2005 CTS-V Maggied
I'm kind of leaning the same way with the front bushing. Ideally you don't want very much resistance for the up and down rotation this joint sees. You don't want it too soft either or else you'll end up with increased wheel hop and poor wheel stability. I'd be curious to see how easy it is to deflect a 70A poly bushing with the long moment arm of this trailing arm. I'm assuming it moves fine but I'm not sure how long the bushing will last from a durability perspective since poly isn't as soft and forgiving as rubber. Typically a bushing setup of this nature isn't meant to see more than 5° of side to side deflection.I'm surprised a poly bushing in the front mounting location would work. Poly is typically used to provide more resistance to torsion than a rubber bushing provides. In that front bushing, you want the trailing arm to pivot up and down freely, so you need the bushing to allow that, but resist forward/aft motion under braking and acceleration. A spherical bearing (or one of the spherical bushings like those offered by Ballistic Fab and others) seems like the right answer IMO.
Can you re-load the pics? I'm getting the same error referred to previously.
Edit: The hollow bolt at the knuckle to allow for greasing through the bolt is a good detail.
Another thing to consider when replacing a rubber bushing with a poly bushing or cross-axis ball-joint is that it will definitely transmit more road noise into the cabin. For some this is a deal breaker, for others not an issue. Anybody that has a BMR trailing arm can comment on this as it should feel the same as what Max is offering, just have less wheel clearance.
Keeping in mind if enough of us want a cross-axis ball-joint in place of the poly bushing Max said in his original post he was willing to consider it based on interest. From a construction standpoint it shouldn't be too difficult to replace that captured bushing end on a jig with a self contained balljoint to weld on. Having a press fit balljoint insert put into the "pipe end" wouldn't be advisable due to the required material thickness needed to hold the balljoint in place. You'd want at least a 3/8" surround holding it in, preferably a cast iron link to maintain the "press fit".
I think I'd fall into the prefer a balljoint category. I'd already be degrading ride quality with a poly front bushing over stock setup and stepping up to a cross-axis ball-joint should be very similar in noise transmission to the poly bushing. I'd take the cross-axis balljoint for durability purposes at that point, only problem being that if they don't last very long, you'd have to replace the entire arm, versus replacing a removable bushing unless they were somehow rebuildable (ballistic fab weld on balljoints are rebuildable).
I think If Max offered this welded on to the front end
it would be the perfect trailing arm.
Keep up the good work Creative Steel. We appreciate the never ending options that you are developing for this platform!