Can you clarify why you mean by "'body' rotation?"

Because in addition to looking way too far in on that side, when the car is lifted in the air there is absolutely no left-right movement of the axle possible by grasping the axle with a hand pulling left and right. It should be capable of sliding a little in an out...like 2cm. The right side works fine to do that.

Please clarify, too arcane.

How much was it bent and could you see it with the naked eye while still on the car?

I have not checked the torsion bar or the mounts. I understood that if the torsion bar is broken the back of the car will be collapsed on the ground. Is that not true? Why would a torsion bar break cause only one wheel to shift inward and stay there perfectly parallel?

I have an extra torsion bar in good shape. I hope it's that but I was dissuaded that it could be that.

What do I check in the torsion bar mounts that could be causing the inward shift of the wheel position?

>"Measurements are in the shop manuals."

Which shop manuals? I don't have any. Are they available online for download? Otherwise, can you take a picture of the measurements page and post it?

When you bend a metal bar you can either produce a small strain along its complete length and the strain will be evenly distributed or you can produce a local deformation which causes the body of the bar to rotate but the majority of the structure would be unstrained.

These result could be that the displacement of the ends could be the same in both cases.

I have not seen bent torsion bar mounts - they are generally quite strong.

You really need to start to dismantle the car a little otherwise it is unlikely you will reach a conclusion..

The angular change you need to make to close up the drive axle is quite small and it does sound as if you have enough deformation to have taken up the plunge in the CV Joints.

I would start by taking off the Spring Plate and looking at the position of the bar in the tube and then look to see if the flange that locates the inner bush has not corroded as the defect you are describing does sound as if there could be some issue in this area.

Here you go, Maestro.
All pages from the factory manual, dated 1980.

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TA monoballs have no ability to flex & give some under impact where the rubber could allow for the TA to move in the mount some. monoballs are desired for their ability to keep suspension geometry set under load where the rubber mounting will distort and allow setting to wander.

Not sure where you are getting your info from? Most alloys I have seen used by Porsche appear to be based off of a variation of 356.0T6. The info I provided was based around this. No doubt determining the actual alloy and using the appropriate temperature is required. If it were 6061 no doubt a temperature like 760 F for 2-3 hours with proper cool down to 500 degrees would be used but clearly these are sand castings. temperatures above 775 are when oxidation and grain growth occur. I highly doubt a non heat treatable alloy like 319 would be used. It would not handle the loads these parts have to endure. I must assume Porsche had set forth some minimum quality standards and porosity would not be a factor. Making a decent porosity free aluminum sand casting is not that difficult besides hydrogen porosity is not a casting issue but stems from excessive soaking periods also known as High temperature oxidation. Hydrogen entering the casting during the solution cycle has been known to cause surface blisters and subsurface patterns or pores. If all controls and parameters are in place this is a nonissue.

Since an alloy like 356 is aged after solution at temperatures of 300-320 F for 1-6 hours a temperature above this and below 775 would relax the bonds. Either annealing or solution treating the parts will remove any cold work present in the material.

Annealing is the best way to bring the alloy to its lowest strength and best formability however they will require solution treatment, quench and age to develop their desired properties once the straightening is accomplished. Essentially once annealed and straightened you are starting over as if it was in F or as cast state. Most times when straightening a sand casting out of an alloy like 356 it is done after the solution and quench and prior to the artificial age if it cannot be done shortly after the casting pour. If it cannot be done soon after the quench the castings is frozen to prevent the onset of the natural aging cycle.

As far as damaged torsion tubes and or failed spring plate covers or stripped splines on torsion bars and end covers I have seen all of the above. We are currently fixing a 69 with these issues.


It is a long shot but you might find some damage to the spline end of the torsion tube on the one side.

If I did find such spline damage on the end of the torsion tube isn't that the mother of all PITA jobs to replace the whole tube, or if so are you implying there is an easier remedy given you wrote "it is a long shot?" Perhaps you were just saying long shot as in small chance.

Thank you very much!! You photo-scanned those yourself or they are available online?

It isn't a common problem but I have seen it happen. It can be repaired but takes work. We are currently repairing an older 911 which had this problem but it requires the equipment and proper measuring tools to do the work. This entire tub is a repair and replace but it is a 911 S. When we are done you won't be able to tell anything was done to this car. Until you start taking measurements and inspecting the components it is all speculation. It could actually be in spec. I have seen cars that have had considerable variations come from the factory. What is concerning is the odd droop you mentioned.

This will be a huge undertaking. http://forums.pelicanparts.com/uploa...1487965230.JPG

When I was still involved with my shop, Red Line Service in Santa Monica, we worked with an incredible body shop in the area called Brace's Auto Body. They had access to frame machines, could do chassis pulls, etc. Brace taught me how to recognize a twisted body, usually from a poorly repaired collision. If you open your engine compartment and look down at the rubber seal along the left and right sides the seal distance should be approximately the same. The part of the chassis just outboard of the seal is called a frame rail, one per side of course. If the car has been hit in the rear, and a frame rail is 'pooched,' you might actually be able to see the ground under the car. If you can, or if the seal is barely touching on one side, you have a bent car, not bent suspension.

FWIW; while performing many, many PPIs I found poorly repaired accident damage on a surprisingly large number of cars, most had been hit in the rear and had a pooched frame rail. My friend Brace was kind enough to write an estimate for a re-repair on some of those cars, but sellers rarely adjusted their selling price, or took their car to Brace's for proper repair!

Interesting topic. My car had been hit in the driver rear during prior ownership. I knew there were issues because I would install new swing arm bushings and within months, it was compressed at the bottom as though it had been on the car for a decade. I repeated the process of changing the bushing more than once.

Finally, I kept taking degree measurements of the driver wheel from vertical while on jackstands, it appeared that the driver wheel had positive camber - bottom in, top out. I ended up swapping out the trailing arm with a known good arm. Bottom line, with no other changes - including the car was never removed from jack stands - than the known good arm, there was a two degree change in camber between the old trailing arm and the new one.

The issues with the bushing basically disappeared. It could have been other issues, including tub issues, in my case things looked clean

octanemaestro,

If the car droops, the spline on that side is likely just off by a few degrees. I doubt there was damage. read below:

My '86 as I said was hit in the driver's rear wheel hard enough to really bend the trailing arm (2") it didn't crack at all it bent.

Didn't bend the Fuchs though btw..

Anyway, this impact (stopping a car) did not bend the trailing arm mount but after I replaced the trailing arm it handles like hell until I got the alignment right.

I completely repainted this car so this impact (not my fault) was really upsetting to me at the time. The 18 year old pizza delivery boy immediately tried blaming me..

I fixed it good as new without cutting off the rear quarter, it took so much time with hammers and dollys though. IIRC 40 hours going back and forth checking the compound curves of the good side..

No frame damage as the wheel took the brunt. No spline damage at all I checked. Tough little cars. The wheel was hit dead on.

http://forums.pelicanparts.com/uploa...1487989977.jpg
you can see the wheel is pushed in about 2" in this shot. See mark on Fuchs, buffed out and was fine, I didn't even have to balance it.
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http://forums.pelicanparts.com/uploa...1487990055.jpg

After fixing it, not too long after I was rear ended by a texter at a red light and the car was totaled, miss this car soo much. Loved every min of ownership for 13 years.

Sounds quite similar...I hope I am as fortunate as you were with the pizza delivery kid who smashed into your 911 wheel. It's hard for me to see in your left rear wheel picture that the wheel is 2" pushed in. Maybe you have another picture? Or a picture of the undercarriage post-impact?

About your second incident with the WhatsApp-SMS text-email-WAZE user rear ending your rear end when you were at the stop light....I notice you had aftermarket brake lights which are smaller than factory. Do you think that could have made your stop state less visible to other drivers, particularly distracted ones?

The extreme of what I am implying would be those "very cool" (not) Dodge Ram brake light trace patterns that decrease the amount of brake light visible but look so cool (not) to get right up to it and see the symbol of a ram's head instead of....wait for it....just a "brake light." Or perhaps even the most extreme would be replacing a motorcycle brake light with a hardly visible tiny dot of an LED because motorcycles don't get hit a lot and aren't dangerous or very hard for other drivers to see already, particularly at night, when at a stop light. There are those that think bicycle riders should remove their reflectors and wear all black...a little off topic, but there's something that seems a little death wishy about all those scenarios.

I don't think those extremes really relate to your scenario but I am curious what you think.

The rear lights I made were custom and very bright, also my '86 had a third brake light which i was sure always worked. No excuse for texting while driving. Our cars are just so low and small, my car's dark color didn't help either. I used to notice in the '90s just how many old ORANGE VWs from the 70s had survived..maybe color had something to do with it.

Anyway, what likely happened with your car is a similar accident to mine in which the trailing arm and spring plate were removed and replaced.

You have to disassemble the trailing arm/radius arm on both side of your car to reset both spring plates (or radius arms) at the same unloaded angle.

Nice side note is you can lower your car for a more aggressive stance too:) Then you'll need the rear suspension aligned of course.