Aftermarket torsion keys, ride question

reb0957 · November 14, 2023

I am almost positive I am going to go 295/6020.

Everything I want to do other than the tire size is improve the ride. Everything I have read, I can just slap the 295/6020 on the stock wheels and run like that. I still would like a little lift and a little rake.

All that being said, I plan to go with a 3" /2" or a 3" / 1" kit. If I don't need the maximum lift of the new torsion keys, would this allow for less tension on the torsion bars and a softer ride? Or am I completely misunderstanding how torsion bars work?

KTDanforth · November 14, 2023

If you are going to go 3" in the front, I would go with new upper control arms or you will bottom out your old arms on the stops and the increased angle will wear out your ball joints.

newdude · November 14, 2023

2 hours ago, reb0957 said:

I am almost positive I am going to go 295/6020.

Everything I want to do other than the tire size is improve the ride. Everything I have read, I can just slap the 295/6020 on the stock wheels and run like that. I still would like a little lift and a little rake.

All that being said, I plan to go with a 3" /2" or a 3" / 1" kit. If I don't need the maximum lift of the new torsion keys, would this allow for less tension on the torsion bars and a softer ride? Or am I completely misunderstanding how torsion bars work?

Ride will change regardless. Keys just re-index to allow for more adjustment front. So turning the stock keys up vs. new keys, you will get more lift out of an aftermarket key by some measure.

You will need upper arms however. If you level or max the stock keys, your stock arms will ride on the down stops and it will really ride like hot garbage. Revised aftermarket arms will allow for the proper clearance to the arm stop so it will retain its ride but get you the lift properly. At ride height, should be between 1/4-3/8" in clearance from the bottom of the arm to the top of the stop.

The 3 inch kits I see appear to have keys, shock mount extenders and diff drop spacers which are also important.

Some kits out there - 2020-2024 GM HD STAGE 1-3" leveling kit (SMX-20251) :: SuspensionMAXX

Cognito 3-Inch Standard Leveling Lift Kit for 20-24 Silverado/Sierra 2500/3500 2WD/4WD (cognitomotorsports.com)

SuspensionMAXX's kit seems the most complete for properly leveling at 3 inches.

Edited November 14, 2023 by newdude

asilverblazer · November 14, 2023

3 hours ago, reb0957 said:

If I don't need the maximum lift of the new torsion keys, would this allow for less tension on the torsion bars and a softer ride? Or am I completely misunderstanding how torsion bars work?

Its a tricky task to describe it with words that aren't ambiguous...

Adjusting the torsion bars whether by turning the adjuster bolts or swapping for new keys or and combination of the two does not change the "torsional stiffness" of the bars (see last two paragraphs). In theory this means the ride does not get stiffer or softer by doing the same. What it does change is the location of the same "torsional stiffness". The difference in ride quality is mostly due to less or no down travel in the suspension from the upper A-Arms hitting the droop stops.

Torsion keys only re-index the bars so that the adjuster bolts can rotate the bars more.

The point is that no amount of 'keys' or 'bolt cranking' will increase the spring rate of the torsion bar. Similarly, strut spacers do not increase the spring rate of a coil spring either. (Exception: you add so much that the torsion bar or spring is extended so far that it is pushing against the droop stops. In this case it would be the same as pre-loading the springs.)

The torsion bar in action is not being bent along its length, it is being twisted where one end is held fixed, the 'key' end, and the other is being turned. As the lower control arm travels in an arc it twists the bar (only a few degrees) against the fixed end.

Another fun factoid... a coil spring and torsion bar create the 'springiness' in the same fashion, by a steel rod resisting being twisted. A coil spring is in effect a torsion bar wound into a coil, as it compresses it is being twisted, just like a torsion bar.

reb0957 · November 14, 2023

For the record, I was changing the UCA's either way.

For some reason, this truck rides really rough to other 2020-2023 GMC or Chevy 2500's I have been in. Even commented on by others. My first thought was the gas engine is to light to dampen the suspension but all the PNs for my front end are correct. That shouldn't be the case.

It does appear the dealer cranked the factory keys a tad and wondered if that may be the problem. Probably...maybe?

After doing hours of reading and me being particular, I finally know what I want to do.

I thought to raise the factory keys would have been applying a tension to the torsion bar. Evidently, that is not the case. My shock decision, and air pressure in tires are going to be my only fix.

Thanks for the lesson @asilverblazer

Another JR · November 15, 2023

Sounds like maybe you need to confirm your torsion keys are at the factory intended height. Maybe you are running into the stops because someone changed the adjustment.

reb0957 · November 17, 2023

I had a local shop recommended to me. I went on a busy day a few weeks ago and he never got back to me.

Stopped in yesterday, explained to him I would never go 37's due to it being a gasser. I had kind of decided on 295/65/20 just not the tire. Also, this truck is rough.

He recommended not to lift/level the truck. Put Bilstein's on all 4 corners, realign (and straighten the damn steering wheel), and he would go over the front end for anything wonky. He recommended Toyo RT Trails. None of this will be done until after Thanksgiving. I will post pics when done.