Bent rear trailing arm?
 

How many of you have ever had a bent rear trailing arm (banana arm) in your 911?

Is it something that happens often? Easily? And what could cause it?

I ask because when I recently went to get my 911 lowered, aligned and corner-balanced, the tech told me that he couldn't get the left rear toe correct and concluded that my trailing arm was likely bent.

However, when I got a used one he still had problems getting the toe correct (said he had to use max. adjustment). Because it's unlikely that both arms were bent, he now thinks I may have a bent torsion bar!

Steel arms can bend a little without being apparent to the eye. You need a jig to test. Aluminum ones are more brittle and will crack more visibly after much less deformation.

A "bent torsion bar" will not affect alignment. It is held captive by the torsion tube and the outer spring plate bushings.

A bent spring plate would make it hard to align, as would a bent chassis. The spring plate is designed as a spring in certain axes and to be rigid up and down. This means it can take a lot of strain elastically so it would be visible if it were bent so far as to be plastically deformed.

I just went through a bent trailing arm, aluminum one even, it was over 3 degrees off.

Supposedly that's impossible, so I'd guess that makes it pretty rare.

Don't think a bent torsion bar would be very doable, but have heard of the torsion tube itself where the bar connects in getting bent in rare cases.

Good luck, I understand the frustration very well.

I bent the crap out of a banana arm when I went four wheel drifting and my right rear whacked a curb. And here is when the fun started as I found one through the classifieds, dropped the motor 6 inches, removed arm, replaced wheel bearings, added monoballs and new axle, installed new/used banana arm, attached almost everything except the shock and realized that I bought one from a different year. Had to take it all off, buy another one, yada........
Moral of the story, make sure you buy the right one and put them side by side before you install.

My 89 supposedly had a bent arm also. The place that did my ppi said it was probably bent because according the alignment print out it seemed within spec except for that corner. The PO had tried to get it aligned but the shop blamed the arm. This worked to my advantage, luckily it helped negotiate the price down. @ $1200, they aren't cheap. I mentioned this finding in the PPI to my mechanic, he said to bring it down that it was most probably adjusted wrong. Well when I got it down here I took it to him, (40 years working on Porsche cars) he put it on his rack and noticed that car was aligned wrong and set it to spec. Its now corner balanced, lowered and best of all straight. Before I found my mechanic I had the dealer align my 86 and it ended up driving worse than before! My car looked to be older than the tech.

You may want to ask around as to a good 80's Porsche alignment shop and get a second opinion. Some shops are great with engines and transmissions but don't have an alignment tech with alot of 911 experience.

Your body may be tweeked, any accidents or curb bump like the guy above?

Good luck