In terms of the mechanical condition of all the parts, that much may be true. But there is more to having a suspension work right than having shocks that don't leak or compress with no resistance, springs that haven't sagged, and bushings that aren't all age/ozone-cracked.

In terms of handling performance it is entirely possible to choose brand-new rear springs that are either too soft or too stiff in relation to the rest of the car's suspension details. Too soft tends to result in understeerish behavior and too stiff may be oversteerish, assuming that the front and rear sta-bars are somewhere near right for a proper spring combination. A little understeer, enough to keep out of immediate oversteer as long as you aren't doing anything jerky or stupid with the brakes or throttle, is about where you want to be.

There is also a ride quality issue that depends on the front and rear spring rates being "matched". A bad mismatch with poor damping can give a "pitch-y" ride - like an old pickup truck with nothing in the bed where you get lots of front to back head toss. There's quite a bit of "wiggle room" on this as long as your shocks/struts are in good condition, but using shock damping to cover for a spring mismatch is a poor approach to getting and keeping overall street handling.

You can't adjust the springs' rate by doing anything besides swapping them out for different springs of different stiffness (lb/in). Rate isn't the same thing as ride height (which with C/O's you can adjust to some extent), although there is a loose relationship between rate and ride height. The advantage of coil spring arrangements here is that there is a wider range of springs that will physically fit to choose from, and they come in smaller stiffness steps.

When you go from your OE spring location on the LCAs to mounting them essentially off the axle directly, there is a motion ratio effect that you need to consider when choosing springs. There is also an effect from the rear geometric roll center being lowered when you go from the rather high OE coverging/triangulated 4-link roll center to a PHB-based roll center that's typically several inches lower. These effects work in opposite directions, since the springs' motion ratio effect would call for softer axle-mounted springs, but the lowered roll center then calls for them to be stiffer. And you still have to work the numbers based on any spring change that you might have made up front.


Norm

 

Wow and Ugh... I'll have to think about this for a bit. Again, thanks for the details/explanation.

 

Try to find a copy of Fred Puhn's softcover book "How To Make Your Car Handle". It's been around for quite a while, and it's about the best introduction to this suspension & handling stuff that I've seen.


Norm

 

Norm – That’s good advice. The book is still in print. We’ve heard a newer book titled, “How to Make Your Muscle Car Handle” by Cartech Books is a good book for beginners too.

 

Yes. Mark Savitske's book, which finally hit the stores early this year. It's slanted somewhat more toward the older musclecars and is I think intentionally lighter on the math than Puhn's book. But the basic concepts and thoughts still apply across model years and platforms.


Norm

 

http://www.musclemustangfastfords.co...ter/index.html
Just saw this and remembered this thread.

 

It took me long enough, but I finally got some parts installed. After all the reading and chatting with folks I ended up with the Stifflers Fit System, Maximum Motorsports Torque Arm and Panhard Bar, UPR Adjustable LCA's, Eibach Shocks (already had the springs). Pictures should be here:

https://mustangforums.com/forum/memb...9102-trans.jpg

https://mustangforums.com/forum/memb...ang-front.html

https://mustangforums.com/forum/memb...ng-middle.html

https://mustangforums.com/forum/memb...tang-back.html

I'm liking most everything so far. The body is so much more rigid that the doors are harder to close as I'm sure the alignment is a bit off now. The ride quality is better, cornering is much stickier.

Only issue that I have is the torque boxes are creaking and popping. I've had a load of welding done and installed battle boxes and 90% of it is gone, but there is still some there. Likely going to get more welding done.

Many thanks to all of you for your feedback. The details and info you provided was helpful.

Waferboy

 

Is that a driveshaft safety loop I see in pic #1?

Glad you like all your new items and that "ladder" style FSC's offer better support than the usual suspects. Expect a whole hell of a lot better lateral grip in the corners and much improved roll-axis.



Jazzer

 

Ever since putting this stuff in my Torque Boxes have been moaning and groaning. Just had the things welded up like crazy, welded in battle boxes and still can't get rid of it. Funny thing is I can't see any tears in the metal. Had any experience with this problem? I'm taking the car in again on Wednesday... will have a different guy look things over and find what else he can weld. A little welding and some touch up painting... This car is making a comeback! :-)