Re: Adjustable Upper Control Arm for '88 Front Suspension
Posted: Wed Apr 02, 2014 8:22 pm
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.
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.