Another cracked K-frame. Haven't seen this before.

[375instroke]

Now how does the strut rod push forward this hard?

[cdr]

When the suspension moves up & down it moves in the direction & eventually it cracks just like you have 

[375instroke]

I'm reinforcing a K-frame right now, steering box, LCA, and I was not going to weld the strut rod reinforcement, me thinking all the forces are in tension, pulling rearward, but guess I'll be welding those, too.  Unfortunately, that K-frame is for another car.

[375instroke]

Now, do I use poly, which these are, or go back to rubber?

[cdr]

Now, do I use poly, which these are, or go back to rubber?

Good question, I used the redesigned Moog rubber ones , right or wrong ? 

[AKcharger]

Now, do I use poly, which these are, or go back to rubber?

I regret using poly, squeeks like crazy and I'm not le mans racing so don't care about .0134 less body lean

[Mike DC]

                             
Another vote for rubber.

[375instroke]

Looks like the Moog Improved Design bushings have been discontinued, so they're five times the price now.  Get 'em while you still can.  Proforged makes some that they say cross to the Improved Design, not the unimproved design, but they don't look like it, and they are unavailable, too, anyways.

[HPP]

The natural arc of the strut will push and pull on that area of the K. Judging from the oxidation in that crack, its been going on for quite a while before the crack got large enough to see.  Rubber would have absorbed some of that motion, but the frame likely would have failed in that spot anyway.

The strut controls all fore/aft motion so it stabilizes the suspension under braking and acceleration while needing to be flexible enough to also move up and down. IMO, it should not be a bushing at all but rather a ball joint, but I doubt most would want that level of NVH in their car.

[Mike DC]

         

The strut controls all fore/aft motion so it stabilizes the suspension under braking and acceleration while needing to be flexible enough to also move up and down. IMO, it should not be a bushing at all but rather a ball joint, but I doubt most would want that level of NVH in their car.

I've always thought the whole LCA + strut deal should have just been a conventional lower A-arm.  The only real selling point I see for the struts is lower unsprung weight, and that cannot possibly be much of a gain in this case.  When you make the struts solid they end up needing a lot of diameter just to maintain stiffness.   Meanwhile the strut deal adds complexity and the front pivot has caused a lot of trouble.   

[Kern Dog]

The design is fine. The whole arrangement is half the weight of a GM 70-81 Camaro/Firebird.

[Mike DC]

     
I mean converting the Mopar LCA + strut into a single A-arm with no other changes.  Still keep the torsion bars & unibody.

The GM F-bodies are a different animal.  Those are basically coil-sprung full-frame cars in front.