I have searched and read all the older posts about this subject but wanted to get some advice on current parts.
I have an all original 1986 Camaro Iroc with 66,000 miles. I am in the process of upgrading the suspension.
I ordered a steering kit from Spohn.
I ordered a Panhard kit from Founders Performance that includes lower rear control arms.
I ordered a Front and Rear sway bar kits from BMR Suspension.
I am stuck on the front struts and rear shocks. Was going to order Bilstein rear shocks. The listing for them is part number 24-192934. Some websites list the the 24-024075 as the shock for the rear but they are for 1993-2002 Camaros and are cheaper. Not sure if they are set up for there Iroc.
I am not going to be racing or taking this car to the track. Just want OEM Ride or just another above that. Will be a weekend cruiser not a Daily Driver but summer driver in good weather only.
I know Koni is the go to but for $600 for the pair is a hard pill to swallow when the KYB's AGX adjustable struts are $320 for the pair.
Should I go Bilstein rears and AGX front struts ?
I am open to opinions.
Pic of car attached.



Thx

 

You're wasting a lot of money on things you don't need if this is just a weekend cruiser. Why the panhard kit, why the rear control arms, why the sway bar kits, why the "performance" oriented shocks? If a cruiser is all you want, put new rubber bushings on it and call it a day. Is your steering sloppy? No reason to replace any parts of the steering linkage unless there is slop. Have you verified this? Just trying to help you be more cost effective with the $$ you are putting in to what looks like a super clean survivor.

Now I would never recommend any of that for a car that will need to handle. Lots of handling improvements can be made with aftermarket suspension members/stiffer bushings, but they all come at the detriment of ride quality and your wallet. Going faster is worth it to me, but not everyone.

You are likely going to be fine with yerbasic Monroe shocks/struts if you want a comfortable ride. Yes, the fourth gen rear shocks will also work. I believe a lot of them are twin tube design as opposed to the monotubes on third gen shocks. Both will work on either application.

I cannot for the life of me recommend AGAINST the AGX shocks enough. They belong in the dumpster. Ridiculous that they cost as much as they do for an "adjustable" shock that is stiff as a wet noodle regardless of how it is adjusted. Trash. AGXs maxed out are still softer than Monroe sensa tracs. I wouldn't be surprised if the adjustment ***** were just there for show and connected to nothing in the shock. I binned them as soon as I came to my senses and went with Koni yellows. What an incredible difference they made, with adjustments actually resulting in noticeable change.

 

For my car, I've got all new MOOG parts to replace old factory stuff. For rear shocks, I found a NOS set of discontinued Bilstein AK1050, which were specifically designed for our cars. I haven't figured out what I'm doing for the front struts yet.

My car is 56k original mile LG4 and I don't plan on making any changes to it at this point. I just want to be able to drive it, so I'm not concerned about upgrading for performance.

 

Thanks for the input. I appreciate it.
I will reconsider all of that. I have some creaking noise in the front end from the suspension when it flexes. Not sure what it is.
Do you recommend the twin or mono tube Bilsteins for our car ?
Thanks

 

^^This. Also, why all the NEW parts? I'd monitor the for sale section for lightly used, or even fire sales from folks that got all those parts and then sold the car. There are deals out there, many times for pennies on the dollar.

Yes, Koni shocks are expensive, but they are quality parts. We're running Kony yellows on our otherwise stock '92 B4C car. Great ride, IMHO, although I prefer a firm ride. I'd 'buy once, cry once' and be done with it in the shock department. We have Koni reds on the CP car (~85 Firebird). Probably be better off with yellows, but are thinking more of custom build Penske's for it instead. The reds do well, too, on a 2800# car.

 

I also agree with RJ IROC. I've built a few of these cars from the ground up, and I always seem to "over" build the suspension. It's easy to do, but not necessary! BTW, the Koni Yellows are AWESOME!!!! -but not necessary for many street applications.
I'm currently building an '86 Z28, and I also own a '16 Camaro SS. Here's what I've learned on my twisty country road runs: The 86 is about as much fun at 45mph as the '16 is at 75mph. I keep the traction control on because losing it at 75 is bad!!!!! ....but at 45....the fact that the 86 doesn't HAVE traction control is acceptable, and you can drift the car in places that maybe you wouldn't in the '16 due to speed. I could argue, and make a case for the 86 actually being MORE fun. Get rid of flex, as well as old worn out parts, bushings, etc. etc., and you'll be surprised out how well the car will drive.

 

What would you suggest to get rid of flex and what struts for street application ?

Thx Pete

 

SFCs for flex, if you're willing to weld them on your pristine car. Maybe a STB too (requires drilling though). Wonder bar if you dont have one (TDS has the nicest one).
Koni yellow here, but i really liked my Tokicos i had before the koni's and they were adjustable too. Koni now has another RED shock called Active that adjust to road conditions, but i havent seen them for our cars...yet!. Probably more $ than the yellow series.

 

Isn't there a saying about there being more fun in driving a slow car fast than a fast car slow?

 

I totally agree. At one time, I owned my '92 'Vette and an '06 Z51. Every day that I went down the the garage, I always chose the '92, b/c it was more fun -especially on the street. On the track, they both felt the same at 9/10ths. The '06 could go 20 mph faster on the front straight, and I bet my lap times were ~10 seconds faster on a ~4.2 mile lap, but they both FELT the same. At the drag track, the '06 would ET 1 second quicker than the '92 and trap 10+ mph faster....but on the street, the acceleration FELT the same. So? Lower consequences and the same or more fun? Add to that, better throttle response, better steering feel, better "cockpit", better clutch, better synchros/shifting, better viz out of all directions....better drivability in general, from the '92. Thus, I sold the '06 eventually, due to lack of use and never regretted it.

I agree with those who've said Koni. For the money, they work pretty darn good.

 

Sorry for the late reply, haven't been online a whole lot! ....for flex, i think EVERY car should have subframe connectors. Don't think you'll get a lot of debate on that issue.

As for shocks/struts, there's honestly not a lot of performance options. Never used the AGX, but never heard a whole lot of positive things either. Used the Koni's on my 88, and DANG, very nice!!!!!!!!! Had the old Tokico HP's on my 89 and loved those, especially for the money, but can't find 'em anymore. I've replaced old stock shock/struts with new Monroes before, and was actually pretty impressed with how they drove on the street. -Further throwing doubt into my understanding of the true needs of a street car compared to a track car. Wouldn't be a bad riding set up, and super cheap to try out. They won't outright fail, you just might find their limit before the car finds yours! If they won't work for ya, you can always go with Koni. I've been considering that approach myself. Honestly not sure yet.

 

Thanks for the info. I may just try some Monroes for now.

 

Not a bad plan, but let me just clarify for you or anyone that may be reading in the future. The KONI yellows are EXCELLENT, and LIGHTYEARS better performers than Monroe, Gabriel or any stock replacement. What I mean is that for a street car, it's an affordable option that'll allow you to comfortably drive the car and get your other suspension and mods/upgrades sorted out, while you get a feel for whether or not you need "more". -and you might! Right? Let's not pretend we're all gonna swap over to Monroe! I'm just saying it's still going to handle pretty good if you do. ....and then you decide where to go from that point.

 

That is what I was thinking. For a car in stock form and just used on weekends and cruising around town, Koni struts may be over kill right now.

 

Overkill is, of course, a personal thing, but since the Kont's are adjustable, they can actually provide a better ride. I set mine on full "soft" for DD'ing, then change them to full firm for track days and auto-x. It makes is much nicer to drive on the street, when set of that softest setting.

 

I can't wait to install my Koni yellows that I bought 3 years ago, but I have some other things I need to take care of first...

 

I've never owned Koni's. Would a combination of Koni's and Ground Control kit be better than using for example Eibach lowering springs? I am debating about lowering my 91 Z28, but do not want the ride to be harsh. thanks! Sorry if I'm hijacking the thread!

 

I think a lowered 3rd gen is going to ride harshly regardless of the shock/strut that is used.

 

You have two choices. You can lower it OR you can have it ride nice. NOT both. Mine was lowered when I got it and it rode like an old truck. I went back to stock springs front & rear. It rides a lot nicer.

 

The weight jacks are great because it allows a lot of fine tuning, whether it be appearance or performance. I had the ground control kit, (on two different cars actually) with a slightly lighter spring kit than they offer through their catalog, along with the Koni's, and it handled excellent, and ride was "pretty good". Donovan at Ground Control was excellent btw. Easy to work with. I had the Eibach ProKit on my 89 early in it's life and, meh....nothing bad to say, nothing really noteworthy either.

I think if there's ONE underlying theme I've seen on social media and forums through the years, is forgetting to really define the different wants and needs of the people discussing a topic. Someone restoring/rebuilding a stock IROC from their childhood memories or dreams, likely doesn't need $1000 dollars in high performance Koni's dampners on each corner. If you ARE building a racecar, and you DO want/need those Koni's, it wouldn't be a stretch to tell the first guy that Koni's are "so much better". For one person, they're a necessity. For the other, they're an expensive piece that'll just ruin the ride quality, and potentially the whole experience. ....and then for a lot of us like me, we land somewhere in the middle. My grey 88 had the Koni's and the GC weight jacks. I think I had 750's up front, and then a few different rates out back over the years. On SOME days I'd lament the harder ride quality. Other days, they were worth every penny being able to push the car through twisty mountain and country roads and feeling an almost 40 year old car handle the road with nimble precision. We're all different. You just have to be honest with yourself about what you want, and do your best to find the parts to best help you do that. .....and in 2026, we have a LOT more people getting these cars back on the road than we did when many of us first got into these cars, and not everyone is building a street monster or track missle!!!!

 

Are the Koni's for F-bods not adjustable?

 

Thanks, guys! This is all good and helpful information.

 

What if you cut only 1/2 a coil on the front, and keep stock springs in the back?
Should I expect a harsh ride with Koni yellows up front?...

 

The more you lower it the more you take away from the amount of travel in your suspension which in turn makes it a stiffer/harsher suspension/ride. You are the only one that can say if it's too harsh for YOU.

 

First, the shock has more to do with a harsh ride than the spring (rate). To ME, "Koni yellow" is an adjustable unit and as such, when set on the softest setting should ride as smoothly as any "smooth" riding shock in a 3rd gen.



Second:

 

Even at it's softest, it wasn't close to a stock replacement shock. Of course, I guess that's subjective though, as is the whole "soft/harsh" debate. I had my red 89 with the GC Weight jacks and Tokico shocks, bought my grey 88 which was bone stock and rode wonderfully, but certainly was less precise, with more body roll, then swapped in another set of GC weight jacks, this time with Koni's. Bout as back to back to back as you can get. While I cannot tell you how you like to roll, and what is soft or harsh, there is no way it was close to being stock ride quality. It was a little more harsh than i would've liked, especially since my wife didn't like the modification to the ride, lol, but boy it certainly handled well!!!! Had I kept the car....not sure what I would've done.

The biggest thing that I noticed about the Koni's was that on rough pavement, patches in the road, etc. etc., it was very jarring. Transferred a lot of that to the driver. It did this regardless of setting. What DID change though, -was when you dove hard into a corner. Quite a difference from softest to hardest. Really needed the weight of the car to really shift, and then you could certainly tell.

 

Weird. My back-to-back was brand new stock replacement Bilsteins on my C4, to Koni's....then back to the Bilsteins....then back to the Koni's. I thought that the Koni's on the softest settings were pretty indistinguishable ride-wise, from the Bilsteins. Koni's are still in the car, I sold the Bilsteins.

 

Full disclosure, I mean, I did have the 750 rate springs too, not stock, but I feel like those shouldn't have made a drastic difference. Not as much as the shocks. -But.....guess it wasn't truly back to back.

 

I agree with you....I don't think the springs make a big diff compared to the shocks.

 

I think my springs are 720 -750 rate, rear 170-180, both eibach. Going on 16-17 years, don't remember the exact rates. They came with GC weight jacks. The konis are definitely stiffer than the Tokicos for the same settings and i have mine on the softest setting, but the tokicos were not available anymore, so i ended up getting the koni yellows thinking they'd be no different than the tokico being adjustable. I can live with it, but i wouldn't mind a slightly softer ride. Those new red konis are road sensing and self adjust accordingly.

Worst shock i ever tried...KYB's, also adjustable. Those things were so stiff on the soft setting. Felt like i was driving a forklift.

 

What's the spring rate of stock 1984 Z-28 springs?...

 

I was not aware that these were available for thirdgens. If they are that's an interesting option, but I haven't seen them for our cars anywhere, or even on the Koni site.

 

I am going to go out on a limb here but our Foxbody needed shocks and they generally are a shopping cart ride to start with,beat you up , with OE stuff,pretty harsh. I ended up getting KYB Excel G's after a long period in the rabbit hole seeing what the opinions were. Love them, actually surprised-totally street driven pretty much unaltered,not racing or destroying it after 43 years and 100k miles. Our 89 IROC has Koni red adjustables on it which absolutely transformed it , but I lucked out and got them with a bunch of other stuff never installed from a guy who sold car,would never have been able to spring for them , and Koni doesn't offer anything now for 3rd gen. just my 2 cents. i wonder if subframe connectors next might be in the mix too, made a big difference on our car and it is NOT a ttop car. good luck with your machine

 

They're not, that's just wishful thinking on my part. I only know about them from some youtube vids.

 

We got them in boxes easily 7 years ago, and that guy had them for who knows how long.sad because they really changed the car, no more standard 3rd gen hood shake on bad roads, and i have a strut tower brace still in box to install as soon as current engine is complete. I didnt look to see if kybs were available for 3rd gen but i was pleasantly surprised on foxbody

 

Edelbrock even longer ago offered a shock/strut for 3rd gens that did the same thing as those self adjusting konis. By the time i needed new shocks they were also discontinued. God damn it!

 

Never experienced a self adjusting shock.ours had a **** that you put on and turned- set ours one notch from softest.was concerned when putting Eibach lowering springs but no issue at all,ride did not suffer at all.stock sway bars both ends,UMI rear lower arms and Spohn panhard bar,replacement rubber bushings in front arms

 

Me neither, but it sure wouldve been nice to not need to manually turn a **** or worse have to remove the damn thing to adjust it, like the rear shocks.

 

4th gen rears fit, and can be adjusted from inside the car.

 

If I remember correctly, they ar in the 400-450lb range.

 

Yeah, but they're mono tube whereas ours are twin tube. I forget the advantage of one vs the other.

Everything I've read are z28 and iroc fr. springs are 548 in. lbs with iroc springs being 1/2 shorter. Which are actually z28 springs, rejected for being too short. I don't remember the rear spring rate exactly. Something around 170 in. lbs. RS fr. spring rates are 340, thereabouts (maybe) and rear same as iroc/z28.

 

GRIP is KING!
A fast suspension needs to have some compliance, otherwise grip is reduced. This means it also needs to be somewhat comfortable for the driver to have confidence. Thus, ultimate grip is tied to having a degree of compliance (comfort).
Therefore, handling and comfort MUST co-exist!

The goal is to control the contact patch of the tires to keep the vehicle on the road, and generate maximum grip.
If you concentrate on making the tire-to-ground interface as efficient as possible, you will maximize the available grip. With more grip comes more confidence and usually more ride comfort.

Damping means producing a force to return a system back to rest.
All dampers or shocks are velocity-sensitive devices, in that they only generate force when there is motion. Springs are displacement-sensitive devices; they generate a force anytime there is load on the suspension and that load varies with the amount of spring compression. So the springs and dampers (part of the suspension) respond to the vehicle’s mass to control the motion.
A properly damped suspension will aim to bring the chassis back to rest as quickly as possible without amplifying the input motion (being too stiff) or allowing excessive oscillations (too soft). Stiff and soft are relative to the user which is why customization of spring rates AND damper profile is crucial to obtaining the proper vehicle performance, whether a pure track car, commuter vehicle or anything in between.

For handling, you want a low-speed damping adjustment and a shock that responds immediately to chassis movement (the better, the more expensive). A twin tube (Koni/KYB/Tokico/Tein/GAZ) will always lag behind a monotube (Bilstein, Penske) due to less displaced volume.

For overall vehicle control, mid and high-speed damping is crucial. This is where monotubes shine. They don’t generate the high internal pressures that twin tubes have to for the same force. Monotubes dissipate heat better and stay more consistent mile after mile than twin tubes.
A suspension that does not keep the tires in constant contact with the ground is not going to be comfortable OR fast! Vehicles like Porsche and BMW come with more gentle low-speed curves and more comfortable and better handling because of it.

Compression:
In a street vehicle you want relatively soft compression. . .you need adequate movement of the suspension to provide ride quality (so it absorbs the bumps as you go over them as opposed to transferring that energy into your seat); so you basically want the spring to handle the suspension when it compresses (bump). You can increase the compression damping of the shock, but the outcome will typically be a harsher ride as you are inducing more force into compressing the spring – like having a very high spring rate. High compression forces cause poor ride quality.
More compression force will help ride quality in an under-sprung car (maybe keeping the suspension from bottoming out), but will hurt ride quality in a properly sprung (or over-sprung) vehicle.

In a more "race oriented" vehicle you are typically traversing a relatively smooth surface, so you don't see much compression due to "bumps"; only compression due to major brake pedal application or major steering wheel rotation.
So compression adjustment becomes a means of slowing down the compression of the suspension.

Rebound:
In a street vehicle you need more rebound in the shock to slow everything down after the suspension has compressed.

The shock plays a major role in when the weight is transferred.
If the shock has too little rebound, the weight will have transferred to the rear before you hit the apex, and the car will push (understeer) as the front tires are picked up off the pavement (not really picked up, but it gives a better visual).

If the shock has too much rebound it will "hold" the front down too long. In this situation the front will still be "overloaded" as you begin applying throttle and the rear will lose grip (causing oversteer, or just spinning, depending on the position of the car in the turn.)

Now, that does not take into account rear rebound, or compression on any corner. Adjustments to these items will affect the timing.

If you optimize for street ride quality, the suspension has moved quite a bit. You now need to slow down the spring pushing the suspension back toward the ground. If you don’t the suspension will travel past ride height, going into extension, then back to compression, starting the whole deal over again and giving that "bouncy" feeling.

In the previously mentioned "race" vehicle, your rebound adjustment now becomes a means of slowing down the extension of the suspension. . .or like keeping the weight on one end or the other (the longer you have more weight on the front tires, the more grip they have further into the turn).

Timing Device:
You have to remember. . .in any application the shock is simply a timing device.
In a "street" vehicle it slows down the time it takes for the suspension to overcome a bump (thereby stopping the "bounce").
In a "race" vehicle it controls when and how the weight is transferred front-to-rear and side-to-side.

Basically, if you have a car that is primarily street driven with the occasional "track day" you are best off having a monotube, rebound adjustable shock. You don't lose much not having compression adjustment (as you'll just make ride quality worse); you want a monotube as the piston is almost twice the size of a twin tube, so it has better "control" (more surface area makes it more effective); and you can still have great ride quality and a fast car on the weekends.
If your vehicle is primarily a race car. . .who cares about ride quality. . .it's only about going fast (which is made possible by the increased ability to control when a car transfers weight.)