Steering column extension

[Eddy]

A further update

The new part arrived. Here it is next to the original, you can see how it is more suited to extension, without the extra joint:



I then cut the brand new part in half, which just felt wrong!



The cross section of the cut has a diameter of about 17mm, which is too big for the 20mm OD 3mm wall tube I bought based on what I had read previously, so I'll need to get some more tube. Let me know if any of you have anything suitable you would like to sell.

A quick look on eBay found some 22mm OD 2mm wall tube which should fit. Will this be up to the job?

[voucht]

Hi Eddy,
Very strange your new steering column has a 17mm outside diameter. Is it from a Sierra ? Anyway, if the tube you bought has a 20mm outside diam with 3mm thick walls, the inside diameter is 14mm. That should be too small anyway to fit on a "normal" Sierra column which is 9/16'' (14,29mm). I think 15mm inside diameter would have been the way to go.

If I had been you, I would have used the first (old) steering column. I would have cut it anywhere above and under the central UJ as Alga says, keeping in mind you want to leave enough length to guide the column inside the tube to keep it straight. I would have used a 3 to 5mm thick wall, 15mm inside diameter seamless tube for the extension.

Are you sure you can not force the tube you already have on this column? It would be worth to try I think. Or perhaps you can find a 9/16'' or 15mm drill and machine the inside diameter on its length.

If you think it is too late for that, you have to find another extension tube to fit the new column which has a 17mm outside diam. To answer your question, I would NOT use 2mm walls, in my opinion, it is too thin. 3mm should be the minimum, 5mm might sound overkilling, but on the safe side. Also, better buying a seamless kind of tube.

Hope this will help

Good luck.

[Eddy]

Thanks for the comments

I was expecting the new column to be a smaller diameter than 17mm. It was advertised as for the Sierra and has the triangular connection one end and the correct splined shaft at the other.

I must admit I took a bit of a guess on the tube as I was placing an order along with some other bits and wanted to combine postage. It was as someone had suggested on locostbuilders and I was away from the build so couldn't check. There is no way it will fit on the column I have without drilling a lot of the inside of the tube, which will reduce the wall width considerably.

The problem with the first column is that the diameter is even bigger than the 17mm replacement one. I had read that the extension tube can't be too big or it will foul one of the uprights.

I will keep my eye out for some 17mm ID seamless tube with a wall thickness of 3mm.

Cheers

Eddy

[Eddy]

Right, I bought a digital caliper to measure the thickness of my cut column accurately - It comes out at 17.8mm:



It comes out with that measurement everywhere except where the part number is raised, but I can grind that down.

What tube should I be getting - I'ver found some 25mm OD, 3mm wall stuff for sale. Will that be a tight enough fit?

Cheers

Eddy

[jps]

Can't you just turn down the cut part until it is 14mm and then use the tubing you already have? Can't imagine it'll compromise strength if it's correctly welded?

[voucht]

Actually JPS is right. Here in Sweden, SFRO (equivalent of your IVA in the UK) even recommends to turn down the column to get a perfectly smooth and regular surface before welding.
Now, if you don't have a lathe, you have to compare if it would be cheaper to buy 1m of 18mm ID thick-wall tube (and 3mm wall being the minimum, you will have a 24mm OD tube. Check in that case that you will have enough clearance beside the U2 upright tube) or to give the 2 parts of the column to an engineering shop to turn them down.

Good luck

[Eddy]

Thanks guys

I hadn't thought about turning the parts down - Seems counter intuitive when the part needs to be as strong as possible, but I suppose it will still be strong enough if some standard parts are thinner anyway.

I've got some time off at the end of the month, so will try and find a friendly local engineering shop

Cheers

[Eddy]

Just to follow up on this, I got a 600mm length of seamless 25mm x 3mm wall tube. The cut column fit reasonable well inside the tube, so I welded it up.

The result, although not neatest of welds, seems to be strong - I turned the steering to full lock and put enough pressure on it to flex the steering wheel with no movement elsewhere!

There is also enough clearance on the upright.

I may add some 6mm dowel through the tube/cut column for additional peace of mine - What do you think?

Some pics:

[Stot]

IVA like to see more than just the welds at the join. Some people slot the extension and weld through the slot for extra support.

I added 2 x 5mm roll pins each end on mine and welded them in too.



Cheers
Stot

[MikeB]

Might be useful for others.
This is the tube I used from ebay.

http://www.ebay.co.uk/itm/3212065946... 4.m1423.l2649

I think 3mm wall thickness if fine, from recollection the triangular section further up the column is hollow, smaller diameter and similar wall thickness.

I've only tacked mine up so far, but reading this thread I may put a roll pin in once fully welded but need to find someone with a more powerful MIG than mine to do the full welds.