best suspension modelling software?

[xlr8tr]

Whats your opinion on the best/easiest to use suspension modelling software? I'm going to re-do a bunch of stuff on my cobra over the winter, and I think I want to do this first, to figure out what changes to actually make. Its set up soooo poorly right now the only thing keeping me on the road is really stiff springs!! I want to pull actual measurements off mine as it sits now, model it, and fix what needs to be fixed.

I've heard good things about WinGeo, by Bill Mitchell, but not sure if its still be sold/supported? I found Performance Trends as well http://performancetrends.com/SuspAnzr.htm

Other options? I have independent front (strut rod style) and triangulated 4 link in the back.

Thanks!

[xlr8tr]

oh come now, hopefully someone has used software here?

[Jim Vander Wal]

I have looked at software but need to know a lot more about designing and modifying to fully understand how & what.
Jim

[xlr8tr]

I've read a bunch of the books (tune to win etc), and they all say software will allow you to model all aspects of what your car is up to: bump steer, roll centers etc. Otherwise, its just guesswork. Ive made mine better with guesswork, but runnign up against hard unsolvable issues now that need changes in things like steering rack width, re-mounting suspension points etc.

[scottj]

I use software, but it's Solidworks. I didn't investigate suspension software as I got the results I needed. Although, with a lot more work involved.

[xlr8tr]

Originally Posted by scottj

I use software, but it's Solidworks. I didn't investigate suspension software as I got the results I needed. Although, with a lot more work involved.

skills I dont have unfortunately

[Jim Vander Wal]

I have SolidWorks and plan to model the chassis but it will be a lot of work, more of a learning experience for me. The dedicated suspension software would be much easier and a bunch faster.
xlr8tr, I hope you document your findings and software selection.
Jim

[strictlypersonl]

Mark,
Unless you are planning on ripping all the attachment points off the chassis, the most important factor for stable driving is the bump-steer curve. That can be measured with relatively cheap/simple tools. Once determined, it's not too hard (relatively) to change the steering gear position and tie-rod length.

If you buy that software, you will have to spend 10's of hours measuring your attachment points, etc. A nice intellectual exercise, but of little real use - your car is already built.

[xlr8tr]

Originally Posted by strictlypersonl

Mark,
Unless you are planning on ripping all the attachment points off the chassis, the most important factor for stable driving is the bump-steer curve. That can be measured with relatively cheap/simple tools. Once determined, it's not too hard (relatively) to change the steering gear position and tie-rod length.

If you buy that software, you will have to spend 10's of hours measuring your attachment points, etc. A nice intellectual exercise, but of little real use - your car is already built.

I agree with you 100%- but inmy case the car was built POORLY. I definitely will be moving suspension points, steering rack ect. Just a couple of examples I have figured out so far from reading/researching:

1) steering rack is about 4 INCHES too wide: from what I have read, to minimize bump steer the sterring rack inner pivot points are supposed be on the imaginary line between the upper and lower A arm inner suspension pivots, and they are INCHES off on each side. The way is is now, any bump steer correction will give perfect bump steer at ride height +/- about 1/4" of travel, then all hell breaks loose.

2) the imaginary lines created by the upper and lower rear 4 link arms are supposed to cross somewhere close to the front of the car, but they actually point BACKWARDS and no way to adjust that out

3) lower A arms at ride height are nowhere near level, they point up about 2" from chassis to where they attach to the uprights. Drop spindles will fix that, but then i have no idea what happens to camber curve etc.

4) I have the old school lower "A" arms that have the strut rod rear arm that connects to the chassis- problem with that is, it severly limits steering angle as tire rubs on the strut arm, sterring radius is probably worse than my 3/4 ton diesl pickup so no auto X possible, I'd have to do 3 point turns in the hairpins

Sooo, bunch of stuff to chop out and re-do, my son is a metal fabricator so I have free skills to use but if I'm re-doing it, I want to do it right. I'd like to auto-X or something occasionally. Impossible now.

[strictlypersonl]

Originally Posted by xlr8tr

I agree with you 100%- but inmy case the car was built POORLY. I definitely will be moving suspension points, steering rack ect. Just a couple of examples I have figured out so far from reading/researching:

1) steering rack is about 4 INCHES too wide: from what I have read, to minimize bump steer the steering rack inner pivot points are supposed be on the imaginary line between the upper and lower A arm inner suspension pivots, and they are INCHES off on each side. The way is is now, any bump steer correction will give perfect bump steer at ride height +/- about 1/4" of travel, then all hell breaks loose.

What length are you looking for?

2) the imaginary lines created by the upper and lower rear 4 link arms are supposed to cross somewhere close to the front of the car, but they actually point BACKWARDS and no way to adjust that out

Interesting. In a bad way. Usually the fix is to weld taller brackets on the rear end housing.

3) lower A arms at ride height are nowhere near level, they point up about 2" from chassis to where they attach to the uprights. Drop spindles will fix that, but then i have no idea what happens to camber curve etc.

That would depend on whether the distance between the top and bottom ball joint changes. Usually dropped spindles keep the original distance.

[Morris]

Mark

I used the Performance Trends software......as mentioned....it’s not easy to get the measurements if the vehicle is on the floor.
The best way we did it was on a lift, with a work bench we cut in half so we could simulate the road surface.....by setting the car down on 4 half size maple block work benches....we were able to level everything and take accurate measurements......which like Bob said....that is the most important part of any suspension configuration......

We removed the springs and could moved the Chassis to any position in Droop or Rebound to take measurements and prove the software was correct in it’s analysis....

So think about what you want to do......we ended up removing the whole steering assembly....and had a new rack & pinion made at Appleton And then Tom Kirkham made up new uprights so we could correct all of the bump steer issues....

Remember I did this back in 2004 before Kirkham realized they had a problem....once they realize how bad it was....Tom K & I worked out the calculations and we even changed the height of the upright and the steering arms of the upright....and it all came together when we got the car on a race track.....the difference is I knew what I was looking for and we found it as KMP259 proved to be very Quick......

Most folks and Mfg. don’t take the time or just don’t understand what it takes to sort out a car and then be willing to cut some item off and relocate the steering or pickup points, just to get the chassis to go around a corner at a higher speed.

[Three Peaks]

I went through some of this when I built my car. I couldn't really afford the cost of the legacy suspension for my original style chassis so I had to do some adaption of what I had and what I wanted to use. With my original style chassis, some of the parts were reasonably easy to source, like the steering rack. The rear links were easy to incorporate into the changes I had to make to my Ford 8.8 IRS uprights but I had to change my pick up points on the lower control arms to level them up and do some imaginative fabrication to make it all work. I think i fabricated my rear control arms 4 times before I figured it out and got it right.
The front was another story altogether. The steering rack was the easy part and it solved some of the puzzle pieces since the pivot points were in the right plane to start with. I used Mustang II front spindles and moved my pick up points as I needed to to accomodate the spindle geometry. I think I made the front control arms twice to get them right. They aren't perfect, but they work pretty well and the car is comfortable to drive, even fairly aggressively.
Regardless if you use the latest and greatest suspension software, you will still need to make compromises unless you want to build an all new chassis. Look at your chassis with what you have and figure out the easiest way to accomplish what you need or close to it. Suspension tuning, from what little I know, isn't absolute unless you absolutely have to get the last ounce of performance out of your car like Morris and other racers.

I wouldn't go with dropped spindles to accomplish what you're proposing. What spindles are you using now? IMO, start with finding a proper steering rack and rod ends to fit your existing system track width. Then adjust or build new pick up points to mount control arms to. You can buy new control arms lots of places. Look into using adjustable control arms so you can more easily get an alignment when you're done and adjust it as needed.

Bob

[xlr8tr]

Thanks all for your input; heres a few pics and some info:
the pivot points for the front lower A arms are 19" apart. In my reasonable level of online digging I haven't found steering racks that are close to that unless you go to a custom setup. which I am willing to do, if I have to.

This beast is 20+ years old, built locally here in Vancouver BC by a small builder called Can-Am. I'm 6'7" 240+ lbs so this car works for me: 4" x2" frame with perimeter raisl means I sit between frame rails so my head is actually below the windshield. If that wasnt the case I'd probably sell it. Always loved the JBL for its built details and suspension. But, even if I wanted to sell mine I cant with the way it is now.

[xlr8tr]

I cant seem to upload other pics- file type is the same, size is the same, 480x640... joys of computers.

Here's a cool video in the mean time, my son driving (he is 6'4", gives you an idea of headroom)

https://www.youtube.com/watch?featur...0Y&app=desktop

[strictlypersonl]

Originally Posted by xlr8tr

Thanks all for your input; heres a few pics and some info:
the pivot points for the front lower A arms are 19" apart. In my reasonable level of online digging I haven't found steering racks that are close to that unless you go to a custom setup. which I am willing to do, if I have to.

The Flaming River FR1502 4X4 is about 20.5" between inner pivots. That might be OK, depending on how high your steering arm is. Otherwise, you're stuck with a custom racing rack. Generally they're not the best for the street, and the pinion usually comes out at the mid-point.

1974-78 Mustang II Manual Rack & Pinion - 1974-78 Mustang II Manual Rack & Pinion - 1974-78 Mustang II Manual Rack & Pinion - Chrome

[Three Peaks]

Do you have pics with the wheels off and the suspension parts exposed? Might help with the suggestions. I think the suggestion of the FR 1502 rack is excellent. Certainly will help with dealing with the bump steer for a start. May need to fabricate some new mounts to locate the unit in a different location to bring it in line with with spindle steering arms.
What spindles are you running now?

[xlr8tr]

sorry all, Ive been away, and had issues with the site: seems to be working now so I'll get some pics and continue the process! Thx for the link to the mustang rack, if I raise the rack a bit that might just work. Holy crap, unless Im reading it wrong, its like $600 bucks for chrome finish vs unfinished!!

[joyridin']

Try this company for a rack. They make one 19.5" wide as a standard. I have one of these in my car and it seems to work really well. Go to the product catalog on the LH side.

Rack-N-Pinion from Pro-Werks