Real Fiero Tech

Series8217 wrote:

The Dark Side of Will wrote: I looked at some BMW spindles and hubs. The hubs were very tall (over 2 inches from base to rotor mounting face). They seem to have have long spindles and correspondingly high steering axis inclination angles to keep the scrub radius reasonably low. There may be other ones that have shallower hubs and spindles. The E34 looks pretty short for example. One big issue with the BMW hubs is the OEM parts are all made with a sculpted inner hub face, so you can't drill another bolt pattern into it.

BMW has a *WIDE* variety of hubs available. They also pick standards and stick with them... for a LONG time. The E30 AWD 5 lug guys are looking at rear hubs from E87 1 series cars, which are about as low offset as BMW hubs get. The BMW 5x120 pattern is also close enough to 4.75 that BMW's and Corvettes can interchange wheels.

Series8217 wrote:

The Dark Side of Will wrote:I remembered that I'd asked about replacement hubs for my bespoke suspension design a while back on Corner-Carvers:

http://www.corner-carvers.com/forums/sh ... hp?t=46969

Interesting post by Dave Deerson about the Jeep Cherokee bearings. Those caught my eye in the Timken catalog. They look like good candidates for the rear.

Yeah, I forgot to thank him for that.

I imagine you would be looking for an OEM XJ front hub. I'm sure by now the aftermarket has had sufficient time to develop a value engineering Ball bearing unit that has the durability to make it out of the corner shop parking lot before play is noticeable by this time. I may look into this more. But I am sure it is a select few assemblies this worked on, and finding those still in existence might prove futile.

Original Jeep parts catalogs list all the components for the hub cartridge with PN's, this is promising for a rebuild-able bolt on assembly in the rear and front if one is willing to use a dummy stub.

53000228 Crown Automotive Tapered Roller Assembly.
I do not know if anyone has successfully pressed a unit apart, but Crown does show the pieces, and new seals and bearings are available.
http://www.crownautomotive.net/category ... -Hubs.html
I can tell you an XJ with enough rust will take the front hub apart in piece with enough air hammer use.

FieroWanaBe1 wrote:I imagine you would be looking for an OEM XJ front hub. I'm sure by now the aftermarket has had sufficient time to develop a value engineering Ball bearing unit that has the durability to make it out of the corner shop parking lot before play is noticeable by this time. I may look into this more. But I am sure it is a select few assemblies this worked on, and finding those still in existence might prove futile.

Maybe now is a good time to clarify the known failure mode for the aftermarket bearings that can be used on Fieros... some of the aftermarket front bearings for the '88 Fiero (such as the eBearing unit) and all of the aftermarket rear wheel bearings for the Fiero (and aftermarket front wheel bearings for the J-body/Achieva/etc) fail under track use by the hub flange breaking off, not by the bearing developing play. Rodney's hub developed play in it, but I probably also didn't drive it long enough to find out if the hub was going to break off.

I suspect that even the aftermarket XJ hubs will be far thicker than what is needed to hold up on a 1200 lb axle weight car at the track.

I see many cartridge bearing failures, at regualr intervals from aftermarket unit, due to the housing race surface failing, and from excessive play. This is especially more common the heavier the vehicle is it came on. Chevy pick-ups have been bad for it in my shop, and Large FWD GM's. Some make it fewer than 5000 city miles.

I'm sure track use on 5x100 hubs on cast iron flanges with little or no quality control from oversea factories will destroy the flange in short order, and an upgrade to SUV grade hubs would provide that improvement in flange thickness, until you reach the next failure mode, and I am used to seeing the bearing retention and subsequent race impact damage, or race fatigue. The way I work would be to design with any known failure mode in mind and provide the best solution from gestation. And serviceability is a key to spotting possible catastrophic failure before it is a catastrophic failure.

Flange failure is another reason I favor a fully shopped out stub axle because it give the freedom of material sourcing and design features like shoulder radius and flange thickness.

Yeah, I expect to see those kinds of failures with inadequate bearings. However, they won't kill you. It's just more maintenance.

I just wanted to point out that the aftermarket designs their parts to roll around at highway speeds with typical street car loads, and that doesn't just go for the bearings themselves but the entire assembly, including the parts which can fail catastrophically and can result in some serious carnage -- such as the hubs. This has been proven by at least half a dozen incidents mentioned on the Fiero Racing List and Pennock's. I had forgotten to explain this earlier so that readers of this thread understand why I plan to move away from certain parts and avoid almost everything that's just aftermarket unless its track proven.

FieroWanaBe1 wrote: I'm sure track use on 5x100 hubs on cast iron flanges with little or no quality control from oversea factories will destroy the flange in short order,

SKF is typically considered a high-end bearing manufacturer with good quality control. These parts even have fully machined steel hubs. The problem isn't the quality control, it's the design and engineering.

I am not going to trust any aftermarket bearing unless I can find direct evidence proving that it works at the track. That also means I'm not going to design a knuckle or spindle to accept any bearings that don't have new, OEM replacements readily available, unless the aftermarket parts are proven to work at the track. That goes for the XJ stuff too -- I would start with the OEM parts if I considered using those in the rear, though it's a nice candidate since it's more likely to be overbuilt even in the aftermarket.

OEM Achieva bearings are available (the AC Delco parts are OE parts --- at least maybe until they run out of stock and farm them out). They have been proven to work on Fieros under track use. OEM C5/C6 bearings are available. They have been proven to work on Corvettes under track use. The BMW parts are proven as well.

Here's some info from Alan Hamilton (from http://racer.net/itafiero/TechPictures/ ... b_Info.txt):

Hub shaft and face measurements:

1) AC/Delco -
Hubs_compared1.jpg

Shaft I.D. - 29.5mm
Shaft O.D. - 42.7mm
Thickness - 6.6mm
Face - 7.5mm

2) SKF latest that broke -
Hubs_compared12.jpg

Shaft I.D. - 29.4mm
Shaft O.D. - 33.8mm
Thickness - 2.2mm
Face - 10.5mm

3) BCA new unused -
Hubs_compared9.jpg

Shaft I.D. - 29.4mm
Shaft O.D. - 39.2mm
Thickness - 4.9mm
Face - 8.0mm

4) SKF Achieva -
Hubs_compared3.jpg

Shaft I.D. - 29.7mm
Shaft O.D. - 38.9mm
Thickness - 4.6mm
Face - 10.7mm
Race (pressed on shaft) - 44.8

Okay here's what I've discovered. Although the new Fiero SKF looked to
be a better hub based on the hub face, it turns out that the shaft is
too thin, 2.2mm. The AC/Delco hubs have the thickest shaft, 6.6mm, this
is the shaft wall thickness near the outer race. The outer race is part
of the hub and is not separate or pressed on providing the greatest
strength where the shaft needs it. The BCA was measured without it being
torn down. So I don't know how the shaft and outer race are assembled.
The face was only slightly thicker than the AC/Delco. The SKF Achieva
hub has a thicker hub shaft, 4.6mm. It also has the thickest face with
round access whole instead of a U access point in the AC/Delco and other
Fiero hubs.

Now I'm still concerned about the shaft thickness. The outer race is
pressed on to the hub and butts up against the face. This might be
enough but I'm not sure. I'm picking up some additional hubs from our
AC/Delco source to do a comparison on them. I'll update you as I find
additional information.

I took a brand new SKF Achieva hub apart and did the measurements.

And here are his pictures (from http://racer.net/itafiero/TechPictures/Hubs/page_01.htm):

I would also pay close attention to LeMons and Chump Car forums for J-body racers, From my in-person conversations, most teams run through a set of Parts-store (lifetime warranty) hubs per race (that being 1 7 hour day, 2 races per weekend, and some times sooner.) there failures are usually due to high axial play. One team I did talk to has seen flange failure as well, but the mode of failure was usually wear and not catastrophic breakage. These teams usually have crappy skinny (205-215) tires, with so-so drivers, because they are cheap and not interested in winning.

The Dark Side of Will wrote:

Series8217 wrote:

The Dark Side of Will wrote: I looked at some BMW spindles and hubs. The hubs were very tall (over 2 inches from base to rotor mounting face). They seem to have have long spindles and correspondingly high steering axis inclination angles to keep the scrub radius reasonably low. There may be other ones that have shallower hubs and spindles. The E34 looks pretty short for example. One big issue with the BMW hubs is the OEM parts are all made with a sculpted inner hub face, so you can't drill another bolt pattern into it.

BMW has a *WIDE* variety of hubs available. They also pick standards and stick with them... for a LONG time. The E30 AWD 5 lug guys are looking at rear hubs from E87 1 series cars, which are about as low offset as BMW hubs get. The BMW 5x120 pattern is also close enough to 4.75 that BMW's and Corvettes can interchange wheels.

The E87 bearing itself is ~4mm larger in OD than the rear bearing carrier on the Fiero. The rear knuckle could be machined to accomodate the bearing and a front seal. A machined retainer would need to be bolted on to the outside of the knuckle to carry the rest of the bearing and the front seal. It doesn't need to be very thick though. You'd need custom axles though.

I think something like that is a good solution for the rear (and it's been done on the Fiero before, to put 6000 HD bearings in the '88 rear knuckle), but doesn't make sense for the front.

FieroWanaBe1 wrote:I would also pay close attention to LeMons and Chump Car forums for J-body racers, From my in-person conversations, most teams run through a set of Parts-store (lifetime warranty) hubs per race (that being 1 7 hour day, 2 races per weekend, and some times sooner.) there failures are usually due to high axial play. One team I did talk to has seen flange failure as well, but the mode of failure was usually wear and not catastrophic breakage. These teams usually have crappy skinny (205-215) tires, with so-so drivers, because they are cheap and not interested in winning.

As I mentioned above, all of the parts store hubs for the J-body are junk. I was going to say I'm surprised they lasted that long, but after you mentioned the tire size, that makes sense.

The original GM and AC Delco ones are the only parts that are worth a damn. Refer to the info I posted above for dimensional comparisons (the J-body hubs are identical to the Achieva). The person who posted that info (Alan Hamilton) ran an ITA class Fiero and used these bearings on the rear.

More compact hubs to look into:
2004-2006 Pontiac GTO
2008-2009 Pontiac G8 / 2011-2013 Chevrolet Caprice
2008-2014 Cadillac CTS / 2010-2014 Chevrolet Camaro (SKF has assymytric units applicable to all 4 corners on the ZL1/1LE)
They are all similar but differ some amount they flange offset is very small on these units. (total depth is short as well)
I imagine the GTO ones have a decent amount of aftermarket support, but OE supply may dwindle, these cars were for sale worldwide, on a more common platform.
The G8 stuff should have decent support since the caprice is a common municiple support vehicle.
and the camaro stuff should be in hugh demand for a forseeable future.

FieroWanaBe1 wrote:More compact hubs to look into:
2004-2006 Pontiac GTO

That's a good one. The flange offset is 1.693 in (43 mm) which is about the same as the Fiero rear and the C6 Corvette. The bolt pattern is 5x120mm (not 4.75 in!).The mounting depth and pilot look smaller than the C6 Corvette but I would need to get one in hand to measure.

2008-2009 Pontiac G8 / 2011-2013 Chevrolet Caprice

Similar flange offset at 1.654 in (42 mm) and 5x120mm bolt pattern. The hub pilot is larger, and appears to have a similar integral ABS ring to the C6 hub.

2008-2014 Cadillac CTS / 2010-2014 Chevrolet Camaro (SKF has assymytric units applicable to all 4 corners on the ZL1/1LE)

This one looks good too. Flange offset 1.651 in (42 mm). Being that it's a modern splined hub, it probably doesn't need a CV axle to hold it together either (but this needs to be verified). OE parts (AC Delco branded) are also available pretty cheap at $120 from Rockauto. Like the G8 and Camaro hubs, these are also 5x120mm, which I find interesting -- it seems GM has finally dropped the 4.75" (120.65mm) circle for everything except the Corvette.

This one won't work in the front (flange pattern on upright is too small), but is an option for the 88 rear. It uses an OEM bearing from the 2006-2009 LS4 application with the large 33 spline CV housing and the 5x115 wheel pattern (but also has room for most other patterns).
http://www.fiero.com/forum/Forum2/HTML/125016.html

4th gen fbody / C4 corvette front hubs from full billet:
http://hoosierperformanceengineering.co ... heel-hubs/

FieroWanaBe1 wrote:4th gen fbody / C4 corvette front hubs from full billet:
http://hoosierperformanceengineering.co ... heel-hubs/

WOW. That is more like what I was thinking would be necessary for the Fiero. I'm not sure about their 2 piece spindle/flange... I'd prefer the 1 piece spindle built by Mark Williams in the other aftermarket C4/F4 setup that was previously linked.

fieroguru wrote:This one won't work in the front (flange pattern on upright is too small), but is an option for the 88 rear. It uses an OEM bearing from the 2006-2009 LS4 application with the large 33 spline CV housing and the 5x115 wheel pattern (but also has room for most other patterns).
http://www.fiero.com/forum/Forum2/HTML/125016.html

Jims88 wrote: I expected the bearing race would come off hard but pulled off relatively easy.

I think this is a big part of the problem when stock hubs loosen up and develop play.

The W-body bearings are huge... I think they're familial with the U-body minivan bearings that are similar to the Pontiac 6000 large pattern bearings, but even larger.

I ordered the crown tapered hub assemblies, I want to be able to get them before they aren't available. Picked the last 2 in stock off an amazon vendor for 89$ each.
When they Arrive I will measure the key characteristics.
If they look like they will suffice, I will be developing a weldment rear knuckle for an 88 cradle to house the hub unit, and probably buy a spare set for track-day maintenance. This is going on a car with a V8Archie wide-body, so a bolt in stock replacement isn't my plan.
Now I just need to figure out the fronts, the Cadillac 513009 route just didn't work out due to part availability.
After this weekend I will be consolidating garage and shop space, and will have my parts at one location for comparative analysis.

Steven,

have you made any more progress regarding a stronger replacement for the front hub/knuckle? very interested...

I picked up some OEM J-body front bearings (same as AC Delco 20-25K) and I'm going to try fit them in some spare front knuckles. I'll update this thread once that happens.

I'm going in another direction with the front knuckles now.

A MK III Golf VR6 front wheel bearing (VW p/n 191498625A, Tiken 510004) has an outer diameter of 72mm and a width of 37mm. This bearing has integral front and rear seals, a one piece outer race, and two inner races.



The hub which presses into this bearing (VW p/n 1H0407613B) is 5x100 with a 57.1mm wheel pilot diameter (same as the Fiero).

The Mk III Golf VR6 front hub:

The ABS ring is easily removed (3 screws).

The hub accepts 14mm screw-in studs/bolts, so it needs to be converted to 12mm studs by drilling out the 14mm threads and pressing in ARP studs.
There are a few options for the ARP studs: 100-7717 (76.2mm length, quick start), 100-7715 (66 mm length, normal), 100-7720 (70mm length, quick start), and 100-7721 (62mm, quick start). All of these are longer than the stock Fiero studs, but it may be possible to use 100-7721 with a tuner style closed-end lug nut, depending on the brake rotor, wheel, and specific lug nut used.

One of the ARP 12mm wheel stud options for the Mk III Golf VR6 hub:


This hub has a very low offset: from the face of the hub to where it touches the wheel bearing is only 22 mm. This means the minimum possible hub offset is LESS than the stock 88 Fiero front hub assembly (which has an offset of 36mm).

I've marked the approximate face of the bearing and hub flange below. The distance between the two lines is 22mm.


To accommodate the 72mm bearing, the knuckle needs to be bored out by about 2mm. The bore needs to be sized precisely so the bearing is a light press fit. I need to bring the GTI knuckle to my friend's shop to measure it with some accurate tools; I'll replicate its bore size.

Since the bearing is 37mm wide, bearing caps need to be machined to capture the bearing as it sticks out the front and/or rear of the knuckle. The depth of the front and rear bearing caps can be selected to change the offset of the flange. If the bearing is flush with the face of the knuckle and just held in with a bolt-on retaining plate, and a carrier bolts onto the rear of the knuckle, the hub face offset (steering axis to hub face distance) will be about 14 mm less than the stock '88 Fiero assembly... meaning a wheel with a 35mm offset now fits like a wheel with a 49mm offset used to with the original '88 Fiero parts. Reducing the hub flange offset also makes it possible to use a rotor with a smaller mounting offset, which will be lighter in weight than one with a deep hat.

This rendering shows the bearing, outer bearing cap, and hub installed on an '88 Fiero knuckle:

The inner bearing cap is not shown.

To allow the inner bearing cap to be bolted to the as-cast side of the knuckle, the knuckle needs to be spot faced on the three threaded mounting holes. This does introduce the possibility of adding some stress risers, since the threaded holes are right next to the balljoint arms. It would be best to magnaflux for cracks before using a donor knuckle, and make sure to grind smooth any rough transitions created by the spot facing on the rear. The threads in the knuckle will be drilled straight through. Eliminating the threads, removes a major potential starting point for cracks. The outer bearing cap will be threaded to accommodate the bolts which hold the inner and outer caps to the knuckle.

I have already acquired enough parts for R&D and have developed models of all of them (including the Fiero knuckle) so this project already has a lot of momentum. I hope to have a pair of prototypes in time for track testing in the spring.

I've got the overall design worked out. This assembly has the same flange offset as the stock '88 Fiero. I will probably use this configuration for the proof fo concept prototype so I don't have to get new wheels and brake rotors.





Now looking at different material options. If I use 1018 steel, I can build a full set of parts for ~$100. However, I will need to have them plated to prevent corrosion. It's also going to be a bit harder to machine than aluminum, but I'm going to use a CNC mill so it's not a huge deal. 7075-T6 is another option. Compared to 1018, it's stronger and has less than half the density, reducing weight from about 2 lbs per side to less than 1 lb. With 7075, the cost in raw materials is a little less than $200, but I would also need to add 3 steel helicoils to each outer bearing cap, and possibly use steel washer inserts in the rear cap to prevent creep under the bolt heads.

Another factor affecting the material choice is the press fit of the bearing into the front cap. With the offset I'm using in the configuration shown in the images above, the inner cap just retains the bearing in the knuckle by forming a step on the back side. There is no press fit. However, 14mm of the bearing's width is held inside the outer bearing cap. This would normally be a press fit in steel. I think galling would be a problem if I used aluminum here.

Is there another steel alloy I should look into that has good corrosion resistance, at least 54 ksi yield strength, and isn't too hard on tools? If I can avoid having to plate the parts that would be great. Anything with similar or better corrosion resistance to the stock cast iron knuckles would be fine.

Here is a list of some vehicles with 40mm hub shafts, that could serve as sources for flanges with different offsets, diameters, bolt patterns, or better availability. NOTE: This list is not complete. I'll continue to keep it updated as I discover more.

maybe I missed it, but is there any reason why you're sticking with a cartridge bearing?