I hit a 4x4 in the road a few years ago, hard enough to bend my wheels. Since then I've had more negative camber on the drivers side. I think my trailing arm is bent. Is there anyway to measure? I'm in the process of going 5 lug, so think I might just replace it.

Its really hard to measure on the vehicle, although you might find a bulged or puckered area on the box section somewhere if the damage is significant.
If the car sits on a very flat (not necessarily level) surface it may be possible to take the required measurements and determine the amount of negative camber inherent in the trailing arm. -1.5 degrees is correct.
That is to say, with the pivot shaft level and at the exact height of the stub axle centerline, the negative camber should be 1.5 deg.

Yeah what Chris said. I think it would be really hard to bend the trailing arm. It seems to me that the suspension ear would move first. If it just camber just reshim it.

Its actually not that hard to bend one enough to be noticeable when aligning the car.

Porsche had a jig that you put them in to test. They had a jig for the front control arm and the steering rack also. Most dealerships and independent shops had one back in the day. Now they are scarce.

I have both arms off as I am replacing the bushing, bearings, etc. I don't see any noticeable damage, but I would think a few mm would make a difference.

I bent one on my 911...

Try having someone follow you and see if the car is pulling the rear sideways... Like a crab on the beach.

When I bent the 911 arm, the car immediately pulled and I had to clock the steering wheel 1/4 turn to keep it straight...

There's a picture with measurements in the Haynes manual. I think it shows the arm held in a vise, and gives a couple of measurements for lines that are supposed to be parallel.

--DD

You can put two 3' rods through the 2 holes. They must be straight. They must be shimmed perfectly or fit perfectly. You can sight along them and see if they're parallel and then measure the distances between the ends.

IIRC, that spec shown in Haynes is for the outer bracket alignment.
It only applies to stock suspensons with rubber bushings, and has nothing to do with the trailing arm shape.

I have seen a factory drawing of the 914 rear trailing arms with all the correct measurements.

Of course now i can't find it ...

12.5 deg toe, -1.5 deg camber.

I've sourced a couple of good arms, just to be sure. I'm ready to press in bushings and bearings.

Thanks