Rack & pinion steering boxes

[ian Howell]

I have just removed the steering column from my 1930 Long Four and stripped it for inspection.

Hmmm . . . .

The rack (the circular toothed rack) seems to be not too bad, but the teeth on the pinion are worn to a 'knife edge' at the crests of the teeth.

But, I put it all back together and then rotated the guide bush tube to give deeper mesh, and Lo (and behold!) there is practically no 'lost motion' in the mechanism.

However, I wonder if anyone has ever looked deeper into this area? I note from the spare parts list (thanks to Alan Benewith) that spare guide tubes were available, but I have been unable to remove mine so far, as it clearly won't go 'down' past the swaged groove in the tube and when going 'up', it gets stiffer and stiffer - I suspect a felt bush somewhere. (I have got it off now!).

Has anyone tried to replace the actual 6-tooth pinion? I think it may be brazed to the steering column.

Answers on a postcard as usual . . .

[Tony Fearn]

Hi Ian.

I've had a look at a spare steering column today, with regard to the pinion end.

I had thought that there must be a hefty rivet through the tube and the inserted pinion to hold firm this vital piece of the steering kit , but can not see any evidence of this.

There's just the slightest trace of brass around one part of the circumference of the pinion where it fits into the end of the tube, which may be due to it being brazed in as you suggest.

But I would have thought a belt and braces approach would have been used. Just imagine what would happen if the pinion turned in the end of the column half way up the Stelvio Pass

Perhaps there's an internal spline or keyway to stop rotation.

Tony.

[ian Howell]

Amen!!

The next question is whether these pinions are available either as a spare part or as a component from another system that might fit / be made to fit.

Any ideas anyone??

[Forumadmin]

It would be even worse half way down the Stelvio. Going up I doubt if you would be doing more than 10mph!

[Dhbangham]

Last winter I decided to tackle my sloppy steering issue. As Ian found, I could improve the situation by rotating the eccentric steering tube to get a better mesh in the rack. This was not however enough for me and I found two other areas of wear that needed tackling. The first was that the disc of steel that the rack is made from had worn away the outer casing of the steering box. I therefore machined out the casing and had the rack disc hard chromed by A Phillpots of Luton and ground down to make a good fit again. On reassembling the steering box, half the play in the steering wheel was taken up. (4 inch down to 2 inch) The second area I decided to be improved was the fit of the steering column into the eccentric steering tube. So this year I have taken the steering column apart (you get the steering tube off the column by removing the steering wheel and sliding it over the top) I then measured the tolerance between the worn column and the worn tube and there was over 1mm of wear. This I am having hard chromed and ground to re-fit it to the steering tube. I will report in the next week or so to let you know how successful it has been. The secondary benfit of the last procedure is that I am hoping to get even better meshing between pinion and rack. My pinion is very worn, but there is still a few hundredth of a millimetre of "flat" on the top of the teeth, so I am hoping to get a few more thousand miles out of it before having to find out how to make and replace the pinion.

[Dhbangham]

I have got the steering column back from being hard chrome plated and ground. So the shaft is now oversize and fits perfectly in the outer sleeve. It has improved the steering, but the pinion is still so worn that it still does not mesh in the rack. I will have to find a less worn column or get a new pinion made. There is still be question of how the pinion was attached to the column tubing.

[Dhbangham]

Here are some pictures of the steering box from my 1929 Long four. There was movement from side to side of the rack ring and the outer casing. This was made like new again, by having the worn surfaces hard chromed and ground to size again.
Considering this steering box is now 86 years old and working successfully it should be considered an extremely good robust design. All the more surprising since it has now possibility of adjusting for wear built into it.

[Tony Fearn]

I've had a look at a spare steering column today, with regard to the pinion end.
I had thought that there must be a hefty rivet through the tube and the inserted pinion to hold firm this vital piece of the steering kit , but can not see any evidence of this. There's just the slightest trace of brass around one part of the circumference of the pinion where it fits into the end of the tube, which may be due to it being brazed in as you suggest. But I would have thought a belt and braces approach would have been used. Perhaps there's an internal spline or keyway to stop rotation.

Well, I had amongst other bits, a scrap early pre-war steering column ready for the chaps that drive around in a white van, so I thought I'd chop off the end and bisect it in the hope the faces would show something.

There was no indication of a pin on the outer surface of the pinion, even when polished up, but the cut-surface showed that there was a pin through the centre which has a thin rim of brazing around it, as well as evidence of brazing between the outer tube and the actual pinion.

I have attempted to photograph this, and the efforts are below.

1. halved.JPG

2. close-up.JPG

3. very close.JPG

I suppose that the pin was driven through the casing as well as the pinion, even though it doesn't show on the outer surface.
Tony.

[Dhbangham]

That is really useful information, what a great idea using a "really" scrap part to learn about how it is made. I will let everyone know if I attempt to fit a replacement.

[Dhbangham]

I have just read the original patent for this steering box design and noticed in line 35 it describes how the rack teeth vary in profile to help adjust for preferential wear in the centre region over the full lock positions.

[ian Howell]

Another possible area where excessive wear could be ameliorated.

The wear on the pinion will occur mostly at the 'twelve o'clock position of the steering wheel.

Obviously simply turning the steering wheel half s turn before reassembly would take the worn part of the pinion to the '6 o'clock' position. This would place the steering wheel spokes out of kilter but possibly a small price to pay for safety.

It might be possible to cut another keyway in the steering column to correct this.

Anyone tried this?

[Dhbangham]

From memory, my pinion was seriously worn all the way round. I think the steering wheel has been installed in lots of orientations over the years. Good suggestion though, so I will look more carefully next time I take it apart.

[Tony Fearn]

It might be possible to cut another keyway in the steering column to correct this.

I think that it's possible. It seems it only needs drilling rather than cutting a keyway. See photos below.
The positioning of the horn dip switch on the pre-war steering wheel is governed by the position of the screw holes in the steering wheel fixing nut. Various thicknesses of washer will help in positioning it.

010.JPG

012.JPG

Tony.

[ian Howell]

Seems possible then, but maybe tricky on cars with horn buttons on the steering wheel.

OK for 1930 and earlier though?

[Tony Fearn]

The horn and dip-switch looks like this on the early 30's cars.

IMG_0015.JPG

The nut holding on the steering wheel has a bolt-like projection which screws into the top of the column.
The keyway hole doesn't need to be too deep.
N.B. There are two switch sections in the picture to show both sides.
Tony.