snapped hollow sway bars

You animal!

(They are aftermarket. There was never any durabilaty testing done to them)

...Until Now! Well Done!!...

Yes,
And it was on the front next to the washer that had been welded on the Bar. Mine to were Hall units. They are in the trash can now!
Replaced mine with 1" bars from Pantera Performance in Colorado.
The Bar's from the Vendors in Ca & Nevada "which I ordered and sent back" were of Poor quality with ameture gubber welds.

Mark

quote:

And it was on the front next to the washer that had been welded on the Bar.

Not that rare if yours was at the washer like Mark's.

Buy Quella's 1" solid, you won't have to change any mounts or the sphere balls, and if you break the new ones.....

Larry

Korina:

The reply from Hall is interesting because I understand hollow bars breaking at the washer is a widely known and common problem. I believe it was Tom Upton from Texas who very nearly put his Pantera into the wall at a race track when his Hall 1" hollow bar snapped. Dennis Quella told me he knows of 7 or 8 people who have had their hollow bars break.

BTW, Jack DeRyke, Mike Drew and Larry Stock tested sway bars on a flat skid pad in Mt View CA back in 1993. They used a Larry's black stock-bodied '72L, fitted with aftermarket 8-inch front, 10-inch rear wheels, 225/50 and 285/50 Pirelli P7 tires (the resultant article was published in the Aug '93 PCNC newsletter). They found that any solid sway bar thickness over 7/8" caused excessive rear sub frame flexing and actually reduced cornering power (the 7/8" rear bar is what was included from the factory on Euro GTS & Gr 3 Panteras and is known as the 'GTS' bar). However, a chassis stiffening kit and/or body seam welding may allow for a larger diameter bar to be fitted, and modern rubber may change things too. The bottom line is that someone needs to reproduce the DeRyke/Stock/Drew test to account for all these variables.

Before rushing out to buy a 1" solid bar, you may want to read an interview that Dave Adler did with Dick Guldstrand in the Spring 2000 edition of PI Magazine, the relevant excerpt from which is as follows:

DA: I read an article once where I think there was a test at Willow Springs with I forgot what kind of car that Guldstrand Engineering prepared and then some other person prepared a car and I think your car was set up, with your settings in a “shoot-out”. Do you still favor setting up a car soft or hard?

DG: Not really. The only thing I really favor is not putting great big sway bars on them because that really…any car that requires a lot of roll couple like a Pantera or a Corvette, something that’s got a lot of power and potential, you can’t overcome, you can’t overwhelm that roll couple with a roll bar because then you’ve tied all of the wheels together and you make it very unstable in braking and cornering. You load the outside tires too severely so the balance has got to be about 60% to 65% of the roll couple in the springs, shocks and bushings etc., and the last 35% or 40% in the sway bars. That’s the big argument I’ve had with so many people for so many years is that they tend to make them way too soft and put huge sway bars on them, which is in my humble opinion, a disaster. Of course we’ve done many magazine articles and shoot-outs and so on where we’ve won them all. There again, you can’t fool mother nature. If it works, it works, whether it be NASCAR or road racing or formula one, there are some basics you have to live with because it is way too easy for folks to sell great big sway bars.

Also of interest on this topic is Jack DeRyke’s article in the March 2006 POCA Newsletter on bushings in which he wrote:

"If the bar is mounted in rubber, such bushings will slightly deflect before loading up and finally twisting the bar, so the stiffness of an anti-sway bar is lessened for a given diameter when mounted in rubber. Or, to put it another way, adding polyurethane bushings to your Pantera will upgrade a given bar’s effectiveness nearly as much as going up one bar size (0.750” dia to 0.875” dia)."

Hope this helps.

- Peter

Pat Mical came to stay at my house a few years ago. He noticed that my car had poly sway bar bushes front and rear. He said poly bushes are not suitable for the front, they do not have enough compliance. He advised me to change them back to rubber. I kept them in there anyway. 2 years later one of the steel brackets that attaches the sway bar to the front chassis snapped. I have now gone back to rubber on the front. No further problems..

Johnny

quote:

2 years later one of the steel brackets that attaches the sway bar to the front chassis snapped.

If you still had the stock factory front flat-strap brackets, the problem wasn't because of the poly bushings.

I have seen at least two cars still with the stock rubber bushings, with those straps broken.

This too is a common problem.

I've never seen a broken billet bracket, though. And you can use them with stock or poly bushings.

Larry

Forgive my ignorance - but is a sway bar what we brits call an Anti-Roll Bar?

Phil

Yes Phil, it is.

I learnt most of the american english names for bits of cars, at least all the common ones.

The one that confused me, long ago, was the rocker panels. I expected to find those on top of the engine

Didn't Corey Gelman(?)in Wisconsin advocate using no front sway/antiroll bar? We had a guy here that went without and he felt the car handled much smoother and quicker.

Hum, interesting. I must point out that the straps have not been a problem for me. It is the factory mounting studs.

I have broken both sides in the front and the left rear.

I have the stock front bar, a factory rear GTS bar, poly bushings and aluminum billet caps in the rea, straps in the front.

I agree that there is no point in going over these sizes.

You need to reduce the roll with stiffer springs. The trick is how much stiffer. My answer to that is don't ask me, I don't know.
There is too much re-engineering of the car involved for that.

You can't make a race horse out of plow horse...but maybe a Zebra, or a Jackass?

Hello Guys,
A closer exam of the broken bar shows that it is broken at the weld where the washer is. I've already had a new one sent but I will take a good look at the new one to see if it's an amateur job on the welding. I'll try to change the bar this weekend if the new one comes in by then and I will look frequently to see if the new bar has issues. It's annoying that the guys who made or sold the bar say I'm the first to have this problem if there's a lot of other guys who have had the same problem. The truth is I really don't hammer the crap out of the car either. No slicks and no auto-x which I always thought was harder on the car's structure than track events. I just ordered a set of the new BRG R-1's. I couldn't get a 335's for the rear but 315's are available. I'll see what breaks now. Thanks everyone as always, you guys are great.

There are too schools of thought when it comes to shock springs and sways.Probably more I don't know about. I fully agree with PanteraDoug.

One go stiffer with the springs and smaller on the sways or softer springs and compensate with bigger sways.The softer springs will place a great load on the sways. One of the reasons your breaking at the washer.

Theirs already alot of preload on the sways to start with. You'll see how hard it is to clamp down the front sways when you go to install the new ones

The BFG R1's are a DOT R rated tire. Super sticky. The car now is going to have more adhension at greater limits.Especially with the sizes your talking about. Which in return is going to place even more load on the sways. Your problem has now increased. Your defintely going to break more than that washer on the front sway bar.

For what its worth I'd go stiffer on the shock springs and help take the load off the sways. Again especially with the type of tires and sizing you've choosen.

Just my 2 cents. For what its worth.

P.S I learned this through experience. It took all of one event with my 911SC track car with sticky Toyo RA-1's.

Dan

Korina:

According to Jack DeRyke, the problem with the hollow "sway" or "anti-roll" bars is not the quality of the welding at the washers, but rather the fact that the manufacturers do not anneal the welded area. This is what he wrote to me on the subject a while back:

"I'd avoid any hollow swaybars that have welded limit-washers anywhere on the bar since no one takes the time & money to heat-treat the welded hollow bars, which crack at the washer-welds."

Also, with regard to the pre-load on the sway bars, John Taphorn has advised as follows:

"...the bar should not have any load when the car is sitting on it's wheels. If it does, it should be shimmed under the bracket on the low side. Otherwise, you alter the cornerweighting and handling."

That's great advice on shimmimg the bars. I should have remeber that from the olden days. I've broken stuff on other cars before but what I was suprised about here was that I really didn't think I was working the car that hard. As far as the corner weighing,I was always concerned by the fact I didn't think any of our cars we're really square. Any one have any thoughts on that?