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Questions about lowering Panhard bar for handling.
So I've read lots of threads on the subject, and have a very basic understanding of what's going on. More to the point, when someone else explains it, it makes sense. I understand the roll center vs. center of gravity, and the moment arm/distance and how it effect the handling on the most basic level. I'd like to lower the car, increase exhaust clearance, and improve the front to rear roll axis. Also, while I do drive the car hard, and will on occasion make an auto-x lap, I'll NEVER have enough wheel time to fine tune while driving on a track, with the car at its limits. I want to make some basic improvements to some low hanging fruit areas to make the car better.
And it stands now, without measuring, the panhard is pretty close to level. So. If I lower the car, AND lower the chassis side to improve exhaust clearance, that's gonna put the chassis side a bit lower than the stock axle side panhard mount. Would/should my goal as this point be to use the axle side bracket to bring the panhard bar back to level? Lowering each side would lower the roll center more than just one side, and I know you can lower the RC too far. This is where I lose the ability to think it through. Is lowering both sides too much? -without being able to fine tune car with trial and error???
Re: Questions about lowering Panhard bar for handling.
Well, not sure how it would work on the ***-end, but many old style hot rods will Z the pitman arm to eliminate bumpsteer, etc. So my uneducated thought is if Z bend the bar, you still have essentially a parallel plane, right?
Re: Questions about lowering Panhard bar for handling.
I am curious to learn about this topic too. I will stay tuned, but I have tried to do my best to keep my panhard bar as close to parallel as possible, yet the chassis side(pass side) is lower than the spot where it mounts on the moser 12 bolt (drivers side) so it goes slightly uphill. I have adjustments on both sides of the UMI panhard bar, as well as the panhard bar lowering bracket (pass side) and a founders upper panhard bar brace. I have always wondered if i could improve on this setup to get the bar more level, so I am staying tuned for how the TGO community answers this topic.
Re: Questions about lowering Panhard bar for handling.
Yeah, Dean knows his stuff. TEDSgrad also has lots of good info, as do some others. I thought I'd read most of the lowered "pan" threads,but missed that one. He definitely suggests NOT lowering the chassis side. -when coupled with the axle side drop it REALLY lowers that roll center. -figured it was TOO low, but I don't really know. He seems to suggest that as well soooo, at least for know I'll go with that.
IROCZman15. - From what I can tell, what you're really looking at, on the most basic level is the roll center, the center of gravity, and the relationship of the two. Then take THAT relationship between RC and CG, and compare that combo to how the FRONT RC and CG is set up. ...the issue as it pertains to the rear panhard bar is that lowering the rear panhard a little helps lower the RC a little which is generally good. Lowering BOTH sides lowers it a LOT, which can actually hurt performance. ...and then of course you want to keep it relatively level. Doing chassis side only on a stock ride height may not be too bad, but on a lowered car, that really throws the panhard geometry (out of level) off. Dropping the axle side on lowered car helps FIX the angle and bring it back to level. ....only issue is axle side doesn't increase room for exhaust, where as the chassis side drop does.
Like all things..... ....balance is key I suppose. Can't have it all.
Re: Questions about lowering Panhard bar for handling.
good info there. ok cool, hmmm, how would you go about lowering the axle side? I can't recall I have seen any type of bracket/mount to lower where the PHB mounts to the axle (driver side), but I was never really looking for one either.
Re: Questions about lowering Panhard bar for handling.
Yes, there are brackets that lower the mounting point. You can bolt it in, but....everyone recommends it being welded. The change in roll center dramatically increases the forces the panhard applies to this bracket.
Re: Questions about lowering Panhard bar for handling.
UMI has a couple of kits to address this situation and the tech guys there know there stuff. I recently went with them to address a panhard brace issue that gave me some much needed exhaust clearance AND corrected the panhard bar level as well.
Re: Questions about lowering Panhard bar for handling.
The axle side will move up under load, thus evening out the bar some - so a little angle is preferred.
You can lower too much, and without corresponding increase in spring rate will cause some problems (steering up front as well). And I don't want to be the one quoted saying it was all-right to do. Even though we can speak of Fr RC and Rr RC for changes and a 'snapshot,' it is important to remember that it is all one axis - so changes at one end effect the whole axis. Not just back to front, but rear to front diagonal. So you do effect how the front tires are worked by changing the Rr RC (front, of course). Additionally, springs and swaybars have to be well thought out for the change in leverage. Lots of multiple things effecting how the weight transfer is being handled.
For street, lowering just the axle side and be cautious is what I recommend. After experience and trial and error, you can always add a chassis side, but most of us (self included) will not need it.
I have the big SW exhaust, and I do not have problems.
UMI had a video around of just how much leverage was put on that bracket. Welding is a must (I bolted in place then welded), and a brace to keep the bracket from deforming is not a bad idea (though I did not use the one supplied by the Jegster unit).
Re: Questions about lowering Panhard bar for handling.
TEDS....that all makes sense. Thank you for the response. -what I'm finding is that most aren't having issues with the exhaust, so that really helps if I don't need to lower that chassis side.
Re: Questions about lowering Panhard bar for handling.
I think I've posted this before, but it helps to conceptualize a multi-moving scenario:
TERMS: Roll Center (RC): Cars have two roll centers - front suspension & the rear suspension. They act as pivot points when discussing them individually – but they are one axis. When a car experiences body rolls during cornering, everything above that pivot point rotates towards the outside of the corner, and everything below the pivot point rotates the opposite direction, towards the inside of the corner.
Center of Gravity (CG): A calculation of the car’s mass to determine where the center is. When a car is cornering, forces act on the car’s Center of Gravity.
Moment Arm: The distance between the height of the CG & the height of the Roll Axis is called the “Moment Arm.” Think of it as a lever. The farther apart the CG & roll axis are, then the more leverage the CG has over the roll axis to make the car roll.
Weight transfer: The car’s weight mass at the CG is acting on the roll & pivot axis of the car and applying “Force” when the driver tries to get the car to stop, turn or accelerate.
Roll Angle: The amount the car “rolls” on its roll axis (side-to-side) in cornering. Pitch Angle: is the amount the car “rotates” front to back under braking or acceleration. Dive: The front suspension compressing under braking & cornering forces. Squat: The car planting the rear end on launch or under acceleration Roll: Side to side body rotation, or body roll. Pitch: Fore & aft body rotation. When the front end dives & back end rises under braking, or when the front end rises & the back end squats under acceleration. Understeer: The front tires have lost grip and the car is going towards the outside of the corner nose first (push). Oversteer: The rear tires have lost grip and the car is going towards the outside of the corner tail first (loose).
Contact patch is the highest priority. This is the overarching theme.This is why dampahhs (shocks/struts) and rubbahhs (tires and their compounds) are critical. You just have to pay the price. Shocks help keep the contact patch. Before we go too far with parts, let’s look at the car and the suspension philosophy.
Re: Questions about lowering Panhard bar for handling.
For cars to handle well, the suspension needs to travel or work (it can’t be flat). It has to roll and pitch. It is dangerous to have a car that rolls a lot, and pitches a lot. So we need to find a balance. There are two common strategies: let the car roll a lot and pitch a little (conventional), OR, pitch a lot and roll a little (modern). The conventional route has stiff front springs and soft rear springs; and small sway bars to allow the car to roll: low travel/ high roll. The modern route has soft front springs and stiff rear springs; and big sway bar in front with smaller one in rear: high travel/low roll. Both these strategies are effective. Soft and stiff are relative terms: total difference in dive could be as little as 2” or less; total difference in roll angle 2*.
The front tires need force, from weight transfer on corner entry, to provide front tire grip. Too little & the car pushes (understeer), too much & the car is loose on entry (oversteer). The rear tires need force, from weight transfer on corner exit, to provide rear tire grip. Too little & the car is loose, too much & the car pushes on exit.
Our cars suffer from:
- the static roll center height is too low, causing too much roll angle
- the dynamic roll center height in dive and roll is too low, causing even more roll angle
- front suspension geometry has a jacking effect and a higher front roll angle vs. rear
- rear roll center was too high
Re: Questions about lowering Panhard bar for handling.
Roll Couple Example: Here are some examples using a 3500# car with 55% front weight to provide some conceptualization:
If the CG is 20” high, and the front roll center is 1” above ground, the car has 55% of the 3500# weight with 19” of leverage to roll the front of the car.
If the CG is 20” high, and the rear roll center is 11” above ground, the car has 45% of the 3500# weight with 9” of leverage to roll the rear of the car.
* Rolling the car that much more in the front overloads the outside front tire & under- utilizes the inside front tire when cornering.
If you lowered the car 2” the CG drops 2”. The front roll center probably moved too, but it’s not linear as it is based on A-arm angles. Let’s say it dropped 1” in the front to 0” above ground and the rear stayed the same at 11”. Now …
If the CG is 18” high, and the front roll center is 0” above ground, the car has 55% of the 3500# weight with 18” of leverage to roll the front of the car.
If the CG is 18” high, and the rear roll center is 11” above ground, the car has 45% of the 3500# weight with 7” of leverage to roll the rear of the car.
* The front now rolls over less & the rear too, making the car run “flatter” - not flat, just less roll angle which works the inside tires better.
So it is very important to know your vehicle, and to minimize the moment arm (leverage) with both front and rear (roll couple) in mind. Getting the front & rear of the car to roll similar is desired. Getting them to roll the same is not, because the goal is: To have optimum grip on all tires and disengage the inside rear tire (to a degree) to turn well, then re-engage the inside rear tire (to a higher degree) for maximum forward bite on exit (Dean would advocate progressive rate rear springs, here). So, on entry & mid-corner, the car needs to roll slightly less in the front to keep both front tires engaged for optimum front end grip (more dive), while allowing the car to roll slightly more in the rear to disengage the inside rear tire, to a small degree, to turn better. For optimal exit, the car will have more roll in the front & less in the rear to re-engage the inside rear tire to a higher degree than it was on entry & exit, for maximum forward bite (traction) on exit.
Going back to the roll couple example, by lowering the car, the front roll center goes to ground level (even below ground under braking-dive). What is needed is to raise the front roll center in order to reduce the moment arm (leverage). Drop spindles are the best method; they can raise 2”, but they are scarce for our cars. Extended ball joints can raise the front RC by 1” - #1. About the rear RC, you can weld-on a bracket to the axle-side panhard bar mount - #2; lowering the attachment point, which lowers the rear RC (small incremental changes, here). In this way, you are decreasing the front roll leverage, and slightly increasing the rear roll leverage so that they are closer together – a better roll couple. These two modifications are the two best changes to make (whether lowered or not), AND they do not cost a whole lot of money. By mitigating the forces applied to the roll couple, you make all your other parts work under less stress/force/leverage. This increases the effectiveness of all the other parts.
By lowering the CG 2”, and using ext. BJ (+1” RC) and PHB mount (-1” RC), the car would have 17” of leverage to roll the front; and, 8” of leverage to roll the rear. These are example numbers, not fact. But that’s a very good outcome for such little money, which also increases the effectiveness of all the other parts.
Lowering the CG helps lessen the moment arm (as in the example). But if we can’t raise the RC out of the weeds, it may be better to raise the car. A bigger sway bar would be necessary to limit the moment arm. Ride height is a tool in the tool kit, not a goal in and of itself.
Now that we have attempted to optimize the roll couple, then we can focus on springs, shocks, and sway bars as tools to control the weight transfer and keep all four contact patches optimal. We tune a car to find the optimum balance of grip. Grip equals speed.
Now the conventional or modern approach needs to be decided upon. High roll/ less pitch (conventional), or low roll/more pitch (modern). Again, these are relative to each other, not extreme positions by themselves. The modern approach puts the nose on the ground (more weight xfer on the front) to provide grip to turn. The conventional approach uses more roll angle to help turn (not that it doesn’t have some pitch). The modern approach can carry more corner speed, but the conventional approach can out-brake going into the corner = two different driving styles.
The conventional will use heavier front springs and lighter sway bar; modern will use softer front spring and bigger sway bar. With a bigger sway bar, you can’t just lock up the front suspension – you need independent wheel movement. Limiting roll helps preserve tire life – better for long road courses. Softer bar with more roll heats up the tires more – better suited for AutoX. But personal driving style/preference will really dictate which to choose. Remember, you have to match the rear with the front choice.
NOW, we get to spend the money. We’re back to dampahhs and rubbahhs. Get the best, or save until you can. This includes lightweight wheels!
Unsprung weight is key to a great handling car. It greatly aids the contact patch. It makes a car more comfortable to drive (less jarring force of inertia). Lightweight and strong parts are expensive. There is no getting around it, and most people are also saving for more horsepower. This is where the rubber meets the road, and the pretenders are separated out. In my opinion, a #19-#20 17x9.5 wheel is the standard goal. If you can find drop spindles, then shoot for #18-#19 17x8’s. Then add aluminum hubs, 2 pc curved vein rotors, FSL calipers, and tubular a-arms. There is much more to be said about weight savings and other performance parts; they are listed in other threads.
I hope this aids your thought process as to how to go about making your car handle better. The best step is the roll couple, the cost is low, and it does apply to cars lowered or not.
Instant Center is the point where a real pivot point is, or two theoretical suspension lines come together, creating a pivot arc.
Front Lateral Load Distribution & Rear Lateral Load Distribution (aka FLLD & RLLD)
FLLD/RLLD are stated in percentages, not pounds. The two always add up to 100% as they are comparing front to rear roll resistance split. Knowing the percentages alone, will not provide clarity as to how much the car will roll … just how the front & rear roll in comparison to each other. If the FLLD % is higher than the RLLD % … that means the front suspension has a higher resistance to roll than the rear suspension ... and therefore the front of the car runs flatter than the rear of the suspension … which is the goal.
Reminder: You’re not creating the Force. The Force already exists when you try to stop, turn or accelerate a 3500# car. When you step on the brakes, Force will make the front end want to compress (dive) & the back end want to lift … also known as “pitch.”. You’re just using the tuning tools available to influence how fast & how far the front end dives & the rear end lifts. When you steer the car hard left or right … Force will make the car roll about its roll centers. You’re just using the tuning tools available to influence how fast & how far the car rolls. On corner exit, under power … you get it.
So how do you work a tire more?
The further the suspension travels … the more weight is transferred TO that end or corner of the car, putting more load & grip on the tire(s) at that end or corner. And more weight is transferred FROM the opposite end or corner, reducing the load & grip on the tire(s) at that end or corner.
Re: Questions about lowering Panhard bar for handling.
TEDSgrad....I'm going to have to read through that more thoroughly again later, but I've definitely read your posts on the subject in many other threads. I appreciate you postsing that up. I have some general questions and comments, but it's gonna have to wait 'til I have a little more time.
Re: Questions about lowering Panhard bar for handling.
TEDSgrad (Brian?) ....I just re-read. Thank you for posting. -and I do understand pretty much all of it. I do have a few questions.
First, with regard to modern/conventional, stiff/soft, front/back ...."relative to each other" as you said, how would you describe the spring and sway bar relationship, front to back, on your average Iroc or WS6? Just looking for a perspective on where many of us are starting. We can look up the numbers, but not how WELL (or not) they're set up relative to each other. -and of course, GM is going for comfort as well, not just handling, but still.
Second. Can you elaborate on the characteristics of springs vs. swaybars? Why are the spring/swaybar (stiff/soft) opposite front to rear? I CAN see how they'd affect pitch or roll respectively, but why they're different front to back....I just don't see. I trust you....I just don't understand why.
Third, wheels. First, you recommend 17". Certainly not arguing AT ALL....just noticed that's what your recommendation was. Second you dropped the width from 9.5" to 8" if you can find drop spindles. I assume because of tie-rod interference, but I suppose that's how strongly you're advocating for the drop spindle/raised ball joint geometry?
Finally. ...and I hate to be the guy who asks this, but how do conventional/modern strategies rank in terms of street driven ride quality? I'm guessing a properly set up suspension on the softer side will do both track and street fairly well, where as a poorly set up, stiff suspension, won't do either very well. I'll admit that on my last 89, I threw all the advertised suspension parts on the car and performance was decent, ride was relatively harsh. I'd really like to be better on BOTH areas this time around. Maybe THINK more....possibly spend less. Or not....but still want to plan it better.
Re: Questions about lowering Panhard bar for handling.
Originally Posted by Abubaca
TEDSgrad (Brian?) ....I just re-read. Thank you for posting. -and I do understand pretty much all of it. I do have a few questions.
Yes, Brian. My username denotes that I am a grad of TEDS (Trinity Evangelical Divinity School) in Deerfield, IL. I am a Philosopher undergrad and a Theologian grad. I like the opposite/visceral discipline of road racing - balances out my heavy intellectualism. My late younger brother was a National Champion of motorcycling - imported the first Aprilia works bike into the US. I was proud to take him out to Laguna Seca (in my Formula) in '94 for the FIMA race where he watched his AMA team race with the President of Aprilia in his box (I had to watch the race at the Corkscrew!)- way cool memory. He passed away in Paris in '96. Here's a pic of him and his Aprilia at Road America '94 taking second (as team owner):
First, with regard to modern/conventional, stiff/soft, front/back ...."relative to each other" as you said, how would you describe the spring and sway bar relationship, front to back, on your average Iroc or WS6? Just looking for a perspective on where many of us are starting. We can look up the numbers, but not how WELL (or not) they're set up relative to each other. -and of course, GM is going for comfort as well, not just handling, but still.
The starting point is what I referred to as what are cars suffer from. The leverage (or moment arm) can be mitigated by Ext. BJ and PHB Bracket - altering the Roll Couple. This helps all the other components do their job better. That is why I preach (pun) improved RC's and with very little cost - BIG bang for Buck. Our platform uses struts vs. double wishbone/shock tech of modern tech. Don't be discouraged, though. BMW still uses strut tech very successfully and it is cheaper than modern double wishbone/shock front suspensions. There is no shame, here. The real shame is in current market tech for struts. Koni Yellows are the bang for the buck option, but outdated. DSE's JRi are a fabulous answer, but unobtainable for my budget - C'mon RideTech fill that middle! GM is concerned with lawsuits, first - not necessarily comfort. Designed Understeer satisfies the lawyers. As we all know and want, a more responsive suspension will bring out the daring in all of us! This is why my recommendations are more moderate, then learn and increase as you go along. I put two wheels in the grass in the 'kink' at Road America. I don't say that with pride (never doing it would be more boastful), but I didn't panic and my shorts were dry. But we push, that's what we do.
With our platform, conventional wisdom says to tie down the front, and match the rear to it (relatively easy). So, flatten the front, and let the rear rotate to aid in turning - that's conventional. Conventional vs Modern also has to take in personal driving style; AND, tire wear!!!! Big concern on road courses vs. Auto cross/street.
There are so many factors to answer your question, I can only give personal opinions. With lightweight components and an LS2, I prefer a custom front bar (stiffer than WS6 36mm) and run relatively softer #900 fronts (most racers are 1k and above but don't have drop spindles and .5" ext BJ's). After the moment arm factoring first, it's a trade-off between bigger bar or bigger springs - you absolutely need independent wheel movement for tire grip! I go bigger bar and softest/ish springs up front (my Fr RC improvements factoring in - I can allow for more travel w/out Fr RC going underground), and harder springs in back with softer bar (#250/19mm). I've seen vids of 3rd Gens lifting the rear tire in corners.
Second. Can you elaborate on the characteristics of springs vs. swaybars? Why are the spring/swaybar (stiff/soft) opposite front to rear? I CAN see how they'd affect pitch or roll respectively, but why they're different front to back....I just don't see. I trust you....I just don't understand why.
Springs keep the ride height - and when compressed they have force to return/over-return. Shocks (simplistically) are a timing device - how fast or how slow they allow the return to ride height. Bars tie the left and right tire together so that they are not independent of each other (important in a roll situation, not desired in road imperfections- harsh ride). In turning, front tire load is crucial to grip, both in terms of moment arm on roll axis (primary) and with sway bar helping to even out both front tires. But road imperfections can upset the car! Maintaining the ultimate contact patch is a balancing act, for sure. That is why I improve Fr RC, big bar, and lighter spring than most w/LS2. Let it shift weight onto the fronts (more travel w/improved RC's) and tie the left/right together to combat roll, and a light-ish spring to allow for independent up/down movement with the lightest wheel assemblies.
Third, wheels. First, you recommend 17". Certainly not arguing AT ALL....just noticed that's what your recommendation was. Second you dropped the width from 9.5" to 8" if you can find drop spindles. I assume because of tie-rod interference, but I suppose that's how strongly you're advocating for the drop spindle/raised ball joint geometry?
Yes, I argue strongly for drop spindles over wider wheels within road rut reason, of coarse. In one of my Grip posts, that is what I argued. I can actually fit an 8.5' custom wheel (255mm tire) because of tie-rod interference. Again, just a larger wheel (metal) and tire (rubber) does not mean that you are controlling that increased tread. And longevity is questionable - but many don't care about that. A heavier wheel assembly and more scrub radius, does not mean you have increase tire patch control! My thread discussed/debated that. Even though one might think 255 vs 275 is a no-brainer, you have to maintain the increased weight assembly, suffer more scrub radius, and last the road race/ street longevity (AX not a consideration). A wider tire does not equate to more tire patch - continuous weight on the width, does. Now if someone wants larger than 275, my argument does not hold. But on the street, the ruts will make driving not fun or enjoyable. I'm a foursquare guy, but I'm tempted to go 255 fr and 275 rear with the LS2. Wheels/Jewelry will be my last mod - yeah, right!
Finally. ...and I hate to be the guy who asks this, but how do conventional/modern strategies rank in terms of street driven ride quality? I'm guessing a properly set up suspension on the softer side will do both track and street fairly well, where as a poorly set up, stiff suspension, won't do either very well. I'll admit that on my last 89, I threw all the advertised suspension parts on the car and performance was decent, ride was relatively harsh. I'd really like to be better on BOTH areas this time around. Maybe THINK more....possibly spend less. Or not....but still want to plan it better.
Absolutely! From The Grip - Shock the Monkey
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.
Re: Questions about lowering Panhard bar for handling.
Brian, thanks for all the info!!!!!!!!!!! It really does make sense once it's explained, though I realize it's still just the tip of the iceberg with regard to the big picture!
Re: Questions about lowering Panhard bar for handling.
Abubaca I will give you my 2 cents since your looking to get the most bang for your buck. Now you been in the game for awhile so im sure you know Koni yellows will give you a great ride with good comfort level. Now you didnt say if you wanted weight jacks or not but I will say up front there is a cut off around the #850 spring mark go more then that and your crossing the invisible line of leaning to more race car stuff and less comfort. The rear is more tricky a little change will have a big impact on ride quality #200 rear coil spring is what I have right now and its fairly stiff back there but I deal since I like to hit the turns hard. So maybe around the #175 mark would be a happy place.
Now on to the panhard bar.. I feel this is important to get the bar back to level after a spring change if your going to be push the car to the limits but with that said I have seen a car with very unlevel PHB beat the pants off a pile of thirdgens one being a full race big money car that travels the country.
Re: Questions about lowering Panhard bar for handling.
Abubaca I will give you my 2 cents...
I appreciate the response! I'll tell you where I'm at.
Koni's are on order. Covid is slowing everything down, but should be here soon. I've also got the Ground Control weight jack kit on order. LAST car had the GC kit with the 850/175 springs, and BIG bars. Before reading through all this info here, my plan still was to do the panhard/raised ball joints, hence my posting this thread. My plan was also to NOT have it ride quite as rough as the last car. I talked with Donovan extensively about spring rates, and with his half hearted approval, I went with a 750/175 spring combo, hoping a closer to stock front spring with a big bar will work. I also FULLY accept that handling may suffer some while hopefully keeping the ride closer to stock. This may be a disaster, and Donovan/GC stated he felt the theory was sound but that I would feel they're too soft. Springs aren't overly expensive so my plan is to give it a go at stock ride height, minus .75" for the ball joints, then match the rear with the jacks accordingly. Last car suspension was OK, but not properly sorted. I hope with THIS car that it'll be a good balance of ride and handling. How exactly i get there isn't 100% certain yet, and I'm fully expecting some trial and error.
Re: Questions about lowering Panhard bar for handling.
Did your last car have Koni's on it? 750/175 will work great I run big bars on mine with zero issues. I used to know the eibach sportlines #s think they come in around 725/125 and I never had a issue with the fronts the rears are way to soft though.
Re: Questions about lowering Panhard bar for handling.
36 ws6 and umi hollow 22 with 850/200 umi weight jack front normal coil spring for the rear. I was going to go all in with the 1050 up front but my front is real light now with the aluminum block and carbon fiber hood.
Re: Questions about lowering Panhard bar for handling.
How does that UMI Hollow 22 compare to stock IROC/WS6? 24 solid, right? Sounds like I'll be fairly close to where you are...just a smidge softer. ....I'll be all aluminum up front soon too!
Re: Questions about lowering Panhard bar for handling.
If you have the 24 already then I wouldn't run out and buy a bar till after you see how the car feels and reacts. Been a long time since I seen a 24 rear bar but I think they are solid. The 22mm seems to be the go to bar for the 4th gen crowd Sam Strano uses it in his kits and he can back up his parts with a lot of wins at the tracks over the years.
Re: Questions about lowering Panhard bar for handling.
I believe the 24 is solid...and frankly, I haven't measured this car, but I think that's what the 88-90 Iroc had. 24/36 IIRC. ....so the 22 hollow would actually be less bar? -Or is modern fabrication methods somehow make it stronger??? Assume with how the discussion has gone, it's a little softer, paired with stiffer springs?
Re: Questions about lowering Panhard bar for handling.
Yes the 22 should still be less bar then the solid 24. The front is more forgiving it likes a big bar and stiffer springs long as the strut is up for it. The rear will be harder to dial in the 24 solid is a serious bar and I have never got to try it with aftermarket springs.
Last edited by obeymybird; 10-02-2020 at 09:31 PM.
Re: Questions about lowering Panhard bar for handling.
This was at UMI last year and my first event ever. I had the front koni’s set to about 50% and rears on 1 click and by the first part of day 2 the car was fast had the fastest lap out of all the thirdgens there beating the famous dragonlady GTA.
Re: Questions about lowering Panhard bar for handling.
This years event was a different story just got the new motor in a week before the event and the only suspension change was zero clicks on the rear koni’s. Most of the same thirdgens came back from last year long with a few others. Much to my surprise I was super slow way back in the pack think I counted 13 thirdgens and I was around the 10 spot. Car felt fast but it was fighting me and sliding a lot in the turns some how on my last run I put up a good time putting me at the 3rd spot just .005 behind dragonlady. Long story short I needed to soften up the front koni’s to make up for the new aluminum block basically had the front suspension locked up.
Re: Questions about lowering Panhard bar for handling.
Don't be so thensitive! Assert yourself!
A lowering of RC requires a stronger spring, yes. FACT.
The conventional wisdom is to tie down the front, and match the rear to it. Keep this in mind.
Without RC improvements, the front dives into the negative ground. And, the rear springs are sooo soft, that the rear solid axle and strong-ish bar prevents independent movement. One cannot maintain rear tire patch. Well-proven. IMO, more rear ###, and less bar.
You cannot have stock weak spring rates, and have performance or control of weight transfer! They (the lawyers) bake the cake. But we can make the platform perform wonderfully.
Spring rates cannot be discussed apart from shock control rates. They work together. An optimal system will account for both. In looking for a 'ballpark' rate, look at the experts. That only gives you a starting point. IMO, DSE knows what they are doing - just over-priced. Press them for details.
Shocks are timing control devices. They have to be matched to spring rates. This is where the winners and losers are separated.
IF there was an alternative front SB, I would consider a lesser spring rate. So far, it is not economical or practical for a street driven car. This may change!
So, you cannot keep stock spring rates and increase shock timing. They are a pair. Springs keep a set height; and the shocks are a timing device to re-set the ride height in time. Talk to a company that will "re-valve" shocks to spring rates and you'll learn. Good assignment for you.
If you go 150mph into a 90* turn, you can't have all the weight transfer onto the front, with no rear traction at all. Spring rates and shocks (timing devices) will determine traction and comfort. IMO, #850 or more in front, will give balance to the back, and allow for controllable weight transfer to the driver, my opinion. Others may disagree.
With lowered RC's, #850 front or more along with a small rear bar and #250 or more in the rear is an excellent staring point. Personal preferences will dictate the rest. Again, look at DSE, and arrive at your own. Don''t take one person's opinion, mine included, look at several.
Also, be willing to challenge your own theory, and do something different. I am a theory guy, but smaller rear bar and more spring was the answer. It works.
Brian, I'm pulling this quote from your answer on that other thread.... didn't wanna clog his thread with our discussion.
You mention coming into a corner at 150mph. I don't wanna go 150mph in a car. Ever. ....and that go me thinking. Everyone can go buy a set of Eibach springs and a set of decent shocks and struts and handle better that joe guy with a stock Iroc. At what point does the revised suspension geometry start to matter? The physics makes perfect sense, but frankly, I may never push the point where it'll matter. I've done parking lot AutoX a few times and hope to experience some time ON the track, but it's certainly not a track car. Do you think your average enthusiast will be able to appreciate the benefits, or do you really need to have your car at nine tenths, to where all the mass is REALLY getting thrown around for it to make a difference? -and I know that's one of those vague "no real answer" questions, but frankly I have absolutely no idea. I've built enough engines to really have a feel as to where the little things make a difference, and where they're just wasted money for the average guy. Suspension, I'm a noob.
Re: Questions about lowering Panhard bar for handling.
About 150mph at a long track like Road America. Even my TPI hit 130mph into turn 5. Here's a video of a crash going into turn 5 - just because it's so interesting to watch.
I think a better suspension is always desired - car control, weight control. Public roadways are much more dangerous, and panic situations, road hazards, ope-range areas, and the like create the need. Now the shocks and shock valving are more critical at high speed. I'm not an engineer, so my knowledge is limited.
The mass is always getting thrown around, anyway. I drive by a skid pad where I watch new WI State Troopers learning car control, kind of fun. Quick maneuvers are sometimes necessary.
Back in 1994, I took my father on a vacation to Glacier Natl Park, Hell's Canyon on the Snake River, and Yellowstone Natl Park. My Dad was white knuckling the arm rest at 125mph, so we agreed on 110mph with AC on and Cruise Control. Those were days when no speed limit in Montana during daylight. He even took over and drove at 110mph. Days of legally doing that are over. But so many more things can happen on a public roadway, that slower speeds are necessary. I was just having fun driving down BearTooth Highway ( http://beartoothhighway.com/ ), came around a corner, and a moose was standing in the road! Go figure.
Re: Questions about lowering Panhard bar for handling.
I say begin somewhere and havefun with it. You can always tweak things later. Could be years before you even care enough to go to the next level. You two clearly do not have the same interests, so I would not expect your cars to be built the same either.
Re: Questions about lowering Panhard bar for handling.
I say begin somewhere and havefun with it. You can always tweak things later. Could be years before you even care enough to go to the next level. You two clearly do not have the same interests, so I would not expect your cars to be built the same either.
Agreed. ...and the parts are on order, so we'll see where that lands me. I keep saying how limited my knowledge is, and compared to Brian and some of you others who really know your stuff, I am limited. Still, I've got a lot of time behind a lot of really good cars over the years, and I do know how I like the car to handle. I may not know WHY, but I can typically feel what's going on enough to be able to articulate it back to someone in conversation. I think I know relatively what to expect. Where it'll do well, and where it's gonna be a little sloppy. -and thanks to Brian and some others I feel I know where to go when I do make changes.
09-23-2020, 08:30 PM
