Speaking as one who has a lot of experience working with aluminum on racing HPV's. Aluminum is a great metal to use because of it strength to weight ratio. However, there are limitation to its use. First of all aluminum has a tendency to have problems with fatique failure. And this failure of the hub could be due to repeated cyclical stress causing catastrophic fatique failure. Most grades of aluminum when they are welded decrease in strength and the fatique life decrease significantly. That is why things made of 6061-T6 grade aluminum have to be heat treated to return them to their rated strength and increase their resistance to fatique failure.
Also, since aluminum grows significantly more than steel in size when heated to welding temperature the person welding the aluminum has to be very good and knowledgeable to keep consistent temperature all the way through the part, otherwise welding will induce further stress in the part from welding one side and letting it cool before welding the other side. This will be seen when you heat treat the aluminum, because those stresses will be relieved resulting in twisted parts. An example of this is a certain aluminum bicycle built in the '80s where they mounted the components in a jig structure to hold them in place, then welded one side together. The frame was then reversed in the jig to allow welding the other side. When these frames were heat treated the spots where it was critical to maintain dimension were bolted into a steel jig for the duration of the heat treating. That way all the critical points were in alignment and dimension. However, the welded in stresses relieved themselves in the unsupported regions resulting in twisting of the chain stays, the down tubes, and all other pieces. The frames were in position in all the critical places, but the tubes were twisted and ugly looking.
So if you welded gussets to this type of hub you could easily twist or add stress to the hub which would cause other problems even if you heat treated the parts.
Posts: 3311 From: Menasha,Wisconsin,USA Registered: Dec 2009
In the aviation world wich I came from we see failure like this all too often in the landing gear struts they too are machined cast aluminum in some instances u need to remember aluminum does not stress like steel and cracks over time with repeated load a good example of this was the jet that lost its roof over hawaii killing one of the flight crew aluminum just shears after while thats why ntd uses x rays to detect the cracks in the skins and parts of a airplane u cant see them with the naked eye most of the time their is also a condition called hydrogen embrittlment wich effects it also but thats more twards the steel side of things. Ive seen on some jets exposed to deicing fluids have holes in the wing roots and rivit heads just sheared off from stress only to find white powder were its head once was, the tail root is the worst area i have seen on gulfsteams their is a ram air intake apart of the tail and it has rivits that seem to take alot of flexing and it was a givin after striping a jet that was one of the first things I looked for aluminum in my opinion bad for a hub on a daily driver save it for the track or it will crack.
[This message has been edited by jetsnvettes2000 (edited 07-31-2010).]
Pete Matos Member
Posts: 2291 From: Port St. Lucie, Florida Registered: Jan 2010
I dunno and I am NO engineer, but I do have a good friend nearby here that has a full blown CNC machine shop and they make lotsa parts for the flat track race cars and they even run their own cars. They make lotsa parts out of 7075 aluminum in suspension and brake applications for these cars. They get run really hard on the track and are well made. I do not think tho that anyone should make a hub or spindle from aluminum simply due to the HUGE stresses and shock loading that these parts get. That part as said before should have been much thicher at the transition area into the wheel flange to be safe but for my car I would want some steel in that area. Never seen anything like this before where a whole wheel and brake assembly was seperated from a car on the street. That is terrifying if you ask me...... To say that this was a lucky result is an understatement.... peace
I do! I was wondering if there was any locals on here! I thought I was the only Alabamian! We should get together sometime and have a beer!
Im an alabamian as well! .. There are a handful of us on here.. I live in Northport..
Well i sure am glad everybody is ok, and most importantly, that beautiful car didnt get hurt to much, lol.. I sure hope you find your wheel too, lol, that would suck to have to buy another set of rims, and the ones you got on there look pretty good..
Doc John Member
Posts: 749 From: Fayetteville, Arkansas Registered: Feb 2007
I have the RCC brakes and suspension on my car, and it already tried to kill me once -- about 7 years ago all the bolts holding the calipers in on one wheel (pass side front) sheared off. The wheel stopped turning pretty suddenly at that point. Fortunately I was only doing about 25-30 at the time. The lower tubular A arm sheared at the same time (I wish I had taken pictures of the damage). It trashed the wheel. Fortunately I was able to pull over to the side of the road w/o any further incident.
Maybe I should switch back to the Fiero front hubs and go with the Grand Am front brakes.
Aug 4th, 2010
Posts: 175 From: Millbrook, AL Registered: Jun 2010