Welcome to our resource for MG Car Information.
MG MGB Technical - Collapsible Type Steering Column
|I have the 'collapsible' steering column fitted to later chrome bumper cras (as opposed to the 'energy absorbing' type fitted to rubber bumper cars).|
I recall reading an article about how to replace the plastic pip between the two shafts, the bit that keeps them together but severs on impact thereby 'collpasing' the inner column. Can anybody help me find it? It was from the USA from memory, and the methodology involved a hot melt glue gun...
Thanks in anticipation,
Attached is a copy of a recent article by David Hoskins, a member and past editor of the Geelong MG Club.
To identify a collapsible column, look under the dashboard in order to examine the outer tube. Collapsible steering columns usually have a plastic wrapping, about 12 inches in length, which covers the section of the column that has been perforated in order to enable it to deform and collapse upon impact. Sometimes the plastic covering is absent, exposing the diamond shaped perforations of the tube. Contrary to appearances, there are no transverse plastic pins in the collapsible column. There are two bands of plastic, injected into the space between the inner and outer steering shafts. This forms a slip joint that allows the steering shaft to collapse telescopically upon impact. The plastic is injected through two opposite pairs of holes in the outer shaft, thus giving the impression that there are two transverse plastic pins. However, one cannot tell what is inside until the steering column is disassembled. Be aware that beating on the end of the shaft in order to loosen the steering wheel so that it can be removed is a very bad practice. Do not do this. Use a proper gear puller in order to do the job. Beating on the shaft can destroy the plastic slip joint. There is a circlip behind the top bearing assembly that will prevent movement. If this circlip is removed or missing you can get as much as 2
|As Stephen says, there are no plastic pips that go completely through the outer and inner parts of the column. I have to replace the lower bush which requires the separation of the two parts. I carefully drilled out the visible plastic, removed the small roll pin fitted on one side only, and pulled the shafts apart. Reassembly requires either some heat treatment and a glue gun, or similar, together with a replacement for the roll pin. I decided to drill through the inner shaft with a 6mm drill, using the outer holes as the guide. I then bought some thin walled 1/4" OD ali tube (model shop). 1/4" is ~6.35mm so I cut a length to suit the width of the outer shaft, then cut along its length with a thin blade. This provides an ali roll pin which drives very easily into the 6mm hole and will sheer easily should that awful requirement ever arise. Although it won't slip out I shall peen the ends into the c'sink of the holes. As to ensuring the shafts aren't loose I intend to fill the gaps with brass shims cut from sheet, again from the model shop.|
Hope this helps.
Mine's definitely a collapsible type. The original was a solid bar type, I got hold of a collapsible column as a safety feature when I rebuilt the car. Only the inner column is collapsible. The one I fitted to the car was 'refurbished' some years back using, so far as I recall, with a piece of aluminium bar through the holes that were the sprues for the plastic (which, when broken, look like pips....). It's never been very satisfactory as I didn't replace the plastic, so I've got hold of another one to refurbish 'in slow time'. I was going to refurbish it then test the collapsibility (have I invented a new word?) before re-refurbishing it (another new word??). Anyway, I didn't know about the little roll pin, so I'll replace that before deciding whether to use plastic or brass (a la Richard) to take up the slop.
Steve - are you talking about the 'energy absorbing column'? There's definitely a pin in mine, no slip joint as such, and no circlip so far as I remember.
As far as I know, they're the same thing.
I think that Neil has a collapsing column, ie one that has an inner and an outer tube, that collapse and the inner slides forward in the outer. This one has a shear pin to hold it in place until there is a force down the column.
What you are thinking of is an energy absorbing column that has that expanded metal part, which slowly deforms and absorbs some energy from the driver hitting the column and slowing him (her) down a bit, unlike the collapsing type, which does stop the column skewering the driver, by collapsing, but does not absorb any energy, thus allowing the driver to hit something else, with full force.
(whew, what a long sentence)
|Remember America and the UK got different columns at different times. America got the energy absorbing in 67, UK not until 72, but only from the start of rubber bumper production was the same column fitted to all cars regardless of model and market. Thus there will be differences, both major and detail, until 74 1/2.|
|As I said, collapsible not energy absorbing. Saves maybe 6" of skewering - after that, the outer column gets you!|
|Neil, give me your email address and I'll forward the directions on how to replace the plastic inerts between the inter and outer shafts.PJ|
|P S Jennings|
This thread was discussed between 04/08/2010 and 10/08/2010
MG MGB Technical index
This thread is from the archive. The Live MG MGB Technical BBS is active now.