Roll Center Height for Triangulated 4-Link Solid Axle Rear Suspension

How do I calculate and visualize the roll center height for a triangulated 4-link solid axle rear suspension, as typically found in 60s and 70s-era GM cars?

I think a solid rear axle has the roll center in the center of the axle since there is no independent motion. Google agreed with me.

https://www.google.com/search?q=solid+rear+axle+roll+center&oq=solid+rear+axle+roll+center&gs_lcrp=EgZjaHJvbWUyCQgAEEUYORirAjIGCAEQRRg80gEINDMwOGowajeoAgiwAgHxBVnfDgQHBvzB8QVZ3w4EBwb8wQ&ie=UTF-8

Google is on crack and that's absolutely incorrect

On a solid rear axle that's located laterally using a Watt's link, the rear roll center height is wherever the propeller pivot point is bolted to. This can be the axle or the chassis, and at virtually any height.

On a solid rear axle that's located with a panhard bar, the rear roll center height is the height at which the panhard bar is attached to the axle. Again, this can be virtually any height depending on the bracket, and can be adjustable.

But those are parallel 3- and 4-link setups. I'm trying to understand how the roll center height is measured on a triangulated 4-link setup, which locates the axle laterally by angling either the upper or lower links toward each other.

In the case of a GM 60s and 70s era car, typically the upper links are angled inward at the axle and outward at the chassis.

Did you actually check the link provided by David? There were multiple guides for answering your question.

Your second paragraph is incorrect, with a Panhard bar the nominal roll centre is the centre of the bar, but in practice, because of the jacking affect, it can vary in height between the left and right sides as it has two pivot points- this is actually a useful tuning aid for "oval" type tracks.

LOL! Why would I click on a link that someone describes as full of crap? 🤣 Of course I hadn't clicked on it.

I did end up finding a relevant diagram that explains where the roll center height is located for my application within that search result.

I would've appreciated an actual discussion about it to complement the info on the HP Academy module rather than a link to a generic search result, especially since this forum thread is the very first search result at that link and that seems to imply that having the info here would be beneficial to the Internet at large. But I guess I got the bare minimum I asked for, so thank you.

I also find it disappointing that the ONLY diagram about this topic I can find on the Internet is figure 17.36 from the book Race Car Vehicle Dynamics, with zero discussion about it or the ways to tune it. This is literally one of the most common solid rear axle suspension designs in production cars, and nobody talks about it 🤷‍♂️ I guess I'll buy that $100 book...