Torsion bar tube inspection '69 T (Problems!!!)

[Mike_72]

So I decided I would pull my torsion bars to have a look at the condition of the tubes and to lower the car to euro height. Well I am very happy with the condition of the torsion bar tubes, everything looks clean and rust free.....However I ran into a little bit of a problem when I went to remove the R/H torsion bar, I noticed that the lower bolt holding the cover on had a different size head than the rest of them and when I went to turn it the bolt would continue to turn and the bolt would not move out from the cover. Seems someone had an issue in the past and replaced the hardware and evidently didn't weld a new nut on the back side. So for all you experts out there, what are my options? I assume I will need to cut an access hole to get a hold of the nut in order to remove it and somehow attach a new nut, then weld up the hole?? Well here are the pics of the good news and bad.

[bgyglfr]

Is that a bolt broken off in the threads on the second pic?

[Mike_72]

Originally Posted by bgyglfr

Is that a bolt broken off in the threads on the second pic?

No I had to cut the head off as it was just spinning without coming out. Based on the fact that it was a different bolt than the rest I am assuming there was an issue here in the past. It seems there is a nut on the other side which has broken free preventing me from being able to remove the bolt.

[bgyglfr]

That's a tough one. Getting access is gonna be tricky. I had a bolt stuck in a kick starter on a dirt bike once. The PO tried to use an easy out and broke it off too. Considering the case was aluminum I was concerned about drilling the easy out because the bit would want to move to the soft aluminum case. I took it to a buddy's shop and he very briefly and extremely accurately shot the center of the bolt with a plasma cutter. It melted the bolt and we just took a pick and cleaned the remaining metal from the threads. It was good as new. That might be an option here to get the old bolt out of the way. Then you just need to figure out how to get a new thread in there. Maybe tap it the next size up?

[john walker's workshop]

How about a threaded insert? A case saver perhaps.

[bgyglfr]

That makes good sense. Seems like a pretty simple and non invasive solution.

[Mike_72]

Originally Posted by bgyglfr

That's a tough one. Getting access is gonna be tricky. I had a bolt stuck in a kick starter on a dirt bike once. The PO tried to use an easy out and broke it off too. Considering the case was aluminum I was concerned about drilling the easy out because the bit would want to move to the soft aluminum case. I took it to a buddy's shop and he very briefly and extremely accurately shot the center of the bolt with a plasma cutter. It melted the bolt and we just took a pick and cleaned the remaining metal from the threads. It was good as new. That might be an option here to get the old bolt out of the way. Then you just need to figure out how to get a new thread in there. Maybe tap it the next size up?

Getting the bolt out is going to be tricky, it is loose in the hole but something is preventing it from going in any more than seen in the picture and because it is so free to spin it will be hard to drill. I suppose I could tack it in place with the welder and then drill it out.

As for the threads I am thinking maybe I can get a heli-coil that size so I can keep the stock size hardware. Looks like I am going to have to do it twice as I have just found that another one on that side is stripped.

[Tim K]

Originally Posted by Mike_72

No I had to cut the head off as it was just spinning without coming out. Based on the fact that it was a different bolt than the rest I am assuming there was an issue here in the past. It seems there is a nut on the other side which has broken free preventing me from being able to remove the bolt.

I'm guessing there is no nut. I don't think that there would be room for a nut anyway because of the very close proximity to the heater channel in behind this lowest bolt.

I don't believe the factory threads can 'spin' in there as the 'insert' is welded to the surrounding sheet metal on the exposed side.

Unless:
a) The threads are stripped
b) The bolt is incorrect (too small)
c) Previous botched thread repair
PLUS something is stuck on the bolt threads past the internal threads I can't guess why that bolt would't back out.

I might try drilling it out. As JW suggested, a threaded insert sounds like a good plan.

Here are some images that might help:
(borrowed from DDK - Die Deutschen Klassiker • View topic - 1965 RHD 911 restoration started)

[Mike_72]

Originally Posted by Tim K

I'm guessing there is no nut. I don't think that there would be room for a nut anyway because of the very close proximity to the heater channel in behind this lowest bolt.

I don't believe the factory threads can 'spin' in there as the 'insert' is welded to the surrounding sheet metal on the exposed side.

Unless:
a) The threads are stripped
b) The bolt is incorrect (too small)
c) Previous botched thread repair
PLUS something is stuck on the bolt threads past the internal threads I can't guess why that bolt would't back out.

I might try drilling it out. As JW suggested, a threaded insert sounds like a good plan.

Here are some images that might help:
(borrowed from DDK - Die Deutschen Klassiker • View topic - 1965 RHD 911 restoration started)

Thank you for that critical piece of information regarding the proximity of the heater tube to that bolt. I would have drilled right into the heater tube without even knowing had you not mentioned that.

[wdfifteen]

Those round things protruding from the sheet metal are the nuts, are they not? Did you use something to try to put some outward pressure in the bolt while turning it? (Vise Grips?) I'm thinking it's just hung up on a couple of threads. You may have to weld something to it to pull it now. Drilling doesn't seem like much of an option.

[Mike_72]

Originally Posted by wdfifteen

Those round things protruding from the sheet metal are the nuts, are they not? Did you use something to try to put some outward pressure in the bolt while turning it? (Vise Grips?) I'm thinking it's just hung up on a couple of threads. You may have to weld something to it to pull it now. Drilling doesn't seem like much of an option.

I was prying under the head with a screwdriver and the bolt would just turn and turn and turn.

[Scheebs]

One of the four bolts uses a spacer because of needed access behind spring plate. That seems to be the one you're having problems with. The nut is indeed welded to the unibody panel.
My suggestion is to tack weld that cut-off bolt to prevent it from turning. Then carefully drill it out. Afterwards you may install a case saver in the hole created, recreating the original nut in the body.

[Mike_72]

Today I managed to drill out the cut bolt, as a result there is a portion of the bolt which is now inside the section of unibody and I am unable to get it out but I don't think that will cause any problems. My big concern now is if there is enough meat available for me to drill out to 25/64th and then tap to install either a heli coil or time sert. it doesn't look like there is a huge amount of wall thickness available.

[wdfifteen]

There is plenty of meat there to drill and tap to the next size. No need for a helicoil.

[Mike_72]

Originally Posted by wdfifteen

There is plenty of meat there to drill and tap to the next size. No need for a helicoil.

I imagine the next standard size would be an M12, should I consider the option to go standard and use a 7/16-20 bolt or just go right to M12?

[JSV798]

As Scheebs noted, isn't this the one with the spacer? So why not weld a nut over the hole and leave out the spacer, maybe add a washer to give correct depth?

Just a thought

[Mike_72]

Originally Posted by JSV798

As Scheebs noted, isn't this the one with the spacer? So why not weld a nut over the hole and leave out the spacer, maybe add a washer to give correct depth?

Just a thought

The removable spacer is required to allow the spring plate to swing down to its unloaded position. I also question the threads and one of the other holes as well so would like to repair it also.

[javadog]

How about cutting the whole insert out, machining a new one to suit, then welding it back in?

JR

[Mike_72]

Originally Posted by javadog

How about cutting the whole insert out, machining a new one to suit, then welding it back in?

JR

Ultimately I think that's probably the best way to do it. First I am going to see if there is enough meat to tap for a 7/16-20 bolt.

[javadog]

If you end up drilling it for a 7/16 bolt, I wonder if a left hand drill might help get the remainder of that bolt out...