Fbody street suspension setup review
01-08-2008, 09:14 PM
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Fbody street suspension setup review I’d like to take a moment to talk about my fbody setup. I’m going to describe these concepts with a handling component review. Some of you may find this useful from performance street and casual track perspectives. I've selected the components and listed them in relevance of suspension theory. I've tons of seat time in various applications in various performance vehicles and the goal is to note results crucial to implementing handling.
Shocks
The shocks are one of the most impactful components with performance vehicles. I chose Koni all around because they're world wide and known in the industry as a premiere suspension component product. The Konis are an excellent shock with exceptional damping for rebound (adjustable) and compression. The standard medium setting is ideal for vehicle rebound control and at applicable adjustment exponentially impressive. With a medium setting the suspension set is solid without abruptness and sharp without sluggishness subsequently in every regard they work very nicely. The compression damping is effective for various road irregularity absorption similar to solid 'European Standard’ sports sedans with performance packages and installing Konis all around results in a diverse range. I've lowered the vehicle using the lower spring perch on the front Konis and of course the heater hose modification utilizing the rear suspension spring architecture for a combined ride height of approximately –0.50"/-0.75". The stance is subtle at all corners.
Sway Bars
There's various anti roll bar combinations for fbody applications ranging from stock to factory available to aftermarket bars. The handling differs in characteristic with different sized ARBs and you shouldn't assume just any roll bars work resisting roll as well as balance front plus rear traction. It turns out to be critical installing a balanced roll bar combination for corner carving performance applications. StranoParts has released a size and set of roll bars in the form of perfectly neutral steady-state cornering including upgraded installation hardware. I was running Strano's front bar and a GM 1le 21 mm rear bar that results in similar roll stiffness as Strano's rear roll bar. The combination is categorized as a balance of handling characteristics applicable to the fbody. With the front bar and factory rear bar the ride was tangibly tighter. There's an effect of increased stiffness with the front bar and cornering was flatter with stability. Interestingly adding the rear bar tied the suspension together effectively resulting in a surprisingly nimble vehicle. Turn-in crispness was sharp with a definite difference in body roll reduction. I found no difference in ride quality with the front bar and noticed a relatively small amount of harshness with the addition of the rear bar with ride quality reduced slightly more, well within average daily driving characteristics.
Panhard Bar
There's a variety of fbody's running single/double adjustable panhard bars. In effect there are countless implementations that work well. The factory bar isn't sturdy compared to an aluminum component with quality rod ends. I specifically chose an aluminum double adjustable rod end panhard bar for upgrading the rear end to factor the sidestepping hitting mid corner bumps during aggressive suspension and/or cornering maneuvers. It has incurred absolutely no extra stiffness whatsoever or harshness in ride quality and I'd recommend a rod/rod PHB for any load bearing application. As far as a double adjustable bar the rear end can be relocated for upgraded wheel/tire combinations (more on my specific wheel/tire combination later) and is categorized as the best way to quell movement of the axle at cornering loads. I built this one with rod ends on both sides using documented instructions here. Assembly is straightforward yet effectively addresses suspension deflection. I utilized Aurora rod-ends though most assemblies utilize QA1 rod-ends, either way will absorb impacts and deflection, without adding harshness to ride quality.
1le LCAs
Lower control arms are a link between the axle and the body frame, having a negative characteristic of LCA deflection. These 1le LCAs stiffen up the chassis in handling accelerating through turns with no excessive play. Simply tightening the overall chassis they consist of a bushing that's twice as spanning as stock, effectively twice as stiff though as far as additional stability the difference may be negligible. Though the difference is not negligible as far as ride quality reduction (the same), and I did notice slight rear end chassis stability improvement when cornering aggressively. The documented instructions are here. This exact setup largely removes the flex associated with stock LCAs and endures performance handling for cases where there's additional slop to be removed from the combo though chassis attachment points dictate the amount of additional ride compromise as you install towards alternate components. If I would upgrade at this point I'd move to an aluminum control arm with a rod end on one side and a rod/rubber combination on the other side, effectively balancing the typical effect of suspension deflection.
Springs
The purpose of springs is to suspend a vehicle between it's outside motion points. I picked up a set of used GM 1le springs. The rates are front rear 360 lbs 130-180 lbs. There's nothing inherently unique about these springs other than the interesting note they're utilized in far less numbers in the market than other springs. They're noticeably stiffer in the rear and marginally stiffer up in front. There's no noticeable effect on vehicle ride quality though for the purpose of this application springs are not a requirement for many performance handling vehicles and not a tangible requirement like other components on this list. Although, a big advantage of running stiffer springs is the decreased pitch fore and aft during velocity changing transitions. Specifically, entering a corner fast and transitioning to steering or the other way around will cause a mismatch of the chassis a moderate amount. The stiffer the spring the less counter effect is required with the disadvantage of a ride harshness hit. While stiffer springs turn out 50/50 yea nea in street driving in track driving it'd be extremely advantageous running springs. Nonetheless the net effect is results of gradual transitions changing directional vectors, largely depending on what springs are on the vehicle. There's no real negative impact with 1le springs and positive impact in the form of noticeably less pitch and roll.
Aluminum Flywheel
The flywheel is the component that absorbs drivetrain vibrations. Not quite a suspension component the aluminum flywheel accounts for increased throttle response resulting from this particular combination. The aluminum flywheel (not designed for drag racing) reduces rotational lag and acceleration inertia by a substantial amount weighing in at a light 13 lbs compared to +-22 lbs. The engine revs much quicker and doesn’t have the overall sensation of a heavy V8 instead similar to a high-revving inline 4 with superbike throttle response. Street manners have yes slightly worsened showing up in the form of proportionately increased complexity in clutch engagement with quicker drops in revs, of course more effective for fast shifting. Rev matching and double clutching is a much closer to applicable for spirited driving applications.
In conclusion all of these components had a tangible improvement in handling, depending on various driving applications. The PHB was a stability upgrade with LCAs also buildable within the context of chassis improvements. Next on the stability list would be springs, as an incremental performance upgrade. The result: the vehicle's completely transformed. It's got the composure of a German sedan with agility of a pouncing sports car. It no longer lumbers like an overweight linebacker instead a 5% lean running-back. For handling purposes it's a big difference from stock and with the addition of beefier control arms and stiffer springs would be an extremely effective track vehicle.
Shocks
The shocks are one of the most impactful components with performance vehicles. I chose Koni all around because they're world wide and known in the industry as a premiere suspension component product. The Konis are an excellent shock with exceptional damping for rebound (adjustable) and compression. The standard medium setting is ideal for vehicle rebound control and at applicable adjustment exponentially impressive. With a medium setting the suspension set is solid without abruptness and sharp without sluggishness subsequently in every regard they work very nicely. The compression damping is effective for various road irregularity absorption similar to solid 'European Standard’ sports sedans with performance packages and installing Konis all around results in a diverse range. I've lowered the vehicle using the lower spring perch on the front Konis and of course the heater hose modification utilizing the rear suspension spring architecture for a combined ride height of approximately –0.50"/-0.75". The stance is subtle at all corners.
Sway Bars
There's various anti roll bar combinations for fbody applications ranging from stock to factory available to aftermarket bars. The handling differs in characteristic with different sized ARBs and you shouldn't assume just any roll bars work resisting roll as well as balance front plus rear traction. It turns out to be critical installing a balanced roll bar combination for corner carving performance applications. StranoParts has released a size and set of roll bars in the form of perfectly neutral steady-state cornering including upgraded installation hardware. I was running Strano's front bar and a GM 1le 21 mm rear bar that results in similar roll stiffness as Strano's rear roll bar. The combination is categorized as a balance of handling characteristics applicable to the fbody. With the front bar and factory rear bar the ride was tangibly tighter. There's an effect of increased stiffness with the front bar and cornering was flatter with stability. Interestingly adding the rear bar tied the suspension together effectively resulting in a surprisingly nimble vehicle. Turn-in crispness was sharp with a definite difference in body roll reduction. I found no difference in ride quality with the front bar and noticed a relatively small amount of harshness with the addition of the rear bar with ride quality reduced slightly more, well within average daily driving characteristics.
Panhard Bar
There's a variety of fbody's running single/double adjustable panhard bars. In effect there are countless implementations that work well. The factory bar isn't sturdy compared to an aluminum component with quality rod ends. I specifically chose an aluminum double adjustable rod end panhard bar for upgrading the rear end to factor the sidestepping hitting mid corner bumps during aggressive suspension and/or cornering maneuvers. It has incurred absolutely no extra stiffness whatsoever or harshness in ride quality and I'd recommend a rod/rod PHB for any load bearing application. As far as a double adjustable bar the rear end can be relocated for upgraded wheel/tire combinations (more on my specific wheel/tire combination later) and is categorized as the best way to quell movement of the axle at cornering loads. I built this one with rod ends on both sides using documented instructions here. Assembly is straightforward yet effectively addresses suspension deflection. I utilized Aurora rod-ends though most assemblies utilize QA1 rod-ends, either way will absorb impacts and deflection, without adding harshness to ride quality.
1le LCAs
Lower control arms are a link between the axle and the body frame, having a negative characteristic of LCA deflection. These 1le LCAs stiffen up the chassis in handling accelerating through turns with no excessive play. Simply tightening the overall chassis they consist of a bushing that's twice as spanning as stock, effectively twice as stiff though as far as additional stability the difference may be negligible. Though the difference is not negligible as far as ride quality reduction (the same), and I did notice slight rear end chassis stability improvement when cornering aggressively. The documented instructions are here. This exact setup largely removes the flex associated with stock LCAs and endures performance handling for cases where there's additional slop to be removed from the combo though chassis attachment points dictate the amount of additional ride compromise as you install towards alternate components. If I would upgrade at this point I'd move to an aluminum control arm with a rod end on one side and a rod/rubber combination on the other side, effectively balancing the typical effect of suspension deflection.
Springs
The purpose of springs is to suspend a vehicle between it's outside motion points. I picked up a set of used GM 1le springs. The rates are front rear 360 lbs 130-180 lbs. There's nothing inherently unique about these springs other than the interesting note they're utilized in far less numbers in the market than other springs. They're noticeably stiffer in the rear and marginally stiffer up in front. There's no noticeable effect on vehicle ride quality though for the purpose of this application springs are not a requirement for many performance handling vehicles and not a tangible requirement like other components on this list. Although, a big advantage of running stiffer springs is the decreased pitch fore and aft during velocity changing transitions. Specifically, entering a corner fast and transitioning to steering or the other way around will cause a mismatch of the chassis a moderate amount. The stiffer the spring the less counter effect is required with the disadvantage of a ride harshness hit. While stiffer springs turn out 50/50 yea nea in street driving in track driving it'd be extremely advantageous running springs. Nonetheless the net effect is results of gradual transitions changing directional vectors, largely depending on what springs are on the vehicle. There's no real negative impact with 1le springs and positive impact in the form of noticeably less pitch and roll.
Aluminum Flywheel
The flywheel is the component that absorbs drivetrain vibrations. Not quite a suspension component the aluminum flywheel accounts for increased throttle response resulting from this particular combination. The aluminum flywheel (not designed for drag racing) reduces rotational lag and acceleration inertia by a substantial amount weighing in at a light 13 lbs compared to +-22 lbs. The engine revs much quicker and doesn’t have the overall sensation of a heavy V8 instead similar to a high-revving inline 4 with superbike throttle response. Street manners have yes slightly worsened showing up in the form of proportionately increased complexity in clutch engagement with quicker drops in revs, of course more effective for fast shifting. Rev matching and double clutching is a much closer to applicable for spirited driving applications.
In conclusion all of these components had a tangible improvement in handling, depending on various driving applications. The PHB was a stability upgrade with LCAs also buildable within the context of chassis improvements. Next on the stability list would be springs, as an incremental performance upgrade. The result: the vehicle's completely transformed. It's got the composure of a German sedan with agility of a pouncing sports car. It no longer lumbers like an overweight linebacker instead a 5% lean running-back. For handling purposes it's a big difference from stock and with the addition of beefier control arms and stiffer springs would be an extremely effective track vehicle.
Last edited by lsx24; 04-04-2011 at 06:16 PM.
01-08-2008, 09:16 PM
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Torsen T2r
Also noteworthy is the effect of Torsen's T2r. The limited slip differential design increases acceleration leaving turns utilizing tangible traction. As a gear diff not a typical clutch pack diff there aren't any durability problems. It will work great in autocross, where there's abrupt transitions with differential variations, handy for road-racing when grip inversly increases with vehicle traction. The T2r was installed along with 4.10 gears and this particular combination worked remarkably.
Wheels/tires
The wheels you see in the pic are 17" x 9" Firehawks with 285 BFG KDW. They're an ultra high performance summer tire with treadwear rating of 300. The combo was extremely grippy with excellent wear characteristics though in street driving you wouldn't approach the practical grip threshold. I upgraded to 17" x 9.5" Z06/Argent wheels to leverage a wider wheel for spanning the tire. The effect was less roll-over during aggressive cornering and greater chassis stability. For handling lateral loads effectively I'd recommend a 275 tire with larger than minimum spec 9.5" wheel for decreased tire roll-over and increased contact area.
LCA relocation
With the LCAs in the stock location there is wheel hop during hard launches or combating traction vs adherence. There was an onset of wheel hop at FIR where the surface was sticky although I modulate the clutch appropriately when drag racing. This technique prevented any lengthy chassis reverberation prior to occurrence. Installing LCA relocation brackets improves rear end geometry strengthening the suspension system. LCA relocation is an upgrade for various handling applications though they aren't a required element.
Also noteworthy is the effect of Torsen's T2r. The limited slip differential design increases acceleration leaving turns utilizing tangible traction. As a gear diff not a typical clutch pack diff there aren't any durability problems. It will work great in autocross, where there's abrupt transitions with differential variations, handy for road-racing when grip inversly increases with vehicle traction. The T2r was installed along with 4.10 gears and this particular combination worked remarkably.
Wheels/tires
The wheels you see in the pic are 17" x 9" Firehawks with 285 BFG KDW. They're an ultra high performance summer tire with treadwear rating of 300. The combo was extremely grippy with excellent wear characteristics though in street driving you wouldn't approach the practical grip threshold. I upgraded to 17" x 9.5" Z06/Argent wheels to leverage a wider wheel for spanning the tire. The effect was less roll-over during aggressive cornering and greater chassis stability. For handling lateral loads effectively I'd recommend a 275 tire with larger than minimum spec 9.5" wheel for decreased tire roll-over and increased contact area.
LCA relocation
With the LCAs in the stock location there is wheel hop during hard launches or combating traction vs adherence. There was an onset of wheel hop at FIR where the surface was sticky although I modulate the clutch appropriately when drag racing. This technique prevented any lengthy chassis reverberation prior to occurrence. Installing LCA relocation brackets improves rear end geometry strengthening the suspension system. LCA relocation is an upgrade for various handling applications though they aren't a required element.
Last edited by lsx24; 01-09-2008 at 10:13 PM.
01-10-2008, 01:42 PM
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Isn't this a bare-bones suspension mod - particularily in regards to the jerry-rigged factory LCAs?
If we are going to have a sticky on this cite, it would be nice if we could have additional commentary on a complete build-up that goes from a Stage 1 to a comprehensive chassis and suspension revamp, step-by-step.
If we are going to have a sticky on this cite, it would be nice if we could have additional commentary on a complete build-up that goes from a Stage 1 to a comprehensive chassis and suspension revamp, step-by-step.
01-10-2008, 02:08 PM
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Launching!
If this is intended to be a reference, please delete "struts" from "struts / shocks".
4th gens do not have struts in front. They're coil over shocks. I see this so often that it drives me nuts sometimes
4th gens do not have struts in front. They're coil over shocks. I see this so often that it drives me nuts sometimes
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01-10-2008, 03:02 PM
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>> Isn't this a bare-bones suspension mod - particularily in regards to the jerry-rigged factory LCAs?
Yes.
>> 4th gens do not have struts in front. They're coil over shocks.
Fixed.
Yes.
>> 4th gens do not have struts in front. They're coil over shocks.
Fixed.
01-10-2008, 03:02 PM
#11
It's the mounting. Struts locate suspension components, like the uprights, shocks do not. The spring over the shock does not = a strut. Fox, SN95 Mustangs and 3rd gen Camaro's as well as some other Chevys have struts where the spring is NOT over top of the damper and that doesn't make them a shock either. 
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01-10-2008, 03:09 PM
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I've lowered the vehicle using the lower spring perch on the front Konis and of course the heater hose modification utilizing the rear suspension spring architecture for a subsequent combined ride height reduction of approximately –0.50"/-0.75". The stance is subtle at all corners.
01-10-2008, 03:24 PM
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>> I would like to do this using Koni SA shocks and reusing the stock springs on my 1999 Z28. Did this amount of lowering require any other suspension changes?
No other suspension changes required, unless you have a 3" (or poorly designed 2.5") dual exhaust. Search for "heater hose modification".
No other suspension changes required, unless you have a 3" (or poorly designed 2.5") dual exhaust. Search for "heater hose modification".
01-10-2008, 03:25 PM
#14
"Did this amount of lowering require any other suspension changes?"
I did the same when I got my Koni's but was waiting on Sam's springs.
I did utilize my aluminum PHR to center the rear, even on that small of a drop.
And I concur with the OP, the 1LE rubber is quite nice; I switched to them early last year after running LG rod end LCA's for 4 years. The ride quality is great (no more banging noise) yet I run the same times in autox as the rod ended arms.
I still say the T2R is the snitz, it really makes a huge difference in coming out of corners.
I did the same when I got my Koni's but was waiting on Sam's springs.
I did utilize my aluminum PHR to center the rear, even on that small of a drop.
And I concur with the OP, the 1LE rubber is quite nice; I switched to them early last year after running LG rod end LCA's for 4 years. The ride quality is great (no more banging noise) yet I run the same times in autox as the rod ended arms.
I still say the T2R is the snitz, it really makes a huge difference in coming out of corners.
01-10-2008, 03:28 PM
#15
I run solid rubber bushings in stock LCA's. $55 for the bushings is a deal compared to arms, no noise, no wheelhop (in my case and I'm lowered and no LCA brackets).
Lowering with the Koni lower perch is very common, and requires nothing else aside from an alignment.
Lowering with the Koni lower perch is very common, and requires nothing else aside from an alignment.
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01-10-2008, 04:35 PM
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Do you have any plans to complete the (e.g., do more) mods on the car?
If yes, please continue with the upgrade narrative including pitures of all subsequent mods. It would be beneficial to all to have a complete record that describes the impact of various stages of suspesion and chassis mods.
I thought anytime you lowered a vehicle you need to re-align the front-end and re-center the rear wheels using an adj. PHB?
If yes, please continue with the upgrade narrative including pitures of all subsequent mods. It would be beneficial to all to have a complete record that describes the impact of various stages of suspesion and chassis mods.
I thought anytime you lowered a vehicle you need to re-align the front-end and re-center the rear wheels using an adj. PHB?
01-11-2008, 05:23 PM
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Alignment An alignment should be completed once mods are done. I talked with my alignment specialist service manager beforehand and with ballast in the car we set it to exactly -0.75* each side with maximum positive caster each side, balanced. The result was a perfect compromise between inner tire wear and street driving style. Most if not all suspension architectures aren't built for easily approaching or exceeding 1* negative camber though there isn't an application where this would be advantageous except at a race track.
Also I have detailed additional pics I'll get to uploading tonight.
Also I have detailed additional pics I'll get to uploading tonight.