Building my first class 11 car and have been trying to find out which rear torsion bar I should use. I went to the sway-away web site and noticed they have three different lengths, some that are hollow!!!! and several different diameters. I'am building a 1970 with the stock gas tank and no tank in the rear. I'am running the new 18\" fox shocks per the new SCORE rules. since class 11 must run a stock width rear torsion tube which length torsion bar fits? what is the advantage/ disadvantage to the hollow torsion bar? what diameter bar are most racers running? Thank you for any information I can get---trying not to make to many expensive mistakes on my first build. This site has been a great help. Thanks agin.

We run 28 intermediates with intermediate springplates. Our car is a little heavier than others tho. I know people run 27's if the car is lighter.

We ran the 29mm longs but our car was too stiff, but it resisted bottoming pretty well. I'm going with 27mm longs this time around, no rear fuel cell but a tire back there for sure. There will also be a jockey crew inside so take that into account.

We ran 28MM diameter bars with a 26 9/16\" length.

Anywhere in the range mentioned above should be fine. The longer the bar, the less torsion load absorbed by the bar as it has to twist less and less. With an adjuster in the rear, you can put enough preload on any of those bars to get the rear to resist quite a hit. The problem however, its difficult to control the rebound. You'll want to revalve the shocks once you get the bars set.

You'll end up wanting as much rebound valving as your shock will handle with a stock reservoir. Some people have exotic reservoirs that keep the oil cool and run up to 4 times the stock rebound to make the car handle better.

Stiffer bars don't need as much preload to achieve the proper ride height either. A stiffer bar will ramp up quicker but will unload to a point with the same authority. Basically you want to run a spring that will keep you off the ground but won't make the back of the car hop off of whoops and kick up.

Thanks for the information it all helps! When you set up the preload on the rear torsion bars do you have any droop at all with the car's weight on the rear suspension? If not I can see why you want all the rebound you can get out of the shocks. When preloading the torsion bars is there a degree angle on the spring plate thats a good starting point----I'am not using an adjuster in the rear so I would like to start somewhere close so I don't have to take it apart to many times!

I did 24 degrees of preload on my 1600 car. Obviously this is a different animal, but I'd say it'd be somewhere between 10-20 degrees. Mike or Dave can give you a for sure measurement.

Depending on the size of the bar you're probably going to end up something near 8-16. More preload with smaller bars and less preload with bigger bars. And yes, under the weight of the car you should have some sag, this is how some measure to get it just right. If it's a street car/prerunner stay on the lesser end of these figures. Preloading will eventually break the bottom of you stops also, you'll need some super stops eventually.....Dave, now is a good time to chime in on that....

After draggin azzz at BAP with stock rear torsion bars. I need a set of SAW's.

26 9/16" 27's a good choice? Or??
28's?

Stay aways (sway away)are the worce bars made,JUNK!! TCS-the converter shop bars are the best going I wont recommend sizes because of expence and differences from car to car , but will say the stock IRS length is good for swing or IRS.