I have the car is running good and I'm at a point where I'm ready to start modifying the suspension. Where would you start? It's an 89 IROC with 275s all the way around on Hawk's 17"s and at stock height. I am contemplating front and rear sway bars and a panhard bar but would like your input on where the money is best spent. I would also like to drop it at least an inch later on which is why I was leaning towards a new panhard bar.

 

Have you looked at the cost of brakes? It's more than all the other mods combined.

* Aftermarket sway bars are very similar size to your stock sway bars. Not going to do much for your car. Maybe just install new sway bar bushings and be done with that.

* Adjustable panhard bar is pointless unless you need to re-center the axle.

* Control arms are needed IF you make power. This is an upgrade where the homemade version actually works really well (weld a plate to the bottom side of stock control arms).

* I think you'll get the most enjoyment from springs since you want to lower the car anyway. But keep in mind that springs might result in the need for different shocks and that can be another $1000 extra. The more grip your tires have the stiffer the springs and shocks to control the suspension.

 

How do you vote None of the Above? SFCs is where you start.

 

Whats the goal for the car fun cruiser or autox crusher?

 

What is the planned use for the car?

 

If your car has t-tops then do this. If not then get the lowering springs first.

 

I have all new bushings, Koni yellows on all 4, new sway bar links and Nitto G2 275s. The car is up to par as is. I have probably $20k into it with a full, down to metal repaint. I'm at the point where I'm going to mod the hell out of it like the DSE-Z or sell it and buy a C6 Z06.

 

I agree,...subframe connectors first 100%

 

Save yourself the pain and just get the C6 Z06. The cost of the Corvette will be about the same as the rest of the mods left to do on your car. The difference is you'll own a Corvette.

 

Silent-blocs are among the first choices

 

This. Its sad but true. However, if you are keeping the 3rd gen than sub frame connectors and upgraded brakes, as quick mentioned, are an absolute must for these cars.

 

subframe connectors make the biggest difference by far...

 

Car had a wonder bar on it when I got it. I did springs and adjustable panhard bar first. Then did LS1 brakes and rear end. SFC's were next. I have done a little at a time as I get money SFC's and brakes were the best upgrades I have done and make the most noticeable difference. It's all in how you drive the car and what you intend on doing with it. I'm building an autocross car primarily with a few weekend drives thrown in.

 

Subframe connectors are widely loved/hated as a first modification. If you choose to add them, UMI 2400 is great.

Then springs, shocks and sway bars. UMI makes a great spring set. Moderate lowering and correct rates. For dampers, Koni is awesome as is Viking. And no, Viking isn't just drag anymore. They have a myriad of valving combinations suitable for nearly everything.

Then the rest of the UMI catalog.

And as mentioned above, it matters how you're going to use your car. With 275's I'd imagine you're shooting for handling.

 

I have designed and installed a stupid amount of new high output Drive-train Systems in 3rd-Gens over the years...

The number one issue that these cars have, after increasing the power...
is rear wheel-hop due to the rear lower control-arms behaving like limp dongs!

Just like the other members have said... box the stock rear lower control-arms or install aftermarket versions.
I personally am addicted to adjustable tubular suspension components on our cars!

Next I usually find that the door gaps (front and rear) have moved/ are uneven...
The wonderful uni-body is now moving around, and sub-frame connectors are needed.

Any of the 3rd-Gens that I build with over 1,000 HP, receive a minimum of the common tubular sub-frame connectors (both types), an 8-Point cage that directly ties in to the sub-frame connectors...
and then I add additional tubing to connect both types of sub-frame connectors together along with addition tie-in points through the floor to the roll-cage.
It ends up like the DSE connectors/ cage... just taken even further.

 

Shocks and struts. Koni yellow minimum.
wheels and tires, 17" or larger, 9 or wider, 275 minimum.
larger from brakes, pbr rear disc's.
then suspension.
springs, I like weightjacks. dont be afraid to go heavier in the front with the konis. I use 1050/250
strut mounts with bearings.
Subframe connectors and steering brace (detroit speed has a good one).
strut tower brace. 3pt
Rear control arms and panhard, no poly, Jonny joints or rod ends. Watts link is an option.
torque arm, relocate it or use aftermarket. I liked the UBE decoupled arm, but its no longer produced.
front LCA, spohn has complaints about theirs, moving the wheels back ect, so avoid that one. You can replace the stock bushings for delums and a new extended balljoint too if you don't want aftermarket.
aluminum driveshaft
Look into building a lower chassis brace

 

the best place to start is getting a set of Koni Yellows and building off that since you already have better tires than stock.

 

What the heck are silent-blocks?

If you want a c6 then get a c6, that and a "fully modded" 3rd gen are 2 VERY different things. One is not going to satisfy the need/want for the other.

SFC's are the best all-around mod for these cars. You can make these cars work without them (and if you want to race in certain classes you might have to) but generally, these cars are not as rigid as a lot of modern chassis and benefit in many ways from SFCs- they allow the rest of the suspension to work better, prevent rattles, prevent body damage (hard top cars generally are the most rigid and you'll feel the difference the least, but without them the roofs crack at the back of the door openings, I've also seen rippled quarter panels on fast drag cars without them). It's just a good place to start. Of course, that's really a chassis mod and not a suspension mod and not a suspension mod.

WRT to suspension, #1- make sure everything is right, nothing is worn out or broken. If your car wheel hops, something is loose, worn out or broken. If it steers funny, doesn't track right, goes to one side when you... something is not right. Almost everything that people complain about with these cars and say that "you need to spend money on _____" is complete and utter BS. These cars were arguably the most competent all-around 80's chassis available a reasonable price. In the 80's and 90's a near stock f-body would outrun a near stock C4 corvette on the road course and dragstrip (though the corvette would feel better doing it on a bumpy surface).

The first mod out of your list- PHR. The "centering your axle," argument is only really a thing with fitting the biggest tire and big ride height changes (do the math and see how little 1" difference in ride height makes WRT axle centering). Stock it's a long sheet metal piece that is flexible. A hard shifting auto or a person rowing the gears can cause the suspension to wind up and the back end will jump out sideways on the shift. It is the only mod on your list that a near-stock car with a GOOD driver will show a difference with at the dragstrip, autox/road course, and feel better on the street.

Brakes are right now leading in your pole... I DON'T GET IT. Are the stock brakes smallish compared to modern brakes? Yes. But in good shape with decent pads, they are more than sufficient to lock up the tires. Repeatedly. You are not going to get more stopping force than what it takes to lock up the tires, that's it, that's the shortest stopping distance you'll get. For 95% or more of the people on this forum, big brake upgrades are just EXPENSIVE appearance mods (they look better behind big wheels with substantial openings in them). Any safety, we need them, modern brakes are bigger... arguments are complete BS. Again, if you can lock up your brakes you will not get shorter stopping distances with brake upgrades. If you can't lock up your brakes something is wrong with your brakes. What about the other 5%? Well if you're a serious road racer (maybe a serious autox'er) you might be able to overheat the stock brakes to the point that they start fading, and that's where brake upgrades will help. Bigger brakes dissipate heat faster and will work correctly longer under extreme conditions. Don't tell me you fade your brakes all the time on the street, because if you do you're doing something wrong, that's next to impossible on most streets under most traffic conditions without getting arrested and/or killing yourself and others. For serious drag racers typically you still don't need bigger than stock brakes unless you're running at speeds that need a parachute, but lighter than stock brakes will make you go faster- of course, I can't tell you the last time someone went lighter than stock on this board (I currently am but I'm different and I'm doing it on a majority streetcar, I'm also assembling my own upgrade and I have probably just over $100 in the whole thing, which includes $32 to have my own brackets laser cut).

Past that- springs have make big appearance and 'feel' changes and are a good tuning aid. Sway bars- for 99% of us this is a factor of getting the right factory sizes on the car to match/tune for your use and the rest of your suspension mods. There's almost no reason to go aftermarket unless you're talking a drag bar on a dedicated and fast drag car. Control arms? I'd bet that 99.9% of us couldn't tell you for sure if a car had aftermarket control arms vs stock ones with good bushings just by driving them, with the possible exception of the extra noise if you're comparing them to aftermarket ones with spherical ends.

 

Hell, the cost of a C6Z when they were new wasn't even close to the cost to build the DSE-Z. Definitely better bang for your buck to buy the C6 than mod a thirdgen.

 

Again, a C6 Z06 is a totally different animal/question. I have the idea of picking one up in the back of my head but it wouldn't replace my 3rd gen project. It's lighter, more refined, a better daily, but it doesn't have the attitude and is not as much fun as a 3rd gen. Honestly, I don't believe that the C6 is anyone's favorite 'Vette (mine would be a C3 followed by a C5, somehow I'm just not interested in the newer ones), but with the C6 GM hit it out of the park with a combination of ability and refinement/$. That said, every C6 that I've ever been around has had some serious hidden damage, I'm surprised how many "midlife crisis" mobiles have been used, abused and broken by boy racers.

 

Agreed. My next build may be a C3. Have to decide between that one, the 1st gen, and the 2nd gen. But compared to what was spent building the DSE-Z, a C6 is a bargain.