CRASH, BANG Collaspe

[POKDUB]

One dark cold night last week I was driving my 911E through road works, hit a pothole, and heard this almighty crack, felt the car dip back, looked in the side mirror, and there was a trail of grey smoke spuing from the back of the car.

My rear suspension has collasped, and one of the tyres was rubbing badly against the wing. (See pic where heat was so intense that it lifted paint off the wing). The back of the car was no more than 3 inches off the deck. I thought I had some luck when I noticed I was in a free recovery zone, but the truck which came to my rescue had these extendable arms, suitable for front wheel connection, not the rear end of a decked 911. (It would have caused more damage to the exhaust). So the only option open was to fit the Space Saver (Saviour) to the side which was badly rubbing, and crawl home (1 mile).

Inspection next day revealed that the torsion tube was broken in two places, not sure yet if the torsion bar(s) are also gone.

So, always have your Space Saver in order and to hand.
Try to avoid bumpy roads, routes with speed ramps, these cars are not Humvees.
Check the condition of your torsion tube.

Help please. Can I fix this center section, with and engine drop and weld in a new tube piece ? How do the torsion bars connect in the center, I have not seen a proper pic/dig of this ?

Any help, suggestions, experience appreciated.

[makaio]

Man that sucks! I'm sure it can be welded and fixed. You'll just have to wait untill one of the more experienced restoration hands wakes up to answer you.

Will your auto insurance cover this?

[Wayne 962]

Yes, it can be fixed - you just need a new torsion tube bar piece. I suspect some rust probably had a hand as well...

-Wayne

[Jerome Ryals]

Out of curiosity what year model is yours. This can be a tedious fix, you will need to pull the torsion bars out and check for damage, mainly being bent from the initial break/flex. Noticed the breaks were close to where the trailing arms also mount to the tube this is part of the 'tedious' since replacement would/could lead to rear end alignment problems. Hope it works out for the best for you.

[Rot 911]

Like the others have said, yes you can weld in a new torsion tube, but my concern is that you have some serious rust problems that need to be addressed. If the torsion tube is rusted out I wonder what the rear sheet metal looks like?

[adomakin]

over here in the UK you can take your local council to court for damages if you contct them within 24 hours with photo evidence etc.
perhaps you could look into it-you may be able to claw some of the expense back

Andy

[POKDUB]

Matt, I dont think my Insurance would cover this. Dont think the road authorities would entertain it either.

Wayne, so you suggest a full tube cut out and replacement. I think this would have to be done to keep the chassis sound.

Kurt, there wasnt any significant rust problem on the tube, it seems to have a clean metal break for the most part. The underside of the car does need a good clean up. The section where the tube fits to the body might need a closer inspection.

[Grady Clay]

One of the reasons for the failure it our early cars don’t have a very useful reinforcement.
It is two small brackets that connect the torsion bar tube to the tunnel.
These are in the direct line if the forces from the inboard trailing arm mount.

It is the two parts at the top of this illustration.



The easy (never easy) way to repair your malfunction is to cut
the old tube about 2” in from the inner frame part and
then section the replacement part to fit in the space.
The difficulty comes if the frame sheet metal is rusted.
In that case it is best to replace the entire torsion bar tube
and the frame parts as necessary.

Anyone who has an early 911 all apart should replace the
center section of the torsion bar tube IMHO.

Best,
Grady

[Jerome Ryals]

Nice looking car Peter, thanks for the illustration Grady I've looking for one all morning since reading Peter's original post.

[POKDUB]

Grady, thanks for the nice diagram. The tube does not have these brackets, so I would have to plan for sourcing an updated tube which incorporates them.

Using your nice dig, I am a bit lost as to how the bars connect in the middle. There are two bars right ? One left, one right.

What do they connect to in the middle, each other, or some section of the torsion tube itself ? If the tube buckled in the middle, would this be sufficient to drop the rear end, or is likely a bar is broken also.

There was little movement of the tube when I lifted the wheel assembly, the transmission mount bracket seemed to keep the remainder reasonably rigid.

[john walker's workshop]

i've repaired a couple of those. the engine, trans, and all the rear suspension has to come out, basically gutting the rear of the car. you also need to cut some access holes through the rear seat bottoms to complete the circle weld around the tube. time consuming, but kind of fun, in my opinion anyway. hope that the frame isn't rotted out too. it gets to be less fun if that happens.

[Grady Clay]

Peter,

There is an internally splined center piece inside the torsion bar tube that the inboard external splines of the torsion bars slide into. The outboard external splines of the torsion bars slide into internal splines in the spring plates. The torsion bars are only supported by the splines.

I would suspect your torsion bars did not break. The combination of the torque from the torsion bars and the forces from the trailing arms caused (the already weakened from rust) tube to fail. I’ll bet upon careful inspection you will find one or two preexisting cracks. The bump that caused the failure was the straw that broke the camel’s back.

This is probably an opportunity to install larger torsion bars as your bars may be as rusty as the tube. Of courts there are all sorts of other goodies.

The torsion bar tube is probably the central part of a 911 body/chassis. The repair needs to be done as original or better.

Best,
Grady

[Zeke]

To answer the question about how the t-bars connect, there is a splined insert inside the tube. Some say the splines go all the way thru allowing the bars to come out either way. Others say that it is necked down in the center so that the bars bottom out at center.

Either way, I suppose it is possible to recover this piece and insert it into a new tube of the appropriate diameter.

I would be doing some reinforcements as well as replacement. JW says open the seat backs to access the front of the tube and I say add a band over the weld and weld it too.

This makes me wonder if I want to race my car. Ceratinly if that happened in a high speed corner, it would be diasterous. Guess where I'll be today.

EDIT: Grady types faster than me. I guess I was looking out of the window and saw some sunshine. Haven't seen the sun in a few days. Only rain.

[POKDUB]

John, Kinda Fun ? I probably think along the same lines. First engine drop to look forward to.

There are probably a lot of other bits to check and fix as I gut the rear end. I know my speedo drive needs replacing.

Should I also fit coil over springs as an added support ?

[POKDUB]

Grady, from what I could see of the overall damage, your assessment of the cause & effect are spot on, as usual.

Sometimes I think you have telepathic powers.

[911AtLast]

Peter - sorry to hear about your excursion into the DPT - you know it's not open yet - right?

Seriously though, if you need a hand for an engine drop I could be persuaded to donate a few hours!

(Never done one, but am keen to learn on someone else's car!)

Warren

(I'm in Dun Laoire)

[awis321]

Knock on wood mine is fine... would converting to a coilover suspension at this point be another possible remedy? If not, would a torsion tube from a later year work? I'm thinking whether I should hold onto the torsion tube from a rear clip I have.

- Dennis

[POKDUB]

Dennis, I have asked the same question on the coil over springs, or even to put on some basic coil overs on the car in addition to share the load. Gradys suggestion on the tube reinforcements is definitely a must.

[Grady Clay]

Prior to the added reinforcements it was easy to salvage the inboard section from a good (but crashed) donor 911. With the addition of the reinforcement brackets I can’t imagine how difficult it would be to successfully remove it. The only exception might be if it was desirable to replace the entire lower-rear pan and frame due to rust.

There is an additional benefit to the replacement torsion bar tube as it has two substantial “dimples” that permit the trailing arm mounting bolts to be removed while the transmission is still in place. Prior, to properly replace a trailing arm, you had to remove the engine and transmission. Of course there is the “not very elegant” torch-off-the-bolt technique.

When replacing the torsion bar tube, you have the opportunity to substantially strengthen the rear chassis. The important areas are where the torsion bar tube goes through the frame sheet metal and where the rear sway bar mounts. If you only replace the inboard section, you should fabricate a ring that goes over the weld between the new and old parts. That ring can include gussets to the frame, bulkhead, pan, and more.

A difficulty in installing the later torsion bar with an assembled 911 is the wiring harness, fuel lines, brake line, clutch cable, parking brake cables, speedometer cable, throttle linkage, and more are in the area where you want to weld the reinforcements to the tunnel. I have never had this done but I think with patients and a TIG welder everything can be kept cool – just do a little at a time and then ice everything down. Others chime in here. Of course it is much easier with the car disassembled.


Lads, where are Drumcondra and Dun Laoire compared to greater downtown Baile Atha Cliath? Perhaps you and more can have a Gathering of the Pelican Flock.

Best,
Grady

[POKDUB]

The cables and lines will have to tied and shielded no doubt. I will take your advise and add the rings to strenghten the connection.

I will file this thread for when I get going with the work.