'88 wheel bearing and hub upgrades

[Series8217]

Got the left side mounted today and tested the articulation. Found some minor interference to the lower control arm at full droop plus left steering with high caster angles, but that's easily fixable with some sanding, and I'll add a relief in the CAD. The real issue is my lower ball joint is sunk too far into the arm because the ball joint sleeve I used is too tall, but it will work fine after clearancing the upright.

The Fiero brake hose works fine with the Corvette banjo bolt.

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Who finally made the uprights?

Would you recommend that vendor?

I went through Xometry for the CNC-machined aluminum parts. I used the economy option which resulted in them being made in India. The parts turned out fine, only some minor cosmetic issues and a small correctable dent where it looks like something fell on the part in a non-critical area.

[draven]

Very very very nice... all the adjustability makes me second guess my choice of coleman racing spindles

6061 or 7075?

"Economy" Unit cost?

[ericjon262]

THATS HAWT!

maybe I missed it, how do they compare to stock weight wise?

[Series8217]

6061. I might switch to 7075 if I make another set to just to avoid having to use a steel insert for the LBJ.

THATS HAWT!

maybe I missed it, how do they compare to stock weight wise?

Comparing the knuckle+steering arm+hub+LBJ the gain is 4 lbs per corner. The brakes obviously add weight as well but that depends on which package you choose... The knuckles support everything from C7 base (12.6", using C8 rotors & C7 calipers) up to massive carbon ceramics, though I've only confirmed base and Z51 so far. Some centering rings or spacers may be required to clear the hats on the two piece Z07 carbon ceramic and Z06 steel rotors.

[draven]

Any change in unit cost from initial estimates?

[Series8217]

Any change in unit cost from initial estimates?

Still in the same ballpark. The bill of materials is still evolving.

[Series8217]

I designed brake hose brackets that work with the stock hose clamp and my the SPC upper ball joint plate in my adjustable upper control arms. The integrated nut is an M6 PEM insert. This finalizes the prototype assembly. I aligned the car and have taken it on a few test drives. No issues so far!

Hoping to be able to make it to an autocross in September for more aggressive testing, but I would like to have the rears on the car before I do that since my rear wheel bearings are shot.

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[Series8217]

Not much room for a larger brake setup in front with a 17" wheel. This is the base C7 caliper so the rotor diameter is 12.6 inches. The next step up is Z51 which has a 13.4 inch rotor. The Z51 package might fit some 17s.

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[Emc209i]

Looks good. I can't imagine you'd need any more braking capacity than that. And for aesthetics, having that multi piston brembo caliper outweighs having any larger of a rotor. Dress it up a little, get the corvette lettering off the calipers, and put a Fiero emblem on the center caps.

[Series8217]

Looks good. I can't imagine you'd need any more braking capacity than that.

Thanks!

Definitely not at this power level, but I'm working on plans for that...

I might refinish the calipers, but I'm going to wait and see how they perform. None of the GM 4 pot Brembos have staggered piston sizes anymore, so I may end up moving to a race caliper if pad wear is a problem.

I don't run wheel center caps. They're just another thing that can fall off at the track.

[num1son]

These updates are the most exciting thing happening in the Fiero world right now. Can't wait to see this finished.

[Series8217]

Rear uprights coming along well.

There are a few options for hubs including 5x120, 5x4.75, and 5x114.3. All accept large 33 spline outer CVs and there are a few different axle solutions that range from an outer CV swap to 930-style CV conversions, depending on your torque requirements.

I'm using the 5x120 hubs to match my front uprights (C8 bearings). BMWs use this bolt pattern and E90 3-series offsets are pretty much spot on. There are plenty of options for track wheels for these cars, in sizes up to 18x12 or larger as well as more tame fitments like 17x7 and 17x8.

The upright is fabricated from laser cut and bent steel components which will be welded together. I designed it to be modular with a face plate accommodating the brake and hub package, and a back structure determining the suspension geometry. Obviously once it is welded together you can't change anything, but the design makes it easier to support customizations without a compete redo.

The test fit of all the components went well. Hoping to have some time to weld the first one up in a few weeks and get it on the car.

Suspension geometry structure:

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Hub and brake carrier plate added:

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Brake and hub package test fit:

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Roughly how it will look when complete, just missing the rotor and parking brake bits:

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[FieroWanaBe1]

Bravo.

This is exactly what I wanted to do with the rebuildable Jeep Bearings, which should take S10 outer CVs, that should fit Fiero Axle shafts.

But I know 934 Stubs are available for $500 a pair from Dutchman for the 33 spline C7 Vette, I have not determined if the F40/LS4 has the clearance on the engine side for a 934 joint before hitting the block. A 934 joint from EMPI is 128mm/5.03" OD.

[ericjon262]

the rears look fantastic! are you considering production of them? I've been slowly working on a design of my own, but I am much more impressed with what you have come up with! does it have provisions for a parking brake?

[Series8217]

the rears look fantastic! are you considering production of them? I've been slowly working on a design of my own, but I am much more impressed with what you have come up with! does it have provisions for a parking brake?

I'm considering putting them in production if there's enough interest.

It uses the C7 Corvette parking brake, but I still need to work out the cables. I have developed a control solution for the electric actuator but haven't found a good place to mount it.

[ericjon262]

I personally would prefer the mechanical parking brake, are the electric units lighter? I can't imagine them being lighter than a cable, but I could be wrong.

[Series8217]

I personally would prefer the mechanical parking brake, are the electric units lighter? I can't imagine them being lighter than a cable, but I could be wrong.

It's a mechanical drum-in-hat brake. The actuator I'm referring to only replaces your stock brake handle with a button you can mount anywhere, and an electric cable actuator that can go somewhere else TBD. Instead you could use the C7 parking brake with custom cables or adapters to connect to the Fiero handle.
I was trying to find a way to get rid of the handle because it hits my racing seat.

[ericjon262]

That's a very valid reason to not want the handle!

April 26th you posted this in my build thread after I replaced my wheel bearings:

The Timkens, like all other aftermarket wheel bearings for the Fiero, are junk. In track use they have been known to break off at the flange. On the street, longevity is poor.

Make sure to tighten your axle nuts properly. Loose axle nuts will ruin the bearings very quickly.

OEM Fiero bearings are discontinued. OEM J body bearings are available NOS (maybe even new new as recently as last year) and are high quality. They do require some machining to the Fiero upright and slotting the mounting holes slightly.

the axle nuts were tightened properly, but unfortunately, earlier this week I made a WOT pull and started noticing a nice loud whirling noise... shook the back tires, and wouldn't you guess, the bearings are already toast in less than 6 months of intermittent street driving (no track time....) guess I need to start pressing forward with wheels/tires/brakes again...

[Series8217]

One fully assembled and painted upright ready to go on the car.

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[ericjon262]

That looks awesome, nice work!