When would it be necessary upgrade or replace a torsion bars. I go out offroading very often. Running 32 in tires also

 

I have almost 300k miles on my stock tbars on the Blazer and 260k miles on the 2500hd. I have never heard of tbars "wearing out", but the rear springs will commonly sag after a few years and mileage. If they ain't broke I say leave them alone.

 

fair enough thanks. Yes the rear end has a 5 stack of new leafs now

 

There info on the torsion bars on here and Google, there different "thicknesses". Maybe look into it and see if a set of zr2 torsion bars would work better.

 

There were 5 or 6 different spring rate bars commonly offered on the S-series trucks. The higher spring rate bars were much less common on the non-ZR2s, so if you find that your front t-bars are not as stiff as you'd like, then a stiffer set from a ZR2 would be a good choice. In my experience the 30.69mm bars (2nd stiffest) were the most common in the ZR2 Blazers, while the pickups came with either those or the stiffest bars. I have the 2nd stiffest bars in my Crew Cab, and I think it rides much nicer and more truck like than the softer premium smooth ride t-bars that came OEM.

To find some donor t-bars, the bars have the last 3 digits of the part number stamped into the front end of the bar, or you could measure the diameter with a caliper. Here's a list of the possible t-bars: