Need opinions on hub materials

[CanAmNova]

I'm putting together a custom brake setup for my '72 Nova and have been looking at my options for hubs so that I can run rotor hats. I'm using some dropped spindles that use GM metric style bearings/races. I've found a few sources for the hubs (mostly stock car racing stuff) however, some suppliers use billet aluminum, some use billet steel, and some use steel forgings. My question is: would billet aluminum hubs stand up to the punishment of track use and be safe to use for this application? The suppliers that use steel are saying that aluminum hubs should not be used in racing applications. I'm running a big block and my thinking here is that with the extra weight of the engine, plus stiff springs and wide rims/tires that I might be looking for trouble if I use the aluminum hubs. Any thoughts? Thanks

[dipren443]

I'm putting together a custom brake setup for my '72 Nova and have been looking at my options for hubs so that I can run rotor hats. I'm using some dropped spindles that use GM metric style bearings/races. I've found a few sources for the hubs (mostly stock car racing stuff) however, some suppliers use billet aluminum, some use billet steel, and some use steel forgings. My question is: would billet aluminum hubs stand up to the punishment of track use and be safe to use for this application? The suppliers that use steel are saying that aluminum hubs should not be used in racing applications. I'm running a big block and my thinking here is that with the extra weight of the engine, plus stiff springs and wide rims/tires that I might be looking for trouble if I use the aluminum hubs. Any thoughts? Thanks

What type of track time will the car see?

Also, have you read the sticky about dropped spindles in here???

If the car is going to see heavy track time, and you are dead set on using aluminum hubs, then make sure you are using a stronger aluminum alloy. If you are going to make custom hubs, start with a aluminum forging.

Just a heads up, you may want to contact Kore3. Tobin will make you custom hubs out of 7075-T6 Aerospace aluminum alloy. Username is Apogee on here.

The main reason the suppliers are saying avoid aluminum hubs are its inferior fatigue properties as compared to steel. But as long as you start with a stronger alloy, then I think you will be ok.

[astroracer]

I am using cut down brake rotors for a 2nd gen F car. The "bearing hat" is made by cutting off the brake rotor which leaves the bearing and lug area intact. Real cheap way to get cast iron hubs that you don't have to worry about breaking... The ones I am using were given to me because the rotor was used up. Just make sure the bearing races are okay and never been run hot...
Mark

[Apogee]

Steel has it's advantages, particularly in a racing application where you plan on hitting other cars and/or other fixed, inanimate objects like the wall. The nice thing about most steels is that you can typically beat it back into shape if you have to and run it...this is not true however of cast iron hubs which tend to break before they bend in my experience. Most of the race cars running steel hubs will also be running steel wheels for similar reasons where durability is worth the weight penalty.

If your flavor of motorsports involves less intimate contact with the surroundings, weight becomes a larger concern and impact strength a smaller one. This is where aluminum typically shines (pun intended). There are three common heat treated aluminum aircraft alloys to choose between, 2024, 6061, & 7075, each with it's own distinct pros and cons. Both 2024 and 7075 have the strength advantage, however 2024 lacks corrosion resistance and as such, is much less suitable for any sort of multi-purpose application IMO. 7075 is more or less the best of the best when it comes to aluminum, and the cost reflects this at more than double what 6061 goes for. 6061 gets the nod for cost, availability, and corrosion resistance and still compares well to mild steel in terms of strength.

Fatigue is always a concern, particularly with aluminum. Hubs are a maintenance part and should be inspected with the appropriate frequency for the type of use the vehicle sustains. We're pretty conservative with our hubs and as such, sacrifice a little weight for additional rigidity and fatigue resitance...so far, so good, and some are going on five years now. Also, considering that none of these operates in a vacuum, long term effects due to elevated temperatures result in a loss of material strength due to tempering of the material as a function of time and temperature.

If you look at a Mazda RX-7, you'll notice that they came from the factory with aluminum front hubs.

Tobin
KORE3

[dipren443]

The nice thing about most steels is that you can typically beat it back into shape if you have to and run it...this is not true however of cast iron hubs which tend to break before they bend in my experience.

Correctamundo. The alloying elements (mostly carbon) mixed with iron to create steel increase the materials ductility. Cast iron is extremely brittle and will definitely crack before it bends.

[CanAmNova]

Thank you everyone for the answers and great information, I appreciate all or your input.

dipren443: Thanks for the heads up on the dropped spindles threads. It looks like I'm gonna be eBaying some spindles. The only reason I had these is that my neighbor sold them to me real cheap--now I know why...

Apogee: Thanks for the great info. Now I need to decide whether to go with the stock spindles + Kore3 hubs or whether I want to go with the AFX spindle setup.

[wendell]

Ask your self why you want to run Al hubs. You've got nothing to gain. I've seen them fail at the track and it's not pretty. You've got a BB so weight can't be a driver.
The stock F/X hub is plenty strong and cheap. The only other thing I'd look at is the 'vette hub that's packaged with the ATS spindle.

[CanAmNova]

Ask your self why you want to run Al hubs. You've got nothing to gain. I've seen them fail at the track and it's not pretty. You've got a BB so weight can't be a driver.
The stock F/X hub is plenty strong and cheap. The only other thing I'd look at is the 'vette hub that's packaged with the ATS spindle.

You've got a good point in that the stock Corvette sealed hub bearing was designed to support the weight of an aluminum small block. Has anyone heard of problems with running a big block with the Corvette hub bearings? Or has anyone ever had one break off from an AFX spindle?