I have a favor to ask of '88 owners:

I am trying to build a short-long A-arm conversion for an '88 rear suspension. the problem is that it is not in my car ('86) yet.
I was hoping I could get a few people to take some measurements on their rear suspensions for me.
Park the car on a flat level surface, and take five measurements:
1) Vertical distance from road surface to center of outer pivot for the lateral links.
2) Vertical distance from road surface to center of inner pivot of rear (fixed) link.
3) Vertical distance from road surface to center of inner pivot of front (adjustable) link.
4) Vertical distance from road surface to bottom center of rear cradle cross member.
5) Vertical distance from road surface to bottom edge of rear fender directly over wheel center line. Pleas include wheel and tire size and tire pressure.

Please be as accurate as possible in measurements. I would like measurements +/- 1/16" or less (+/- 1 mm or less for metric types)
Please tell me what engine you have and what model of car (Coupe, GT, Formula).
Besure to say whether you have stock or lowered springs.

Thank you very much for your time and cooperation.
When I finish the design, I will share it with the rest of the Fiero community.

I have only received one reply; that via e-mail. I was hoping for a larger sample than that.
So I will just move this back to the top

I thought of two other measurements that could be useful:

The vertical distances from road surface to the centers of the forward and aft pivots of the trailing arm.

This stuff isn't hard. It might take 5-10 minutes.
Is there only one '88 owner on this forum who is willing to take 5 minutes to help a fellow Fiero enthusiast?
Come on, people, prove me wrong.

Try the Fiero newsgroup (Can't remember what it is, just search for Fiero)... They are great for this kind of stuff! Thats why I got my car welded back together... And I thought that was hard.. (Damn clutch)

You dont need the lengths of the arms?

I would help you out Will but my 88-rear suspension is out of the car sitting on a pair of sawhorses waiting for a 3.4 Camaro engine. I can't give you those measurements with the cradle out of the car.

88formula:
I have exactly the same problem. The cradle and suspension I got from the junkyard are sitting around waiting to accept the new engine.

TOM:
I already have the lengths of the arms, I just need to know the relationships of the components at stock ride height.

Found my plumb bob, and plan on measuring Saturday.
I'll be putting these coordinates into my own suspension program. However I'm missing the coordinates for the upper strut mount points. Do you happen to have them? They would useful for figuring out the anti-squat values.

Check yer E-mail.

Thanks very much, gixxer.

For the benefit of everyone in the forum, here is what gixxer measured:
>Rear tire is a half worn Eagle GT >215/60R-15, stock springs, 32 PSI.
>Here's what I got:
>1) C/L of outer pivot of both lateral links is 8.5"
>2) C/L of inner pivot of rear lateral link is ~8.0"
>3) C/L of inner pivot of front lateral link is 8.0"
>4) C/L of lower surface of the subframe rear transverse member is 6.5"
>5) Lower lip of wheel arch at tire C/L is 27.2"
>6) C/L of rear pivot of fore/aft radius rod is 6.2"
>7) C/L of front pivot of fore/aft radius rod is 9.2"
>The rear tire eventually had to come off and >I had to use #4 and #6 as
>baseline measurements, using jacks to hold >everything in orientation.
>Everything was remeasured with the tire off.
>Let me know what measurements YOU have as >I'd like to plug some of this
>stuff into my own suspension program >(Performance Trends).

I have an '88 shop manual. It has some body measurements, but does not reference strut tower location to cradle mount points, or anything else ont he bottom of the car for that matter. The cradle dimensions it has do not include the suspension link pivots. It's basically useless for what we want to do. I will meaure body CL to pivot dimensions, arm length, and a few other things tomorrow and post them soon after.
What other measurements are required?

Oh yeah, did you ever look at the Ryane web site where he goes into a little detail about converting an '88 cradle and suspension to an earlier model?
See http://www.ryanemotorsports.com/
GM chassis parts+engine cradles+88 engine cradle
There is some sort of adaptor for the upper strut mount.

Ryane Motorsports' info is almost right. The '88 cradle does not need to be modified in ANY way to bolt into an early chassis.
However, for '88, the forward hole in the engine mount bracket on the cradle moved forward 21 mm (0.827") and inboard 47 mm (1.850"). The rear engine mount bracket bolt hole moved forward 33 mm (1.299"), and inboard 36 mm (1.417").
The strut towers also changed for '88. The moved closer together by 74 mm (2.913"), which is a 37 mm (1.457") inboard move for each one. They also moved aft by 5 mm (0.197"). The strut top adapters accomplish this movement in the early chassis by relocating the tops of coil over struts. This maintains the stock '88 geometry. It's amazing the money people put into maintaining stock geometry, isn't it?
The bloody shop manual does not reference anything on the top of the chassis to anything on the bottom of the chassis. Thus, in order to know the position of the strut towers wrt the cradle mounts, one would have to drill reference hole "N" all the way down through the chassis and drop a plumb bob through it. I'm not inclined to do that this afternoon.
However, a plumb bob could be dropped through one of the holes to which the strut top mounts. It would require removal of the strut at least, and probably all the suspension links and axle half on that side, but it could be done.

[This message has been edited by Will (edited 09-17-2000).]

Excellent!
I thank you for measuring everything using dimensions along a plane.
The only thing I can think of is info on the strut, disc and wheel to locate the center of the tire contact patch. Also, X,Y,Z coord. of the top mount of that stupid Chapman strut.
With that info plus the CG height (19.5"?), we'll have enough info to reverse-engineer the suspension.
Thanks again.

I don't know how much anti-squat the current setup has, but more could be dialed in by raising the front pivot of the trailing arm. To do this, I think it would be possible to weld a sleeve on top of the cradle rail and reinforce it heavily. This would raise the forward pivot 1 - 1 1/2".
A good tuning aid would be to cut the ends off the trailing arm, weld nuts (RH on one end and LH on the other) on and use rod ends. That way, the length of the trailing arm could be adjusted to fine-tune anti-squat for best performance on strip, oval, or road course. It's unlikely that my car will see the latter two in any formal sense, however.
By measuring the strut towers center-center across the engine bay, and dividing that result by two, you could find the lateral distance the strut top is from car CL, without even taking out the strut. You could do a good job with the camber curve that way, but it's not quite enough for anti-squat.
What about measuring the angle of the strut wrt vertical in the fore-aft plane? I have a combination protractor/level that would make short work of that job. I'm sure with a little resourcefulness you could come up with one as well.
I read in a road test somewhere that the Fiero's CG height is 19.5". I have never taken any measurements to verfiy, though.
I can give you fore-aft CG location based on weight by wheel measurements. But not until tomorrow.
What is "Performance Trends" like? I have Computer Aided Racing, and some freeware that I downloaded. Neither of them seem particularly advanced (both are DOS based, although I guess that it really doesn't take much to figure this stuff out).

"Roll Center" is the program. It is 2D, but I like it. A person still has to run the numbers, but this program helps take care of the drafting board stuff. A demo to download is at- http://www.performancetrends.com
Chao.