The Buy:

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 Shells
8x Spacers
4x Bearings
4x Snap rings
1x Installation/Removal tool
8x Seals for '88's

Approximate Kit Prices:
1984-1987:
3 Buyers: $515
11 Buyers: $445

1988:
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)
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.

[This message has been edited by Will (edited 08-02-2020).]

quote Originally posted by Iain: Fascinating Will, especially since I'm in the middle of refurbishing my '88 fronts with poly. I have been thinking of making my own upper/lower arms with spherical housing cups, I'd never considered fitting them to the standard arms. Soooo, questions: Would you consider selling just the shells and spacers? Being in Scotland, it would cut down my carriage cost considerably. I know my way round sphericals, sourcing and fitting is not a problem. ;-) sorry, couldn't resist. Is the shell parallel, not tapered/stepped like the annoying standard ones? Only reason I can think it needs aligned before welding, unless I'm being thick as usual and missing something. Is the spacer a reducer spacer, running as big a spherical as possible? Regards, iain

Thanks for responding!

If you were about to install polyurethane, I posted this just in time for you, then!

The bearings for which I designed the shells are are Aurora COM-10T units. Any 5/8" spherical bearing should fit, but the preload torque may be more or less for other parts. I would have loved to run a -12 part, but I did not think I'd have enough wall thickness left in the shell after adding the ID snap ring groove. I can send you a "basic" kit with just the shells and spacers and a BOM for the rest... but the shells and spacers are the majority of the weight in a kit with a weight ~5 lbs, so you won't save much on shipping.

I'm not sure what you mean by "tapered/stepped like the annoying ones". My parts are not annoying at all, just me When installing a bearing into a shell, you'd use my installation tool and bench vice to seat the bearing against the integral shoulder inside the shell. With the bearing fully seated against that shoulder, the snap ring can be installed to make sure the bearing does not unintentionally come out.

The outside diameter of the shell is stepped so that the shells are a close slip fit in the holes in the control arms. Tack welding in place is more about making sure that the axial distance between the shells matches the crossmember the control arm will be installed to. This allows the control arm to be installed and reinstalled to the crossmember smoothly and easily. The slip fit between the shells and control arms is snug enough that there's no real angular variation possible.

The spacers are stepped so that they can both clamp the bearing and center it on the 12mm bolts in the suspension pivots. They're also exactly the right length to duplicate the installed length of the original bushings, again contributing to easy installation and R&R.

Here are some other photos of the rear arms following powder coating and assembly:







//

If you're interested in building adjustable upper arms, check this thread out: http://www.realfierotech.co...opic.php?f=3&t=17936

[This message has been edited by Will (edited 08-01-2020).]

------------------
"I am not what you so glibly call to be a civilized man. I have broken with society for reasons which I alone am able to appreciate. I am therefore not subject to it's stupid laws, and I ask you to never allude to them in my presence again."

cognita semper

https://joj2020.com/ <--- She isn't a sexual predator.

[This message has been edited by Will (edited 08-02-2020).]

[This message has been edited by Will (edited 08-06-2020).]

------------------
88 Coupe: 2.0L Turbo 4 Cylinder, W2A, T25 Turbo, water/meth injection
84 Indy #64: Restoration Project
84 IMSA wide body SE: 3800 Supercharged
Rear Engine Shop on youtube: https://www.youtube.com/user/fast88fiero