Thread: 4 link or ladder?

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Originally Posted by florida

Please educate or entertain me. Why do you say, "OMG, not the dreaded Panhard bar"?

If you haven't figured it out yet Florida.... the "dreaded Panhard bar" has been an item of discussion on this forum at least once a year probably since a week after CHR was created!!!!!

Anyway, every time the "discussion" comes up, we all choose sides and pound on each other for a week, then "the dreaded Panhard bar" discussion just goes away again!!!!!!!

no i am done

Originally Posted by pat mccarthy

no i am done

Geez, ya mean you don't wanna play this year Pat???????

PS--That picture of your Goat is great!!! What a gorgeous car!!! Pontiac sure did know how to build them back when Uncle John was there and they actually had a styling department!!!!!!

I too need a education. I thought the upper " triangulated" bars negated the need for the panhard bar or watts linkage. I drove my 34 3/W many years with the triangulated 4 bar set up without a panhard or watts and liked how it handled on the street and at the strip the few times I raced it there. I admit to being a complete dummy when it comes to knowing what great handling cars drive like so maybe I need a education on what I have been missing. I have been re-doing the 34 for some time now and planed on leaving the 4 bar as is. I may need to re-think this.

Jack.

You don't have to run a Watts linkage or Panhard bar with a triangulated 4 link..... But it does keep the car "hooked up" better in turns. For the street, a Watt's linkage can use urethene bushed ends which kills the noise of heim joints. In normal driving, probably never even notice the Watt's linkage is there but when you start really stuffing the car into turns, you'll definitely notice the increased stability. Leaf springs and curvy roads shouldn't even be in the same sentence....no tunability in ride or handling with a leaf spring. With coilovers you can change the spring rate, go to a progressive rate coil, change the ride height, play with the shock valving, etc. etc. Do you need all this on the street for normal driving???? Heck no. But if we only put the things on a car it had to have, it wouldn't even be a Hot Rod, would it????

I was actually responding to Jack's post, too. and, as I said, you don't need this for normal street driving....

As for adding springs to old springs, think I'd probably spend a couple extra bucks and get new springs rated correctly for the weight and desired ride of the truck.....

Also, I did not say leaf springs weren't part of Hot Rods, i said they have no tuneability....

Dave,
Thanks for the reply. It sounds like handling can be improved with a panhard, although clearing the exhaust might be a problem. You mentioned leaf springs in your reply; I am using the original coil springs (bed springs) from the 4 bar setup of the 66 GTO rear in the 34. Of course they are not the same as leafs but they still don't have the adjustment of coil overs. Maybe I should look at coil overs. I hope things aren't getting too complicated.

Jack.

Originally Posted by lcacnav75

I have done some research and decided to go with the 4 link, it seems that the ladder bar system was designed more for the track and will not handle well around turns or on the street. thank you for your input.

Good choice on the 4 link, a triangulated 4 link should fit the bill just fine for a very streetable setup....

Originally Posted by Jack F

Dave,
Thanks for the reply. It sounds like handling can be improved with a panhard, although clearing the exhaust might be a problem. You mentioned leaf springs in your reply; I am using the original coil springs from the 4 bar setup of the 66 GTO rear in the 34. Of course they are not the same as leafs but they still don't have the adjustment of coil overs. Maybe I should look at coil overs. I hope things aren't getting too complicated.

Jack.

I wasn't referring to your car about the leaf springs... The coil springs work good, one of the reasons I prefer a coil over unit is that both the spring and shock are one unit and take up less space and leave plenty of room for exhaust, even with a Watt's linkage. I like to place the bottom mount of the coilover as far outboard as possible with the tops angled in to the center of the car at about 25 degrees to improve ride stability. I also like to weigh my cars before I select the coil spring weight for the rear end....if you have access to a set of scales it is certainly better then guessing at the weight.... One final thing, when you determine the weight of the car and the spring rate required, remember that the weight of the rear end complete is unsprung weight and should be deducted from the rear weight of the car.... Seems a lot of the newer techs () at the parts stores and manufacturer's don't take this into consideration!!!!! Jerry Clayton pointed this out the other day....I made a couple calls and guess what???? Jerry is (as usual) right on the money!!!!!!!

Dave,

Thanks again, most helpful information.

Jack.

Jack, let me see if I can unshroud this Panhard bar thing for you. It is unclear whether René Panhard or Émile Levassor or one of their hired engineers came up with the Panhard bar, but I'm pretty sure that whomever came up with it, they installed the bar with the longest possible length to fit into the car and also installed it parallel with the road surface to prevent pre-loading one side of the car or the other from the neutral ride height position.
http://www.citroenet.org.uk/panhard-...anhard-01.html

Now, along comes some of us goofy hot-rodders and the Panhard bar looks like a good, cheap, easy way to prevent lateral body movement in relation to the differential housing and it is. Problem arises when the builder fails to take into consideration that the bar must be as long as possible to keep the degree of angularity as low as possible and prevent jerking the body laterally on bump and rebound.

Proper bar construction and installation would dictate that mounts would be constructed to attach to the frame and to the housing that would allow the attachment ends of the bar to be right at the brake backing plates on each side of the car, thus allowing the longest possible bar length within the space available. The bar doesn't necessarily have to be straight, it can be curved or bent up like a pretzel, so long as the attachment points are as far as possible apart from each other and each attachment points are parallel with the road surface and the material used is stiff enough to resist deflection. That's where the Panhard bar gets its bad name, when shadetree engineers make the bar short because it is easy and expedient to do so. In my experience on this rock, I have figured out that if anything can be FUBAR'd, human beings can and will do it.

Bottom line: A properly engineered and installed Panhard bar will do a fine job of locating the differential laterally to the body. Not as precisely as a Watt's Link, but good enough. The key is the length of the bar and having both attachment points parallel with the track surface at ride height.

Here's a hastily-drawn diagram carried out to the point of silliness to illustrate my meaning......

Originally Posted by TO-FAST-4U

What in the hell is that ?

Just illustrating a point that the bar can be bent up to clear other components and still meet the engineering criteria required to make it work properly.

Here's another illustration of one of the abortions we most normally see, engineered and installed by Billy Joe Bob....

Billy Joe Bob is a great guy, Just needs to suspend his suspension engineering.

Technoman,
You don't mind if I give you a new nick name do you. I just hate to type anymore than I have to. The fact that I even typed that last sentence shows you how smart i am. Anyway, that drawing of the pretzel panhard bar makes me wonder how much lateral support it can give. It looks like I need to find a way to make a straight (or as straight as I can) panhard bar as long as I can, horizontal to the road surface, and still avoid the exhaust. This is going to take some doing. I will see what I can do.

Jack.