1 2 3 4 5
series8217
series8217 Reader
10/15/14 2:45 p.m.
Mezzanine wrote: Awesome! I knew nothing about this engine before watching the promo video. Do you happen to know what the engine weighs fully dressed with the transmission? Also, what trans are you using? LSD?

The transmission is a Getrag 282 "hybrid" with the Fiero bellhousing but early 90's shift assembly and differential with larger spider gears. The engine is stupid heavy... The site I posted all the weights on is down right now so I can't get them, but if I recall correctly it's 475 lbs fully dressed without trans. The motor is a pig. The cams alone weigh 10 lbs EACH. The trans is ~100 lbs. It's a durable engine though. 400whp is common for ~13 psi with a relatively primitive turbocharger and stock internals. NA builds can reach nearly 300 hp. My motor weighs a bit less than the published value due to the chopped up intake manifold which saved maybe 5 to 8 lbs.

series8217
series8217 Reader
12/4/14 12:11 a.m.

Forgot to upgrade my build thread with the dirty fun I had at Glen Helen Raceway last month.

I removed my aero parts, raised my suspension, and borrowed some gravel tires mounted on 15x6" GTI wheels from my friend to run the Fiero at a rallycross practice event. I have experience competing in an AWD car but this was my first time on the dirt with a RWD.

Here's a video of one of the runs. Sorry about the sound, I didn't have my external mic.

https://www.youtube.com/watch?v=2lTO_BN4Lqg

To prep the car for rallycross, I removed the lateral link relocation brackets, raised the coilovers by 2 inches, and removed the splitter and wing. The car behaved VERY well. Surface irregularities were easily soaked up by my springs and dampers and even the largest dips did not upset the chassis or result in tires losing contact with the ground. The fast steering made for very easy corrections. The 3.4 DOHC makes enough torque that 2nd gear can be used for almost the entire course. First was only needed if I messed up and lost a lot of momentum. Even in second gear at 2500 RPM I could spin the tires at full throttle. Even on a freshly-wetted surface, handling was predictable. The torque delivery is so linear that it's easy to control the rotation of the car by feathering the throttle and making minor steering adjustments.

On to the pics:

series8217
series8217 Reader
1/3/15 3:52 p.m.

I'm tired of replacing front wheel bearings every other weekend, and trying to source decent ones from the dwindling supply of hubs. They are unique to the '88 Fiero, and the aftermarket ones won't even last a single day at the track so I have to use OEM hubs. This is no longer practical.

I originally planned to make a new knuckle which accepts the C5/C6 Corvette sealed hub assembly. However, I don't have the time to work on such a big design and fabrication project right now. This week I re-evaluated another idea I had which was to convert the OE knuckle to accept a press-in bearing.

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 (the 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.

series8217
series8217 Reader
1/3/15 4:00 p.m.

I've got the overall design worked out. This assembly has the same flange offset as the stock '88 Fiero (36mm). 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 I'm looking at different material options for the bearing caps (the light gray parts in the renderings). 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.

series8217
series8217 Reader
1/5/15 2:11 a.m.

I disassembled a Fiero bearing/hub and a 1997 Volkswagen GTI VR6 front hub assembly to compare the two dimensionally.

The stock Fiero hub is what the industry considers a "Gen III" hub/bearing unit, meaning that the hub, bearing, and shaft are one assembly. In the case of the Fiero, the carrier / outer race has a 3-bolt flange. The outer bearing races are integral with the carrier, and the inner race on the hub side is integral with the hub. The inner race on the knuckle side is separate. This is what the assembled unit looks like (photo stolen from my website post on extended wheel studs):

The Mk III GTI uses a "Gen I" assembly, where the bearing presses into the knuckle, and the hub (with shaft) presses into the bearing. Each part (knuckle, bearing, hub/shaft) is replaceable.

Here is a photo of the disassembled Fiero hub next to the GTI parts:

I disassembled and measured the dimensions of the VW GTI MKIII and 1988 Fiero front bearings:

(Is there a way to do preformatted text/code on this forum?)

With respect to the separation distance, the effective bearing spread is dependent on the contact angle, which I haven't figured out how to measure. See this note from Timken's bearing engineering manual:

When a load is applied to a tapered roller or angular contact ball bearing, the internal forces at each rolling element-to-outer raceway contact act normal to the raceway. These forces have radial and axial components. With the exception of the special case of pure axial loads, the inner ring and the shaft will experience moments imposed by the asymmetrical axial components of the forces on the rolling elements. The effective center for tapered roller bearings is defined as the point at which the lines of force normal to the outer ring raceway intersect the bearing axis. As an approximation, it also applies to angular contact ball bearings. The effective spread is then defined as the distance between the bearing effective centers for a two-bearing system. It can be demonstrated mathematically that, if the shaft is modeled as being supported at its effective bearing center rather than at its geometric bearing center, the bearing moment may be ignored when calculating radial loads on the bearing.

If we assume that the effective bearing spread is the same between the two bearings, the GTI MK III bearing is stronger by virtue of its 12.6% larger outer diameter.

There are other reasons the new setup should be stronger and longer lasting than the original Fiero setup: * Less deflection due to a stiffer hub shaft (40mm vs 28mm diameter) * Stiffer outer race assembly due to the bearing being supported by the press fit into the knuckle and bearing caps (over 7mm thickness total), instead of a 5.3mm thick housing. * New parts are available for the GTI MK III. The '88 Fiero bearing assembly has been out of production for over a decade, and new OE units are not available. The aftermarket ones fail catastrophically or wear out in one weekend. The remaining OE bearings are almost 30 years old and most have 100,000+ miles on them; needless to say, they aren't in great shape. Low-mileage units should last a season on the track, but I can't find any more of them.

Mezzanine
Mezzanine Reader
1/5/15 11:03 a.m.

Nice job bringing the tech! I hope this mod holds together- it's nice to see the effort you put into it.

Nashco
Nashco UberDork
1/5/15 11:15 p.m.

Did you see the mod I did (bore center out slightly) to the 88 front knuckle to accept rear hubs on my AWD Fiero? It pushes the hub face further out, requiring a Subaru rotor, so it's not as ideal. However, the hubs are then dirt cheap and available and the mod was extremely easy. I actually have a spare set of knuckles that are already machined that I'd sell if you wanted to try it out.

Bryce

series8217
series8217 Reader
1/6/15 12:19 a.m.

Yeah, I saw that on the AWD Hybrid Fiero build. Unfortunately all the new rear hubs that are available have catastrophic failures on track, and vehicles with the OE hubs (the only ones that last) are hard to find in the junkyard these days with less than 200k miles on them. The OE J-body hubs are the proven solution for the rear but I don't want to bore the front knuckle out that far (73.5mm). I'm already afraid of the 72mm of the GTI bearing. The stock bore is 70mm and the thinnest section of the wall is less than 10!

series8217
series8217 Reader
1/13/15 1:26 a.m.
series8217 wrote: Yeah, I saw that on the AWD Hybrid Fiero build. Unfortunately all the new rear hubs that are available have catastrophic failures on track, and vehicles with the OE hubs (the only ones that last) are hard to find in the junkyard these days with less than 200k miles on them. The OE J-body hubs are the proven solution for the rear but I don't want to bore the front knuckle out that far (73.5mm). I'm already afraid of the 72mm of the GTI bearing. The stock bore is 70mm and the thinnest section of the wall is less than 10!

I took a look at the J-body bearing again and the 73.5mm bearing carrier steps down to 72.5 mm at a distance of 10.5mm from the mounting surface of the flange. If I were to take a little off the bearing and a little off the Fiero knuckle (70mm) to meet the size mismatch in the middle, the amount I'm boring out the knuckle is pretty much the same as the 72mm GTI bearing... and ultimately a lot less work than making two bearings retainer caps and honing the modified knuckle / cap assembly. It's also $200 cheaper per corner for new parts...

series8217
series8217 Reader
1/22/15 1:49 a.m.

I took a break from the front bearings project to work on the rears.

I took the common path used by Fiero racers as documented on the Yahoo Fiero Racing List (https://groups.yahoo.com/neo/groups/FieroRacingList/info). I believe this mod was pioneered by Alan Hamilton, who found that all the aftermarket rear hubs for the Fiero broke in various bad ways. GM parts are no longer available, and with the age of these cars, junkyard parts are pretty high up there in miles.

J-body front bearings (GM p/n 07470014 or AC Delco 20-25K) were used in J-body and N-body cars, including the Chevy Cavalier and Oldsmobile Achieva. Cavaliers were produced up until 2005, so GM bearings (and the practically identical AC Delco version) are still available for prices ranging from $100 to $120. According to discussions on the Fiero Racing List, the aftermarket J-body bearings are not suitable -- they break like the aftermarket Fiero parts.

I've been making some trips to the local Pick Your Parts over the past year or two and have amassed quite a collection of hubs and spare knuckles, so I figured it was time to put them to use.

The 84-88 Fiero rear bearing (the same bearing was used for all years) has a 71mm hub pilot diameter (minimum bore size in the knuckle) and a 102mm bolt circle on the mounting flange. On the other hand, the J-body bearing has a 73.5mm hub pilot diameter, and a 98mm bolt circle. Adapting the J-body bearing to the '88 Fiero rear knuckle requires boring out the knuckle to 73.74mm (this is the diameter that accepts the press-in axle seal used on the J-body) and slotting the bearing mounting flange holes by 2mm.

The flange offset on the J-body bearing is 44.43 mm, compared to the Fiero rear bearing's 42.2mm offset. If this matters, 2.2mm can be removed from the face of the knuckle so that the stock offset is retained.

One member of the Fiero Racing List said that an ~0.25 inch spacer is required to prevent the outer CV from binding up with the knuckle, due to the shallower height of the J-body bearing cartridge. However, based on my initial test fits I don't see that this is going to be a problem. I don't have the axle seal installed yet -- I'll know for sure once I'm at that point, and of course I'll document it here when I find out.

On to the machining:

Knuckle installed face down on the mill table:

I zeroed the mill by touching off to three points inside the bore then calculating the center of the circle from those three points.

Checking zero by spinning the boring head around to scrape the bore:

G-code for each cutting cycle: (NOTE: ignore the feed rate and spindle speed here -- this was some template code that I later modified)

Making a pass:

A depth of cut of ~0.17 mm ended up working pretty well, but I tried as much as 0.25 mm. The slot at the bottom of the bore was banging up the boring bar pretty bad when I tried to make deep cuts.

Close enough for my purposes:

Decent surface finish when the cut depth was kept under 0.15mm:

Slotted hole on the bearing cartridge mounting flange (sorry, no in progress pics; I didn't like my fixture):

Showing the slotted hole, how it lines up with the knuckle:

Final assembly:

Next steps:

  • Install axle seal (waiting for the parts to arrive)
  • Test fit axle
  • Test fit brake assembly
series8217
series8217 Reader
2/4/15 12:15 a.m.

Almost done with the rear hub upgrade now. I installed the J-body axle seals in my knuckles (they fit perfectly!), measured the required spacer thickness, drew them up, and machined them.

A small axler spacer is required to use the J-body hub assembly in the '88 Fiero knuckle because the back side of the new hub pulls the axle in further, causing it to bind when the axle nut is tightened down. The spacer pushes the axle back out a bit so it doesn't hit the back of the knuckle.

Sorry for the crappy pictures lately, I didn't have my camera with me in the dirty machine shop, so these are all cell phone pics.

Raw material:

The drawing I came up with for the spacer:

The spacer I used is 44.2mm x 29.2mm with a 3mm 45-degree chamfer to clear the fillet on the axle. It needs to be made of steel, and have parallel, flat-ground faces. Aluminum may creep or distort. A non-parallel spacer may not sit right, or may bend the axle. If you need to put spacers on your axle, make them carefully and double- or triple-check dimensions and fitment. Be absolutely sure your fillet clears the axle spacer. If the spacer sits on the fillet you're going to have problems.

The axle end without the spacer is shown below. Note that I had previously removed the dust shield to measure clearances. The assembly will clear with the axle dust shield in place.

The axle with the spacer installed:

The spacer sitting on the hub bearing to make sure it doesn't hit anything except the inner bearing race.

And finally, the axle installed in the modified knuckle using the J-body bearing, J-body seal, and custom spacer. As you can see, there is plenty of clearance now!

series8217
series8217 Reader
2/21/15 4:00 a.m.

I've really been slacking on getting mod writeups done for the past year and a half so I've made a point to do some this month. We'll start with the radiator install, Part 1 of 2.

Griffin Radiator Install, Part 1

I could not keep coolant temps down below 250*F with the stock radiator at the track. A hood vent might have made it workable, but I wasn't ready to cut the hood.

I ended up installing a Griffin 1-25201-X radiator; it's a universal radiator so I had to build a fan mount (Spal fan) and radiator mounts. However, it fits without any cutting or grinding of the chassis.

The 1-25201-X is close in dimensions to the stock Fiero radiator. The main differences are that it's a little thicker, has two rows instead of one, is of entirely aluminum welded construction (no plastic end tanks), and has the cap in a slightly different spot. The inlet and outlet tubes are different dimensions, so the stock hsoes won't fit.

Since the Griffin radiator is an inch shorter than the Fiero radiator, the hood clears the radiator cap despite it pointing straight up.

Griffin 1-25201-X (left) vs Fiero radiator (right):

1-row stock Fiero:

2-row Griffin:

The Griffin weighs 9.14 lbs empty, and the Fiero radiator weighs 7.80 lbs.

When filled with water, the Griffin is 18.06 lbs, and the Fiero radiator is 12.78 lbs. So we'll gain 5.28 lbs if the mount stays the same.

We're going to use all these hoses except the one on the far right:

From left to right: Stock '88 Fiero upper (inlet) radiator hose. Goodyear 52016 flex hose 15.5" length with 1.5" ID on one end and 1.25" ID on the other end. Dayco B71159. Original '88 Fiero lower (outlet) radiator hose.

For the upper hose, cut the stock Fiero hose in half, and couple it to the flex hose using a W0133-1788945 OES Genuine cooling hose coupler as shown:

Here's what it will look like installed:

For the lower (outlet) hose, use Dayco B71159 with an inch or two trimmed off the small end. I had to carefully twist the hose to get it to line up with the '88 Fiero coolant pipe, not kink, and clear the overflow container. There is probably another hose out there that's a better fit.

Here's what it looks like installed:

Now we need a mount to hold the Griffin radiator in place. The new radiator dropped into the existing lower radiator mount with some minor tweaking of the lower support lip with some pliers to clear the endtank welds. You can see the interference here, right under the weld bead:

First I tried using the stock upper radiator mount, this 2.58 lbs piece of steel:

There is no way it would fit over the right side of the Griffin because of the location of the cap, so I looped that end of the mount off:

Here it is in place:

It looks close but there'es actually a big gap since the Griffin radiator is an inch shorter than the Fiero radiator. This picture is with the mount set down on the radiator as far as it will go until it interferes with the endtank, but it doesn't line up with the mounting holes in the chassis at all.

Here are the mounting holes for the stock mount; I'll use these holes for a custom bracket in part 2:

To be continued in Part 2 -- Radiator and Fan Mounts....

wheelsmithy
wheelsmithy GRM+ Memberand HalfDork
2/21/15 7:14 p.m.

I really enjoy reading all this. It's hard to add much when your level of knowledge both on the car, and machining is so advanced. Just wanted to drop a note to say thanks! Very informative thread!

Also, sweet ride. Really makes me look at Fieros with the same 14 year old eyes I did when they came out. My best friend and I vowed to save money and split one. Thank Jehovah that didn't happen.

amg_rx7
amg_rx7 SuperDork
2/22/15 1:20 a.m.

Nice work. Loving the updates.
I'm curious... What brand vernier caliper do you recommend for occasional home use?

series8217
series8217 Reader
3/17/15 2:52 a.m.

Part 2 - Radiator and Fan Mounts

I ended Part 1 with the radiator installed in the car and (mostly) plumbed up.

Time to finish the plumbing:

The Griffin radiator did not come with a radiator cap. The stock Fiero cap, or an aftermarket replacement such as the Stant 10330 16 psi cap would work fine. Some of the parts catalogs list an incorrect unvented cap, so if you want to buy a cap listed for the Fiero, make sure it's a vented cap (16 psi should work).

Expansion tank / overflow connection: a 3/8" barb x 1/8" NPT fitting is needed to connect the expansion tank hose. I don't think my Griffin radiator came with one, so I'm not sure if they're supposed to. You can source a brass or aluminum fitting from McMaster or a local supplier, and a couple feet of 3/8" ID rubber hose, rated for coolant.

Now on to the mounts. As we saw before, the stock mount wasn't going to fit. It looked close in the pic but doesn't really fit at all. It's also heavy, so I got rid of it. For the new mounts, I made some CAD templates -- that's cardboard-aided-design -- to locate some rubber radiator cushions on the end tanks, transferred the cardboard to metal, bent them up in a vice, drilled mounting holes (two for the mount bolts, one for the rubber cushion), and voila! Here are the mount brackets I came up with:

I recycled these cushions from the stock upper radiator mount:

The cushion fits into the small hole in each bracket, and a bent lip keeps it straight:

Here they are installed:

Finally, I had to mount my Spal 30102082 radiator fan to the new radiator. I chose to mount it flat against the radiator because this large fan has sufficient area to keep the car cool at idle without a shroud, and when the car is at speed, there will be airflow through the portion of the radiator that the fan doesn't cover.

This fan has T slots which conveniently accept M6 hex head bolts with 10mm heads. For the bottom, I bent some aluminum brackets from 1" wide aluminum strips to grab the bottom radiator lip:

For the top, a simple aluminum angle with a speed nut is sufficient to hold the radiator fan in place. The bottom straps keep the fan from moving up or back, and the top straps keep it from moving down or back.

The final detail is to shroud radiator so that air can't flow under, around, or above it. All airflow in the inlet duct from the front bumper must go THROUGH the radiator. Any gaps around the radiator will cause air to bypass the cooling system! I already upgraded the stock radiator ducting by adding more panels and taping off seams.

When I removed the stock upper mount in Part 1, the stock upper shroud went with it. Pontiac had used a sheet of recycled rubber to prevent air from flowing over the radiator. I added back something similar -- I used a sheet of EPDM rubber clamped to the upper flange of the radiator. The rubber sheet is draped over the radiator and AC condensor, and then folded back around to the upper flange. It effectively forms a big bulb seal, and it actually works quite well. Feel free to laugh at the binder clips, but they work great, they're easy to remove and replace, and they cost nothing.

This radiator upgrade brought coolant temps down by roughly 20 degrees at the track. I had already been using this fan with my stock radiator, so the improvement is attributable directly to the radiator itself. Awesome!

series8217
series8217 Reader
3/17/15 3:05 a.m.
amg_rx7 wrote: Nice work. Loving the updates. I'm curious... What brand vernier caliper do you recommend for occasional home use?

I'm not a real machinist, but I've used many different brands of calipers at work and at home so I feel like I can answer that question.

I do have some nice vernier calipers from the 70's that were handed down from my grandfather but I don't know why you'd want to use them these days when digital calipers are so much faster to use... so I'll answer assuming you meant that you wanted digital calipers.

For stuff you're doing at home where +/- 0.001 is more accurate than you'd need, the cheapies you can get at Harbor Freight for ~$20 will work just fine. They're advertised at something like +/- 0.0005" but I wouldn't expect repeatability better than 0.002". If you want something with a little better accuracy and quality, look at Fowler's mid-range offering or spend a few extra bills and get something from Starrett like these. (Amazon doesn't pay me for links, I just love Prime!)

series8217
series8217 Reader
3/30/15 1:19 p.m.

I installed my modified rear knuckles and hubs over the weekend.

Modified knuckle and axle spacer installed:

I had to modify the axle spacers because the fillets on the axles on my car were larger than the fillet on the axle I used as a template. I'll update the drawing when I get a chance.

Always make sure you confirm fitment on parts like this by checking for a gap between the parts using a strong light. It may not be possible to see without the light. You could also probably use marking blue.

J-body hub bearing installed (with ARP 100-7708 studs):

I used a new axle nut and axle nut washer (not shown) for a J-body. I'm not sure if they're the same as the Fiero parts.

There are three torque specs listed for these hubs, despite the hubs being the same for all years: 1984-1997: 184 ft-lbs (260 Nm) 1998-2001: 144 ft-lbs (195 Nm) 2002-2003: 148 ft-lbs (200 N*m)

from: http://www.speedwayautoparts.com/Torque%20Specs.pdf

I do not know the reason for the different torque specs. I used 184 ft-lbs.

series8217
series8217 Reader
4/13/15 5:34 p.m.

Time for some more aero experimentation, this time with brake/hub cooling ducts fed from the bottom of the splitter. I rarely get the brakes too hot but it does happen sometimes on some tracks. If I can drop the hub/rotor peak temperature it should improve the longevity of the wheel bearings too.

Starting with the splitter I built earlier, and some "small NACA ducts" from Racer Parts Wholesale. These aren't really NACA ducts, as they don't have the right floor profile, angle, or overall shape. Will they work anyway? Maybe!

The duct as it arrives from RPW needs to have the border trimmed and the center hole cut out with a 2.5" holesaw.

Shape transferred to the alumalite splitter and cut out with a portable jigsaw:

Test fitting the duct:

Viewed from the bottom side (inlet):

Ducts riveted to the splitter with 1/8" x 1/2" aluminum rivets

Top side (outlets):

On the car with the 3" brake duct hose installed:

Top side where the 3" brake duct hose attaches:

The zip ties hold the duct to the tie rod so that the duct is pulled away from the brake rotor when the wheel is turned.

Backing plates are the next item on the list. Right now the duct just points at the middle of the rotor. The backing plates will also help guide the duct and keep it off the rotor. Then I just need a single attachment point on the duct to keep it away from the tire when the wheel is turned all the way.

I'm hoping to have the car ready to track test this setup this weekend.

series8217
series8217 Reader
4/16/15 2:47 a.m.

I figured I'd take some updated pics of the car in case I wad it up at the track this weekend....

fujioko
fujioko HalfDork
4/16/15 8:54 a.m.

This thread is an awesome read with great pictures! How did you shoot the last two pictures?

series8217
series8217 Reader
4/16/15 2:47 p.m.

Thanks fujioko! Those last two shots were taken at a 20 second exposure and illuminated exclusively with a bright flashlight by walking around the car. In post processing I made contrast adjustments, removed a flashlight beam from above the car, and darkened the background.

Here is one of the original photos pretty much straight from the camera. I did increase the exposure before generating the JPG because it was very under exposed.

Original:

Final:

pinchvalve
pinchvalve GRM+ Memberand MegaDork
4/16/15 3:01 p.m.

Amazing what you can do with a brain and a machine shop. I wish I had both.

series8217
series8217 Reader
4/16/15 7:33 p.m.

I don't actually have a machine shop.

I built this car in my home garage and driveway with simple hand and power tools, except for 3 parts I machined on the CNC at work (steering wheel adapter, ball joint plates, and rear knuckles), and a few others that I had laser cut or waterjetted by local suppliers, such as the seat mount rails, wing stands, and endplates. I don't even own a drill press. I go through a lot of cutoff wheels and hacksaw blades though ;-).

I'd like to think that anyone can build something like this by leveraging the resources available to them. It takes some strong ingenuity and a DIY ethic, but you can build some pretty amazing stuff with basic resources.

Gearheadotaku
Gearheadotaku GRM+ Memberand PowerDork
4/17/15 3:31 p.m.

As a former Fiero owner, I really enjoy (and envy) your build and problem solving. Wish I had my '88 V8 still so I could apply this new-found knowledge!

G_Body_Man
G_Body_Man HalfDork
4/17/15 3:34 p.m.

Part of me wishes I bought a Fiero instead of my Cutlass. A red 84 Iron Duke model owned by my neighbour was my personal hero car during my formative years.

1 2 3 4 5

You'll need to log in to post.

Our Preferred Partners
ojFCHQgfs708oBv4DV3UpaFlZSPZnFADz0mzAxRi6RUftYetwqASb5mB96FZmNpQ