Starfury - Sway bars transfer weight from the inside tire to the outside tire. This has the effect of lowering total lateral traction provided by the inside tire.

MBDiagman, 67Mustang302 - Isn't it funny how hard it is to try and get people to understand that making a car neutrally balanced will make it corner harder and is surprisingly cheap to do? They will waste untold amounts of money on rollerizing everything on their car when a $150 adjustable rear bar would completely revolutionize their understanding of of well an old Mustang can handle. Then they complain about how crappy the suspension design is and how you just can't get one to handle as well as their Accord.

My favorite argument against the rear bar is how it will somehow mysteriously cause your car to be unsafe cause "snap understreer" - which, btw, is only seen in mid engined cars with a low polar moment of inertia. That is like arguing that we should all keep our kitchen knives dull and blunt because we are too stupid to learn how to use them corectly when they are sharp.

It never ceases to amaze me how hard internet "knowledge" is to correct.

Good luck....

 

1) If a car rolls excessively, a lot of weight is being transferred to the outside tire. If you limit body roll, you're moving that weight back towards the center of gravity. If you add a reasonably larger sway bar (the stock non-GT Mustang sway bars are ridiculously small), you decrease excessive body roll and move some of the vehicle's weight off that outside tire. If you add a monster front sway bar, then yes, you're going to stiffen up the front end so much that the inside tire is going to want to lift while you're cornering.

2) The stock suspension design IS crappy. Until you do the Shelby drop, the camber curve is going to suck. Period. A rear bar won't help that. Rollerized parts DO help things, but they do different things than sway bars, so you can't say that money spent on rollerized suspension parts rather than a rear sway bar is wasted.

3) Snap-understeer may not be the "industry correct" term, but everyone else knew what I was talking about. If you stiffen up the rear, the rear is going to have more tendency to come around when powering out of a corner, even slow, tight corners encountered during street driving. Mustangs are already a little tail-happy, so my warning was to be careful with adding a rear bar until you're absolutely sure it's necessary. If you read the entire post, you'll note that I'm going to add one to my car at some point because I decided I need it after some really harsh driving.

4) It's possible to disagree with people without trying to sound superior to everyone else. Try that.

 

I'm looking at going with a Stam-Bar: http://www.swaybar.com/index.htm.

But every setup will be different. For me, I am running 520lb springs on my 1" UCA dropped front end.

 

Billy,

You have had some advice go in different directions. The consensus among members that own and have modified these old cars is to buy a 1" sway for the front and not purchase a rear. I live in AZ and would be happy to meet you at the pavilions show one saturday night to let you check out my car.

I recommend you buy a front, install it, drive it and if after a while you feel the need for a rear then go for it. Your original post only asked for recommendations on a front sway and you got it. As for improving the handling of these antiques, there is a widely accepted minimum that makes huge improvements. It seems you have already done your homework but I will reiterate for those with less knowledge than you.

The factory placement of the upper control arm leads to postive camber under suspension compression. This allows the sidewall roll more and puts less contact patch on the blacktop. The arning drop lowers the interior pivot point of the UCA so that when the suspension compresses it pulls the top of the spindle in closer to create negative camber. This counteracts the affect of tire roll and body lean and nets a bigger contact patch.

Rollerized spring perches minimize the binding in the stock pieces effectively allowing the suspension to go to work. This makes the same spring feel stiffer by not wasting energy to turn the rod in the perch bushing.

By using stiffer springs and rollerizing the perches you no longer need shocks as stiff as was used back in the day. That's why many like the GR-2's for street and occasional track use.

The 1" sway is simply a nice compromise between purely track oriented and strictly street oriented. This bar is for spirited street drivers.

Stock strut rods are the goo the screws it all up. They tend to move around under braking and non braking situations forwver allowing the LCA to wander a degree or two here or there. This creates a vague feeling and unpredictable braking. The overwhelming consensus is to install a solid mounted adjustable strut rod. This will keep the wheels true to the alignment specs. and also aids in straightline braking. THis is a highly recommended safety measure for sure.

Rear leaf springs are much simpler to improve. 4.5 leaf or 5 leaf is dependent on what you are willing to sacrifice for road quality. I like 5 leafs for nondaily driven cars. The ride hieght can be dialed in with burling of the springs, reverse eye and mideye as they are commonly reffered to. The rear of the car carries less weight and will need less sway prevention. The leaf springs provide a measure of antisway. When your rear end rolls you springs twist. It takes a lot of force to twist them. Rear sway bars will only help keep them from twisting. A better addtion to the rear is a device to keep the rear end from traveling side to side. This can be accomplished a number of ways. Del alum bushings prevent the shift from occuring within the spring/shackle connection. Another way is with a panhard bar. The panhard bar has its own intracacies I won't get into here.

What happens when you bend metal repeatedly? It fatigues and becomes easier to bend. Our 40 year old cars twist with every bump and turn the manuever. These unibodies aren't as stiff as they were when new. Even when they were new, there was a significant amount of twist from front subframe to rear subframe. Stiffening the chassis should be performed before attempting to improve the handling through suspension adjustments. Otherwise you are attempting to tune out a moving target. Subframe connectors tie the front and rear together to minimize twist. Export braces tie the front to the cowl. Monte's help. Torque boxes tie the cowl to the rocker panels aiding in stiffening the front to rear connection.

I'll add more later, I have to get back to work. Keep in ming I am not speaking in generalities. This information is specific to vintage mustang handling. If you have a different experiance then please post it. I am old enough to know I don't know everything.

Posted after lunch
The icing on the cake. Alignment and wheels/tires
Your front end alignment can be your friend or worst enemy. Different driving situations will perform better under different alignment settings. Setting a car up for track racing would make it too damn exciting for street use. Track cars want to turn quickly, too quickly. This can be achived with toe, caster and camber settings. Track specific settings for quick steering will eat tires. Most cannot afford this on a street driven car, nor would you want it due to its 'nervous' handling. So while there are methods to improve 'handling', you do not want those on your street driven car. Always be sure to build a car for its' intended purpose. See the forest through the trees. Don't expect to make all these changes, put the hubcaps back on your stock steelies and try to run with anything sportier than a civic si. It 's not gonna happen. Tire contact patch and compound is directly related to cornering ability and power to the ground capablities. Smaller wheels and taller sidewalls will create an understeer situation. You power the rear, turn the wheel and the car pushes. It is nearly impossible to create a driveable caster camber setting to minimize tire roll on stock like towers.

What is the point of all this 'internet knowledge'? While you may be able to tune a car with a rear sway bar, it would have to be the 'right car'. The OP, in my opinion, doesn't have a car that would require fine tuning with a sway bar, few do. After all other mods were made and he felt that he needed a sway bar, my bet is it would be put back on the shelf in a month.

 

I am definitely not talking WITHOUT early Mustang experience. I owned and modified two of them in the seventies and Autocrossed one of them.

Handling fundamentals are like laws of physics, they are givens and don't change from vehicle to vehicle.

Yes, the control arm relocation changes the game. That said, with everything else equal a stiffer front sway bar ADDS understeer while a stiffer rear sway bar REMOVES some of it. Period!

A great book to read and keep handy is "How to Make Your Car Handle." I believe it is published by HP books. This book has been out at least 30 years, but like laws of physics, these principles don't change.

 

Very interesting and informative post. Thanks to those that contributed, I learned a few things.

If I've gotten the point at all, it seems that the best addition to the UCA drop and 1" front bar would be a quick disconnect rear bar. Connect it for track use and disconnect it for street use.

 

Adjustable front and rear bars.

And excessive body roll actually causes little weight transfer, since the center of gravity migrates very little. What it will do is cause excessive extension and compression of the suspension and screw the geometry all up. It al allows tire loading to occur more quickly, so load transfer(different than weight transfer) will increase.

 

Do you remember your suspension settings from the autocrossed car? I'd be interested in hearing them.

 

Does someone make that?

 

Thank you MBDiagman and 67Mustang302....

I would also recommend Chassis Engineering by herb Adams as mandatory reading.