Hello All,

Just inspecting the car after 5 hours of track time beating on it hard at Summit Point Shenadoah. The carousel sure is fun but hammers the car pretty good. I never noticed this buckling before however there is surface rust where the paint is cracked. Maybe this last track weekend made it worse. Can chassis flex cause this to happen? How worried should I be? Thanks for the help. For reference, car is fully caged but not tied into front shock towers. Click to view attachment

Race rubber without the factory chassis stiffening kit.

I have all sorts of chassis stiffening in the rear. What is available for front?

good point modern tyres will do that,chuck in a bit more extra HP,large swaybars,a good driver and some early 911's to dice with you have the perfect recipe .
These cars are not stiff even when not rusty,my 6 conversion flexs like a bugger and it is noticeable on rough roads,when I'am legal and certified on the road with mine I will have the welder out .

Add a couple more photos of the trunk. Wheelhouses right side of the bulk head etc. The torsion bar mounts below the kink on the curve. I need to see a little more.

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I'm a bit suspicious that it is right above the rear end of the torsion tube.
It looks like a compression fold.

Do you recall bottoming out on something?
Bump that hit the rear end of the a-arm at the mount or a pothole maybe?

Is that a tear at the bottom of the semicircle reinforcement? If so, I would imagine that would not help the strength of the whole area.

--DD

Great observation Sir Andy. I agree with a vertical compression load causing the buckling. I think it happened diving into carousel at Shenandoah where the car momentarily gets airborne transitioning into the banked concrete bowl under braking. It lands hard and chirps the tire back to spinning on the left front. That severe fore/aft loading would create vertical reaction force at rear a-arm mount. With two drivers that area got hit over 50 times during the weekend.

So now what to do about it? The vertical deformation doesn't appear too bad. Can I weld in a doubler plate for now? Then at end of season extend cage to strut tower and triangulate forward of the bulkhead. Or does the area have to be pulled out first due to adverse effect on suspension geometry?

Good eyes Dave. I checked closely and it appears to just be sloppy POR-15.

I'm pretty sure the geometry has already been compromised. The good news is from the looks of it it should be pretty straight forward (downward?) to pull this back.

If you weld in plates now, you'll be reinforcing the skewed geometry ...

iirc the old stories about the first 914(6's) that ran Nürburgring suffered such

- the stories refer to several reinforcing plates being welded into the front - but never said where -

i've never seen a picture of that anywhere

(we all know about the longs & rear plate kits)

Look underneath. The mounting surface must be pounded upward
It’s effecting alignment and corner balance significantly I bet

Shock has to be blown also

I had a similar repair once but not as bad

Stay off of the curbs and bumps. Faster when Not unsettled anyways

Couple things others have pointed out. Can't really tell but it looks like there is a crack along the bottom of the reinforcement into the wheelhouse. I agree with Brant. Check the strut and left suspension mounting as well as alignment.

Just out of curiosity, what sort of control arm bushings are you running in the front? What size sway bar?

call Derek at Europro's. he put mine up on the bench and pulled out about a 2 inch twist.

Looks to have been welded back together at some point, maybe accident history? That can't help

I think this suspension attachment point is a little bit higher then before and compressed the sheet metal over it.

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running stock rubber bushings, no sway bar. 23mm torsion bars. planning to upgrade bushings, add swaybar but now need to address chassis issue

thanks for this photo. I'll carefully inspect in that area. If its only bent up a few millimeters, maybe shimming the suspension mount down could compensate rather than trying to pull out.

I've tried this in the past with mixed results.

You need to remove the torsion bar and disconnect the wheel/hub (pop it off at the ball joint), add your shims, tighten the a-arm bolts and then the a-arm has to *freely* rotate up and down.
If it is in any sort of bind, your geometry is off and you'll be adding untold pounds to your spring rate on that corner.

I used self aligning spacers to be able to deal with slightly skewed mounting points (see pic below) but in the long run, you really want to get this pulled back and properly reinforced.


PS: And while you are in there, double check and make sure the a-arm itself isn't bend!

Thanks for all the help so far. I spent some more time inspecting the car. I have found no other indication of damage or deformation. Our leading theory was vertical loading at the rear a-arm mount. The a - arm rotates freely and I drove the vehicle and found no alignment issues or handling problems. Notice in the photo that the a-arm is parallel to floor pan which indicates its not bent upwards. As far as possible crack at wheelhouse inside trunk - I stripped out body sealer and no evidence of cracking. I'm thinking now that overall elastic body flex has caused this localized buckling on the trunk bulkhead.

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