Steering column rebuild & Rack Fail Safe

 Rolling Chassis, Steering Column  3 Responses »
May 232014
 

There was slight play in the upper steering which was found to be caused by a broken wave washer in the lower bearing components. Otherwise it appeared to be a simple matter of giving the painted parts a fresh coat of paint before rebuilding.

The ignition switch introduced for the S2 cars incorporated a steering column lock and is secured to the steering column housing with a security bolt. The hexagonal part of the bolt is designed to shear at a certain torque. Therefore, once in place, the only way of removing the switch/lock would be to drill out the remaining rounded head.

Steering column components Steering lock security bolt Ignition switch secured

First the outer column shaft needs to be secured into the column housing. The shaft is fed through the upper roller bearing into the housing and then locked into position by the lower bearing. The lower bearing and seat fit under a larger retaining cap and then a series of washers is fitted before the final circlip.

Outer column shaft Upper roller bearing Lower roller bearing

One of the washers under the circlip is a wave washer which provides a spring pressure once compressed. This preload removes the free play of the column shaft within the column housing.

The inner and outer shafts engage on splines so the torque applied at the steering wheel is transferred from the inner shaft to outer shaft and finally on to the steering rack. However the inner shaft can slide longitudinally into the outer shaft to provide a level of adjustability in the steering wheel position. The rightmost picture below shows the inner and outer column shafts at both ends of their adjustability.

Fitting splined bearing race Retaining cap over bearing race Adjustability of column shafts

The stop button screwed into the outer shaft protrudes into a slot machined into the inner shaft, thus limiting its length of travel. A locking nut in the shape of a large black cup (not shown) is attached to the split collet by a circlip. When the cup is rotated clockwise it screws further onto the thread at the end of the outer shaft, compressing the collet and locking the inner and outer shaft together. Similarly rotating it anti-clockwise allows the collet to expand sufficiently, to unlock the shafts and enable the steering wheel to be adjusted.

The photo also shows the two nylon pins that enable the steering column to collapse. If the steering wheel is hit with sufficient force, such as in the event of an accident, the pins shear allowing the lower section of the outer shaft to slide into the upper section. At the same time the lattice structure of the column housing will also compress.

Finally to the trickiest part of the rebuild – the fitting of the indicator stalk mechanism. One which caused quite a bit of head scratching! Although in my defence, this was because one of the critical parts was missing. A previous owner had obviously taken the indicator off at some stage and bodged the refitting.

The missing item was the retaining clip (19). The correct fitting is the two screws pass through both the clip and a packing piece (16) and into the threaded holes in the indicator body. The combination of these two parts ensures that the rotational parts of the indicator are concentric with the column shaft.

The previous owner, Cap’n Bodger, had used the packing piece as the retaining clip as they are fairly similar in shape. However without a packing piece in the correct position, the indicator housing had been pulled too close to the steering shaft.

Over time this had worn down the white nylon ring operating the indicator mechanism. Unfortunately you can’t buy the nylon ring on its own and so the only solution was to purchase an entire replacement indicator stalk unit. However this still wouldn’t resolve the problem of the missing clip, which is no longer available from all the usual suppliers.

Even Google and eBay searches hadn’t found anything so the only option would be to fabricate one based on the packing piece. The completion of the steering column was put on hold for a month or so while I pondered what to do. When it was picked up again, I made one final eBay search, just in case …. a USA auction for a clip had finished two weeks ago although without any bidders.

A speculative message was sent on the off chance they still had the clip. Shortly after came the reply that they did and a deal was done within an hour of contacting them. Result!

Back to the rebuild. The indicator stalk unit (13) followed by the indicator drive clip (9) are passed over the inner column shaft. The indicator packing piece (16) can then be placed in position but the corresponding clip (19) isn’t fitted at this stage as it will be necessary to move the indicator stalk unit and drive clip around to fit other parts. However once these parts are fitted it would be very difficult (if not impossible) to insert the packing piece. I fitted the split collet at this stage although this can wait until the cup-shaped lock washer needs to be fitted.

The packing piece has a small round protrusion which is aligned to fit into the corresponding hole in the indicator unit mounting bracket. This ensures the indicator stalk is at the correct angle once everything is mounted to the bulkhead. (Note: my mounting bracket had two holes and therefore possible indicator angles, I’ll adjust later to the preferred position)

Protrusion on packing piece Hole in mounting bracket Exposing stop button hole

The indicator stalk unit and the drive clip need to be pushed towards the steering column housing to fully expose the hole for the Stop Button so it can be inserted. The raised section of the stop button should end up near to being perpendicular to the column shaft.

The drive clip must then be push away from the steering column until it rests against the raised section of the stop button. This will expose the screw holes for the clamping bolts which secure the drive clip. Once clamped, this will obviously also lock the stop button in position.

Drive clip locks stop button Drive clip bolts & washers Finally the clip is fitted

The clip to lock the indicator stalk unit and packing piece tightly into position can now be attached.

The tab on the drive clip needs to engage with one of the slots in the white nylon indicator ring. Therefore when the column shaft is turned the nylon indicator ring turns at the same time.

A tooth on the rotating nylon ring will then engage with the cancelling arms to automatically cancel the indicator when the wheel is turned.

When connecting up the whole steering column on its various splines, the wheels will need to be in the dead ahead position and the indicator cancelling tooth mid-way between the cancelling arms.

The final components to go on are the split collet (although I had added this much earlier) followed by the large black cup shaped locking nut, which needs to be fully screwed onto the outer column shaft to reveal the circlip groove inside.

Fitting the circlip locks the two together and completes the upper steering column rebuild.

Later the steering wheel & boss will to be attached to the inner shaft. Once the split cone has been located in its grove, the splined steering wheel boss slides onto the inner column shaft until it meets the split cone and the central nut locks everything in place.

Steering Rack Fail Safe

Although the steering rack had been fitted for a while, I hadn’t added the steering rack fail safe bolts. Now the upper steering column had been completed it was time for a complete check of the steering system and fathom out the fail safe set up.

Note: this is only my understanding/interpretation of the fail safe as I see it, based on common sense rather than any qualified knowledge.

Rubber steering rack mounts are used to absorb some of the impact that would otherwise be transmitted directly through to the steering wheel if solid mounts were used. Therefore the ability to steer is totally reliant on in the integrity of the rubber and its bonding to the metal mounting plates.

The purpose of the fail safe set-up is therefore twofold; to maintain a level of steering input if the rubber/bond failed but, in doing so, avoid introducing any harshness to the steering feel that the rubber mounts were designed to remove.

Essentially the fail safe needs to allow the rack to move unhindered on its rubber mounts but to ‘catch’ it and limit its travels if the rubber fails.

Large retaining washers are fitted under the heads of the fail safe bolts. The bolts then pass through holes in the steering rack before being secured to the picture frame.

However retaining washers do not exert a clamping force on the rack and the holes in the steering rack are almost twice the diameter of the bolts. Therefore the rack is free to move on the rubber mounts.
Jaguar used different components for the driver and passenger sides but both are designed to achieve the same result; to stop the fail safe bolt & washer exerting a force on the rack.

Passenger Side Fail Safe – with lock nuts Driver Side Fail Safe – with spacer tubes

On the driver side, spacer tubes are fitted over the bolts. The length of the spacer ensures retaining washers are just proud of the steering rack. The spacer diameter is marginally smaller than the holes in the rack so rack movement is still not restricted.

On the passenger side, lock nuts are fitted to the bolts (or more correctly setscrews) instead of the spacer tubes. The lock nut and Nyloc nut secure the bolts to the picture frame so that the washers under the bolt heads are just in contact with the rack. Again, as it is only lightly in contact, it does not restrict the free movement of the rack.

If either rubber fails, the rack will only be able to move a small distance until the fail safe bolts or spacer tubes come into contact with the edge of the holes in the steering rack.

The question of why Jaguar used different components on each side of the car has been asked many times on the E-Type forum but there’s never been a definitive answer.

My guess, and it is a guess, is that the use of spacer tubes is a compromise between allowing the rack to move freely on the rubber mount and the need to provide sufficient steering input in the event of a failure by limiting its free travel.

The manual specifically states the spacers are to be fitted on the driver side of the car, so regardless of whether the car is LH or RH drive, the spacers will always be at the pinion end of the steering rack.

I suspect, if the rubber has failed, limiting the range of free travel is more critical at the pinion end where the steering column attaches. The spacers would reduce this range considerably. The trade off, in normal use, would be that the spacers are more likely to impact the edges of the steering rack holes on heavier impacts and therefore transmit more unwanted harshness to the steering wheel.

Steering wheel indecisions leads to more work

 Interior Trim, Steering Column  4 Responses »
Mar 272014
 

At some stage the previous owner had fitted an aftermarket 16″ Moto-lita steering wheel. Even though there was absolutely nothing wrong with it, I was toying with the idea of swapping for either a 15″ or possibly even a 14″ wheel, which a number of owners fit to increase the leg room. The steering would also be more direct with the smaller wheels with the obvious trade off being progressively heavier steering around town and parking.

Still, the unanswered question was, how much heavier would the steering become? Finally I decided to stick with my approach of keeping to the standard specification and only making changes once I’d driven it for a while. However, while I was dithering on what to do, I got distracted by an original rather ropey 16″ wheel on eBay. The wood had dried and split beyond repair so it needed to be re-rimmed … as though I didn’t have enough to be getting on with already!

16″ Moto-lita wheel Original wheel from eBay Splits in the wooden rim

The splits in the rim ran almost for the full circumference which made its removal very straight forward. Fortunately there are a couple of people offering replacement mahogany rim kits. The new rims are ever so slightly thicker and so will have the benefit of being more rigid.

Unlike the very early E-Type steering wheels, the aluminium ring is entirely enclosed, in a groove cut into the bottom half of the wooden rim. The two halves are then bonded and a gloss varnish applied to the wood.

Splits made removal a doddle Aluminium section freed Replacement rim kit

The Series 2 steering wheels changed from the polished finished to avoid the reflective surface. I wasn’t convinced I’d be able to get a satisfactory brushed effect and so have decided to go for a polished finish.

The numerous scratches and light pitting in the aluminium section were too deep to be removed by polishing alone. So it was necessary to lightly sand it to remove the blemishes, prior to polishing. Initially 600-grit paper was used and then 800-grit until the scratches had disappeared. It was rather worrying at the start as you tend to question whether you’re making it worse rather than improving things!

Sanding started with 600-grit Followed by 800-grit

The grade of paper was then progressively made finer at each pass, finishing with 2000-grit. The aluminium started to gain an even sheen during the last few passes and then it was ready for polishing.

Fortunately I had a second bench grinder and so replaced the stones with two 6″ polishing wheels; one for use with a cutting paste and one for the final polishing paste. I’m sure it would have been a much more difficult task without it or trying to fit a polishing wheel to a power drill.

Getting close : 1500-grit 2000-grit produces an even sheen After polishing with cutting paste

The polishing cutting paste soon obtains a smooth shiny finish. Once the majority of surface blemishes have been removed, the polishing paste is used to obtain the final finish. The key point is to polish evenly rather than over polishing by concentrating on a specific area. It’s surprising how much heat is generated during the polishing process so there were frequent breaks to allow the wheel (and motor) to cool.

The steering wheel boss was also given the same treatment.

I believe the aluminium spokes were originally protected by a clear lacquer. I used Pro-XL two pack clear lacquer which should provide a tough scratch resistant layer, with both the steering wheel and boss given three coats. The curing time is 24 hours after which it can be mechanically polished.

However, once the aerosol is activated, it only has a pot life of about 24 hours. So it’s not possible to address imperfections in between coats. It was a fine line between getting an uneven orange peel finish and over-spraying causing runs.

I managed to get a combination of the two! Plus a few high spots due to dust pick up and areas where the lacquer flowed through the holes in the spokes and pooled underneath.

The wheel and boss were then rubbed down with 2500-grit wet & dry paper to correct any imperfections, adding a little water to the surface before sanding. A sanding block is a good idea for the wheel to ensure a flat finish.

The lacquer takes on an opaque appearance once sanded so removing areas of orange peel was very easy. Once the glossy low spots had disappeared, producing a uniform opaque finish, it was ready for buffing up with some standard polish. In this case, Menzerna Fast Gloss FG400.

Finally, it was time to re-rim the wheel! A suitable epoxy that had been recommended to bond the rim was Pacer Z-poxy. Several types are available, having different curing times. I opted for the 30 minute variety (PT-39) to provide plenty of time to make any adjustments! Like many epoxies, the resin and hardener are mixed in equal quantities.

To be on the safe side, I chose to tackle it in two stages; first bonding the aluminium wheel into the grove in the lower half and then once cured bonding the top half. The only issue was to make sure the countersunk side of aluminium wheel was the right way round!! Numerous clamps were used when bonding the second half of the rim, alternating between clamping the two halves together and ensuring the edges of the two halves were perfectly aligned.

One of the reasons for choosing Z-poxy was that it can be sanded. However any excess squeezed out by the clamping was quickly removed with methylated spirits. If I were to do it again, I’d not use the clamps to keep the edges of the two halves aligned. Clamping in this way did not squeeze out all the excess epoxy, so there is a slightly more visible join in places. Nothing too disastrous but not perfect.

A better approach would have been to use all 8 clamps to squeeze the halves together a firmly as possible. Any slight alignment issues could then be addressed when the rim is sanded down before the final finishing.

I believe many of the steering wheel restoration companies then apply a hard polyester lacquer to the rim. Although I’ve decided not to go down that route for a number of reasons; it’s not readily available, difficult to apply and I think not as pleasant in the hand.

My preference is just to apply Colron finishing oil to keep the natural feel of the wood. The aluminium spokes were masked off and the wood sanded down with 240-grit and then 320-grit sandpaper.

The finishing oil was then wiped on with a lint-free cloth and allowed to dry for approximately 5-6 hours between coats. Once each coat had dried, the rim was rubbed down with ultra fine Steel Wool (0000) before applying the next coat.

Initially the oil produces a matt finish which progressively becomes glossier as additional coats are applied. In the end I had applied about 12 coats until I had the finish I wanted.

To keep the wheel in tip top condition, it should only be a matter of rubbing down with steel wool and reapplying additional coats. Far easier maintenance wise than varnishes or lacquers.

The downside of finishing oil is that it doesn’t offer the same protection against damage that a hard lacquer would provide. I’ll just have to be careful.

After multiple coats of finishing oil …. the final finish

The final problem was the central E-Type motif (or horn push for the earlier cars – the S2 horn being operated via the indicator stalk). The clear plastic had numerous fissures on the surface and some had propagated to reach the base, causing these areas to lose the gold colouring.

Surface cracks on horn push Comparison: Repro (L) v Original (R)

I’d hoped that it might be possible to repair it, in a similar manner to repairing cracks in windscreens. However my investigations so far have not found a suitable method to repair it. The general consensus on the E-Type forum was that it wouldn’t be possible to repair.

A reproduction motif was purchased as a fall back but I hadn’t noticed the differences between the originals and the repro ones until the moderator of the forum pointed them out; the colouring is more of yellowy silver than the deep gold of the original.

Why they can’t get simple things like this right I’ll never know. Chinese no doubt! So I’ll fit the repro one for now until an original comes up on eBay. Fingers crossed …..

Overhauling the steering column

 Steering Column  2 Responses »
Oct 152013
 

One of the safety features introduced during the production of S1 4.2 cars and carried over to the S2 was a collapsible steering column. The lower section of the steering column housing consists of a lattice structure. In the event of an accident where the steering wheel is impacted with sufficient force, the column’s two upper mounting points are designed to shear and the lattice structure collapse to absorb some of the impact and allow the steering wheel to travel forward.

To enable the column to collaspe, the total length of the inner steering shaft must also be allowed to shorten. To achieve this, the inner shaft is comprised of two sections which are fixed in position by two nylon pins. An impact will cause the pins to shear, allowing the two halves to slide over each other.

The same design is used for the lower steering shaft, connecting the steering wheel column to the rack. Therefore some care needs to be taken when handling and refitting the steering shaft to avoid any heavy impacts and the use of mallets to fully engage the splines!

The steering wheel’s fore and aft position can be adjusted by rotating the large black cup-shaped locking nut to release the clamping pressure on a split collet, thus allowing splined inner columns to slide over each other.

Another difference between the early S1 and later cars was that the horn was now activated by pressing the indicator stalk rather than the E-Type motif in the centre of the steering wheel. I assume this might have been partly due to having to make the steering column collapsible but it does simplify the dismantling.

The E-Type motif is normally held in place by three grub screws in the aluminium steering wheel boss but for some reason a previous owner had also glued it in place! It’s removal provides access to the nut clamping the boss against a split cone located in a recess in the inner shaft.

A split cone is located in a recess in the inner shaft. The central nut clamps the steering wheel boss against the cone.I was surprising how much force was needed to loosen the nut. It was necessary put on full lock and then use an extension tube over the socket wrench handle to get enough leverage.

It’s just as well I didn’t take it off the car as a complete unit as it would have been a struggle without having the resistance of the steering rack at full lock.

As mentioned, the adjustability in the steering wheel position is achieved by two splined inner columns being able to slide over each other. Their travel is limited by a ‘stop button’ which is screwed through the female inner column and locates in a machined slot in the male inner column.

The steering wheel is then locked in place by a splined split collet, which is attached to the underside of the cup-shaped lock nut by a circlip. When there is no clamping force, the male column is free to move on the splines. However, by screwing the lock nut onto the female column, the collet is compressed and clamps the two inner shafts together.

Once the circlip is removed, the lock nut can be unscrewed and withdrawn, followed by the collet. Next is the stop button to allow the male inner column to be removed.

The black cup shape lock nut can be withdrawn once the circlip is removed The split collet can then be removed by sliding it over the inner column splines The stop button which limits the travel of the male inner column within the female column.

The female inner column passes through the indicator mechanism, attached to the main steering column housing by a semi-circular bracket. Automatic indicator cancelling is built into the mechanism by the use of a control striker attached to the inner column.

Removal of the semi-circular bracket securing the indicator mechanism to the steer column housing The indicator control striker is secured by two set of screws and curved washers/spacers

The striker interlocks within a white nylon ring in the indicator mechanism so that the ring rotates as the steering wheel is rotated. Protrusions moulded into the nylon ring hit ‘cancelling’ cams which force the indicator stalk back to its non-indicating state when the steering wheel returns towards the straight ahead position.

All that remained was to liberate the female inner column from the steering column housing. The inner column rotates in roller bearings at each end. The lower bearing is held in place by a retaining cover which itself is secured by a circlip and a number of washers. One of which is a wave or spring washer which takes up any free play and provides a small amount of load bearing capacity.

Once the cover and washers are removed, the splined inner bearing race can be slid off the inner steering column and the roller bearing withdrawn. The outer bearing race is simply a press fit into the steering column housing.

The lower bearing and a series of washers are secured in place by circlip Removal of the inner bearing race and roller bearing

The steering column housing’s upper end cover can be removed by releasing the three small retaining bolts.

At which point the key needs to be turned in the ignition to withdraw the steering lock. This enables the female inner column to be removed.

The ignition switch and steering lock housing is secured to the main housing by a security bolt, which needs to be drilled out in order to remove the lock. The security bolts are designed so the hexagonal part used to tighten the bolt shears, removing the ability to remove it easily.

It’s worth noting that it would be possible to remove the whole inner column as a single unit, even keeping the steering wheel in place, by:

  • Removing the lower roller bearing circlip and withdrawing the washers, cover and inner race
  • Undoing the three bolts securing the steering housing’s upper cover
  • Turning the key in the ignition and withdrawing the entire inner column

This would enable the roller bearings to be replaced without resorting to dismantling the entire steering column.

Steering rack woes

 Steering Rack  Comments Off on Steering rack woes
Aug 042013
 

There wasn’t too much wrong with the steering rack, apart from some splits in the ball joint rubbers and bellows, which could be expected for the age of the car. Externally it looked a bit tatty but there didn’t appear to be any significant wear in the rack and pinion. There was only some very minor pitting in a couple of the rack’s teeth.

Therefore the aim was only to re-grease the internals and re-paint the housing. The pinion end of the housing is fixed to the picture frame via an attachment plate and beneath that is a pinion retaining plate. The profile of the pinion is such that there is a middle section that has a smaller diameter than the outer ends.

The retaining plate has a machined slot in the shape of two overlapping circles matching the two pinion diameters. The larger of which is off-centre. The plate slides over the end of the pinion through the larger hole before it can being centralised once it has reached the narrow section. Therefore the three studs must be removed to enable the retaining plate to be withdrawn.

Pinion attachment plate Pinion retaining plate Removal of sprung plunger

A sprung plunger is used to remove the free play in the rack and is held in place by a cover and circlip. Similar sprung plungers are used to provide sufficient resistance in the movement of the tie rod ball joints in their retaining housings.

Tie rod ball housing Rack, pinion and housing

Unfortunately there was a considerable break between the dismantling phase and finally getting round to rebuilding it. Sufficient time for the rack to be misplaced while in storage and numerous searches failed to locate it.

With time running out, I had little option but to bite the bullet and purchase a new rack and pinion from Kiley-Clinton engineering. I knew I’d probably find the original rack shortly afterwards but the knock on affect of replacement would also be a full rebuild of the steering unit.

The profile of the pinion changed during the production of the Series 2 cars and with it the size of the larger of the pinion bearings. Naturally I had the later type and the replacement rack and pinions are only available in the earlier size. So I would need to replace the bearings to suit and, in a case of shipwright’s disease, it made sense to replace the brass bush pressed into the housing at the same time.

The removal of the brass bush proved rather tricky without access to proper presses. As it’s fairly thin walled it’s difficult to get a drift on to it and I had to resort to a cold chisel to get it out.

I thought it best to get the local garage to press in the new bush and bearings to avoid any further mishaps. How wrong could I be!! They had pressed the outer pinion bearing in as far as it would go until it had reached a shoulder in the alloy housing. This resulted in the bearing protruding into the main shaft and stopping the rack being inserted.

A bearing pressed too far!! Resulting in a protruding bearing

It would have to be re-done so I carefully ground down the bearing casing until it could be removed. With hindsight I should probably have sacrificed the smaller end bearing which would have given access for it to be drifted out.

The brass bushes are made slightly oversized and so it needs to be reamed in order to insert the rack, which should be a snug fit. I had to rely on the local machine shop as I didn’t want to purchase an adjustable reamer for a one off job.

Just as all the components were ready to be rebuilt, I was searching for the gearbox breather when I stumbled upon the long lost original rack. Aaaargh!

Copious amounts of grease was applied during the rebuild. The only two points of interest were the need to shim the sprung plunger to give the correct end float of 0.15-0.25mm in the rack and obtaining the correct resistance in the tie rod ball joints.

The service manual recommends using a spring balance to check that the tie rod only starts to move under a load of 7lbs. It was a rather fiddly process as a large change in clamping force is achieved by a very small rotation of the ball housing. A process not helped by my Heath-Robinson replacement for the spring balance – kitchen scales weights and a bag of flour!