Looking into the replacement fo the nodular FE steering knuckles on the 4th gens with an aluminum fabbed one.

The Vettes carry alloy spindles, so it seems just a matter of the engineering and the $$.

Objective: save some unsprung weight!!!
Thinking T6 alloy.
Anybody with experience in this??

For the mods. This is Advance Tech. This is an advance tech Q, even though it is not engine.
Thanks......

 

Thanks for explaining that.

You might want to try the "Autocross....." forum, or the "Drag Racing" forum, since those are two groups of people who would use such a part.

But who am I to tell you what to do

 

Well, I didn't mean it THAT way.....
Thought I'd try here first, since it's really a mettalurgical problem. That plus fabrication. Thought I might get a different perspective.
Most of the guys in Autox, RR are Autocross guys. Sometimes they see things a little differently than we roadracers do...

 

Designing, testing and building a safe aluminum knuckle would be quite expensive. I'm not sure what the market for expensive knuckles is, but sure, it can be done.

Forging is out for tooling expense and sand casting for strength. That leaves welding and machining or CNC machining from a billet of 6061 T6 aluminum. The Gen 4 ductile iron knuckles weigh about 16 lbs. An aluminum one would weigh about half that to have adequate strength. Maybe a stronger than stock one for racing might be wise. Anyhow, we're talking a total weight savings of 16 lbs. per car. Those are VERY expensive pounds: my guess is $100-$150 a pound depending on how many one could sell.

I think the lack of a market would preclude someone trying to build them.

My $.02

 

Thanks for the reply OldSS...

Well, I'm not doing them to market. Just trying to get some built for my weekend road racer.

CNC machine is pretty much the only solution. Would be around 40% weight reduction if 1to1 replacement on the stock ones.
I would have to make them beefier than stock as the T6 is not quite as elastic as the stock steel. Tendency to deform is greater on a mass for mass comparison.

a 7 or 8 lb unsprung weight difference is fairly significant and can increase both perfomance and ride comfort. The only two questions I can see that need to be answered are
1. What will be the service life of the part?
2. what are the areas of reinforcement required by going from one material to the other?

 

DucaT,

I'm in your camp on alot of things, and Old SStroker is the guy I would ask about this stuff if it was me.

On that note, the engineering and suspension design knowledge that he has leaves this problem right in his ally.

Now to your deal. The 8lbs of unsprung weight on each corner is a big benefit, but going this route might not be the best way to do it.

Looking at it another way. Let's look at the package. Springs, brakes, wheels, A arms tires etc.... What can be fixed and lightened at the same time.

If I was doing it the aluminum upright would be the hardest way to solve your problem.

How about looking at different parts.

Wheels can save you a ton of weight and different tires at that too. A shaved tire that is lighter than another brand is worth some pounds. A 2002 up ZO6 OEM front wheel is going to be much lighter than most aftermarket and OEM F-body stuff.

A lightweight brake rotor or one with an aluminum hat on it like the Eradispeeds would take out some weight too. If you have a LT1 car then swapping to a C5 bake setup with aluminum calipers, a aluminum caliper mounting bracket and the Eradispeeds is going to save some weight. You also take off some of the cast iron on the spindles doing that conversion and there is even more that could be taken off safely, but not a huge amount.

How about tubular A arms? They might only consist of 1/2 of the unsprung weight but they will take off some weight and fix some geometry at the same time. How about coil overs? A good setup will have a smaller spring and a aluminum shock absorber too so there is definately a savings there.

I would look there first. There is at least 8lbs in doing all of that stuff.

Then I would look at a new front clip with a C5 setup on it. That's going to take some work but it will fix alot of the problems on the front end and give you a lighter setup. Probably in the end also give you more bang for your buck than a set of safe, tested Aluminum uprights.

Bret

 

Well, I'm looking to get what I can out of what I have now.
Needed to go to larger wheel/tire: have Z06 wheels.
Brakes are stoptechs, and already have the AL hat.

I drive on the street and haven't decided to go with other a arms because of the heim ends that are always accompanied by them, bringing a little too much NVH.

Coilovers are next on the list as soon as I get my move across the country finshed!! Looking at Ledas and hypercoils if I can get Leda to fab one for the *** end for me.

Just looking into the feasability of having these things engineered to fit in the car. My line of thinking is that if I wanted C5 parts I would go back to driving a C5. Plus, there would be too much fabrication for my tastes to get away from the leaf spring.

Thank you for the post.

 

I don't think service life will be a problem. Aluminum suspension bits, both cast and forged are used a lot on even low buck OEM cars. As for strength, unless you have a designer with a decent FEA computer program and suspension experience, it will be a guess.

Here's a quote: The front steering knuckles for police versions of the fwd Impala are made of cast steel instead of weight-saving aluminum, though Chevy says the aluminum knuckles--as well as the rest of the car--exceeded durability tests. Off the record, Chevy's engineers said the new Impala passed tests that projected its life span at 400,000 miles. These tests included curb-hopping, which is not normally part of a new car's durability cycle.

IMO, you are looking at many thousands to do the aluminum knuckles correctly; probably more than all the rest of your suspension parts combined.

Remember, Z06 aftermarket wheels are quite a bit heavier than OEM ones. There are other wheel companies which make lighter but strong racing wheels. Larger tires are heavier, but you can select the lightest, stickiest ones.

You might look at aluminum hubs in place of the ductile iron OEM ones. These will require fabrication, but at lots less cost than knuckles.

IMO, unless your pockets are VERY deep, forget saving the few pounds on purpose-built parts, and spend the $ on the lightest and best existing parts you can find. Even the lightest bits don't change the geometry which can use some help. Coilovers probably won't save weight, but it will make adjustment easier.

Low unsprung weight is important, but it's not the "be-all and end-all" of ride and handling. My highly opinionated bottom-line advice about the alum. knuckle is forgetaboutit.