I developed a bespoke design for shells to replace the stock rubber Fiero front lower control arm bushings with spherical bearings. The bushings are the same across all years of Fiero production, and thus the shells fit all years as well.
I started looking at getting 8 shells (two vehicle sets) made. That quote runs just under $100 each shell for quantity of 8.
The CNC program development and machine setup are fully half the cost of the quote, so if I could run more parts, the price per part will come down significantly. A run of 20 (3 additional sets) will be $51 each; a run of 52 parts (11 additional sets) will be $42 each
In addition to four shells, a full kit will require two spacers per shell, one spherical bearing per shell, one ID snap ring per shell and, for '88s only, two shaft seals per shell. Each kit will need one of my installation/removal tools as well.
One kit will include:
4x Snap rings
1x Installation/Removal tool
8x Seals for '88's
Approximate Kit Prices:
3 Buyers: $515
11 Buyers: $445
3 Buyers: $560
11 Buyers: $490
Since the group buy is to bring down the cost of the shells, the number of buyers does not have to be for a single type of kit. Two '84-'87 buyers and 1 '88 buyer are still 3 buyers and kits will be priced accordingly.
The kit price will interpolate more or less linearly for number of kits between 3 and 11.
The shells fit ALL years of Fiero front lower control arms.
They WELD in place.
The difference between '84-'87 kits and '88 kits are only the shaft seals.Why spherical bearings?
OEMs use rubbber bushings because they are CHEAP.
As the suspension gets further from static ride height, the "wind up" of twisting the rubber bushings becomes a second spring.
Under high loads in hard corners, rubber bushings deflect. Bushing deflection in a hard corner reduces camber and prevents the chassis from making the best possible use of the tires. In a car with very short knuckles, such as a Fiero, a modest amount of bushing deflection becomes a large amount of camber loss. This reduces ultimate grip and unpredictable deflection makes the "ragged edge" more ragged. The car is inconsistent at the limit and can be upset by bumps that change any tire's camber in mid-corner.
Making these problems worse is the fact that modern performance tires are very much stickier than '80's performance tires... to the point that modern performance tires are almost what race tires were in the '80's. Greater grip available with modern tires makes the problems with OE rubber that much more obvious.
There are alternatives to OE rubber. Polyurethane is by far the most common, with Delrin or UHMW available for rare applications. Urethane is a "sticky" plastic which requires frequent greasing and can add significant stiction and preload torque to a suspension pivot. Urethane is actually a poor material choice for bushings. Aftermarket manufacturers use urethane because it's cheap and easy to mold. Delrin and UHMW are "slippery" plastics and have less frictional torque, but are also very rare and typically custom made. They are rare because they have to be machined--a fundamentally more expensive process--rather than molded like urethane. There is also significant engineering involved in designing Delrin or UHMW bushings in order to minimize pre-load and maximize bushing life. Both are plastics with hardness measured on the Shore durometer scale, which makes them still fairly soft materials.
Spherical bearings are free moving with very little preload torque. When installed in my shells, these bearings have a typical preload of 20-40 inch-lbs, with a few getting as high as 60 inch-lbs. Spherical bearings have essentially zero deflection, as you would expect from materials measured by Rockwell--as opposed to Shore--hardness.
Installing spherical bearings will make your car's ragged edge significantly less ragged. Spherical bearings will improve your car's "path accuracy" and your ability to place the car wherever you want on the line through any given corner. Consistent camber behavior will produce consistent grip from your tires, allowing you to push the car harder with more confidence.
For the '84-'87 Fiero specifically, in each front lower control arm, the forward and rear pivots are neither parallel nor coaxial. This means that there is a large amount of "off axis" motion in each pivot. This is not a problem for a rubber bushing or a spherical bearing, but IS a problem for polyurethane, resulting in excess stiction and binding above and beyond what would otherwise result from simply using urethane. This off axis motion does not bother spherical bearings in the slightest. However, it DOES cause problems with any seals used with the spherical bearing, as the spacer ends up off center in the shell, which is bad for a seal. That is why I will only send seals with kits for '88 cars. The 1988 Fiero suspension design uses more conventional A-arms with coaxial pivots and thus can have seals.
Spherical bearings will increase NVH *slightly*. I have not driven a Fiero with spherical bearing front pivots yet (thats why I'm having these shells made...), but I have driven my Formula with spherical bearing rear lateral link pivots for years; I did not notice *ANY* change in NVH when I installed those.How to install:
1. Remove control arm from car
2. Remove current bushings AND SHELLS from control arm
3. Install spherical bearings to spherical bearing shells using installation tool and bench vise.
4. Slip spherical bearing shells into control arm
5. Install control arms to chassis with spherical bearing spacers installed in spherical bearings. Snug the control arm pivot bolts. There is no need to apply full bolt torque at this time.
6. Tack weld spherical bearing shells into control arms
7. Remove control arms from chassis
8. Remove spherical bearings from shells without breaking tack welds
9. Completely weld shells into control arms. I *STRONGLY*
recommend TIG welding. Take the control arm to a welding shop if you are not 100% confident in your skills.
10. Reinstall bearings, install seals as required, install spacers
11. Install control arms to chassis, bring bolts to full torque (60 ftlbs for 12mm class 10.9; 80ftlbs for 12mm class 12.9)
12. Reassemble suspension
13. Drive the hell out of it!Installed:
Welding as shown below does not distort the bore. I measured preload before and after welding and it only changed by +/-2 lnlbs across the 4 units. Pictured are of shells of a very similar design installed in a pair of REAR arms that I used for proof of concept for spherical bearing shells on The Mule, my 1987 GT Northstar car.Things you should know:
The '88 crossmember has mounting ears that make +/-0.030 overall length tolerance still installable.
The '84-'87 front end has the rear pivots welded to the body, but the forward pivots on the crossmember. This means that the crossmember bolts can be loosened to shift the crossmember to accommodate overall length tolerance mis-matches.
These facts mean that the front control arm shells could probably be tacked in one crossmember or chassis, then installed into a different crossmember or chassis with minimal problems.Buyers:
You have an order when I have a $100 deposit from you. PM for payment info.
Full payment will be due prior to shipment.
Buyer will pay actual shipping costs.
I will mark buyers as paid as they provide a deposit.
1. Will ('84-'87; Paid)
2. Will ('88; Paid)
4. ericjon262 ('84-'87; Paid)
3. pmbrunelle ('84-'87; Paid)
[This message has been edited by Will (edited 08-02-2020).]