Why doesnt anyone use a panhard bar (track Bar) on our cars?
I see that a rear tie bar is beneficial because it prevents the trailing arms from moving laterally with respect to each other but that does nothing to prevent the whole torsion beam assembly from moving laterally as well.
When the whole torsion beam moves laterally this induces a bit of percieved oversteer because the rear is now steering opposite to the front. I have not been able to find anything about a panhard bar for our cars.
I understand that it would be difficult to fabricate mounts to the body seing as theres just a whole lot of sheetmetal but it could be done.
I was wondering if anyone has seen this and what your thoughts are on this. Is this something worth attempting?
I know the oversteer effect due to rear suspension sideplay in my 68 firebird is very noticeable. It definitely makes for a more difficult car to drive and less precise suspension movement.
We have a rear torsion bar that can't move laterally. It's bolted in, directly to the "frame". The RWD vehicle you mentioned does not have anywhere near the same setup. It has a hard drive axle, which is
not bolted directly to the frame, it has links.
There is no need for such an item, it would have no effect. Not to mention our cars have nautral understeer, so we can use all the oversteer we can get (stock-wise anyway).
I have a 2 link panhard that we just dropped in but thats for a totally different reason. For our project we shortened my rear axle 3.5 inches, used bellow bags off the rear axle, and dropped the rear trailing arm back an inch from stock with a crossmember running across in the gas tanks old location. Its not really needed though unless you have some wild custom plan that requires it
Somepeople of our team, tells me about this Panhard bar. But in fact, I was thinking the same thing as CTS said, but I found an application that have an rear torsion bar cross-member and uses a Panhard Bar. Just check out the old 92-93 or earlier Mitsubishi Galant. These cars makes me think, really.
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panhard bars are mostly for solid axle applications, example like mustangs live axles...
I agree that panhard bars are mainly used in solid axle cars but that doesnt mean that they cant benefit our cars. The front part of our twist beam is essentially a solid axle with 2 links to the car. All 2 link cars I know of also have a panhard bar because of the extreme forces these 2 pivots would be subjected to if they did not. These pivots are set up to allow the suspension to move up and down but they cant possibly stop all lateral movement unless they are solid and extremely strong. This is where the panhard bar could come into play, to eliminate the side play that the front bushings allow.
Also...I dont think that it should be desireable to allow the back suspension to move around to comensate for any understeer we might have. It would be much better to make sure the suspension freeplay is eliminated and then tune handling characteristics by changing sway bar size or the length of the sway bar ends. Isnt consistency what its all about?
The main factor in the equation here is that our torsion axle is bolted to the frame. There is nothing in between. On a RWD live axle car, like the aforementioned mustang or firebird, the axle is bolted to something else (leaf springs, or links), which is in turn bolted to the frame. That second connectino adds alot of potential play in the system, which is why panhard bars were created, to minimize that play. Our axle has extremely little lateral play, and those bushings will not compress nearly as much as you apparently think they will. If you're really concerned about them, replace them with
urethane bushings. I would be much more worried about axle flex, which is what a
tie bar is for. And while you're at it, might as well do a
rear sway bar.
Dennis Rolston wrote:I agree that panhard bars are mainly used in solid axle cars but that doesnt mean that they cant benefit our cars. The front part of our twist beam is essentially a solid axle with 2 links to the car. All 2 link cars I know of also have a panhard bar because of the extreme forces these 2 pivots would be subjected to if they did not. These pivots are set up to allow the suspension to move up and down but they cant possibly stop all lateral movement unless they are solid and extremely strong. This is where the panhard bar could come into play, to eliminate the side play that the front bushings allow.
Also...I dont think that it should be desireable to allow the back suspension to move around to comensate for any understeer we might have. It would be much better to make sure the suspension freeplay is eliminated and then tune handling characteristics by changing sway bar size or the length of the sway bar ends. Isnt consistency what its all about?
consistency is what its all about, but panhard bars are to keep the live axle centered.
the trailing arm on our car is mounted in 2 spots, meaning if it shimmys from side to side, a panhard bar is the least of your worries to add....
if you want to stop any lateral movement near the front of the 2 pivot points simply upgrade to poly bushings in the rear trailing arm from rsm...
Quote:
if you want to stop any lateral movement near the front of the 2 pivot points simply upgrade to poly bushings in the rear trailing arm from rsm...
Still havent figured out where that its.
But at $250, not so sure about that.
-M
Remember....syringes go in the RED waste basket.
dang, that is a lot of good information.
i would have just said panhard bar/track bar = RWD vehicles.
red 99 coupe.... no rust and it runs.
Quote:
Thats where the axle bolts to the unibody
Oooo,
Will look in the morning thanks,
-M
Remember....syringes go in the RED waste basket.
Ok...I have a revised idea. I still insist that a locating device is needed in the back of our cars, I think there may be a better way to take out the factory slop than a tie bar or a panhard bar setup. As I am thinking now, A dual Scott-russel linkage(one for each trailing arm) could be used to insure that there is perfectly vertical suspension travel rather than the induced toe out /bind that is had with a tie bar. A panhard bar would also induce unwanted lateral travel with the suspension because as a straight bar (panhard or tie bar)pivots from one end it swings in an arc therefore decreasing its length relative to its original position. Nisan maximas use what they call multilink suspension which uses a scott-russel linkage. see this link for more info.
http://www.se-r.net/about/g20/scc/oct98/tb.html.
There is a picture of the linkage they use which allows perfect vertical travel while eliminating all lateral movement. I am hellbent on breaking the bad rap our cars get for having "minivan suspension". I realize this would not be easy to implement but it would allow our rear suspension to work exactly as does in theory without the real world deflection. I am trying to come up with a better solution than the typical tie bar bandaid which I see as only a patch to a greater problem. any thoughts?
You goofed on the link:
Linky
You vastly overestimate the amound of lateral movement in our rear axle. And that axle is quite different than ours. Have you even seen a J-Body Torsion Beam Rear Axle??
Also, their "perfect vertical travel" is only as "perfect" as the bushings it uses.
thanks for the improved link.
I know the maxima suspension is different but I was referencing more the scott-russel linkage picture than the rest of it. The idea I am working on replaces the tie bar completely with a scott russel linkage to each trailing arm with the slider side connected to the car with a drop down crossmember.
With the tie bar we usually use the suspension is forced to bind if one wheel travels up and the other doesnt. This as a problem because since the tie bar rotates, each end swings an arc, which if one trailing arm is up and the other is down, will cause the trailing arms to squeeze inward toward each other.
I believe most bushing deflection of a dual scott-russel locating device or others could be near eliminated by using delrin or a nylon type bushing as well as on the slider portion. I do know what the suspension looks like and how it is intended to work. The reason a tie bar is so effective on the back is because there IS play back there, but its far from optimal. I will try to get some sort of visuals if I can to try to better explain what I am thinking.
yeah you are really overestimating movement....
to keep the ends of the trailing arm from flexing in, thats where a tie bar comes into play.... other than that,your chassis would have to be REALLY fubar to warrant the ENTIRE structure swaying side to side... or your bushings are EXTREMELY worn... but then a bar would be the least of your worries...
tie bars dont bind if you build em correctly. and the articulation of one wheel going up is no where near what you experience in offroad, in other words the trailing arm doesnt flex nearly as much as your overestimating it would for one wheel to travel up and the other doesnt.
even on a stock trailing arm, base model no swaybar, if one wheel travels up the other side will have a light tendency to travel upwards with it, although gravity and the weight of the wheel, drum, weakness of the arm base will keep it planted...
thats the downside of our suspension VS IRS and multilink rear suspensions... the handling is not as precise...
dont know where the minivan suspension fits in as many cars have different types of suspension as well as minivans...
there are some minivans that have the same suspension setup as civics, the gto, and other IRS setups, some use trailing arms, others use multilinks...
its not like trailing arm or semi independent rear is exclusive to minivans and j-bodies only...
sounds like someone made a statement and it got under your skin
nino wrote:panhard bar/track bar = RWD vehicles.
that would have been my answer....... i dont have as much knowlage as Event on suspension...... so I'll leave that to him.
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SpeedRacerZ wrote:nino wrote:panhard bar/track bar = RWD vehicles.
that would have been my answer....... i dont have as much knowlage as Event on suspension...... so I'll leave that to him.
hey i am always still learnin
Dennis: Well if you're bent on trying it,
please post pictures.
Just don't be too disappointed if there's not a big difference.
