ShopTalk Forums | Aircooled VW Tech & Restoration Help

I need to know if it's possible to cut 2 in. out of a stock sway bar so that it will fit on a 2 in. narrowed beam. Thanx in advance.

www.airspeedparts.com sells them.

So does http://www.aircooled.net. I plan on purchasing a narrowed one after I finish paying for the parts that I got from CB.

http://www.aircooled.net/new-bin/viewpr ... 02&cartid=

Welding sway bars is incredibly dangerous. If you have ever had an outer link snap in a sweeping curve at high speed....you will quickly realize that its a very fast way to roll the car...if the weld eventually breaks...which it always will.

Marc had the right idea. If you must cut it, you should use at least a tube or bar stock block as a mechanical center clamp. Then spot weld just for insurance. Any heavy application of heat destroys the spring. Also...if you narrow it....it totally changes the spring rate. The spring rate is based on diameter, and total spring mass....or length....as well as leverage generated on the body of the rod, by the length of the "L" portions at the end . If you are only narrowing a couple inches...and the ends of the sway bar do not interfere with the wheels or turning, I would suggest simply fabbing a different pair of outere links for the "L" arms...that reach inward to clamp onto the suspension arms. This way (a) the outer links will most probably be adjustable for fine tuning.....ie: moving them closer to the horizontal rod decreases leverage exerted on it by the suspension arms...and makes the bar stiffer...and moving it farther out toward the tips of the L-arms makes it softer by exerting more leverage...very desirable (b) you preserve the correct and total amount of factory spring force. Shortening the bar reduces the amount of available spring force. Ray

Ray, I think you should pass this info onto John at Aircooled.net. This would probably be good info for development or something.

raygreenwood wrote:Welding sway bars is incredibly dangerous...

Realistically, if your bug's front swaybar suddenly ceases to function the car will transition towards oversteer. Not fun but usually easier to control than a chassis that suddenly goes into understeer because a front shock absorber or ball joint bottoms out due to excessive lowering - how many "slammed" cars are there running around at risk of this these days?

On a suspension that uses the swaybar as a locating link (like many MacPherson strut cars, including SuperBeetles) don't even think about welding the bar, the consequences of it breaking could be dire.

raygreenwood wrote:
Welding sway bars is incredibly dangerous.

if the weld eventually breaks...which it always will.

Ray

I agree that welding a sway bar "can" be dangerous. But, it can be done correctlly and safely. It just requires a little thought, information concerning materials, a qualified welder and weld process.

Why would you say that the weld always will break? Are we to assume that all welds will always break? I disagree.

Ray,
I am in NO way trying to flame you or your post. I just wanted to state my opinion on this matter.

Cool...but realize you are not welding just a steel bar. you are welding spring steel. The grain structure is in constant movement as compared to just plain mild steel. These parts are tempered. You have this same problem welding any spring. Regardless of what it does to the spring tempering....the weld will never be the same as the steel it is attached to. Its not an issue of wether weld is strong. Most correctly done welds will be stronger than teh metal. But the attachment point of a welded sway bar will constantly be stretched. The entire surface of spring steel distorts in order for it to work. The weld will sooner or later break. That is why you use a mechanical clamp type attachment.

This is also one of the reasons why the outer ends on centerlinks is crimped on insetad of welding. Take a look at any of those. Those may not have spring tempering, but they have the same issue. They are stressed. The flexing is a huge risk.

What Marc noted...is what I was really refering to. Yes...on some cars...a broken sway bar is less of a risk...but on a strut type suspension...or on rear full trailing wisshbone suspnsion, the sudden unloading of a broken link or sway bar can be deadly to the quick body roll it will induce. Ray

Why Beast: We already sell adjustable swaybars!

John
Aircooled.Net Inc.

raygreenwood wrote: Shortening the bar reduces the amount of available spring force. Ray

I think that's backwards. For torsion springs the spring rate is inversely proportional to length. The longer the twisting portion, the lesser the force per degree of displacement.

I wasn't sure if they were a completely new bar altogether. My bad.

VW_Voodoo wrote:Why would you say that the weld always will break? Are we to assume that all welds will always break? I disagree.

To make any spring you have to start with the proper alloy of hi carbon steel. Once they are shaped they must be heat treated. The process involves heating it until its glowing red hot then quenching it in oil. This rapid controlled rate of cooling re-orients the crystals making it extremely hard, and brittle. To give it the flexability required by a spring, you now have to temper it. To do this you have to heat it slowly to the proper temp (~600ºF), then let it cool slowly.
If you weld it, you are heating it to a temp higher than the initial heat treating temp, destroying the tempering that was done in that small area. And at the same time, when you take away the heat source, the surrounding metal cools the weld at a rate fast enough to alter the grain structure and make it extremely brittle again right at the weld. Now when you put it on your car and start to twist it around, since the weld area is brittle, it will break eventually.

R2.0...nope I have it right. The more mass the bar has the more available load and twisting force, but.... "apparent" torque or twist is what you are referring to. For example, Shorter ARM length will decrease the amount of leverage available to twist the body of the bar....so it will decrease the response rate...but not the actual load capacity.

Having a shorter length body on the bar simply gives it less to twist. The arm ...or lever length is still the same...so why would axial torque on the body of the bar change? You simply have less mass of spring and the same amount of load. Ray

I can't follow Ray's explanation, he loses me whenever he starts using terms like "apparent"...
But R2.0 is correct, torsion bar rate is directly proportional to diameter and inversely proportional to length. Same thing holds true for helical, commonly and innacurately called "coil" springs, which are nothing but torsion bars wrapped in a helix...when you shorten a "coil" spring or a torsion bar it does get stiffer.