How to figure out what torsion bars I have on my car??

[chrisbruck]

Is there any easy way to tell what size torsion bars I have in my car? Where are the sizes marked? Do I have to take it all apart to really know?

My history records indicate they were upgraded to 22/28 at some point with adj Koni shocks.

Presently the car has Boge std shocks and who knows what torsion bars. Could be the PO went back to stock from the previous upgrade. May have left the TB's and only replaced the shocks.

Just trying to see what I got for sure before I order my new shocks tonight.

[will hung]

A way I can think of is to have the car weighed,

Double check your ride height,

Get an angle finder, with the car off the ground, find your rear spring plate angle,

Go to this site,
911 Spring Plate Angle Calculator

Enter the car's weight, ride height, and play with the torsion bar size until you get the spring plate angle you found. When they all match, there is your torsion bar size.

When I rebuilt the suspension on my car, I used a similar method to back calculate my car's weight. It was accurate enough that I was able to lower the car to the new ride height I wanted with heavier torsion bars.

[Steve@Rennsport]

Originally Posted by chrisbruck

Is there any easy way to tell what size torsion bars I have in my car? Where are the sizes marked? Do I have to take it all apart to really know?

Not easily. You should plan on at least partial disassembly.

Sander Engineering & Elephant bars must be measured (inboard of the splines) to know what you have. Weltmeister ones are painted white and stamped on the end.

[Tidybuoy]

Many times the bars have a number stamped in the ends - can be a 4 digit code that translates into the mm size. The rears are easy to check for this with the end cap removed. In my case, I used a camera and took a photo and then viewed on the computer zoomed in, otherwise it's very hard to see those little numbers.

For the fronts, they are also stamped on the ends but may be harder to see. It's fairly easy to jack the car up and remove the torsion bar adjusting cap and "usually" the bars can be pulled out from the rear with ease. You could do this but only pull the bars out a few inches and measure with a gauge. Unfortunately, you will have to re-measure and re-set the ride height.

Lastly, get rig of those Boges and replace with Bilsteins - I have a brand new set on the classifieds and they are for the later Boges, like your '87 Carrera

FS - Brand New Bilstein HD Strut Inserts for Later 911 w/Outer Threads at top

[LEAKYSEALS951]

I forget all the different torsion bar sizes, so I dont know if the 22/28 would be considered sport or race, but, here's my $0.02

If thats a race size bar(s), it beat him to death on the street and changed back. If he didn't change it back, it would beat you to death and you'd know it.
If thats a sport/street bar, they are still in there. If the PO paid that much money to revert to original, that's a receipt he would have kept.

I bet the later PO didn't want to spring for Koni's and just wanted new shocks.
If I remember correctly on my car, to get the original angle on the spring plate (if you use the angle estimator), you still have to disconnect the banana, or at least take out that small bolt in the back bottom corner of the spring plate cover to let the spring plate drop all the way. I could be totally wrong thoug-it's been a while.

That's my two cents and I'm stickin' to it.
Ron

[chrisbruck]

Contrary to popular opinion here, I'm not going to worry about it anymore.

It's really just a street car with a few track days thrown in here and there. New shocks alone will make me happy.

I'm not a good enough driver to notice the little handling details!..... YET!!

[Flieger]

I have 22/29 so your 22/28 would not have beaten anyone to death. Spring rate is proportional to the 4th power of the diameter so you would notice a difference between a millimeter of diameter if you drove the car back to back on the different bars. I went from 22/27 to 22/29 in an afternoon and it made the ride much more level and made the car much more willing to rotate, eliminated the mid-corner understeer (except under power).