'88 wheel bearing and hub upgrades

[Series8217]

None of the 1988 Fiero wheel bearings are durable enough to hold up to track use.

There are reports of the eBearings units failing after as little as one lap.

The original GM units can last for part of a season, but they are becoming very hard to find and many have unknown mileage.

Rodney's new tapered-roller bearings were a possible fix. Rodney acknowledges that his bearings aren't designed for track use, and has mentioned that making bearings as strong as the original GM ones is simply not feasible with the limited market for these parts. I tried Rodney's bearings and unfortunately ran into a failure after one weekend of HPDE at a relatively low speed track on 200 treadwear tires.

This leaves only a few options:
1) Adapt a knuckle from another car that already has a durable bearing assembly
2) Modify the knuckle to accommodate a durable bearing assembly
3) Fabricate a new knuckle that accommodates a durable bearing assembly
4) Make a new bearing that's at least as durable as the original Fiero part

Here's the current state of the different directions:
1) Kappa Platform (Pontiac Solstice / Saturn Sky) knuckles have been adapted to the '88 front suspension using alternate ball joints and a tie-rod rod-end adapter: http://www.fiero.com/forum/Forum3/HTML/0 ... .html#p286

2) I haven't seen this yet, but I have some ideas.

3) Held / Arraut makes drop spindles for the '88 Fiero that use the rear Fiero bearings: http://arrautmotorsports.com/suspension-information/
I don't like the design or engineering (if any) of these parts, but they would work.

4) Some FWD Cadillac rear hubs have been adapted to the '88 Fiero bearing housings: http://www.fiero.com/forum/Archives/Arch ... 6.html#p31
I suspect these aren't any stronger than Rodney's bearings, since they are subject to much of the same geometry limitations.

So back to #2...

The '88 Fiero front knuckle has an extremely limited hub bore size (~70mm) -- the '88 Fiero bearing is really the only one that fits in it. However, it's a generous amount of space for a bolt-on spindle.


Consider a straight spindle shaft like on the 1994-2004 Ford Mustang front knuckle:


These hub shafts accept a bearing/flange assembly with a 5x114.3 bolt pattern.


The hubs are relatively inexpensive ($50 to $90 including bearings) and are extremely durable. Wheels with the 5x114.3 pattern are common and available in a variety of offsets from ~30 up to 63mm.

A spindle could be fabricated which bolts into the '88 front knuckle and accepts the Mustang hub, or something similar. The only custom parts required would the bolt-on spindle itself and possibly a new brake caliper adapter. Obviously the rotors would have to be drilled for 5x114.3 as well, but that isn't a new operation since larger-than-stock rotors are probably already being used from another vehicle.

[bse53]

Fiero's aren't unique to this problem. You'll find the same issue with the C4 vette.
Ron Sutton at lateral g forum devotes time discussing the inadequate stock bearings on the pro touring cars.
The spindle idea sounds like it has merit.
Even finding a hub that would adapt doesn't mean the bearings would stand up to the forces in racing.
Of course the best solution would be custom hubs. Could fix the other geometry issues at the same time.

[Series8217]

I would love to use the C5/C6 bearing assemblies, but the knuckles are very tall so I don't know if they will fit in the front of a Fiero. I should have my hands on some C6 knuckles either tonight or on Saturday for a quick test fit. My friend has some in a storage unit. I also purchased an SN95 mustang knuckle and hub assembly for assessment.

An alternate for the C6 knuckles is the C6 retrofit knuckles from Classic Industries. The part number is CP30013. These knuckles take C5/C6 brakes and wheel bearing assemblies, but bolt onto early F-body suspension. I don't have any dimensions, but judging from the photos they appear to be just a shorter version of the C5/C6 knuckle, with a taper hole in the top instead of a ball joint. They're pretty cheap at $268 a pair.



They are also working on 1" and 2" drop versions, which look like they're shorter overall, and maybe a better fit for the Fiero. However, they aren't available yet.

I found a picture of the back side of the CP30013 knuckle (see http://goo.gl/WjPXpF) and it looks like the axle centerline is too close to the lower balljoint to work on the Fiero. The ride height will be too high. The distance to the axle centerline appears to be ~40-50mm. The '88 Fiero knuckle is about 85mm.

A rough measurement using that picture and a rotor diameter of 325 mm gives a distance of ~250mm between the lower and upper balljoints compared to the '88 Fiero's 173mm. I don't know if the CP30013 knuckle would leave enough room in the wheel to use Rodney's 1" lowering balljoints to restore the ride height.

I might order some to take real measurements on, but waiting for the lowering knuckles to be released may be the wiser option.

[Series8217]

Fiero's aren't unique to this problem. You'll find the same issue with the C4 vette.
Ron Sutton at lateral g forum devotes time discussing the inadequate stock bearings on the pro touring cars.

Is this the post you're referring to?

http://www.lateral-g.net/forums/showpos ... stcount=71
continued here:
http://www.lateral-g.net/forums/showpos ... stcount=76

[Series8217]

I acquired an SN95 (1994 to 2004 Mustang) knuckle and hub. I don't have a big enough axle nut socket and the auto parts store is closed now, so I'll have to take it apart tomorrow. However, I was able to make some preliminary measurements, and it looks like the best offset I could hope to achieve with a fabricated spindle is +12 to +15mm over the '88 Fiero knuckle. That's really going to be too much to fit the wheel package I want, and it's also too much to get any other Fiero people interested in buying them (so I can have more made and recoup some of the costs).

The C6 hub offset is only about 7mm longer than the '88 Fiero hub, so I think making a new knuckle to accommodate this hub is feasible. Unfortunately, wheel fitment is a big problem with this pattern. I can't find a 17x8 fitment with high enough offset in this bolt pattern. 17x9 and 18x9 are available with 50mm offset (TSW Interlagos). 5x114.3 is the better pattern for the front, since S2000 fitment has an extremely high offset (63mm). Many wheels have both the 5x100 and 5x114.3 patterns, which makes it likely that proper fitments can be achieved without mixing and matching wheels for a Fiero with 5x114.3 up front and 5x100 in the rear. That said, it does look like 5x114.3 will fit on the C6 hub.. I'm just not sure if there's enough room to get the studs in from the backside.

[Series8217]

In Nashco's AWD Hybrid Fiero build, he bored out the front knuckles by 0.040" to accommodate the stock 84-88 Fiero rear bearings. That sure looks easy.

An axle stub has to be added to hold the bearing together, and I'm not sure if the bolt circle exactly matches.. this seems like the easiest fix until I have time to fabricate new knuckles or spindles.

The flange offset for the front hub is 36mm, and the rear hub is 42mm. Since I'm already running a 5mm wheel spacer I can just pull that out. I'm using a 3mm rotor spacer which I will also remove. That puts the rotor 2mm further out than it was with my spacer... very close to the limit of the sliders. I might need to thin the caliper bracket a bit.

[draven]

Did Nascho use the stock rear hub/bearing or the stronger Achieva front hubs?

[Series8217]

Did Nascho use the stock rear hub/bearing or the stronger Achieva front hubs?

Stock Fiero rear wheel bearing. Like the fronts, the aftermarket rear wheel bearings are still all useless for the track. However there are MANY cars that used the Fiero rear wheel bearings, so it's easier to find good OEM ones at the junkyard. The '88s are nearly impossible to find. I actually got one today by an awesome twist of luck.. but the second one on the car is an eBearing unit

[fieroguru]

An axle stub has to be added to hold the bearing together, and I'm not sure if the bolt circle exactly matches.. this seems like the easiest fix until I have time to fabricate new knuckles or spindles.

The mounting bolt pattern for the Fiero rear bearing is 4.02". The 88 Front pattern is 3.74". The achieva 513017K is 3.86"

[Series8217]

An axle stub has to be added to hold the bearing together, and I'm not sure if the bolt circle exactly matches.. this seems like the easiest fix until I have time to fabricate new knuckles or spindles.

The mounting bolt pattern for the Fiero rear bearing is 4.02". The 88 Front pattern is 3.74". The achieva 513017K is 3.86"

Good to know. Thanks!

So the Achieva bearing has a better fit on the bolt circle, but it needs an 0.100" larger bore than the rear bearing (so ~0.140" larger than the front).

The Achieva bearing has a flange offset of 44.4 mm which is ~10mm more than the Fiero front bearing. A little much, but maybe still workable on the wheels. I'm not sure about brake rotors.

[ericjon262]

on the mustang spindle, the hub itself isn't that complicated of a part, could you just have a new one made (or redrill and existing one) for 5x100 or whatever bolt pattern you want? the hub isn't a wear surface so you don't have to worry about sourcing a replacement, just new races and bearings.

[fieroguru]

An axle stub has to be added to hold the bearing together, and I'm not sure if the bolt circle exactly matches.. this seems like the easiest fix until I have time to fabricate new knuckles or spindles.

The mounting bolt pattern for the Fiero rear bearing is 4.02". The 88 Front pattern is 3.74". The achieva 513017K is 3.86"

The Achieva bearing has a flange offset of 44.4 mm which is ~10mm more than the Fiero front bearing. A little much, but maybe still workable on the wheels. I'm not sure about brake rotors.

You might consider taking .125" off the face of the upright to pull things back in slightly.

[The Dark Side of Will]

However, I was able to make some preliminary measurements, and it looks like the best offset I could hope to achieve with a fabricated spindle is +12 to +15mm over the '88 Fiero knuckle. That's really going to be too much to fit the wheel package I want, and it's also too much to get any other Fiero people interested in buying them (so I can have more made and recoup some of the costs).

Mill the inside of the knuckle flat and bolt the spindle on from the inside... drop the inner bearing on the hub inside the original bore in the knuckle.

The C6 hub offset is only about 7mm longer than the '88 Fiero hub, so I think making a new knuckle to accommodate this hub is feasible. Unfortunately, wheel fitment is a big problem with this pattern. I can't find a 17x8 fitment with high enough offset in this bolt pattern. 17x9 and 18x9 are available with 50mm offset (TSW Interlagos). 5x114.3 is the better pattern for the front, since S2000 fitment has an extremely high offset (63mm). Many wheels have both the 5x100 and 5x114.3 patterns, which makes it likely that proper fitments can be achieved without mixing and matching wheels for a Fiero with 5x114.3 up front and 5x100 in the rear. That said, it does look like 5x114.3 will fit on the C6 hub.. I'm just not sure if there's enough room to get the studs in from the backside.

Don't stock C5's and C6's have pretty high offset wheels?

What went wrong with the Rodney's tapered roller hubs? Have you autopsied? If it's just a matter of the collar that secures the cone of the inner bearing being pushed back, you could pop the cover off, tack weld the collar, then put the cover back on and tack weld it in place.

Rodney knows a lot of automotive suppliers, but they are *NOT* motorsports suppliers, so they don't really know what they're doing. I suggested some design improvements to Rodney when he was working on the design of those hubs, but was rebuffed. Serious case of NIH syndrome... Even though he took someone else's idea to make the hubs in the first place.

Building a better hub cartridge might be an option also. The load on the bearings is proportional to something like the inverse of the 4th power of the distance between the bearings... so spreading the bearings a little bit has a HUGE impact on bearing loads. The cartridge shell is something that could be made on a lathe. I'll have to put my thinking cap on with regard to a way to make the spindles longer. Maybe get custom spindles from Strange or another shop that does custom live axles for musclecars. With an intelligent design of those parts, the back end of the cartridge shell could protrude toward the spring at least 2 inches, which would at least quadruple the distance between the bearings. You could also design the back end of the spindle to have a *THREADED* collar for adjusting the preload and a better dust cover.

I suggested to Rodney that he might look at making the new hubs deeper than the originals and was told that if he did that, his wheel bearing customers wouldn't be able to use his ball joint separator tool. Talk about not getting it...

[Series8217]

on the mustang spindle, the hub itself isn't that complicated of a part, could you just have a new one made (or redrill and existing one) for 5x100 or whatever bolt pattern you want? the hub isn't a wear surface so you don't have to worry about sourcing a replacement, just new races and bearings.

The Mustang has the right bolt pattern. The problem is the flange offset is way too high. It pushes the wheel out too far.

However, I was able to make some preliminary measurements, and it looks like the best offset I could hope to achieve with a fabricated spindle is +12 to +15mm over the '88 Fiero knuckle. That's really going to be too much to fit the wheel package I want, and it's also too much to get any other Fiero people interested in buying them (so I can have more made and recoup some of the costs).

Mill the inside of the knuckle flat and bolt the spindle on from the inside... drop the inner bearing on the hub inside the original bore in the knuckle.

I thought about it, but I don't like the idea of supporting the spindle on the three bolts alone. I'd rather have a light interference fit in the bore. to help distribute the load.

Don't stock C5's and C6's have pretty high offset wheels?

Yes, but they are also extremely wide.

What went wrong with the Rodney's tapered roller hubs? Have you autopsied? If it's just a matter of the collar that secures the cone of the inner bearing being pushed back, you could pop the cover off, tack weld the collar, then put the cover back on and tack weld it in place.

Something metallic failed inside. There is metal powder in the grease. Beyond that, I don't know.

Rodney suggested any of the following could be the issue: the outer races are surface hardened (flame hardening?) and may not be as durable as a through-hardened race. The wall thickness is thin (it's thinner than stock) so the housing may distort under load. The bearing depth (distance between inner and outer bearings) is short (shorter than GM? not sure), limited by Rodney's design requirement of fitting within the OE bearing package space.

I think the housing distortion is probably what's happening. It explains why the dust covers pop off too (though they don't have any kind of sealant like the GM ones did).

I'm not going to argue with Rodney's design decisions or the requirements he dictated. I'm glad there is someone making or sourcing products that we need (clutch hydraulics, ball joints, etc). It's too bad that on the wheel bearing project he favored packaging constraints over having the same durability as stock, but that was his choice in developing the product.

Building a better hub cartridge might be an option also. The load on the bearings is proportional to something like the inverse of the 4th power of the distance between the bearings... so spreading the bearings a little bit has a HUGE impact on bearing loads. The cartridge shell is something that could be made on a lathe. I'll have to put my thinking cap on with regard to a way to make the spindles longer. Maybe get custom spindles from Strange or another shop that does custom live axles for musclecars. With an intelligent design of those parts, the back end of the cartridge shell could protrude toward the spring at least 2 inches, which would at least quadruple the distance between the bearings. You could also design the back end of the spindle to have a *THREADED* collar for adjusting the preload and a better dust cover.

While that's all possible, I think it makes more sense to address the issue by using a known-good bearing (which is hard to design and fabricate) with a custom/customized knuckle (which is easier to design and fabricate).

[The Dark Side of Will]

True, there's WAY more engineering in the hub than in the knuckle.

Crack Rodney's unit apart and see what failed.
Maybe the bearings failed because the collar backed off. Maybe they failed because they're junk... I don't know. If they're standard cups/cones, you should be able to get SKF's or similar to replace them, and then come up with a threaded adjuster for the preload.

The extremely low "offset" from the mounting flange to the hub flange on the '88 bearing is going to make replacing it with *anything* difficult.

It might be possible to have Weldcraft narrow some Corvette fronts for you. The C5 high polish and early C6 wheels are fantastic.

Alternatively, find something with the 5x108 pattern and slap a set of Farrari 360 OE wheels on your car

[fieroguru]

Alternatively, find something with the 5x108 pattern and slap a set of Farrari 360 OE wheels on your car

FYI, there is a vendor (not me) who has modified the front/rear 88 wheel bearings with threaded M14 inserts at the 5 x 108 pattern so OEM Ferrari wheels and lug bolts can be used on a fiero. I sold a brake kit to someone who had their bearings modified and he sent me some pictures. The inserts need a signficant overbore and the overbore happens right over the stock 5x100 pattern with the needed offset to achieve the 5 x 108 pattern.

[Series8217]

Alternatively, find something with the 5x108 pattern and slap a set of Farrari 360 OE wheels on your car

Too narrow and the offset is too low.. Close though.

[Series8217]

I would love to use the C5/C6 bearing assemblies, but the knuckles are very tall so I don't know if they will fit in the front of a Fiero. I should have my hands on some C6 knuckles either tonight or on Saturday for a quick test fit. My friend has some in a storage unit. I also purchased an SN95 mustang knuckle and hub assembly for assessment.

An alternate for the C6 knuckles is the C6 retrofit knuckles from Classic Industries. The part number is CP30013. These knuckles take C5/C6 brakes and wheel bearing assemblies, but bolt onto early F-body suspension. I don't have any dimensions, but judging from the photos they appear to be just a shorter version of the C5/C6 knuckle, with a taper hole in the top instead of a ball joint. They're pretty cheap at $268 a pair.



They are also working on 1" and 2" drop versions, which look like they're shorter overall, and maybe a better fit for the Fiero. However, they aren't available yet.

I contacted CPP and they couldn't give me any information about release dates for the upcoming drop spindles. They did tell me that the CP30013 has the same kingpin inclination angle as the OE parts (first-gen F-body). Some Googling indicates that they ran a KPI of around 8*.

I contacted Speedtech about their spindles. These are very highly regarded on Lateral G, Corner Carvers, etc. Hopefully they can get back to me with some specific dimensions.

[The Dark Side of Will]

I contacted Speedtech about their spindles. These are very highly regarded on Lateral G, Corner Carvers, etc. Hopefully they can get back to me with some specific dimensions.

One of the ideas I used to think was a good idea is "dropping in" a well-supported suspension from another car. The GM Muscle car setup might be a good candidate, considering what the aftermarket is doing with it.

Although I'm more likely just to roll my own.

[FieroWanaBe1]

I have been kicking around the idea of C6 corvette zr1 hubs all around.