70 charger suspension upgrades

[nicjasno]

Yeah, that's what i thought.

What kind of anti roll bar setup is recommended front/rear?

[myk]

Most if not all front sway bars are an inch thick at least.  There may be a difference in how the different bars mount to the suspension.  Same deal applies to the rear bars, although some would argue whether a rear sway bar is necessary or not.  DC.com member MSRacing89, who actually races his orgasmically beautiful '68, has been known to disconnect his rear bar if he felt he didn't need it on certain courses.  There are many brands to choose from, so it's largely a matter of preference.

I've turned into a Hotchkis fanboi, so I'll recommend their quality, but expensive parts all day long...

[303 Mopar]

Firmfeel's rear anti-sway bar actually goes up over the rear end like stock, all others that I know of go under.

[nicjasno]

One question about behaviour under breaking... how does one prevent rear axle hop during heavy breaking? Are the suspension upgrades we were talking about before already the fix for that (too little damping in the stock suspension, better leaf springs, front not diving as much..) ?

Or is a brake bias adjustment also needed?

[HPP]

The asymmetrical design of a mopar leaf spring naturally resists brake tramping, however, if it is a concern you can add a half leaf on the top of the pack from under the axle housing up to behind the spring eye.  Hotchkis springs already have this modification made to them. They also are made using berlin eyes to accomplish some ride height reduction over regular leaf springs.

[Kern Dog]

Their eyes are German made?
maybe you meant Delrin?

[HPP]

No, delrin is a bushing material, like rubber, poly, or bronze. Berlin eye is a style of wrapping the eye and its location in relation to the spring centerline. See below.

This is the decieving aspect of leaf springs. While many poo-poo them as antiquated and simple, there actually are a lot of variables involved in making performance leafs and they are much more complex than a coil spring. Eye style, leaf count, leaf material, leaf location, interliner material and length,  tapered method, rounded, pressed or diamond cut ends, degrees of camber, banding method and location,  metalurgery, etc. In the mounting area there is anti-squat, instant center, roll center and and roll steer characteritics to consider. There is a lot of detail to a good set of leafs. The biggest drawback to leafs is simply their size and weight. Otherwise they are a very capable method of suspending a vehicle.

[Kern Dog]

Thank you for that. I really did think he meant the bushing material. I do enjoy learning new stuff. 

[Mike DC]

 
I'm fond of saying it - show me somebody who makes a big point of hating leaf springs.  I will probably show you a GM or Ford guy who never had a leaf setup that was designed right. 

[HPP]

Bingo!

Most guys don't know it, but the whole Cal-Trac system was created by a Ford racer who was trying to emulate the Mopar SS spring action on his symmetrical Mustang springs.

[nicjasno]

What about having more leafs on one side, like on hemi cars, to counteract the driveshaft torque? How does this affect the overall handling?

[HPP]

The XHD bias design springs used under our cars does not have a significant impact on handling. The additional half leaves in a bias spring design have a direct impact on the control ratio of the pack, and a minor impact on load rate, but it does not have an appreciable impact on the spring rate.

However, if you are a finely tuned driver who is very familiar with the car, you may feel a slight difference on corner exit as a result of the different control ratios left to right. I'll put it this way, the difference are so slight that the changes in weight that a 1/4 tank of gas difference produce may be comparable to the difference in bias springs control function.

Now, having said that, the usual approach for performance handling is have equal rates between right and left so most people tend to put identical springs on both sides. Although one could argue that the additional control of torque needed in the right spring could be equaled by additional load rate that should be installed on the left spring to support the driver. Which gets us back to nearly equal rate springs. Like I said further up, there is  a lot of technology in a good set of leaf springs that is hidden in its design.