable shocks
-RD racing harness bar which also stiffens the car
-Camber Brace
-Poly bushings
-Upgraded sways
-17x11s all around w/Hoosiers

I would call DRM or Exotic and tell them your plans for the car. They should then be able to recommend the right sway bar setup and then make sure you get the right springs and shock valvings for your car. Hell if this isn't enough you need to go get a formula car!

Strick

You know, trying to make a C4 handle as well as a Z06 is almost impossible. Money will get in your way. The C5 chassie is just better and the extras on the Z06 make it even better. I run with 2 Z06s and they out run me by 3-4 seconds on a 60 second course. Our driving abilities are about equal. Good luck.

luvmy92

I run with 'em all day long on a road course. Here is my setup:

Z07 Springs
Poly bushings
Lowered (like your dad I have to drive up on wood blocks to jack the car up)
30MM/24MM solid sway bars
FX3 shocks that have been revalved stiffer w/DRM FX3 Controller/Chip
Camber Brace
275/40 and 315/35 Kumho Victoracers

Alignment
-----------
F Camber: - 2.2
F Caster: 6.5
F Toe: 0

R Camber: -1.7
R Toe: 1/8" in on both sides

I say bring it on...

Mike

Strick

Hey Mike, you forgot about your 400 plus hp to the rears. That makes up for a lot of suspension differencies.

redbullapril23

4 pt weld in roll bar!


coil overs
brakes cross drilled and slotted
larger diameter tires

eschoendorff

I see this at every event, too. The C5 Z06s consistently run about 2-5 sec quicker than the standard C4 and C5 coupes on any given course.

Tires will probably give you your biggest gain. Even with teh FE1 suspension, you will get a lot more stick from R compound tires. If I had the $$$, that's what I would try first.

That being said, with the amount of $$$ that you would have to invest in suspension mods to even get close to Z06 levels, you would probably be better off selling your wife and kids (or you soul... whatever ya got) and buying a Z06. Remember: anything taht you do to your C4 is going to bump you out of your class and then you'll be competing with other modded cars. But you already knew that. Also remember that although the Z06 has a familiar looking suspension, it's specs are unique to the C5s (wheelbase, for example).

I'm poor, so I tell myself that I'm going to stay with what I have right now and simply concentrate of driver skill. So far, I've got myself fooled.

luvmy92

When I only had 350 to the rear wheel I was putting up better numbers than the Z06's with more to the rear wheel. I do not have any new times since I put in the stroker motor...

Mike

ANTI VENOM

I have a 91 with the Z07 option and a 92 with a FE1 suspension.
Comparing the two cars is like night and day. My 91 is also lowered and has poly bushings throughout. I'm not saying that I can stomp on the Z06's, but you may be able to convert to the Z07 specs and still be "stock". I'm just letting you know that there are big differences between the suspensions, even on the same year car. A setup like Luvmy92 or my 91 would be a step in the right direction, IMHO, just depends on what you want. Good luck with your decisions!!!!

JrRifleCoach

AutoCrossing is a driver skill event. That being said I'd concentrate on buying four matching wheels and tires. Doesn't have to be the best, just good name brand products. Check your shocks. Are they more than 6 years old? If so buy some new good quality shocks. QA-1's or Koni Sports are going to serve you best for the next 2-3 seasons of Auto-Xing. Check the brakes as well. Get some good semi-metallic pads and turn the rotors. Change the fluid with fresh DOT3 rated fluid. Don't bother with "trick" synthetic fluids. Check all the suspension and anti-roll bar (aka;sway bar) bushings. Consider changing out the anti-roll bar bushings with "polys" to tighten the roll. Don't spend any money on chassis stiffeners until your past the first season.

Now go out and learn to drive it. All that will be necessary is to adjust tire pressure. You'll carve out a set of tires quickly so be prepared to buy UP to a set of Yokohamas or better tires. Remember that full tread depth tires will squirm and wear down quickly. If your running them on the street, the constant heat cycling will remove the "oils" in the rubber causing the loss of softness.

After the first year you can start planning the next set of mods.

IMHO; there are a lot of bench racers out there with lots of great ideas and suggestions. The advice I offer here was given to me years ago by two national champion autocrossers. After listening to these guys my times continously dropped for the next season. Afterwards I planned the mods based on the needs of learning the car better.

AORoads

This sounds like very, very good advice. I'd also reinforce the thing about the tires (as with the shocks). If your tires are pushing 5 years old, they need to be replaced; they're starting to harden up and have lost much of their stickiness, if they had much in the beginning. While in the hands of an expert, the stickiest vs. the slipperiest tire can make a difference, the biggest difference will be in driver skill---driving well, what you already got. After that, you can only get better if you put on better rubber. And with new rubber, even in the lower half of great handling, you will at least get all that you can out of the car for the time being as you hone your skills with the car.

JCD

What class do you want to be in?

Next year the C4 very likely will move up to super stock, if you put on poly bushings that moves you to BSP (if you're not there already), swapping out springs from a Z07 car and getting a 30 mm front swaybar is the best you can do in stock. Coilovers is right into SM2...

Those drag radials can't be helping, a matched set of tires is a must!

Raistlin

I would (and did):

lower the car (homemade kit)
add poly bushings (ES hyperflex kit)
stiffen the shocks (revalved and rebuilt factory adjustable bilsteins)
buy new tires (Kuhmo MX)
get alignment (-1.75* camber, 0 toe up front, some toe in out back)

next I will change springs and anti-roll bars.

JrRifleCoach

Which way? Stiffer springs and bars? Why? Up to this point your mods are making sense. Not questioning your decision, but asking for your reasoning .