GM Gurus: Any way to look up torsion bar spring rates?

Herbie

Adventurist
#1
If memory serves, there are a couple of folks here who have deep background on all things General Motors, so hoping someone can point me in the right direction on this:

Is there any way to look up the specs (particularly the spring rate) for the torsion bars in the front suspension on GM IFS vehicles?

I've had good success by mining the General's parts bin for upgrades to our 2003 Astro AWD (now 4x4, thanks to this practice). One of the weak spots on the van is that we still have the factory torsion springs in the front. I am not looking to re-index the existing bars - my preload is more or less where I want it, but I would like to have a slightly stiffer spring rate. (I've been very cautious about front-end weight with the existing springs - I'd like to have the option of a beefier bumper, etc.) I have a hope that I might be able to find a similar part from an Express, Colorado, etc. that has a higher rate but might be made to fit. (Length and end-shape become the next obvious variables to worry about.)

Just to head off any helpful alternative suggestions: No way to fit a coilover without control arm interference, not interested in pursuing SAS for this project at this time.

Thanks all!
 
#4
Digging into the memory banks from my S10 days....
The end of the t-bar has a number on it that translates to spring rate. There were at least three different variations with a GM part number in the S10s but I don't recall the specifics of numbers. The three different tbars were interchangeable in application.
That's all that comes t mind at this point but maybe there's enough in there to send you in the right direction.
Advance Auto Parts carries t-bars from Dorman. May be other options out there. Not sure how much of a factor age on those things will be.
 

Herbie

Adventurist
#5
That's a help, everyone. Even knowing there may be different rates lets me start digging into part#s to look for deviations. (I'm going to guess that thicker bars were used with heavier powertrain packages, etc.)

Thanks!

EDIT: Have reached out to SwayAway. We'll see if they get back to me, I give it 50/50 odds. They do make bars for several GMs, but all are longer than the parts on my van. (That by itself is useful info as it lets me cast a narrower net when looking for parts-bin options.)

EDIT2: Holy carp, they got back to me within hours! I need to source them a set of OEM bars to make engineering drawings from, but they're amenable to making me a stiffer set. Thanks Bob!
 
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