HD Torsion Bars: Independent4x.com

[VXorado]

Installed mine today with help from a friend since I had my shoulder surgery 2 weeks ago. It took us 3 hours, but we had some rust issues and the SFIFS kit makes it way more difficult for assembly. I set it up with the front about an inch lower than the rear. CVs are completely level (I installed diff drop a few years ago). Seems stiffer, but I haven't had it out and about yet. I will say that the change in height verse the adjustment nut is much more. I am also SFIFS, so I can't compare to the factory adjustment, but about 1/2 turn on the nut gets me close 3/8" in ride height change. I also noticed that I significantly bent the passenger rear lower link at some point. Like a lot....guess I will have to order the adjustable lowers from indy when tax return comes The tabs on the perches are also bent, will have to hammer them out to get the old links off. I will probably add some 1/4" plate the perches to protect them more. I also noticed that she got a good whack on the transfer case skid plate at some point, good thing I added those. Amazing how much you notice while laying under the truck for a few hours.

I wonder if the HD torsion bars will limit IFS flex because the stiffer bars won't allow the suspension to compress as much. I'm also curious how the HD torsion bars affect SFIFS... seems like the stiffer suspension would actually transfer the torsion load easier.

[Marlin]

That is a fair question and I would guess that the rate of change will be much faster, not sure if they are so much stiffer that they will limit compression or not. I do have shaved bump stops. Next I will remove the rear sway bar and install retainers for the springs. My springs have been installed upside down for 4 years, so I may have to flip them over to put any kind of retainer in there. We shall see. We have URE run in April, although I never pull the pin on any of those trails, maybe I can do some comparisons.

[Ldub]

FWIW...

The approximate change in spring rate sounds significant to me.

A full turn on the adjustment nut with stock bars = about 1/4" of lift VS
1/2 turn with the HD bars = about 3/8", which should be about 3/4" at a full turn...

By way of the limited comparative info, that sounds like close to 3 times the torsional resistance.

When linked to an equally resistant "spring", by way of the SFIFS...

[Marlin]

FWIW...

The approximate change in spring rate sounds significant to me.

A full turn on the adjustment nut with stock bars = about 1/4" of lift VS
1/2 turn with the HD bars = about 3/8", which should be about 3/4" at a full turn...

By way of the limited comparative info, that sounds like close to 3 times the torsional resistance.

When linked to an equally resistant "spring", by way of the SFIFS...

That would seem to make it more stable as well. I dunno. There is a...gulp...Jeep dealership here in my area that has a club and they have ramps they use for owners to test flex and whatnot. It may be worth a trip for me just to make them look silly as well as gather some tangible empirical data.

[Marlin]

In relation to the change in height vs the turns on the adjuster. The adjusting bolt is a 1.25.inch bolt. Thr stock one was 22 or 24 mm iirc. I don't know if we can really compare the two as far as rate of change.

[Ldub]

In relation to the change in height vs the turns on the adjuster. The adjusting bolt is a 1.25.inch bolt. Thr stock one was 22 or 24 mm iirc. I don't know if we can really compare the two as far as rate of change.

That'd depend on pitch (TPI)

[Marlin]

That'd depend on pitch (TPI)

Also true, but the way it adjusts is completely different than the factory setup. The adjusting bolt on the SFIFS is a direct connection meaning it is perpendicular to the torsion bar coupling. There are no angles involved so I think the actual distance the torsion bar is moved per thread is higher than with the OEM setup. It is also a gigantic PITA since it is adjusted with a wrench vice a socket. 1/16-1/8" of a turn at a time. A 2" body lift would help a lot
I didn't do any comparisons with the OEM bars. I know that my passenger side bar was way "looser" than the driver's side. Seemed odd to me and I cannot fathom why, but it was what it was.