Affordable aluminum rear knuckles?

I am making my own IRS for the E30. I would love to use some existing knuckles from saaaay a thunderbird or mustang cobra but holy crap... people are selling them for $125 each at the junkyard all the way up to an "I E36 M3 you not" $450 for a new pair. I am sure I've seen the whole t-bird for $500. WTF?

So, what has light, strong rear knuckles that will work with unequal length control arms? Maybe some AWD fronts? BMW X cars? The rear I'm using is a Speedway Engineering quick change setup with Porsche 930 axle stubs so maybe something from Audi that uses the same axle spline for the hub (too much to hope for...?)

Cheap, light, strong... I know, pick two... so Cheap and light :) The car weighs 2400 w/ driver and might make 400 to the crank someday. Today it makes 280.

I wish I had info, but all I have is a request to document your endeavor...

That's awesome.

ransom wrote: I wish I had info, but all I have is a request to document your endeavor... That's awesome.

I will do a build thread, I promise. I am still making sketches and trying to line up donors - there is one more race this season and then the cutting starts in October.

The T-Bird ones have gone up in price since that's what the Cobra replicas use. Ford has even taken to selling them through the FRPP catalog.

You might be able to find Audi units in various degrees of aluminum. That may be your best bet.

IIRC, Boxsters are four wheel strut, plus the Porsche tax.

I kinda remember C5 bits being in the $75 range at junkyards. Like the Boxster, they use the same parts on the front and rear.

Uh....Miata?

Box flares plus the rear subframe from an e36?

For some reason I want to say the RX7 has a multilink setup with AL knuckles that can be adapted to SLA.

240sx? FC RX7?

Timeormoney wrote: Box flares plus the rear subframe from an e36?

I have big fat flares now but the E36 parts are cast with huge heavy forward links attached so there is no easy way to set them up for a proper formula car style triangulated unequal length control arm setup. The subframe is also set up for E36 geometry and while that isn't a bad thing - it isn't optimized for racing or easily adjustable for squat, caster, camber etc - I'm also bringing the dampers inboard and using a SWE quick change rear so it buys me nothing to use the frame.

FC are iron, I believe. Plus, they are a multilink swingarm, not much better than the stock E30 setup.

Had a dumb thought. It's a rear suspension, so you don't need to have an upper ball joint to compensate for steering.

Depending on how you wanted to go, you could use a front knuckle from something. LOTS of '00s minivans from GM and Chrysler had aluminum uprights in the front.

emodspitfire wrote: Uh....Miata?

Huh. Why this didn't immediately spring to mind is beyond me. Follow on questions:

How large is the hub diameter? Can it be welded and redrilled 5x120?

How strong are the axles? I would need to go from Porsche 930 CV to whatever is outboard on the Miata. Are they going to be a weak point at 250ft/lbs being pushed thru Hoosier slicks? Calling Kieth: Are you guys snapping these on V8 cars with sticky gumballs when pushing hard?

Knurled wrote: FC are iron, I believe. Plus, they are a multilink swingarm, not much better than the stock E30 setup. Had a dumb thought. It's a rear suspension, so you don't need to have an upper ball joint to compensate for steering. Depending on how you wanted to go, you could use a front knuckle from something. LOTS of '00s minivans from GM and Chrysler had aluminum uprights in the front.

I considered using mcpherson struts instead but I want the dampers inboard and easy ability to swap spring/dampers for setup changes and I want the upper arm for progressive camber gain.

I thought about front knuckles from BMW/Audi/Porsche but you are right - anything that fits inside a 15" wheel and can handle the loads of a mini van could be made to work as long as it didn't have some crazy built in anti-dive angles.

I was at the PullAPart and saw aluminum rear knuckles on a Jaguar XJS for $10 each. I've bought C5/6 Corvette knuckles off Ebay for $50 to $100. Jeep XJs are steel, but pretty lightweight and might work for cheap. XJS Jeep XJ

Re FWD knuckles, you don't have to use the strut, you can fab an adaptor that bolts on in it's place at the top.
That gives you the freedom to use whatever you want/need.

Carter

Z32 300ZX has aluminum spindles with a multilink setup. Same as 240SX except those are steel so the Z32 pieces are a common upgrade.

Why not buy an entire tbird and take the whole rear axle assembly w/ driveshaft and junk the rest? Like you said buy the car for $500 and scrap it for almost the same price.

My short list at this point is:

• C5/C6
• Thunderbird

But, favoring the first due to the steering arm making rear toe adjustability as simple as tie rod to turnbuckle as well as very easy hub install/removal w/o a press.

I am overlooking the miata right now because those hubs look like they have tiny little wheel bearings and side loads with fat slicks might eat them up.

Gasoline wrote: I was at the PullAPart and saw aluminum rear knuckles on a Jaguar XJS for $10 each. I've bought C5/6 Corvette knuckles off Ebay for $50 to $100. Jeep XJs are steel, but pretty lightweight and might work for cheap. XJS

Why does this remind me of the enemies from the Descent series?

Cool inboard brakes though.

The problem with the Jag IRS setup in that picture is the axle shaft is also the upper control arm, that means it loads hell out of the diff flange bearings. Later Jags had outboard brakes and short/long arm rear suspension. Should be pretty junkyardy by now.

EDIT: If this listing was any indication, even a Snorkelwacker can afford them. http://www.ebay.com/itm/2004-2005-2006-2007-JAGUAR-XJ8-XJ8L-VANDEN-PLAS-REAR-WHEEL-SPINDLE-W-HUB-/120957030632?_trksid=p4340.m1850&_trkparms=aid%3D222001%26algo%3DSIC.CURRENT%26ao%3D1%26asc%3D11%26meid%3D1832958550257222885%26pid%3D100011%26prg%3D1005%26rk%3D1%26

for a while, the lincoln aviator (rebadged ford explorer) with independent suspension was the same as the explorer, but cast aluminum. not that they are thick on the ground, but if you see one in the yard....

What about C4 Corvette?

I think the 95+ Lexus LS400 might have aluminum rear knuckles. I'm not sure though.

GameboyRMH wrote:

Gasoline wrote: I was at the PullAPart and saw aluminum rear knuckles on a Jaguar XJS for $10 each. I've bought C5/6 Corvette knuckles off Ebay for $50 to $100. Jeep XJs are steel, but pretty lightweight and might work for cheap. XJS

Why does this remind me of the enemies from the Descent series? Cool inboard brakes though.

That is great!

LS400 rear suspension:

Real similar to the Jag setup. Dunno if the knucles are aluminum, though.