Adwest Marles power steering box.

[cass3958]

Taking my Adwest power steering box out as I have a small persistent leak and as I am still in the Corona Virus lockdown and can't use the car thought this was a good time to do it.
I will post my workings as I go along but has anyone got a workshop manual showing the Adwest. All my blue books just show the Burgman types 1 and 2 so I need a manual showing the Adwest if anyone has a copy please.

PLEASE DISREGARD THIS POST AS I HAVE NOW GOT A COPY OF THE JAGUAR 420 MANUAL WHICH INCLUDES THE ADWEST STEERING BOX.

[cass3958]

Today I removed the Adwest Marles power steering box from my 1967 S Type.
All the blue S Type workshop manuals I have only talk about the Burman type 1 and 2 boxes and there is no mention of the Adwest Variomatic box. Taking the box out is slightly more complicated than the manual states and possibly different because it is the Adwest not Burman.
Because the Adwest is not mentioned in the S Type Blue manual I bought a downloaded copy of the Jaguar 420 manual which does cover the Adwest steering box but the method of removing the steering box has not altered from the S Type to 420 manuals. They both lie. Hardly any of what follows is in the Manual as it makes it sound very easy by undoing a couple of bolts and then the fairies lift it out for you. Not so.
First job is to get access to the box and the hydraulic pipes by undoing the inner steering tie rods and the steering box drop arm bolt allowing the steering arms to drop down out of the way. Second was to drain all the power steering fluid which is not entirely possible and you will have power steering fluid going everywhere so have plenty of paper towels ready to mop it up. There are two metal hydraulic pipes running across the back of the subframe from the PAS pump to the steering box which I removed at both ends and allowed the fluid to drain in to a catch tank but it just kept on dripping all the time I was working on the box. Removing the pipes allows you to get a socket on to the three ½ bolts (not four as the manual states) that holds the box to the subframe. One long two short.
Now the hard part.
To remove the box (Which comes out the back of the subframe) you have to disconnect the lower steering column pinch bolts. The manual states “Remove the top pinch bolt securing the steering column upper universal joint to the inner column. Pull the steering wheel and inner column upwards to clear the splines from the universal joint splines.” In reality it is not as simple as it suggests. First the oil filter is in the way and could be removed but instead I managed to undo both upper and lower pinch bolts on the lower column but as the steering box has no forward movement only to the rear compressing the lower steering column on to its splines, you cannot slide the splines off the column. It states you can pull the steering wheel up to release the splines but it does not mention that you cannot do this until you have undone the two nuts holding the column in place under the dash, disconnected the Autobox selector arm and the four bolts securing the foot of the column to the bulkhead behind the brake/clutch pedal. Only then can you pull the steering wheel far enough up towards you to give you enough room to remove the lower steering column from both splined ends. If you leave the lower column attached to the steering box you cannot remove the box and lower steering column together without removing the oil filter. So four hours later the steering box can now be withdrawn from the subframe. It is very tight and heavy so be careful.
Tomorrow I will take some photos and add them and start to strip the oil seals from the steering box for replacing.

[John Quilter]

Just checked my official factory REPAIR LABOUR SCHEDULE (issued January 1966) and the published time, probably for the Burman unit, is 2.5 hours to remove and refit. I'm guessing a bit optimistic. And then, only an additional 2.0 hours to overhaul after removal.

[Glyn Ruck]

Rob ~ Just remember when re installing drop arm 33 that there is a crucial centering procedure with the Varamatic due to it's variable ratio off centre. Also Varamatic has a fixed length centre tie rod with adjustable left & right tie rods for adjusting toe. Opposite to Burman boxes where toe is set on the centre tie rod.

PS Box Varamatic.PNG (156.47 KiB) Viewed 4429 times

[cass3958]

Thanks guys.
I have no intention of stripping it down fully, just enough to change the seals. I have done the steering column seals but cannot at the moment get the drop arm (33) off the box to get to the seals under the arm. I have broken one set of pullers, snapped the toe of one of the legs clean off under pressure, so I have now bastardized the puller to work another way and I have tensioned it up and will now leave it possibly over night hoping to ease it off. I have marked the arm with punch dots so I can get the orientation correct on reassembly. If I cannot get the arm off with this puller I have ordered a new heavy duty set which will arrive Wednesday or Thursday. Cannot just go out and buy one as it is not essential apparently during the Corona lockdown and it is Easter weekend so no one is working on line either.
2.5 hours is very optimistic. It takes me that long to get my tools out and to put them back after.lol. Maybe if you did this everyday and knew how it was supposed to be done then maybe but the blue book is very misleading as it does not cover all the preparation work you need to do, releasing the steering column, hydraulic pipes, oil filter and steering arms. Putting it back in by myself will be fun trying to line up the lower steering column with the upper steering column through the bulkhead. Might have to get one of my lads to help there.

[cass3958]

OK my intention was just to replace the seals with minimal intrusion in to the steering box but as I went along I found this was impossible.
The new kit of seals comes with all sorts. There are seal kits for the two splined drives called the Worm drive and the Sector shaft which are what I wanted to replace as these are the two that are possible or more likely to leak. Then there are three large seals for the top cover, Cylinder cover and valve housing. There is also a replacement seal for the adjustment plug and hydraulic nipple inserts which I had no intention of using.
To strip the old Worm and Sector shaft seals out I found it necessary to remove both shafts. The drop arm eventually came off after tightening the puller up a little bit at a time for a couple of hours. With the drop arm off the splines I was then able to get to the seals. With the splined ends still in the seals it does not allow you to get behind the seals to pull them out. A partial strip down was required so I started with the Valve cover. Remove the hydraulic pipe at both ends then four bolts and the cover comes off. New seal on the inside of the cover and the shaft seals removed and replaced after the circlip is removed. The splines are a smaller diameter than the internal diameter of the seal so there is no need to cover the spines when fitting the two seals. The Worm does not come out and is left in place. The book says check the Teflon rings and replace if required but I doubt that is something I could do but a visual check was made and they appeared to be fine. What I did notice as I tipped out the remaining steering fluid was 1. That the fluid had a lot of very fine metal sparkles in its colour and 2. It appeared the fluid was also contaminated slightly with water. The first was disconcerting but as I will explain further not a problem and the second was possibly due to the fact the steering box had never had a full service before, still had the original seals and possibly apart from being topped up, the same fluid, so 50 years of moisture ingress.

Metal glitter in fluid 2.JPG (2.53 MiB) Viewed 4358 times

Valve housing back on with new seal and the Top cover was then removed. Four bolts and the cover comes off with the sector shaft attached. With the shaft out you can get to the sector shaft seals. These are the ones which are more likely to leak than any others due to the fact that the splined shaft is a larger diameter than the internal diameter of the rubber seal. The seals are held in with a large circlip which requires a large set of heavy duty circlip pliers which I did not have. Mine broke after half an hour of attempts and I had to remove the centre rivet on the pliers and replace it with a nut and bolt to stop them twisting. Finally got enough purchase to allow me to get a small screw driver behind the circlip and ease it out. Possibly took two hours to just get this circlip out, so much for two hours to strip the whole box. With the circlip out the old seals were removed but I did not at this point put the new ones in as I wanted the shaft to be in place before the seals as I will explain.
With the shaft out I decided to bite the bullet and remove the cylinder cover, piston and rack as there is a seal inside here. On the end of the cylinder cover there is a large spring ring. To remove this there is a small hole in the out cover which you place a small centre punch and hit it lightly with a hammer. The punch knocks the end of the spring ring out of the groove and with a flat bladed screw driver you can ease the rest of the spring ring out.

punch and metal spring ring.JPG (2.89 MiB) Viewed 4358 times

To remove the cylinder end plate cover it says you pull it out with a pair of pliers. I used a pair of Mole grips as it was quite tight.

Mole grips on Cylinder cover.JPG (3.53 MiB) Viewed 4358 times

The cover comes off with the seal which is replaced. Inside is a piston and by inserting a bolt in to the head of the piston you can slide it out of the bore with the rack all attached.

Piston and rack removed.JPG (2.4 MiB) Viewed 4358 times

There is a small metal domed thrust pad which will fall out. This sits behind the plug screw on the side of the body which is the next thing to remove. There is a small Allen grub screw which you remove which allows you to turn the plug with a large screw driver and remove it. There is a seal on the plug which is replaced.
Looking inside the housing all that is left is the worm shaft which I left in place but further inspection showed where the metal sparkles had come from. There are no fast rotating parts in the mechanism of the steering box just the worm shaft that rotates 3 times from lock to lock, the sector shaft that turns through 45 degrees from lock to lock and the piston which moves two inches from end to end and they are all in a bath of steering fluid so wear should be minimal. On inspecting the Worm, Sector and rack there was literally no wear to be seen but what I did notice was the bottom of the three teeth on the sector shaft had been touching the inside of the steering box causing a slight groove in the casing. This has possibly been caused by an over tightening of the adjusting bolt on the top of the Top cover forcing the sector shaft lower than it should perhaps sit. No damage to the sector shaft as this is hardened steel and the housing of the box is soft cast iron.
At this point I washed the box out with white spirit. A liberal slosh of White spirits in the top, A good swirl round and a minute to soak and then poured back out cleaned all the detritus out.
To reassemble you first need to put the piston and rack back in to the cylinder and push it in so it sits 42.5mm or 1.675 inches from the mouth of the cylinder. This centralises the three teeth in the housing. If you leave the bolt in the piston it will let you wiggle the piston in the cylinder a little. Next turn the worm gear spline until it is set to centre using the round plate with the slot which sits over the spline and line the slot up with the hole.

steering centralising washer.JPG (3.82 MiB) Viewed 4358 times

Next lower the sector shaft in to the housing having changed the seal. There is only one way it will go, so the three teeth match up with the three teeth on the piston rack. A little wiggling is required. Once all three are in place I tested the steering from lock to lock to make sure everything was central and lined up. I placed the domed thrust pad in place and lightly tightened the plug to keep it in place. The purpose of this plug and thrust pad is to adjust the distance between the three teeth on the sector shaft and rack thereby taking out any slack feel or movement you might have between the worm drive shaft and the sector shaft. The lock nut adjuster that caused my wear on the inner casing is also used to adjust the sector shaft roller down in to the groves of the worm shaft eliminating any other movement in the box but I will come to adjusting all these at the end.
With all the shafts and rack in place the top cover can be tightened with its new seal.
Next replace the cylinder cover with its new seal and metal spring ring. To refit the ring just place one end in the grove and tap it in to place with a hammer.
Now you can fit the new seals on the splined shaft of the sector shaft as stated are smaller than the splines and if you try and push the seals over the top of the splines you are likely to damage the inside of the seals and they will leak. This is why the seals are replaced once the shaft is in position rather than fitting the seals then forcing the splines of the shaft through the seals. To stop the splines damaging the seals I wrapped the splines in black pallet wrap clingfilm and then coated it with grease. Now the rubber seals will slide over the clingfilm into place not touching the sharp splines and the clingfilm can be pulled off the splines once the seals are in place.

Clingfilm on splines.JPG (2.65 MiB) Viewed 4358 times

The nasty circlip was replaced and all was good to go.

Large circlip on bottom of Sector shaft seal.JPG (1.94 MiB) Viewed 4358 times

The drop arm was replaced. There are a couple of grooves in the splines of the drop arm which only allow it to go on in its correct orientation. The hydraulic pipe was replaced and I used PTFE tape on the threads to seal them.
To check the play in the box and adjust it the book says you need a torque wrench that will measure 4 ft lbs or it also says “Using a torque wrench or just by “feel”...” so I went by the “feel” method. With a set of mole grips on the worm shaft splines and the drop arm I was able to turn the box from lock to lock. I then tightened up both the top cover adjuster for the sector shaft to worm shaft and the plug screw to adjust the distance between the three teeth of the sector shaft and rack until I could feel some resistance in both and then wound them back a fraction each eliminating all gaps but not restricting any movement.
Final check everything was tightened down and the box is ready to fit back in to the car.
All the above is for the Adwest Marles Variomatic power steering box which is fitted to the later S types from around 1967 on. As far as I am aware this PAS system is not covered in the S Type blue manual but I have got hold of a digital copy of the Jaguar 420 manual which used this box. I have forwarded a copy of the manual to David and have asked him to attach it above in the maintenance documents. The PAS system is covered between pages 191 and 204.
Now to refit the box back into the car.

[Glyn Ruck]

Great write up Rob! I helped a friend do one on a MkX/420G many years back that was leaking. Sounds as though there might have been some minor improvements over time or maybe it is just my bad memory. I remember us having to go through a centering procedure for the variable ratio but that might just have been the 3 tie rods to keep things centered while adjusting the toe/wheel alignment. I thought it was locating the drop arm correctly on the output shaft.

Varamatic was fitted to the MkX/420G earlier than other models.

[cass3958]

Thanks Glyn trying to keep busy whilst being in lockdown.
Before removing the drop arm from the spline I made a couple of punch holes one on the arm the other on the bottom of the threaded spline so I knew where the two should sit on rebuild. I used a puller to remove the drop arm but I left the nut on the thread so it would not fall of and all be lost. When I did take it off I noticed that there are two flats, the size of two splines so there is only one way the drop arm can go on the splines. As long as you centre the worm shaft and the three teeth of the sector shaft match up with the rack everything goes back in quite well.
I will be fitting the box tomorrow but dreading trying to line up the lower column with the box and steering wheel to get everything straight in the dead ahead. Might have to call on the wife to hold the steering wheel for me.

[Glyn Ruck]

Some commentary on what Jaguar calls the Varamatic Steering & others the Variomatic that you may find interesting.

Marles Variomatic Bendix Power Assisted Steering was the complete & correct name according to Taylor.

Varamatic Steering..JPG (202.22 KiB) Viewed 4326 times

Courtesy of James Taylor.

[cass3958]

Interesting reading Glyn I have the Taylor book which has lots of facts with some degree of inaccuracy.

My car with its original Adwest Marles PAS system was manufactured in September 1967 although not registered for the road until February 1968. According to the chassis numbers it was not the first to be fitted with the Adwest so Taylors dates are slightly out here. Maybe there was a crossover in the parts bins.

I mentioned at the beginning that the blue manual states there are four bolts holding the box to the cross member but mine only has holes in the steering box for three although there are four threaded holes in the cross member, presumably left over from the Burman box fittings.