What is the advantage of a hollow sway bar over a solid one or is a solid one better? The hollow 34mm was the best GM had, but why is spohns solid? Or could GM not affort to put solid bars in?

 

weight is the biggest issue with the sway bars. Which is the reason GM made them hollow. A 34mm hollow is weaker then a solid 34mm. I believe that the material that spohn uses is alot lighter (chromoly) then the stock material. (possibly steel? iron?)

 

So the bigger the better and the lighter the better.

 

FYI, GM made the so-called 1LE sway bar, which was a hollow 36 mm. These came on some 89-92 Camaros and some 86-92 Firebirds in conjunction with a solid 24 mm rear. These are available at bone yards and, I believe, can still be had from GM. The front is part # is 14094344, the rear 10035033. I can provide the part numbers for the bushings (a higher durometer rubber) should you need them. I suggest, however, going with the greaseables from Top-Down Solutions or Spohn. Check my sig.

JamesC

 

Hollow bars have the advantage of being much lighter, and only being slightly weaker. If you look at the stresses and Polar Moment of Inertia of a torsional member, like a swaybar, you will see all of the loadis carried by the outer portion of the member. So the middle or inner part really does nothing but add weight!

 

FYI, Chromoly is 41XX series steel. The reason why it is lighter in some applications is due to it's higher strength compared to carbon steel (10XX series steel). For example a 1020 steel has a tensile strength of 64K lb/sq-in in normalized condition and 57.25K lb/sq-in in annealed condition. Yield strength is 50.25K lb/sq-in normalized and 42.75K lb/sq-in. By comparison a 4130 series steel has a tensile strength of 97K lb/sq-in normalized and 81.25K lb/sq-in annealed. Yield strength of 63.25K and 52.25K respectively. This allows the manufacturer to build the parts with much thinner wall section, saving weight and maintaining the same or better strength as a thicker-walled mild steel. The weight savings comes from less material being used, not from it being a lighter material. I don't have a density chart in front of me to compare the two, but it is negligible. Unlike substituting a lighter (less dense) material such as magnesium or aluminum for a heavier (denser) steel. If weight savings is an important issue and you don't mind paying the extra cost to shed a few lbs, then selecting parts made of thinner walled Chromoly is something to consider.

Lon Salgren
Top-Down Solutions