C3 Aluminum Control Arms

B

Bad Bird

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Joined
Aug 19, 2011
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56
Location
Newcastle, Australia
At the risk of sounding cretinous, I'm going to ask this question. Has anyone here tried Speed Direct's (yes, I know...) aluminum upper control arms?

natural_w_balljoints.jpg


I like the idea of an heightened roll center, and the reduction in unsprung weight (albeit maybe only 1/2 to 1/3 of their claimed 4 pounds). My fear is that they might not be safe, as Speed Direct has a bit of a reputation for underbuilding their products (Steeroids, Sharkbite).
 
offset pivots

Look at the pic of the arms in post 1. Notice the center line of the inner pivot is offset below the mounting slots. Arms themselve do nothing to the geometry it's all in the pivot. Moving the UCA inner pivot centerline down results in a shorter VSA length and a higher roll center

Grampy
 
Yes they are cast, I wouldn't run them either. Cast arms are not uncommon, I think the C5/6lowers are cast but they could be forged. The rears are cast but I am positive the upper ones are forged.They are not beefy like the lower ones, I wouldn't trust thin cast arms. On top, I'm willing to bet the factory c5/6stuff is pressyre cast, the steeroids is probably just grvity cast in a sand mold. Who is going to check for porosity or contaminants??

Those guys took all the ideas from corvette forum and turned them into junk products.The steeroids is a copy of the saab rack conversion from Idar Andersson. The roll center mods were heavily discussed years ago and offset shafts were proposed amongst other things.
Same with the shark bite, there were a lot of threads about the IRS back then, 5 bars, 6 links, coil over conversion and...sure enough cam operated systems. Too bad they didn't pay enough attention on the shark bite coil over and have the cams the wrong way around making it severely inefficient (and hence the need for a backup shock in the stock location in the original test vid, they ater changed to much stiffer shocks and springs to combat the probs)

As for the arm shafts, a machine shop could set you up with some easily. Add a long howe moduar ball joint and you have what you want.
Here's a better pic of the arms.

G87410.jpg
 
OK then, I know it's been discussed a lot of times but why not here again?


What would be the best mods, or parts whatever to the control arms to do with our stock frame?
simple thing, not a1100$ exotic alu part.

I like simple things and I'm cheap LOL
 
1Michel said:
OK then, I know it's been discussed a lot of times but why not here again?


What would be the best mods, or parts whatever to the control arms to do with our stock frame?
simple thing, not a1100$ exotic alu part.

I like simple things and I'm cheap LOL
Click to expand...

Well, our upper Ball joints have 3 bolts in the mounting, I understand there is another similar joint out there that is fairly common, using 4 bolts and with a longer stem that effectively raises the height of the spindle, and of course the upper pivot but it's only maybe 1/2 inch or so....so to lower the inner pivot or raise the outer pivot (ball joint knuckle) I would think some part could be machined to do that with a stock ball joint...a taper hole cut, with threads on the bottom of the hole for the stem to screw into, and the outside machined like a stem to fit into the spindle.....

ME, I think it's too much to mess with...lazy....:clobbered:
 
Thank you guys. The VetteMOD crew really are the Corner-Carvers.com of the Corvette world (and I mean that with the utmost respect). Gosh it's good to get some real tech rather than marketing rubbish.
 
Twin_Turbo said:
Yes they are cast, I wouldn't run them either. Cast arms are not uncommon, I think the C5/6lowers are cast but they could be forged. The rears are cast but I am positive the upper ones are forged.They are not beefy like the lower ones, I wouldn't trust thin cast arms. On top, I'm willing to bet the factory c5/6stuff is pressyre cast, the steeroids is probably just grvity cast in a sand mold. Who is going to check for porosity or contaminants??
Click to expand...

Speed Direct claim (which is no real tech threshold) that the arms are produced by an 'OEM' supplier and are heat treated. Here is their tech page:

http://speeddirect.com/index.aspx?nodeid=135

What this means in the real world... I'm not sure. Apparently a guy on Digital Corvettes has been using them for years, but a sample size of 1 is hardly scientific.

G87410.jpg
 
I don't have my price comparison at hand - but consider the SPC upper A Arms. With the taller (longer) ball joints (Howe).
thum_12694f6121f239064.jpg

This is a "stock" image - and now they use hex shaped arms for easier adjusting.

Fine piece of gear.
Mark Savitske is the purveyor - and author of "How to "Make Your Muscle Car Handle." He great for a "chin wag" - so get some credits on your Skype mate - and "give 'em a bell."
TT even has at least one set - so two data points for starters - but I haven't driven mine yet.

Cheers - Jim
 
I don't have a SCandC set, mine are even older, they are the original pole position ones.
 
I've always, based on nothing other than instinct, been wary of those adjustable arms for reliability during street driving on the cattle tracks that they call 'roads' around here. Maybe I should forget my unfounded bias and look at running them, or some of the other tubular-type control arms instead.

My interest in raising the roll centre height is to give me a bit less body roll when I go to softer springs, to increase compliance over the rutted roads I have to drive on. I guess I could do that with a tall balljoint on the SPC arms rather than dropping the inner pivot of the UCA like Speed Direct.
 
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The stock arms are perhaps heavy ( i don't know if anyone has done a weight comparison) but they are very robust. If they start to crack and tear, they will fail in a slow and controlled mannor where the driver should feel the steering geometry problem and pull over. They have to tear about 6" to a foot to fail completely. That's not going to happen instantaneously.

The way those tube arms fail is they snap (normally at the weld) without warning sending you into a wall at 140 mph. I saw it happen to a mustang at New Hamphsire Motor Speedway.

But they'd look pisser on a show n' shiner. Just like big ass 6 piston pimpin calipers do.
 
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turtlevette said:
The stock arms are perhaps heavy ( i don't know if anyone has done a weight comparison) but they are very robust. If they start to crack and tear, they will fail in a slow and controlled mannor where the driver should feel the steering geometry problem and pull over. They have to tear about 6" to a foot to fail completely. That's not going to happen instantaneously.

The way those tube arms fail is they snap (normally at the weld) without warning sending you into a wall at 140 mph. I saw it happen to a mustang at New Hamphsire Motor Speedway.

But they'd look pisser on a show n' shiner. Just like big ass 6 piston pimpin calipers do.
Click to expand...

There is good stuff, and there is crappy stuff. All Nascar and Indy cars have these type of arms. They are just made well, and hold up just fine.:rolleyes:
 
Only, those are tig welded by highly skilled craftsmen and all the welds are checked. And even then, they don't put on the miles that a street car does and do not see curbs and potholes
 
I have to agree. I want to modify this car for safe, reliable road use. I feel that I just can't get enough caster to make the car drive the way I want it to. I really do prefer the feel of 5 to 6 degrees of caster. I know that I can slot my UCA cross shafts and get a bit more caster.

In terms of reliability, what would you find preferable, TT? The SPC adjustable arms, or some good quality Tig-welded tubular arms? This car gets driven at most 2000 miles a year...

Best wishes,
Matt.
 
Does OZ have a Low Volume Vehicle Technical Assistance Program - like across the Tazzie? When in NZ - I was considering doing some mods to my POS Honda - and was concered about passing the WOF. Got switched on to the LVTAA for advice. At the end of the day, opted not too - but it might be a good resource.

Cheers - Jim

The LVVTA is for homebuilders, kit cars, and modifications and has technical advice for those wanting to do mods and stay "road-worthy," i.e. pass the WOF.
 
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