Real Fiero Tech

Weight
Let's get the weight out of the way first.

The OE 1988 Fiero front upper control arm weighs 5.24 pounds (2.38 kg), complete, with the OE balljoint and rubber bushings:


My adjustable upper control arm weighs 5.38 pounds (2.44 kg), complete, with the Rodney Dickman balljoint.


That's a gain of 0.14 pounds (0.064 kg) per control arm.

You may notice an errant stud sticking out the bottom of my original upper control arm. That's a droop limiter so I don't have to jack the car so far up to get the front tires off the ground. The droop limiter hits the crossmember shortly after the spring becomes slack, but before the shock reaches its droop limit.

The new control arm has no provisions for a droop limiter, so that's still something I need to work on.

Parts List
The following parts list is for one (1) control arm, but does not include the bushing reducer sleeves (5/8" OD / 11.9 mm ID) and ball joint plate, which are not available as off-the-shelf components:
- (1) Race bushing kit, SPC p/n 92021 (includes 2x delrin pivots 92025, 2x bushing pivot studs 92005, 1x slotted stud 92013, and jam nuts and bolts)
- (2) 3 3/4" adjusting sleeve, steel, SPC p/n 92040
- (1) 1988 Fiero upper control arm cross shaft, Fiero Store p/n 57205
- (4) Bushing thrust washers (need to finalize these)

The SPC parts are available from Summit Racing, among other places. To build two control arms, order double the above (two race bushing kits, 4 sleeves, etc).

I used the OE cross shafts, and I don't have any experience with the Fiero Store cross shafts. If they are dimensionally the same there is no reason they shouldn't work.

I will post the drawings and/or part numbers for the ball joint plate, reducer sleeves, and thrust washers once I have finalized them. I want to change the dimensions on the thrust washers and reducer sleeves so they fit better.

Installation Photo
Here is the new adjustable upper control arm installed on my Fiero:


Alignment Settings
I dialed in -3 deg of camber and 10 deg of caster. More caster and camber are not a problem. It should easily be possible to achieve 15+ deg of caster and -5 camber or more (stance it!), with wheel clearance or balljoint angle probably being the limiting factor.

With 10 deg of caster and -3 deg of camber the camber gains to a little over -6 deg on the outside wheel with a steering angle of 20 degrees.

These are awesome.

Ditto.
Congrats that these worked out so well.

Nice job man. I am interested. I will message you on FB

Good Shit.

Going into production at West Coast Fiero. WCF is also working on a new cross shaft design so we don't have to buy the very pricy ones from the Fiero Store. With the new cross shafts there should be no need for a reducer bushing either.

I was up at the shop a few weeks ago and spotted this stack of raw ball joint plates, ready to be chamfered and have studs welded on:

Series8217 wrote:and have studs welded on:
http://i.imgur.com/SaX0btFm.png

Is there no room for a bolt head underneath? Welded studs are horrible engineering.

The Dark Side of Will wrote:

Series8217 wrote:and have studs welded on:
http://i.imgur.com/SaX0btFm.png

Is there no room for a bolt head underneath? Welded studs are horrible engineering.

Are you suggesting using the bolted slotted stud like on the other side of the pivot plate?

While there's room for it (I think), that would add another degree of freedom to the balljoint plate which makes setup/adjustment more difficult. It also increases the parts count. The slotted, drilled, and faced stud is also waayyy more expensive to produce than the slotted weld-on stud.

SPC uses welded studs on their race arms, so I did the same on my prototypes.

What problems do you see with the welded-stud ball joint plate design like SPC and my prototypes use?

SPC:


Mine:

That's a clevis

I thought you were saying that the bolts that hold the ball joint were studs welded into the plate...

Rodney Dickman and RCC weld studs into completely silly places and ship the risk that damaging external threads scraps the entire part to their customers.

Yeah, its a clevis, but SPC's catalog listing is "pivot plate stud" so that's how it's listed on my BOM.

Will these work with the upcoming WCF C5/C6 hub knuckle design ? Or will they even be needed?

I haven't yet decided which upper ball joint to use for the new knuckles, but there will be a ball joint plate for these control arms that's compatible.

WCF just finished the first set of these. I'll post pricing here once I find out.

Any updates?

Call WCF for pricing until it's officially up on their web site.

Advertisement: http://www.fiero.com/forum/Forum3/HTML/0 ... .html#p978

Getting started on a pivot block for use with rod ends.





Same part, just viewed from the top and bottom.

SPC 92013 "pivot stud" (really a clevis) has 7/16" hole and 1/4" slot.

ETA: It also has 3/4" threads. Interesting. It's certainly the most compact clevis on the market.

The plate is about 0.242 thick while the slot in the clevis is about 0.264, so there needs to be about 0.020 shim between for the bolted joint to be effective. As is, when tightening the bolt down, only the tips of the tines of the clevis make contact with the plate, meaning that even with the bolt fairly tight, the clevis can be shifted by hand. This is undesirable. McMaster had a 12x18x0.5mm round shim that looks perfect on paper. I have some, but am not co-located with the parts this weekend, so I can't check them out now.

saweet!

keeping my eye on this as I'm sure I'll need more caster 'when' I get this thing on a track....