Targa body flexes when jacked up?
 

Jacked my 78 Targa up today to do the winter oil change and when I lowered down onto jack stands using the the the torsion bar supports I noticed that the passenger side door spacing grew approximately 3/4 of an inch - drivers side didn't. Took it off the jack stand and put a support under the rear wheel and the gap closed back up.

So that got me thinking that I remembered seeing some supports that mounted internally, used the seat belt bolts as a connecting point - trying to find them, can't as of yet.

Not even sure if they will help.

Also not sure if that gap has appeared in the past.

Thoughts?

I think the bar you're referring to was for body twisting, like a strut bar used in the front. I don't recall ever seeing anything for lateral body flex, but I'm guessing someone out there has an aid of some sort.
The gap you're seeing is fairly common in cars with no roof (targa/cab), and I think it probably gets worse with age of the car.

I had a speedster replica and I had two pieces of 2" square stock welded at 45* from a vertical support behind the rear of the doors to the frame running under the door sill. It was amazing the difference it made in stability.

That is our infamous Targa Body Flex.

The mod you are looking for is the Targa Body Brace: http://forums.pelicanparts.com/porsche-911-used-parts-sale-wanted/740126-fs-targa-body-braces.html

It will help but not get rid of it entirely, that is the nature of the Targa.

Even with the Targa body brace it will flex when lifted and supported at the torsison bars or floor jacking points.
I have them, it flexes a little less when lifted. It goes right back to normal when back on the ground.

Just the nature of the beast. :)

One of the few cars on the road that a driver can reach out the window and wipe the taillight lenses clean, mid corner! :D

*Credit Tim (tirwin) for that lil' gem!!!

^^^ lol :d

http://forums.pelicanparts.com/uploa...1483187381.jpg

During the resto on my 1974 targa, welded in these steel plates to stiffen the body. Work like a champ.

yes, when I had my targa on rear jack stands, it got to the point that when I opened the door, it would not close again, unless I jacked up under the motor, to reduce some of the body flex.

The Targa's have inherent body flex. It is is normal. That is why the factory put in extra steel up front (and on cabs too) to reinforce the tub and reduce flex. It is also why cab and Targa pedal boards are different shape than the coupe. Get the Targa body braces from Helion. They certainly help control it.

I will add that are certain accomplished race cars drivers that actually preferred the Targa to coupes as they felt they could use the inherent flexing as a source of extra oomph coming out of corners.

My '75 flexes when jacked up, but not nearly that much (maybe 1/8" at the top of the door seam). 3/4" seems excessive to me.

back when I used my 85 911 NA for DE, installed a full bolt in cage. totally transformed the car, almost as stiff as a coupe.

but now almost back to stock. I have a set of those targa body braces and they do seem to help a bit.

Thanks for all of the replies - helps reduce the stomach acid as I lay in bed thinking my baby has a broken back - just had never noticed it before. I will pursue getting the braces, always wanted them in the back of my mind, now it is just a bit more forward.

Might want to check for rocker rust/cracks.

Makes me wonder - if you have a cab/targa, is it better to lower the cab top/remove the targa panel before raising the car since not doing so would seem to suggest that undesirable forces would then be applied to the cab top/targa panel fixing points?

Normal. As John says, do a rust explore, but otherwise don't fret.

If it's normal body flex, why is the passenger side worse ?

The coupe also has some flex when you jack it up by one wheel.

I've noticed the door latch doesn't seat the same way when jacked.
Sometimes, I leave the door ajar while jacked.

Early 911s were never privy to CAD and thus relied on design and engineering expertise at the time. Here is some vintage discussion (2006) and numbers to provide context..... also some solutions.

http://forums.pelicanparts.com/porsche-911-technical-forum/259557-structural-reinforcement.html

Sherwood

I'm concerned for you that the flex is asymmetrical and so dramatic on one side. Mine flexes, maybe by an 1/8 of an inch, but it's even on both sides. I'm not sure where I would look, but perhaps there's signs of over stress somewhere on the tub?

I also have noticed this flex when lifted. I lift on the torsion bar covers out back and on the floor pan corners behind the front wheels out front. The amount of flex was potentially "excessive" when i got the car but soon found out I had lots of rot at the base of the B pillar where it meets the sill on the driver side. Once I cut this out i found even more internally to the sill which had to be cut and repaired. The passenger side was not as bad but still needed work.

Now that I've got it all fixed up and fully painted i haven't had it back on the hoist to notice how much of an improvement this has made. I think a brace is a good idea but i think a better angle more like a 45 degree would offer more support. Anyone do a brace that does not use the seat belt bolts but goes forward further on the sill frame?

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