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Old 02-10-2020, 06:46 PM
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69427 69427 is offline
United States | The Artist formerly known as Turbo84
Join Date: Mar 2008
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Originally Posted by SuperBuickGuy View Post
Originally Posted by 69427 View Post
Originally Posted by SuperBuickGuy View Post

Quick question. On the aluminum LCA crossmember, I'm trying to see what Chevrolet did. Do the LCAs bolt/tighten directly against the aluminum "tabs", or are there any steel washers between the LCA bushings and the aluminum tabs?

I'm getting nearer to fabricating version 2.0 (aluminum) of my LCA crossmember, and I'm assuming I'll need washer clearance in the pocket where the LCA bushing reside, unless there's a reason I don't need/want steel washers in there.


The lower control arm are attached via GM cam bolts - that is how you adjust the camber and caster. There is a steel tube (at least, presume steel but I never tested it) that keeps the bolt from crushing the rubber bushing which keeps it from the arm. The cam is steel on cast aluminum.

The upper arms are forged aluminum, however the inner sleeve is steel, as are the tabs and the bolts are steel as well. The bolts go through steel tabs that are floating in rubber in the arm itself

To the bottom arm adjustment - I presume GM knew what they were doing - and as these parts had 100k on them and there is no corrosion - I can only presume that the alloy is important here.... and in my experience some kinds of aluminum are far more susceptible to galvanic corrosion then other alloys.

In the boating world, it's stainless steel/aluminum that makes the aluminum the anode to stainless steel.... regular steel? not my in my experience. There are 12 points where they touch, 8 of which were GM-designed.

Good question - I'll give a qualified "I dunno" but with the caveat that this is why I kept it all GM, I think GM's QC is world class

and of course, I can't even imagine trying to drive this car in a situation where salt is on the road, I can't get it up my driveway if the gravel is even slightly moist. Thankfully, I'm not GM and I'm not building my cars to protect the darwin end of the gene pool.
I appreciate the reply. I'm running a similar material front suspension (C4), but with a steel custom crossmember (similar material as C4 crossmember). With the future change to an aluminum crossmember I was wondering if the LCA steel bushings chew into the aluminum when the pivot bolt/nut is tightened. I never worried about it with the present steel crossmember, but with a softer aluminum piece it's gotten me curious.

Keep us updated on what lightweight battery you end up with. I've been looking to put one in my car (currently using a 16# lead/acid battery), but I haven't been able to get a decent reply from the lithium battery suppliers on which of their batteries will crank over a big block without having a battery weight damn close to what I'm already running, which makes for a damn high $/# expense when trying to take additional weight off the car.
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