After getting my 340 running and driving again I've found the steering to be unsafe to say the least. I knew I had quite a bit of free play in the steering box but this coupled with having power steering and bias ply tires has made it a bear to drive. I've only had the nerve to take it out a few blocks at a time and only making it to second gear. My question is should I have the box rebuilt and stay with what I have or convert to rack and pinion? The rack and pinion seems like the way to go but I don't know what to do about making it power steering and using my original generator. Can anyone give me some guidance on this?
As always thanks in advance.

 

It is impossible to get your Ackermann angles correct with a rack & pinion. You will suffer front tyre scrub every time you turn a corner with Jaguar geometry. I'll post you a pic.




Simple. The front wheels have to turn at a different radius to one another to be accurate.

 

A lot has been written about the conversion to a rack and pinion steering set up and 90% of it is complaints about getting the steering geometry correct.
I have found nothing wrong with the original steering set up on my S type but it has been completely rebuild. The box is tight and all the steering joints have been replaced so there is no play. I also run on modern radials not cross ply tyres. As long as the system is well maintained there is nothing wrong with a steering box set up. Mercedes are still using a steering box on some of their modern cars.

If your steering is to say the least wayward then check for movement in the joints. One joint might move one millimetre but unfortunately there are a least four joints in the steering arms, the steering box and then the U/J on the steering column. If you have one millimetre of movement in each joint which is not a lot you will have 6 millimeters of movement over the complete system. 6 mm is 1/4 of an inch of movement which you will feel. 2mm in each joint which again is tiny and you have got 1/2 of play across the whole system. This is possibly the only reason to go to a rack and pinion system as you are eliminating the number joints and the accumulation of unwanted movement.

 

The top plunging CV joint in the engine compartment part of the steering column has nylon rollers. Wear of these is frequently the cause of play. They are available from Barratts. Check them while you are checking UJ & ball joints. Get a new cover/gaiter & grease with minimum 3% Moly grease. Just 2 circlips to remove to fit new rollers.










These were clearly worn out. Look at the bright scuffing on the steel shaft.

 

Quite a lot of owners have converted to racks, but nowadays there are electric bolt-on systems available where the original non-PS steering box is left in situ. But you say you're car is PS.
It is possible to adjust steering boxes to take up play. Do you have the Burman recirculating-ball box or the later Marles Varamatic ?
Frankly, you really need to check out all the suspension bushes and ball joints, because if the vehicle is as dangerous to drive as you say, I suspect it is not all down to the steering box.

 

Oxendine, get rid of the Bias Ply tires.
The stiff sidewalls grab every rut and hole in the pavement, it's like herding cats down the road.
The soft tread makes this even worse.

I say this from experience going from bias ply to radials on my Bentley _ the car was just awful to drive.

 

The only bias ply tyre that I could half live with is an Avon as made for Aston Martin. There is a certain synergy there. They were designed to work together. When Dudley Gershon was Engineering Director at Aston in the DB4/5/6/S era, Aston bought a new Corvette to allow customers to compare handling. They spent their life pulling the Corvette out of ditches. He admits the only thing they learnt from the crude Corvette was how to improve their air conditioning.

 

I agree that with all the joints in the system there will be some movement but I'm talking just turning the steering wheel at rest before anything starts to move I have around 5 inches free play in the wheel. One can see with that much slop the car can't be driven safely.

 

When I bought my Jag it was really bad too, the steering box had been leaking oil all over the rubber steering joints for years and turned them into goo.
Aside from the Bias Ply tires, it's pretty self explanatory to go through the front end and look what's causing the free play, other than the power steering box.

My steering box is nice and tight, but there's very little road feel at all, one has a tendency to over steer as it's very light with no road feel at 60 to 70 mph.
What seems like a sloppy steering wheel, really isn't on mine.

 

I suspect the play is in the joints in the center track rod, not the steering box itself. As mentioned, those are rubber joints and they perish with age. There are modern replacements for the joint that are much better. You're looking for this, but the teflon lined uprated ones.:

 

The problem with the rubber ones too is that people tighten up the tapers without the car in the static sitting position and with the wheels tracking forward.
This goes for the control arms as well.

 

I would not want to drive your car either with five inches of play in the steering.
I think you need to workout where the slop is. You need to be under the car on a four wheel ramp whilst someone is sat in the car turning the steering wheel. Look to see where the parts are turning but the movement is not being passed on. Frazer asked which steering box you have? Is it the Burman type 1 or 2 or do you have the later Adwest Marles Variomatic. Pictures of the Adwest and Burman are below. Generally this is age related so the Burman was used up to around 1966/67 and after this the Adwest was used.
I do not have any slop in my system which has the Adwest but I rebuilt the box a couple of years ago. The Adwest has two adjusting screws that you can tighten to take out any movement in the box. One on the top and one on the side. The one on the side cannot be reached on a RHD car without removing the steering box as it is tight up against the sump. LHD it can be reached.
The Burman box has no adjustment screws and the only way you can adjust them is with shims which allow you to raise or lower the top plate creating pressure on the internals tightening up the slop. If you get to this point though you need a rebuild 9 times out of 10.
All the PAS systems, Burman and Adwest are very light when the car is being driven at speed. They are not like modern PAS systems which have computers which vary the stiffness of the system so they are light at low speeds and stiffer at high speeds. The consequence of this is the Burman and Adwest are very light at low speeds and very light at high speeds and take a little getting used to. I can spin my wheel with one finger at 10 MPH and the same at 100 MPH. The other thing is the Burman has a lock to lock ratio of 4.25 turns where as the Adwest has a lock to lock of just 3.25.

Adwest Marles Variomatic PAS steering box

Burman Type 2 PAS steering box

 

I fitted the Teflon (PTFE) lined ones to my car at the insistence of our local Jagman in Somerset West. I hope they last for more than 5 minutes

 

Oxendine, my advice whether to resurrect your original steering gear or convert to a rack would depend upon how you intend to use the car. If it's to be an occasional Sunday driver I'd suggest you leave well enough alone and try to bring things back. If you intend to drive the car a power rack brings the handling into this century. I've done two conversions. The first was a kit from British Auto (now SNG Barratt) using an XJ6 rack and pump. This worked fine with 185/15 radials and scrub and bump steer were not a problem. My only complaint was the increased turning radius. You should find lots of threads here on the available kits. My other conversion used a narrow rack from the Unisteer folks in Ohio. This would require a custom installation from someone who knows steering geometry (I used some local race shop folks and lots of trial and error), but would get you closer to proper geometry. Here's one of my front tires after 20k miles of hard driving on wide sticky performance tires (i.e., normal, even wear). Also advising not to convert to racing calipers and pads unless you're willing to live with lots of brake dust:0) Good luck with the Jag.

 

Cars that do mainly highway driving need not worry about Ackermann angles. Those that spend a lot of time on the twisties, as I'm forced to do, will severely scrub their front tyres. I can't stand it. It is even audible on a Jag. You can't overcome science & physics with some sort of magic. High profile tyres can get away with more than low profile because of give in the sidewall. Others fart around by running slight toe out.

 

If you want to go rack & pinion go for a centre steer rack and plumb it into the centre tie rod of your existing steering. End steer racks simply can't really work with the Jag set up and maintain Ackermann angles. Change your steering box to another idler arm. The Aussies make just such a device or Opel/Vauxhall.

 

The take-off from the couple of Opel racks that I've seen is from the front of the rack, which makes arranging the brackets to support the rack on the front subframe difficult and complicated. It's a problem with many centre take-off racks as they are often used high up on strut suspension. There may be others that are easier to adapt, but I've not found them. The Aussie rack is a true work of art, totally adaptable and the one to use, if you can afford it.

I think a conventional end take-off rack could be made to work. To achieve Ackerman (yet another case of credit not going to the original inventor) requires a lot more offset between the steering arms on the uprights and the king pin axis of the uprights than our cars have as standard. Whether it's something reasonable or not, I don't know. One day, I'll get around to doing some measurements and calculations ... .

 

There are Opel centre steer racks that are easy to mount & can be made to work. Once again the Aussies do it all the time. My guy has just done one on a Studebaker GT Hawk & it works a treat & Ackermann is correct.

The above Aussie centre steer on Jay's program is a work of art. That's what I would use if I ever changed to R&P. The M & C Wilkinson R&P system sucks.

 

The Chinese solution to Ackermann. It's a long paper and the calculations make my head sore. That gear mechanism alone. Getting too old! I enjoy driving my S Type & will leave it at that. Every joint is new & how many miles am I really going to run up if I keep things correctly lubricated & without play. It's a great car to drive. If I want something more modern I have the Merc.

 

The Hawk series have a chassis and the front cross member is part of it, rigidly attached. The rack can be attached to the longitudinal chassis rails with brackets sitting behind to above the CL of the rack leaving plenty space for track rods attached to a centre take-off on the front of the rack. Geometrically, it may well be possible to do this with our cars. However, unless the front subframe were rigidly mounted, lateral flexibility in the mounts might make the steering feel a bit uncertain. Or perhaps not - after all a lot of racks have rubber mounts?

The original steering gear of most Studebakers is interesting in combining a steering box with a centre take-off of the track rods. I've always been interested in Studebakers, ever since I was given Dinky and Corgi models. I regret that I never found one to buy when I was living in the US.