Washer under Nut Rocker Shaft XK 120 Steering Box

Working on my Burman Steering Box. I found a Washer underneath the Nut that holds the Drop Arm to the Rocker Shaft. It’s a special washer to hold an O ring or similar. Cannot find this washer anywhere in the XK 120 SPC. See pic below with the washer upside down to show the place for the O ring. This washer was heavily corroded.

Am i right in assuming that this is a later addition from e.g. the Mk 2 (like Washer Jaguar code 6428) probably used in an attempt to stop oil leaking via the Rocker Shaft? But the XK 120 has an Oil Seal in that position which makes another O ring unnecessary.

Bob K.

Certainly this was not found on my Mark V nor XK120, and in fact I can’t see it working on either as the splines show between the steering box and the pitman drop arm.

Same here. No such washer on my march '53 120.

Thanks Rob and Mitch. I leave it out then during assembly. Bob K.

Today I assembled the steering box which is a nice exercise to remain patient under all circumstances! But in the end all the balls remained in the races (with lots of grease) and everything turns fine. I also understand now why there was a washer under the nut (see above) as even with the nut fully tightened there still was some play. An extra (standard) washer secured that the Drop Arm was now fully tightened.
I then tried to fit my steering wheel onto the splines of the Inner Column but only got a few inches and not any further. I remember that the steering wheel was stuck/corroded when I took the system apart and it was very difficult to get it off the Inner Column.
I understand that I have to clean-up the splines (see photo) and also saw that some people recommend using a screw thread file. But what are the dimensions of these splines?

I saw somewhere that the XK 120 Inner Column measures ⅞” in diameter over the section where the splines are. Someone else mentioned 48 splines in total. Is that correct?
That would imply that the (circumference divided by 48) distance between the splines is about 18 TPI or just a bit over 1.4 mm.
Does anybody have better figures or even a better idea to clean these splines?

Bob K.


Couldn’t you just use some penetrating oil or WD40 and whatever the Netherlands equivalent is of a “Scotchbrite” pad? The oil would help loosen the rust and the pads are not very coarse so would not damage the splines I wouldn’t think.



Thanks for your quick reaction.
I’ve sprayed the splines with this new type WD40 Special Penetrating oil and waiting to see what has happened tomorrow morning.
To make life easier: the Netherlands equivalent for Scotchbrite is Scotchbrite (the dream of every multinational is having only one product name all over the world), but I wonder whether I can really reach the bottom of the spline with these pad as I guess that it’s the bottom of these (60 degree?) splines that cause the problem. But I will give it a try first thing tomorrow.

Bob K.

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In that case I would use a brass brush

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If you mean there was play in the vertical rocker shaft, there is a spring loaded adjuster screw on the top cover for adjusting the play. You shouldn’t need a washer between the box and the pitman arm.

For the steering wheel splines, I would use a stainless steel wire brush. I use them for everything, buy them by the case, McMaster-Carr 7206T4 $17.64 for a dozen.

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Thanks for your advice guys: have a lot of steel brushes but none in SS nor Brass, so will get some.

Rob, the play was between the tapered spline of the Rocker Shaft and the Drop Arm. The Nut didn’t come far enough to get the Drop Arm fully down: by adding a washer everything was solved (see pic). I’ve adjusted the axial play of the Rocker Shaft according the manual.

Bob K.

Cleaning of the Inner Column spline worked perfect, however best results not obtained with the brush but by using the thread file (see pic).

At the end of the file is a shorter piece where the (18 TPI is correct) profile is perpendicular to the rest. This was a great help and I could clean-up every spline down to the bottom.

The steering wheel now slides all the way down and can even by held in position with the Locking Nut.

Bob K.

Ah, ok, must be a different variation. Mark VII had shims there.
My Mark V does not.