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Panhard Bar & Rear End ' Dog Tracking ' ?

vwnate1

vwnate1

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All ;

I'm a bit out of water here as I can't recall ever owning a vehicle with a Panhard bar before , this new '69 C10 has coil springs , trailing arms and a Panhard bar ~

Wiki says : " The advantage of the Panhard rod is its simplicity. Its major disadvantage is that the axle must necessarily move in an arc relative to the body, with the radius equal to the length of the Panhard rod. If the rod is too short, there will be excessive sideways movement between the axle and the body at the ends of the spring travel. Therefore, the Panhard rod is less desirable on smaller cars than larger ones."

It all looks O.K. underneath *but* the truck appears to ' dog track ' a bit as due to the very nature of this device , it moves the rear end laterally (side to side) as the body/frame goes up and down.......

I'm just wondering what you alls know about it , my rear end appears to be a bit to the right and everything is there and in good shape .
 
Hey Nate, Check out this thread I posted back in April 2011: https://talk.classicparts.com/showthread.php?t=14368

I have always interpreted the term "dog track" as the rear end not being parallel with the front axle, thus the car/truck body goes down the road a bit sideways. A typical problem with older leaf spring vehicles if the axle isn't located on the pins that ensure the axle is perpendicular to the body centerline. Sometimes these get so bad they leave 4 seperate tire tracks! :eek: Old Novas and Camaros were known to do this, especially if new leaf springs were installed incorrectly.

The rear panhard bar, sometimes known as a "track bar" (dog "track"), locates the rear end in relation to side to side movement, but the axle will still be parallel (within reason) with the front axle due to the trailing arms, so the body of the vehicle doesn't dog tracking much at all.

A panhard bar is always a compromise. Theoretically the rear axle will almost never be centered. Any up or down movement throws it off center. That being said it works pretty well, and the longer the panhard bar is the less the side to side axle movement will be experienced during normal axle up and down movement.

I wouldn't worry about the rear being a bit to the right. As long as you have adequate tire to fender lip clearance and the difference isn't obviously noticeable it should be just fine. But if it bothers ya, many manufacturers make adjustable panhard bars that are bolt in replacements. they allow you to adjust the bar and locate the rear where you want it.

Normally I would post a link to our hosts parts, but I didn't see bolt in stock style adjustable panhard bars. Here is a link to Early Classics adjustable panhard bars: http://www.earlyclassic.com/catalog.aspx?category=panhard bars

If you notice in the above link these same manufacturers sell "Super Track Bars" that are longer than stock and move the axle mount for the track bar all the way over to the passenger side trailing arm. For a coil spring vehicle it isn't really needed. On an air bagged vehicle where the vertical suspension travel is more extreme, sometimes the Super Track bar is beneficial. If tire to fender clearances are very tight however these long bars can be helpful.

Hope this helps,

John
 
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I've never seen a panhard bar on a leaf spring car or truck. Only on three link and four link suspensions. Liked how they worked on the racecars i've worked on over the years.
 
The rear suspension of your truck is what NASCAR rear ends are based off of. If the rear is lifted a little, the panhard will shift the rear ever so slightly. The same applies if it is lowered. The factory designed arc should never allow the rear to move enough to contact anything, and it should pe parrellel to the front suspension at all times, never to cause dog tracking. That said, if the rear was ever pulled in the past and reinstalled a little off, that may cause a little shift in the alignment.
 
Thanx guys !

John ;

You have the correct understanding of what ' Dog Tracking ' means .

Looking it standing still , all seems well , so far I've not bothered to find a puddle to run it through .

Cralwing underneath the truck , all seems 1,000 % original and untouched , no crash damage anywhere I can see , it drives very nicely indeed , I just ordered up a ful set of Bilstein BS-4 HD gas shocks for it so it should handle better soon .

I didn't know NASCAR used these but I'm not surprised , this truck is the light duty one so it has rear coil springs & ladder bars , not leafs .
 
If the truck has been lowered or possibly has sagging springs it could force the rear end to appear off to one side, you could always get a adjustable pan hard bar or modify yours to be adjustable.....Big Tim :cool:
 
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