Hello all
I'm new to this forum today.
I have a 1966 3.8 mk2 which has been fitted with the later Adwest power steering box, possibly from a 420 as the cross member and brakes are 420. The steering is stiff and the car wanders all over the place.
​ I believe that the pump on the back of the dynamo is not producing enough pressure, it is the roller type as I have dismantled it, but it is probably meant for the earlier system.
Does anyone have a 1000 psi version available please?

 

Welcome to the group!

I've no practical experience of the Adwest system on the 420, though I have everything ready to install on my Mk2 and have read about it extensively. I don't think it's unlikely that your problem is the pump as the old type pump was used on the S type and later Mk2 cars with the Adwest box. I would check the following:

The box is correctly adjusted for play. There's a screw on top of the box.
The fluid is new and clean. It should be ATF type F, such as Castrol TQF.
The hyraulic pipes to the box are all good.
There is no play in the steering tie rods.
The tie rods are properly centred - the wheels should be adjusted to straight ahead with the box pinned to its straight ahead position.
Tyres are good.
There is an adjustment on the side of the box to balance the application of assistance. That's more complicated, so it's better to try the other points first.

Working on the system requires a good manual. The last version of the factory Mk2 manual and the 420 manual both cover most aspects.

Hope that helps. Cass (Rob) may be along later with more advice as he has the Adwest box in his S type.

 

Hello Peter3442,

Thanks for your quick reply, there's some very useful information you've given.

I have replaced the fluid with ATF and there's no play in the tie rods.

I wasn't aware of the adjustment possibilities on the box or the straight ahead wheel adjustment in conjunction with centering the box. I have adjusted the tracking to normal.

I did read something about the pump for the Adwest system producing more pressure than the older version, they do have different part numbers and are both driven off the back of the dynamo.

Unfortunately, my box is leaking badly so will have to come out for seal replacement, it doesn't look like a simple job due to the difficult access to everything.

Good advice about the pipes, mine look quite ancient. The carbs will need to come off to gain access to the pipes on the box. It seems that the Adwest system is very good when working properly.

I just need to get hold of a later repair manual.

 

https://www.jagstyperegister.com/for...pic.php?t=1038

https://www.jagstyperegister.com/for...pic.php?t=1397

https://www.jaguarforums.com/forum/m...ng-box-255247/

Some of the links above may help. There's someone on YouTube called Britannica Restorations who has some videos on the Adwest Marles Varamatic power steering box as fitted to Land Rovers and Rovers. Simliar steering boxes were used on several vehicles. The external case changes, but the operation is the same.

It is a good system. It's possible to adjust out free play in the straight ahead position; away from straight ahead, the gearing is loaded and play doesn't matter. It was used in a non-assisted form in several sporting vehicles. It's main negatives are that the box is heavy and it was expensive to manufacture. As a retrofit for a Mk2, it has some advantages over the rack and pinion conversions in providing a good turning circle and maintaining correct geometry (bump steer and Ackerman). I started collecting parts for a R & P, but decided this was better and easier.

 

Hello,
the Jaguar Daimler Heritage Trust ( jdht.com ) might have the manual.
I think they still sell manuals in CD.
​​​
if not, Jaguar Clubs of North America ( jcna.com ) might have it.

If not, there is a member of this forum in Australia who sells manuals in .PDF format.

 

Other thing to consider is if the belt is slipping. The original spring loaded tensioner doesn't produce that much tension and under both steering and electrical load it's easy to slip the belt.

 

Welcome to the forum
I have a 1968 S Type which is fitted from factory with the Adwest steering box and the pump on the back of the generator. The 420 had a separate pump running off a belt which is what Jagboi is possibly referring to but if you have the pump on the back of the generator then there is no belt. The 420 pump produced 1200 psi and the original back of the generator pump produces 1000 psi which more than enough especially if you have some leaks.
The Adwest pump is very easy to work on and I did a write up on my service of the box on the S Type forum which you can read here. Adwest Marles power steering box. - THE INTERNATIONAL JAGUAR 'S'-TYPE REGISTER FORUM
You do not need to remove the carbs to remove the steering box but to adjust the box on a right hand car you do need to remove it from the car. There are two adjustment screws one on the top and a second on the side. Unfortunately the one on the side is tight up against the sump and so you can only get to it by removing the steering box. All the information is in my write up with photos at the above link but if you have any questions please ask.
The service kit you can buy from SNG Barrett contains all the new seals you need and inside the steering box there are some nylon bands which I decided not to replace as I had a fear of breaking them and mine appeared to be in good condition anyway. Very easy to take apart and re seal unlike the older Burman box. I have no leaks on mine and it has been over four years since I serviced it.
As Peter has said there are a lot of things that can give you a sloppy feel in the steering. The Adwest can have some play but if serviced and adjusted will become tight again. The adjustments you can make are designed to take up any wear the box might have produced over the years. Jaguar fitted the Adwest to the later Post 1967 cars 240, 340, S type and the 420 but as far as I can find never updated the S Type service manual with details of the new steering box so for information on it you need a 420 manual for the steering box but the original behind the generator pump is detailed in the original Mk2 service manual. Here is a link to a copy of the 420 manual.
chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://www.jagstyperegister.com/images/maintdocs/servicemanual420.pdf
On the Mk2 and S Type there are lots of joints in the steering arms and you only need a couple of mm of wear movement in each joint for it to add up to 10 or 20 mm of movement over the whole system giving you a sloppy feel. Old and worn tyres can also give you an imprecise feel as can badly balanced wire wheels, different tread patterns on each front tyre or different tyre pressures. The one thing it will not be will be your pump. This will either work or not work making the steering feel either very light or very stiff.
Hope this helps.