Collapsible Steering Shaft Demystified

[Dana67Dart]

So @charliec had a dilima, reuse his steering shaft that showed signs of having been molested or replace it.

As luck would have it I had an unmolested steering shaft for the application and I have always wanted to cut apart a steering shaft. So we agreed to swap shafts, I paid postage to him and he paid postage to me. A Win Win for both of us.

Like a kid on Christmas morning I got the box and unwrapped it. I looked it over and then....

Cut it in half!

The red arrow points to the missing bit of plastic. The first indication Charliec had that something was wrong.

The green arrow points to a bit of plastic that was still in place BUT was no longer attached to where it was supposed to be.

The other side also looked fine BUT they were not!

In my first attempt at separating the outer part from the inner part I put a open end wrench on the inner shaft and with the inner shaft chucked in a vice I started tapping on the outer part in the direction of the arrow (making the shaft longer if it was still intact) but it stopped after about an inch.

Never giving up I tapper the outer shaft the other direction (making the shaft shorter which could cause the shaft to come out of the coupler) The outer piece slid right over the inner shaft with relative ease. Unfortunately I did not get a photo of that. BUT due to the inner and outer shaft profiles the outer shaft could not slip off the inner shaft by the be upper bearing and splined end.


So to get the outer piece of shaft off I decided to cut it lengthwise on both sides
The green circles show where the plastics bits fell out of the outer shaft
The blue circles show where the plastic bit retained in the outer shaft
The Red arrows show where the inner shaft is smooshed to make it wider and where the outer shaft is crushed down to make it narrower preventing the inner and outer shaft from getting longer buy more then an inch or so. BUT nothing stops it from getting shorter, and remember shorter is bad!

Here you can see the injected plastic that would normally keep the two shafts aligned.
The red arrows point to where the plastic that is visible on the outside of the outer shaft was attached at one time.

Now there was some discussion that the visible plastic was just injected into a through hole in the inner shaft.

That was not the case on this shaft

I melted off the (Nylon or Teflon) and there was only a channel, No through hole. Perhaps on newer shafts they modified the design.

Here is what the inner and outer shafts look like when aligned properly. (Obviously I took this photo AFTER melting off the alignment plastic)

This is one of the bits of visible plastic, I knocked it out of the outer 1/2 The OD of the shear part is about 0.090"

Continued

 

[Dana67Dart]

Here is a view of the two halves and the inner shaft.

The upper half has the visible plastic bits removed and the bottom still retains them

So my conclusion is without drilling a small hole through plastic on the inner shaft there is no practical way to re-anchor the two shafts together.

If you just put adhesive or melt plastic into the hole the contact would only be flat surface to flat surface. Very little effort would be needed to shear that chemically bonded joint. Now if you drilled a hole into the plastic and filled it with adhesive or plastics the joint would have an actual shear joint.

 

[67Dart273]

I would be VERY tempted to drill through one and stick a BRASS 6 or 8-32 screw and lock nut in there

 

[Dana67Dart]

I would be VERY tempted to drill through one and stick a BRASS 6 or 8-32 screw and lock nut in there

There is more than enough metal to drill out the small hole and tap it. Then put a set screw in.
With a dimple in the inner shaft it would lock things together well.

Best option is to not hammer on the top or bottom of the shaft.

 

[S'cuder]

I would be VERY tempted to drill through one and stick a BRASS 6 or 8-32 screw and lock nut in there

Maybe a snowblower shear bolt?

 

[Syleng1]

Awesome write up as usual Dana.
I have always knew how the joint was supposed to work and seeing it as a cut away is perfect. After 50years old- I’m surprised the plastic holds at all BUT they do.
I like the set screw idea over a bolt. Lock tite it in place with a small torque to me would be safer than a drill thru bolt. But let’s face it, we all do not anticipate a crash.

Regardless- nice work!
Syleng1

 

[RustyRatRod]

Cool stuff! Thanks for sharing this!

 

[Murray]

Very good info.

 

[Dana67Dart]

possible solution to maintain an amount of shear

1. Remove the visible plastic
2. Align the outer shaft with the center of the plastic on the inner shaft
3. Drill a small pilot hole through the existing outer shaft hole where the visible plastic was, just to the inner shaft but through the inner plastic.
4. Insert a plastic rod with some adhesive into the hole
5. Trim to the outer surface

Alternately

1. Tap the hole in the outer shaft
2. Install a plastic set screw

Green Outer Shaft
Grey Inner Plastic
Magenta Inner Shaft

 

[cudamark]

I never thought those plastic pins had anything to do with changing the crashworthiness of a column. I always thought that they were there just to keep the lower shaft from falling out or getting out of adjustment when being installed on the assembly line. I can't imagine those factory pins would do a darn thing in a collision other than just break easily. If they will break just tapping on the column with a hammer, they can't be doing much to keep the lower shaft from moving. Heck, I've seen people break those pins just trying to pull the column out with a stubborn couple that won't let go. I certainly wouldn't want that column not to collapse during a collision, so, changing it to be stiffer/tighter than stock might not be a good idea.

 

[Dana67Dart]

I can't imagine those factory pins would do a darn thing in a collision other than just break easily

That's the point. They shear but under a specific load, the FSM talks about not hammering on the shaft. They do a perfectly fine job of keeping the shaft aligned. Remember there is a dimension from the coupler to the dot on the shaft when adjusting the column in the car. The lower plate and the upper brake away slides have adjustability in them.

I agree making the break away (shear) force greater than design is not optimal but removing the same is also not optimal.

Choose your poison

 

[cudamark]

I'm trying to figure out the problem with those pin not being there. They really don't prevent the shaft from collapsing in a wreck to any significant extent. So the column without the pins collapses 2" instead of 1 7/8"?

 

[rmchrgr]

I'm trying to figure out the problem with those pin not being there. They really don't prevent the shaft from collapsing in a wreck to any significant extent. So the column without the pins collapses 2" instead of 1 7/8"?

I'm almost certain that the pins are there because without them the shaft becomes an NVH concern. (Noise, Vibration, Harshness in dealer tech lingo). NVH complaints are probably the number one concern for cars under warranty. When I was a dealer tech, I spent more time than I care to think about driving brand-new cars trying to figure out what someone might be feeling or hearing. People go nuts over the most insiginificant crap.

As shown in the pics above, the steering shaft itself is two pieces - the bottom of the upper section goes inside the receptacle end of lower part. Without the pins/plastic 'insulating' the two pieces from each other, you have metal-to-metal contact which will obviously transmit the slightest vibration from the chassis directly to your hands. That's also why you have an upper column bearing insulator because that's where the shaft is physically connected to the rest of the column.

The shaft mounts in a fixed position between the column and coupler so it has nothing to do with keeping the two halves from moving until a collision impact is severe enough to shove the steering box/mount towards the driver. That's the only time I can think of that the pins are expressly 'needed.'

Mopar used to have a repair kit for broken steering shaft pins but I have not seen one in many years. It was probably for collison shops and not for the general public anyway. Even if you were to find a kit now it would likely be dried up/useless. Best solution is probably to insert nylon screws in place of the broken pins and grind off the ends flush.

 

[cudamark]

The upper and lower shafts fit tightly together, so, I doubt you would have any rattle whether the plastic pins were there or not.

 

[dadsbee]

Pins and the mesh column section are there to collapse when you hit the wheel. Why the column is mounted on slider blocks are not solidly fixed. Just ask my Dad... when he ditched the Bee back when I was a kid... LOL I had to fix that mess when restoring my Bee, but we never even noticed it mind you for 40+ years until I tore the car apart. Plastic sheared, outer column collapsed and broken.

I have to ask though, what year is this column from Dana, as '68, 69, 70 B bodies are nothing but a hole drilled right through each piece that line up and get the injection of plastic, the injection you said you didn't think was correct in the previous thread. Glad you took the time to reassure yourself I wasn't blowing smoke..

 

[cudamark]

The shear pins and expanded mesh are not there to keep you from hitting the wheel. It's there to keep the steering column from getting shoved back into your face on a major collision.

 

[dadsbee]

Is that not basically what I said... He ditched the car... chest into the wheel when he was the only thing still moving forward.

 

[rmchrgr]

The upper and lower shafts fit tightly together, so, I doubt you would have any rattle whether the plastic pins were there or not.

Who says the pins didn't serve two functions ?

It's not so much about the shaft itself rattling as a result of imperfect fit but that it transmits vibrations from the road to the steering wheel.

 

[charliec]

So my conclusion is without drilling a small hole through plastic on the inner shaft there is no practical way to re-anchor the two shafts together.

If you just put adhesive or melt plastic into the hole the contact would only be flat surface to flat surface. Very little effort would be needed to shear that chemically bonded joint. Now if you drilled a hole into the plastic and filled it with adhesive or plastics the joint would have an actual shear joint.

I think I referenced this video earlier. Everything on youtube is not gospel truth of course, but I've found much of what Angel Garrido posts is very useful. I clipped it, but you can watch the whole video of his steering shaft work or other very well-done video for yourself.

 

[rmchrgr]

I found some pictures on another forum of the old pin repair kit. Snap rings are for 1970 tilt columns only. Basically looks like a bottle of spray glue and a tube of Loctite.

 

[cudamark]

Who says the pins didn't serve two functions ?

It's not so much about the shaft itself rattling as a result of imperfect fit but that it transmits vibrations from the road to the steering wheel.

It's not as if these pins are rubber and fully separated the upper and lower shafts. They're hard plastic and only in a couple of places. The rest is metal to metal between the two shafts with maybe a thin layer of lube between them. If anything, the pins would help transmit vibration rather than relieve it. With a sliding coupler down below, it's not likely to transmit much in the way of vibration anyway. Now an A100 van would be a different story. The have a solid center shaft that goes directly into the steering gear.

 

[Dana67Dart]

I'm trying to figure out the problem with those pin not being there. They really don't prevent the shaft from collapsing in a wreck to any significant extent. So the column without the pins collapses 2" instead of 1 7/8

Without the pins the column can work it's way shorter and ultimately pull out of the coupler under the correct circumstances.

That's the problem

 

[cudamark]

Without the pins the column can work it's way shorter and untimatly pull out of the coupler under the correct circumstances.

That's the problem

If the coupler is in good shape, it can't happen. There are pins that keep the sliding shoes from coming out. I can't see the lower shaft overcoming gravity and moving up and out of the coupler even if those pins were missing, but, I guess anything is possible. I've never seen or heard of it happening myself.

 

[Mattax]

Looks like a '67 column

 

[Dana67Dart]

67-69
The shafts in my comparison of ps vs manual are 67 and 68 no visable difference except for the length