Does anybody know the specifics of FD suspension geometry? I mean ALL of it...

toe
caster
camber
scrub radius
swing arm radius
king pin inclination angle
lower control arm length
upper control arm length
track
ride height
wheelbase
wheel travel

 

I would look in either the technical data section of the FSM, or in the suspension section of the Mazda 1993 Service Highlights Manual. I have neither in front of me to check tho.

Dave

 

or click on the search button and go to Advanced Search and look for posts from "howard coleman" (not sure if that is one word). he has lots of useful info along those lines in the suspension section.

 

Do a search for Damon also. He and howard are usually in the same posts.
John

 

It might be in the "body" factory service manual. Dale Clark said it has some detailed alignment info...

-s-

 

Hello-

I may be able to help you out. I've taken a lot of measurements from the stock FD suspension and performed a good number of analyses... interesting stuff.

But, you need to be more specific. "ALL" of it isn't specific enough because, believe me, there's far more than what you have listed below :-). In fact, there's far more than I've taken measurements for (i.e. I haven't taken any compliance measurements... only kinematic, and then only 2D, so no anti-squat or anti-dive geometry). What is your goal? What are you trying to do? Let me know...

Take care,
Shad

 

This is from Mazda's 1993 Service Highlights book. It includes discussion of the suspension geometry, but not many other numbers.

Dave

 

^ I think bradg is actually trying to model the FD suspension and that's a whole 'nother ball of wax.

To model the suspension you have to define all of the pivot points in space. To generate just a camber curve for instance you'd need to know the locations in space of the inner suspension arm bushings and the outer ball joints. The length of the links doesn't matter so much, it's how the location of the pivots change relative to eachother in space as the suspension moves that defines everything. Longer arms are nearly always better though as they induce less tire scrub as the suspension compresses.

Basically the suspension could be easily modeled IF you were willing to spend a lot of time taking proper measurements. Every movable joint in the suspension would have to be defined in space in order to generate an accurate model. On the front that would be inner bushings on the upper arm, ball joint on the upper arm, inner bushings on the lower arm, ball joint on the lower arm and the locations of the inner and outer tie rods if you wanted to include bump steer. The orientation of the ball joints to eachother gives you the caster and the steering axis inclination. If you measured the back spacing of a given wheel and knew the ball joint locations you can compute scrub radius, etc.

 

This book also has very clear views of some/all of the suspension members, as well as free-body diagrams showing the kinematics. They appear to be accurate line art - just scale them using some known measurements and they should do nicely.

BradG, if DamonB is correct, I suggest a copy of this book.

Dave

 

One of my projects at work involves designing an independent front suspension system. I'm attempting to learn all I can about the designs of what I would consider some of the better handling or at least more sophisticated cars on the road. That includes 3rd gen rx7, e36 beamer, z32, etc.

I may try to model some of these systems. If worse comes to worse, we have a laser scanning system that I could use to turn physical parts into digital parts. But I would have a hard time explaining to my boss why I paid $X for sports car suspension parts!

DamonB - yep, ultimately I would need tons more info than I listed, including stuff for bump steer, anti-dive, instant roll center, etc. But that starts getting more into vehicle specific data (which would include center of gravity I guess). I'm willing to ignore everything but the front modules right now. Rear suspension is in another dept

Shad - Care to share your measurements?

Dgeesaman - did you mean to include a link in your post, or by "this book" did you mean the Service H'lights book?

Lol, Anybody want to donate old stock suspension parts?

 

The 1993 Mazda RX-7 Service Highlights book. $40. It discusses in some detail how the suspension geometry performs.

Dave