Why are panhard rods always on that side?

They always seem to be attached to the drivers side of the frame.

Any reason for this?

I ask because I think if I attached my rear one on the passenger side of the frame it could be longer and have fewer clearance issues.

Ideas anyone?


Thanks,
Motor

 

The idea is to match your steering drag link which runs from your steering box mounted to the frame on the drivers side. In a perfect set up the bars would be parallel to each other to prevent any bump steer.

Bill

 

Maybe I don't understand the response but It sounds more like you're describing the radius rods. I believe that the panhard bar runs across the frame and mounts from the frame to the rear end to keep it from moving sideways. Also on the front axle to keep it moving sideways.

As for mounting it on the passenger side... I don't know. My total lack of engineering knowledge would say it doesn't matter. But there could be a reason. Not much help sorry!
Bill

 

good point. never thought of that, but why would it affect bumb steer? i still can't see how it would...the parrallel is not an issue, and how does this affect a car with rack and pinion?

 

Theory, (and most builders) says if you have front and rear bars or cross-steer the frame connection should be on the same side front and rear. the panhard bar effects the roll center and if they are opposite front to rear they may work against each other.
If you only have the rear bar and a fore-aft drag link steering it doesnt matter which side, (unless it's a circle track racer...)

 

In a cross steer vehicle the steering link is attached to the box which is mounted to the left frame rail. As the suspension moves the steering link scribes an arc using the pitman arm tierod end as the steady point.

To match that arc and prevent bumpsteer the Panhard bar is also solid mounted to the left side so the arc of the front axle can match the arc of the steering link instead of fighting against each other, which would result in bumpsteer even with the Panhard bar. Angles and lengths should idealy match.

A left side mounted steering box will push the tierod in a consistant path. The Panhard bar pushes the axle in the same path...thus making both move to the side without varience between them. If the Panhard were opposite the box the paths of the tierod and the axle would be in different directions as the suspension worked, thus causing bumpsteer.

If a drag link style steering setup were used, it really wouldn't matter where the steady point of the Panhard rod was in a regular vehicle...but most still mount it to the left side.

 

ok, sounds good, now how is this going to affect either a Watts or a WOBLE link rear set up?...thanks

 

it sounds like all but DrJ are refering to a front panhard bar,
not the rear, which is what the question was about.

 

Sherman, that's only true on cars that are built to be driven north of the equator.

By the way, if you drive carefully, directly along the equator, you don't need a panhard bar at all.

Dave
http://www.roadsters.com/

 

I don't really understand the question...but that never stopped me before!

Basicly a Watts link will prevent the minor side to side movement a Panhard would cause and I guess it can have a different tuning effect as compared to a simple Panhard bar...not really sure! Would be a tougher setup in a rough enviroment though.

WOBLE link? I think I know what you mean...don't know that name though...

A Jacob's ladder is designed to load the inside tire in a dirt car while there are other designs (eg: Mumford link) that are used to set the roll center BELOW ground level in road racing solid rear axle car.

Can't see a huge issue on which side the rear is on...other than the front goes on the box side of the frame and to prevent twitchiness the rear should match...

 

i'm not tryin to be an ass. really. i've learned a million things here & wanna learn all i can.
ok. what do you mean by "cross steer"?
the reason i'm asking is after 35 yrs of building race cars & learning about ackerman & bump steer & rear steer & roll centers & roll couple distribution & camber gain/loss & caster gain/loss/split & anti dive & anti squat & all that, none of what your describing makes any sense to me. especially your mention of bump steer in regards to the front versus back.
i'm thinking i musta never worked on a cross steering car. what does that mean?...mel

 

Cross steer would be Vega box or later Fords.
I misunderstood the question to mean the FRONT suspension but he meant the rear! Read it too quick...

"the reason i'm asking is after 35 yrs of building race cars & learning about ackerman & bump steer & rear steer & roll centers & roll couple distribution & camber gain/loss & caster gain/loss/split & anti dive & anti squat & all that"

JUST bumpsteer is involved here and if your getting it from the REAR Panhard, your right...BIG issues!

I don't think your an ass...I guess I just made a reply that wasn't clear. Sorry.

Your response IS a little sarcastic though. I really don't think I deserve that for trying to help...

If you've been into race suspensions for 35 years...HELP the guy get his answers...don't waste time on me!

 

Your response IS a little sarcastic though. I really don't think I deserve that for trying to help...

sorry,i didn't mean to sound sarcastic at all.
you don't deserve anything but cheers for tryin to help the guy.

as far as me helpin i'm just starting to get a feel for some of the different suspensions/steering that y'all use on these kinda cars so i'm really just reading & listening & trying to learn. i've never heard the term cross steer. i'm still not sure wtf "bones" are. lol.

 

Hackerbill described exactly what a Panhard does.
It accuratly locates the axle sideways and its a nice simple sollution.
Drawback is the Axle pivot point moves around a arc, giving a bit of sideways movement on the axle as well.
This sideways movement gets worse with shorter Panhard Bars and with softer suspensions ( longer travel ).

A way around that problem is the Watts Link.
It basicly works just like the Panhard.
But by using 2 bars instead of one, connected to eachother with a bellcrank, the arcs of the 2 Bars cancel each other out.
So the Axle moves up and down in a perfectly straight line.
Drawbacks are a bit more complex construction ( takes up more space ), and the height of the bellcrank limits how low the Rollcenter can be.

Next sollution is the Wob Link. ( see pic )
Rollcenter can be chosen as low as the Panhard.
Axle moves up and down in a perfectly straight line.
Drawbacks are: complex, takes up more space, and the many pivot points multiply play if there is any in the Heim Joints.

I build a Woblink on a Homebuilt racer once and it worked really well.

On my Hot Rod I built a Panhard, I did not think the little bit of sideways movement justified the extra complication.
( But my Panhard bar is more than 2 times as long as the Panhard bars you can buy in kits...)

 

By the sound of it I read way more into your post than was there!
I really thought you were giving me a rough time of it!!!
It's so easy to miss a persons meaning when you can't actually hear their voice ya know.
100% MY mistake! Sorry about the mixup!

BTW...I have great respect for anyone who can set up an independent suspension and then tune it for handling. Thats WAY more than I know how to do.

"Bones" are the stock early Ford suspension location members. Stock would be an unsplit V and pivoting on a center mounted ball while split bones are cut and moved out to meet the frame rails or at least spread enough to clear a swapped in transmission...

 

The Rear Panhard bar on my Roadster is attached to the driver side of the Frame as well.

And it doesnt have a Front Panhard, or Cross steer.

But if I ever would deside to put those on, the Rear Panhard is already in the right spot. ( I dont think I would want the Front and the Rear Panhard to come of the opposite sides off the Frame... )

 

One more variation:

The Mumford Link.

Axle moves up and down in a straight line like the Watts and the Wob Link.
But because of the geometry, the Roll center is actually lower than any of the parts of the Link.

 

as far as me helpin i'm just starting to get a feel for some of the different suspensions/steering that y'all use on these kinda cars so i'm really just reading & listening & trying to learn. i've never heard the term cross steer. i'm still not sure wtf "bones" are. lol.[/QUOTE]

Old kid, You do realize we're talking about an axle here right? The front panhard bar is pivoted off the frame on the driver's side in approximately the same plane as the tie rod, for the reasons described above. I agree that the rear bar should swing from the same side of the frame as the front. Most brackets for the rear end mount on the passenger side of the "pig" (on a Ford anyhow) to allow the rear bar to be as long as possible.

 

Old kid, You do realize we're talking about an axle here right? The front panhard bar is pivoted off the frame on the driver's side in approximately the same plane as the tie rod, for the reasons described above. I agree that the rear bar should swing from the same side of the frame as the front. Most brackets for the rear end mount on the passenger side of the "pig" (on a Ford anyhow) to allow the rear bar to be as long as possible.[/QUOTE]


not singling you out but having the bars on the same side MIGHT be prefered BUT OEM apps aren't.

i'm under a lot of late model vehicles and i have yet to see both bars coming from the same side of the frame.

what's correct?
beats the hell out of me...
the one constant is that the front bar is ALWAYS off the drivers side frame rail

 

A good book to buy for ANY builder..ADAVANCED RACE CAR SUSPENSION DEVELOPEMENT by Steve Smith...read it and all this suspension mumbo jumbo and voo-doo will make sense...http://www.ssapubl.com/

 

Old Kid. Amongst all the confusion I don't think anyone actually answered your question about cross steer.

Cross steer: The steering box is mounted to the frame rail somewhere near the front crossmember and the output from it actuates a drag link in a left / right direction to the steering arm on the passenger side and a tie rod runs parallel back to the steering arm on the driver side. Most modern cars.

Side steer: The steering box is mounted back some distance and the output actuates a drag link in a forward / aft direction to the steering arm on the driver side. A tie rod then runs across to the steering arm on the other side.

I know that you would be very familiar with both set ups but maybe not the terminology used here.

Hope this helps

Pete

 

I've made front and rear panhard bars on my Roadster. Both are attached to the frame on the passenger side and I have cross steering. They work great and I never gave it a thought when I was making them. It really should not matter.

 

Please help me understanding how the different
mounting points are going to effect the roll center.

If the center of the pahnard bar crosses the roll center like it is supposed to why does it matter which side is mounted on the frame?

Is the difference enough to be noticed on a street car?

This reminds me of the "Ackerman and roll center" thread
a couple years ago... Where are Carps and ElPolako.

 

Pictures!

Go here for more

 

I wouldn't doubt your 100% correct BEATNIK!
Lots of variables come into play like length of the Panhard bar and actual suspension range of motion.
The right way to do it, to allow for the extreme cases where bar length may be shorter than you would like or the vehicle has a very active and soft suspension, would be to go with the side the box mounts to.
There are exceptions to every rule...and the following proves it.


I've been looking at some late model straight axle vehicles...not many to choose from except for Jeeps...and discovered that TOMSLIK is right on the money...with TJ's and YJ's at least!!!

They DO have opposite mounted front and rear Panhard bars! I guess the normal range of suspension movement (on road) plus the length of the bar makes them stable with the setup.
I still wonder WHY they chose to go that route with the bars when most (all?) cars use bars attached to the left side.
Perhaps it helps in off road situations...keeping the vehicle a little more stable in tippy situations or something?
I have absolutely no idea why they went that route but it sure is an interesting twist!!!

When you consider that a YJ is a LEAF SPRING vehicle and has little side movement even with no Panhard in place (unlike a coil which will twist like your sister) it just goes to show how very little side thrust is created thru a long Panhard bars normal range of movement! It could be measured in thousands of an inch.

Having seen the opposing bars in high CG Jeeps I can't imagine how it could hurt in a lower vehicle with a full length rear bar. A short bar might be another story, but there is NO arguing the fact that some factory vehicles are equipped with opposing Panhard bars...stock.

I guess it just proves there are no absolutes in anything...

 

The height of the mounting points affect the height of the rollcenter.

No, I dont think it does. ( as far as the Roll center goes ), but I would't want the 2 axles to be pulled in 2 different directions when the suspension goes into full droop, or bump. ( why put in a extra variable if you dont have to...)

There might be a issue with weight transer, but I'm not sure about that ( maybe a Oval Track Racer can help us out with that Info...)

According to Arthur Mallock its important for the Roll center to be a fixed point on the Chassis.

A Panhard isn't, it moves up and down by half of the axle travel.

A watts is worse, it moves with the Axle.

A Wob link has a fixed point on the chassis.

A Mumford can have a fixed R/C to within .1 of a Inch...

 

YJ's use VERY soft spring rates for a nice cush ride. They also run big sway bars to combat body roll.

Without panhards and swaybars, a YJ can be a handfull.

 

An old fart told me that the rear panhard goes to the drivers side of the chassis because of the way the chassis loads/twists.

Ideally you want the rear panhard to be as close to level as possible when the car is at rest to minimize the amount that it pushes the rear to one side or the other when it swings its arc.

Also if you mount one on the front it would also want to be as close to level as possibel for the same reason and you would want them to both to be running in the same direction.

 

llike this??...

 

Shouldn't matter which side the rear panhard bar mounts to. Rear roll center is determined by the point the rear panhard bar crosses the centerline of the vehicle. Which side the bar is attached to will not change this.