Why do you only recommend 1.5”
1.5" is a general safe zone. When you account for the total amount of travel in the suspension, putting it closer to maximum "droop/extension" by 1.5" isn't detrimental. It's still 1.5" lost. But, most travel is "bump/compression" (upward travel). If you don't do any serious offroading, these factors are less critical.
How would you know if the torsion bars are worn out.
With these things, age and mileage are pretty much a guarantee of their wear. lol
It's the nature of torsion bars. Any spring, really. But, torsion bars relax a lot with age and use. Ever noticed how so many high-mileage GMT800s look lowered and all they need is a 2" spindle to look like a 4" front drop on a GMT900? My point about the sagging bars was that you might could "lift" it an inch or so just by installing some fresh springs (torsion bars) with the stock keys adjusted to their current positions rather than performing extra lifting measures to to overcome their sagging to lift it where you want it.
Generally speaking, new bars would be more firm. So, if it's currently what you could call "soft and flexy" and you don't wanna change that, then keep your bars and lift it otherwise, accordingly. Shocks play a factor in ride quality, but not ride height.
And are you saying that no matter how much you crank the keys the ride quality is degraded?
The way the suspension works on these is there's a dense foam rubber thing in the front that looks like a bump stop, mounted in the frame, directly above a pad on the top of the lower control arm. It's actually called a "jounce bumper" and it supplements the spring/suspension system. The lower control arm is supposed to lightly rest on this at ride height. When you lift it, there will then be a gap between the arm and this bumper. During up travel, the arm moves freely for the first few degrees of travel then it contacts this bumper. This is one aspect to lifting a torsion bar suspension affecting ride quality. The other is control arm angles. When the arms are flat or even upward, they can
absorb more shock/motion. The more they're angled downward, the more
resistant to shock/motion they will be, feeling stiffer. Picture them as table legs and the sprung weight (frame, body, engine, you, etc.) is the tabletop. If the table legs are bowed outward at a nearly flat angle, they won't support much weight and you can easily put that tabletop on the ground. The legs (suspension) would be soft. If the legs are straight vertical, you'd have a much more difficult time pushing that tabletop down and it'll support a lot of weight. The legs (suspension) would be very rigid. No, your control arms will never droop straight down, perpendicular to the ground. But, anything angled downward beyond flat (parallel to the ground) will be exponentially increasingly firmer. It's not linear as multiple arcs are involved, but that's beyond the scope of this example. It's not just that lifting by cranking the keys will adversely affect the ride. It's that, when it's lifted, whether it be from new springs or cranked keys or "lift" keys, the control arms will increase in angle along with the amount of lift. Being reasonable about it will minimize any effects, likely being undetected.
For the most part, it won't be an issue if you have good shocks. But, keep the full function of this suspension in mind when modding it.
