Double panhard rod???

I just thought up the idea because i was bored (when am i not). So, does anyone think it would be worth to put two in? Here's what i was thinking, one of two ways.

1) get two and run then side by side/parallel
or
2) Get one running one way then another running the other, so it makes an "X" like thing.

Anyone think any of this would add to the firmness of the suspension or am i just thinking up a load of BS?

ShibbyZ

If your looking for the upper...you can run an upper BMR Bar like the pic off their webite site. BMR Upper PHR (http://www.bmrfabrication.com/phr/Uphr-installed2.jpg). Your idea sounds complicated about an "X" design but try it and let us know. :D

The X setup would make it plenty firm. Like "preventing suspension travel" firm.
I don't see 2 parallel rods being beneficial to anyone but BMR.

The upper bolts would also need to travel from side to side in the suspension at all 4 points of the X. The top and bottom two would be wider apart the lower the car is, and closer together when the suspension is extended.

As Bud M said, an X would eliminate all rear suspension travel. You might as well bolt the rear end to the frame.

If, as toby360 said, you allowed for bolt travel, you would lose the firmness you were going for in the first place.

One panhard rod is all you need!

-Jake

If your looking for the upper...you can run an upper BMR Bar like the pic off their webite site. BMR Upper PHR (http://www.bmrfabrication.com/phr/Uphr-installed2.jpg). Your idea sounds complicated about an "X" design but try it and let us know. :D
My parallel PHR would look something like that picture but it's just be two side by side. Just bolted maybe 2 inches apart from eachother.

The X style i knew would stop sway period. I was just wondering if anyone tried/thought of it before. Would the X style also stop my up and down suspension? So that way my back end wouldn't squat at all? basically what i was looking for is ultimate suspension/firmness with only PHR and LCA's.

EDIT: Just had a thought. Would the X style put my front end in danger of rolling? Like drag cars when they have a ton of torque put on the car and the front end lifts up on one side. Could my front possibly have that happen around hard corners? Or would the two PHR's take care of that and keep all 4's on the ground? Maybe a bigger front sway bar....

X style would stop up and down, period. It would not stop sway, but it would make sway feel weird. I've thought of it before (when I was first learning what a panhard rod was), but ruled it out quickly.

Experiment:
Materials needed:
- two pair of chopsticks
- 4 sewing needles (or other small pins or needles, long enough to go through two chopsticks, and thin enough to do so without splitting the wood)
- knife sharp enough to cleanly cut the chopsticks
Description:
- Two of the chopsticks will be your panhard rods. Another is the rear axle assembly, and another is the rear subframe. We will use this to demonstrate the range of motion allowed by the proposed configuration.

Steps:


Take two chopsticks and cut an inch off the end. Lay them parallel to each other, 1.5" apart, oriented horizontally (these are the rear subframe and axle assembly).

Take a third chopstick and lay it across the first two, on an angle, like a panhard rod would be. Press one pin through each end of the panhard rod chopstick, making sure to have it go through the subframe chopstick and rear axle chopstick.

Flip the whole assembly over, so that the panhard rod chopstick is now on the bottom.

Attach the second panhard rod chopstick in the same manner that you attached the first one, only angled the other way.


You should now have an X-shaped assembly. Stand it up so that the rear axle chopstick is on the ground (or a table, or whatever), and the subframe assembly is directly above it (oriented like it would be on the car). You may need to set it on something small (paperback book?), so that the attachment points have the room that they need to pivot.

Press down (lightly! don't break the chopsticks!) equally on both ends of the rear subframe chopstick. It doesn't move! Now press down lightly on only one end. Experiment with the motion of the assembly. See the other end rise? Notice the shift to the side? Those are both motions that would be highly undesirable in a car making a turn.

-Jake

Very good experiment, just tried it and now i know what you're talking about. I also came up with a new idea.

Weld everything together so nothing can move... :D

But seriously, i did. The X'd PHR's would kind of cancel out the rocking or lifting of one side. Because they aren't attached to eachother. So one would knock out the rock to one side, and it wouldn't rock hardly at all, and the second would knock it out to the other. So even if there was a lean to a side, it would probably be so small i wouldn't notice it. Am i making any sense or did i just think up another POS?

I'm glad you tried my experiment, and I'm glad it worked, because I came up with it on the spot and described it without trying it first. :)

Are you looking for a completely solid suspension? What's your goal here?

-Jake

I'm glad you tried my experiment, and I'm glad it worked, because I came up with it on the spot and described it without trying it first. :)

Are you looking for a completely solid suspension? What's your goal here?

-Jake

It worked with some minor adjustments...like tape... ;)

My goal is to get a perfect cornering car. I road in a buddies and he has his suspension done to the max. PHR, LCA, subframe connectors, KONI shocks, 1.5" lowering sport springs, the works. I guess he spoiled me. I'd like my car to have less lean then it does now when cornering. After riding in his it feels like mine's a boat. I just thought up the idea hoping it would solve my problem without getting everything he has. Would LCA and PHR solve this to a very good extent? He told me the PHR was a huge improvement over stock.

It worked with some minor adjustments...like tape...
By using "tape" you defeated the purpose and results. You added a feature that bolted or pinned conections don't provide - "slip". Make the connections rigid with pins eliminates most of the possible movement.

Rather than reinvent the Panhard bar, why not consider a Watts Linkage in its place? That improves the lateral location, by elminating the offset that occurs when the body starts to roll.

http://www.fays2.net/fays2_watts_link_4_.html

And remember, the Panhard rod is providing lateral location, not roll resistance. The "sway" bar provides the roll resistance.

And remember, the Panhard rod is providing lateral location, not roll resistance. The "sway" bar provides the roll resistance.
Ha, I didn't even think to point that out!

He's right. The Panhard rod is there to keep the rear axle from moving from side to side -- it really isn't intended to reduce body roll.

LCAs don't do that either. If you want your car to corner like your friend's car, you need the shocks, the springs, and the swaybar(s) (which you didn't mention, but I'm guessing he has). The LCAs, SFCs, PHR, torque arms, and all that other stuff help the car transfer power to the ground, and have a minimal effect on cornering ability.

-Jake

Hmmm, now that i think twice, it does make sense that the PHR is for the lateral and not sway motions. Maybe i can custom make a sway bar 3" thick... ;)

just kidding. So i guess sway bar, shocks and springs are my biggy for cornering. For power to the ground, PHR, LCA, SFC's and torque arm. well now i have something to work with till i get enough money. Thanks guys.

You don't need to use a sway bar 3" thick.... you can get them made from 1-5/16" chrome moly spring steel, and it will keep your car as flat as possible on cornering. However, simply beefing up the rear sway bar is not the correct way to control body roll. As I understand it, it can cause excessive oversteer. You need to increase the torsional strength of both the front and rear sway bars to keep it balanced. I'm only into "straight line" traction... there are others far more knowledgable in going around corners. :)

This is the Spohn "drag" rear sway bar:

http://members.aol.com/InjuneerZZ/images/Photos/Susp.jpg

I plan on getting bigger sway bars for both front and back, but i just didn't know which to get. The biggest i found was 36mm hollow ones but i want a solid one. The biggest solid one i found was i think 32mm. I also noticed something, why is the back in inches and the front measured in millimeters?

There's a 35mm solid front bar available, I think from Suspension Techniques (it may be advertised as 1-3/8", but you can safely ignore the difference between 1.375" OD and 1.378" OD - the difference in stiffnesses would be less than 1%). I don't know if this is stiffer or softer than the 36mm tubular bar without knowing either the inside diameter or the wall thickness of the 36.

Several rear bars are available in metric diameters (OE sizes 19, 21, and 22 that I can think of right away for the 4th gen, and there's a 24mm for 3rd gens). Metric vs inch sizes may be an OE vs aftermarket thing. Just remember that 25.4 mm = 1 inch and convert everything to the units you prefer.

Depending on your use and the rest of your suspension tuning, it's entirely possible to have too much bar, particularly too much rear bar. If you make too much of the lateral load transfer happen at the rear (which a huge rear bar will do to you) you won't have much traction left for acceleration until after you've gotten the car mostly straightened out. Translation: you'll be slow and will probably remain overly cautious with the throttle even while driving a better-balanced car because you will have learned to not trust the rear to stay stuck.

I suggest you talk with Sam Strano, Jr. ( www.stranoparts.com ) as soon as he gets back from the SCCA Nationals in Topeka.

And see if you can find a copy of Fred Puhn's softcover book ("How to Make Your Car Handle").

Norm

I was actually wondering if a huge front bar would be bad. If i did get one that was huge like a 35mm how could the back not have traction if that also was huge? I'm pretty sure 3rd and 4th gens are interchangeable (if wrong correct me) so i might get the 24mm rear. I do want acceleration around the corner. Right now when i take a corner that says "25 MPH" i can take it at about 50, but the car rocks to the side and lifts up the inside, side of the car. I want to get rid of this rock from that side. I know shocks and springs are the biggy but money is even bigger here. So sway bars are my first step. Are there any other things that i should think/do when it comes to cornering suspension and acceleration?

The 3rd Gen and 4th Gens sway bars are the same in the back. The fronts are different.

You will also see an improved effectiveness of the sway bars by using firmer polyurethane bar bushings, and end link bushings.

Yeah, i definitely planned on getting the heavier duty end links and poly bushings. I put the "extreme duty" end links on my 83 and those bolts were huge. I think they were twice as big as the stock size. can't remember exactly, been so long since i've had it... :cry: Just out of curiousity, would a strut tower brace help any? thought it might help stiffen the front and stop flex there...

. . . so i might get the 24mm rear. I do want acceleration around the corner. Right now when i take a corner that says "25 MPH" i can take it at about 50, but the car rocks to the side and lifts up the inside, side of the car. I want to get rid of this rock from that side. I know shocks and springs are the biggy but money is even bigger here. So sway bars are my first step. Are there any other things that i should think/do when it comes to cornering suspension and acceleration?There might be one person that I know of who's using a rear bar bigger than 22 mm for auto-x; everybody else seems to be deciding between 19, 21, and Sam Strano's 22 mm hollow bar. And maybe a couple of other folks who don't really have an F-body rear suspension under their Camaros anymore (and require different spring/bar tuning). FWIW, the rear bar is the least effective of all the springs and bars at reducing roll, so it's really only good for tuning the understeer/oversteer balance to your liking.

I suspect your car needs shocks, and you might want to be less 'abrupt' with the steering inputs.

As far as the bars are concerned, do the front bar first and then see.

Norm

be less 'abrupt' with the steering inputs
I don't think this can be emphasized enough!

I don't think this can be emphasized enough!
What exactly do you mean by abrupt? don't just go to the biggest size available?

I thought the rear was the more important one but now that i think of it, the front would keep it down, then transfer it to the back. So the front one first it is. Also this weekend, i took an off ramp at almost 65, pretty fun, but amazingly the car didn't lean at all, the tires were squealing half the way down. But on some other corners i take slower and virtually the same turning degree, and it'll lean. And it's the same side, right turn. hmmmm

"Abrupt steering inputs" = "jerking the wheel"

The car will be able to corner harder if it you turn the wheel smoothly.

If you jerk the wheel hard enough to slide the car, it's normal for it to stay more level than it would be if you made the same turn without breaking traction. Newton's first law... every action has an equal and opposite reaction. When you're cornering hard, but you have not lost traction, the outside tires are pushing hard against the turn. Part of the equal and opposite reaction is the car leaning against the force of the tires.

I don't think I explained that very well. Somebody want to do a free body diagram?

Norm got it right -- the front sway bar will adjust your body roll. Once you get that right, adjust the rear bar until you have the understeer/oversteer behavior you want.

-Jake

I don't jerk the wheel when i go around corners, i smoothly enter it like i would if i was going slow. There's also another thing i think we should probably clear up. My driving style. Now, it's not exactly horrible or bad, but it is probably borderline dangerous when it comes to corners. I don't speed and i accelerate "briskly" when merging. But corners, i like pushing the limits on my car. I find it way more fun trying to sit upright and steer while trying to push the car faster around the corner. That is why i want something that will give me complete traction to the road and maintain my stability. With that said...

Are the hollow front sway bars any good? I see them all the time on ebay that are 34-35-36mm's. or would i be better off with a solid 32mm?

ShibbyZ

You think your car's loose now....:rolleyes: If you were to do it, one of them would have to be able to change length..

Too stiff of a rear means it will be really loose..... I think....

I don't jerk the wheel when i go around corners, i smoothly enter it like i would if i was going slow.That wasn't obvious from the wording of your earlier description,

but the car rocks to the side and lifts up the insidenor is there anything readily available to suggest how much experience you have behind the wheel. Try not to take any of this nonmechanical stuff the wrong way - I'm just including possible explanations for the "car rocking" that can't be fixed by throwing parts at the car.


That is why i want something that will give me complete traction to the road and maintain my stability. Complete traction is a myth. You can make a car have more linear response up to higher limits, but there's a downside in that there's apt to be less warning when you do get up to that limit and are about to step over it.


Are the hollow front sway bars any good? I see them all the time on ebay that are 34-35-36mm's. or would i be better off with a solid 32mm?For any given stiffness, a tubular sta-bar is larger in outside diameter and is lighter than a solid one. It will be less rigid than a solid bar of the same outside diameter. Right about here, the question of just what use you have planned (street only, auto-x, open-tracking, etc.) comes up. Your choice affects some of the compromises.

The best recommendation I can give at this point is to talk to Sam Strano after he gets back from Topeka.


Norm