I’m in the process of refurbishing a front subframe brakes and steering from a 420 that I bought that I will fit to my 1966 S Type, which is in the process of a full restoration.

I’ve got to the Varamatic steering box and am just investigating what to do with this. I have read Cass posts re replacing the seals and a few other things including the stuff in the 420 manual. The box is of course extremely dirty and covered in oil so the first job is to clean it up a bit.

I’ve read the 420 manual and particularly the centering procedure. Looking at the box I think I might have a problem. The centering washer with the notch on the input shaft arrowed in the sketch below moves freely around the input shaft. It’s not caught on the splines of the input shaft. It does catch them if you pull it slightly away from the steering box towards the steering column. I’m assuming that this washer should be caught on the splines and not rotate freely? There doesn’t seem to be any end float on the input shaft. I would welcome any comments.

 

The Centering is obviously crucial to maintain the Varamatic curve. Toe is adjusted with the side tie rods unlike S Types/Mk2's that are set with the centre tie rod.

Lucky man!. Jaguar call it a Varamatic.

Other than that Cass has said just about everything about a Varamatic that there is to say other than maybe the 420 became the first of the compact Jaguars to have the latest Marles Variomatic Bendix power-assisted steering. Made by Adwest under license in Reading in the UK

The system had actually been introduced on the 4.2-litre version of the Mk X Jaguar in October 1964, and that car was the first production model in the world to have it. It was a natural choice to help distinguish the 420 from the other compact Jaguars, and in due course it would also become an option on the S-types (in January 1968) and the Mk 2 (in March 1967).

The 420, however, would have it as an option from the start of production in 1966. Variomatic was a variable-ratio, power-assisted steering system based on an original design by an Australian, Arthur Bishop, and developed by the Bendix Corporation in the USA for use in cars. Its design was derived from an aircraft nose-wheel gear in the mid-1950s, and Bendix adopted it for production in 1958.

Ran at 1200psi with the Saginaw pump on a 420 and a 1000psi with the Hobourn Eaton on S Types & Mk2's

Replace all rubbers/elastomers before placing in service. Kits are available.

 

The subframe will need modifying to take the Varamatic box. It is in the form of a cutout, which is then covered in with a suitable piece of formed sheet steel welded all round to maintain strength. There was a thread on this very problem last year, I think, so search the forum

 

Hi Fraser,

I have the whole subframe, steering and brakes from the 420, so no need to modify the subframe, it has the necessary cut out

 

Your car if it came out of a 420 has the Saginaw standalone pump.

If it came our of an S or Mk2 it had the Hobourn Easton pump on the back of the generator as before.

 

Paddy from memory that washer with the indent for centring on mine was set on the splines and rotated when the steering rotated. As you have read this is how you set the centering of the box and if yours has been able to rotate freely then it is possibly no longer in the correct position. Again though from memory I seem to remember that on the splines there was an area where two splines were joined giving a marker where the washer could only go on to the splines in on place as there was an area on the washer where two teeth were missing. I have just looked through my photos and I do not have a clear photo showing this and as I said this is just from memory but as I took the whole thing apart there had to be something to indicate to me where the washer went back on in its set position on the spline.

 

I'm told the full drop arm centering adjustment procedure is in the MkX manual.


General.

 

Jolly good ! So now you just have to refurb the Varamatic box.

 

Do you have the standalone Saginaw pump or the Hobourn Eaton on the back of the generator?

I would check the pumps.

Houbourn Eaton 1000 psi
Saginaw 1200 psi

 

Thanks. Yes my washer will rotate freely and I seem to be able to pull it towards the steering column slightly and it will engage with the splines anywhere! I suppose to find the center of the steering box, it will lie half way between the full left and full right lock? I am going to strip it down and refurbish and replace what I can. Did you use these two kits from SNG?
https://www.sngbarratt.com/English(U...60varamatic%60
https://www.sngbarratt.com/English(U...60varamatic%60

 

Glyn
The pump I'm using is the one the one that came on the rear of my dynamo. My S type has power steering fitted but not the Varamatic unit. So I'm refurbing a 420 front subframe with the Varamatic steering box that I got hold of and will fit that fed from the original power steering pump. I think they will work together as the Varamtic was fitted to the S type using the dynamo driven Eaton pump.

 

That will work just fine. Just need 1000psi at about 1000 engine RPM. Steering at full lock

 

I had the second kit in a box of many things I had bought as a job lot. When I stripped mine down I did not find any wear on the nylon seals/piston rings so knowing how difficult they are to replace I did not even attempt it. I was happy that once all the external seals had been replaced the box no longer leaked.

 

I have found this is the one thing with the Variomatic that I dislike. I have an Auto which at tick over is running at 600 RPM so when stationary the steering is not as light as it is when you are driving. Still assisted but not as smooth and light as it could be. With a manual you can lift the RPM slightly by slipping the clutch to give you the 1000psi at 1000 RPM but with an Auto you can't do this making the steering heavy. Once up and running with more than 1000 RPM the system is great with a small lock to lock and light steering at low speeds.

 

Yes Rob ~ you have mentioned this. The only answer is a smaller pulley on the generator to spin it more quickly. I know you have an alternator conversion but that's no issue. The electronics will handle that for you. I believe that Jagboi has fitted a smaller pulley. I think it was from a specific model E Type. IIRC

 

I will have to look into a suitable smaller pulley wheel as that could make a difference.