POST 51 - MARCH 2013 - SCREEN WIPERS

Although my official retirement date was the end of December last year, the reality of retirement is only just starting to kick in.  I continued to help out during the transition up to the end of February but the normal pressures of business are now totally gone - forever, so it's strange to wake with the thought - what shall I do today?  This is even more the case with the car away at the trimmers

First job in the workshop is to take advantage of the space and have a sort out of parts.  A few small items have been mislaid over the past couple of months, but will hopefully appear in the process of reorganising
things.

Long overdue sort out of remaining parts

Since the beginning of this year I've deliberately avoided doing anything that can be done whilst the car is away at the trimmers, so that I would not be 'kicking my heels' for a month or so.  Consequently I have a small list of jobs lined up for the next few week, the first one being to strip and re-con the wiper motor and rack, or possibly upgrade it.



Before starting on this I did some research and looked at alternatives.  The original item has a few downsides in that it is single speed, not self parking and uses a wound field coil motor rather than the later and more powerful / efficient permanent magnet type. Will it still work after around sixty years of inaction, and if so, could it be made to operate satisfactorily in spite of its drawbacks?  With the rack removed I applied 12 volts with a 2 amp limit to avoid any disasters but nothing happened.

Grease is solid due to fifty years of inactivity - no wonder it wont run.

Looking at the almost solid grease in the gearbox this wasn't really surprising so the gearbox was also removed, but to no avail.  Next the end cover was removed then the brushes.  It was clear now that the output shaft was seized solid in its bearing, probably just through lack of use.

Output shaft (other end) seized solid in it's bearing

I left it to soak in a shallow bowl of thinners then turned my attention to the seriously 'gunged' up gearbox.  This was stripped, cleaned and checked for wear.  Once cleaned up, every part looked almost as good as new (as did the motor commutator and brushes).  I was quite impressed by the design detail of the gearbox, particularly the two sets of needle roller bearings supporting the intermediate gear driven by the motors worm gear.

Nicely made with two sets of 15 needle roller bearings to support intermediate gear

 
After an hour or so of soaking, the rotor shaft was free allowing the rotor to be withdrawn.  After a good clean and a coat of crackle finish paint to the motor casing, it was re-assembled and again connected to a 12 Volt supply.  This time it ran beautifully drawing just over 2 Amps without any load.  Increasing the load by slowing the worm gear drive increased the current draw by up to half an amp.  This will be a very useful way to determine the friction created by the gearbox and rack.

Motor cleaned, painted and re-assembled - as good as new

Next the gearbox was added and the current draw remained constant indicating that all was nice and free with little friction.

Gearbox added - no increase in friction

The motor with gearbox attached was left running whilst the rack and wheel boxes were stripped, cleaned and given an ample coating of Graphogen grease.  Again the wheel boxes were in exceptional, good as new condition with no perceptible wear.
The whole assembly, motor, rack and wheel boxes were now reunited.  Initially the current draw was around 0.3 Amps higher but slackening the rack retainers on the wheel boxes brought it back to around 2 Amps.  Playing with the positions of the rack outer casing ends and gradually tightening them up with the motor running seemed to allow them to settle into their preferred location and the 2 amp draw was again achieved.  After a couple of hours running, the current actually settled to 1.7 Amps (20 watts) which I would guess is about right.

Rack and wheel boxes added.  Current settles to 1.7 Amps when run in.

There seems to be an abundance of torque available at the spindles, (I can't grip them well enough to slow them down) and I can't help wondering if the bad rep the original set up suffered from was partly down to poor assembly and lubrication, generating high levels of friction.

The dash board now has the benefit of connectors so is much easier to remove which makes access to the wiper assembly straight forward.  If it transpires that they are in fact hopeless then I will have to look at upgrading.  Local fellow 120 owner Tony Hamnet wrote an excellent article in the January 2013 XK Gazette detailing everything necessary to fit a more powerful two speed, self parking arrangement.  Quite an involved bit of work not to be undertaken lightly but good to know it can be done if necessary.

Uniquely for an old car, my XK140 fixed head has excellent self parking two speed wipers, but I really miss the single wipe facility of a modern car.  In the UK it's as likely to 'drizzle' as it is to rain making a single wipe facility much more useful than a second higher speed.  So one possible side benefit of the original very basic system is that it may be possible to add a second switched supply to the motor via some sort of pulse switched timer relay allowing for a single wipe. With a mere 1.5 secs for a wipe back and forth, getting the timing right might be a problem or even impossible but it could be an interesting and cheap solution.  I'll look into it.  In the meantime it'll be fun honing the skill of switching off at exactly the right moment to neatly park the blades in the right place.

Miscellany
Trimmer John was most adamant about the need to be able to drive the car in and out of his workshop, so the run up to its delivery to him, due to this additional work, was very busy.  I had not intended to install the engine until April and bringing this forward meant not doing a few other jobs.  Consequently I was duly chastised for my lack of preparation.  As the starting procedure was complicated by the battery isolator switch and immobiliser I had written out the order of actions - Isolator on - blip immobiliser - ignition on - choke on if cold - starter button - then - choke off after a couple of minutes.   I explained all of this to John and his response was "all looks a bit complicated - I don't think I'll be bothering to move it after all".
Good trimmers are hard to find so I bit my tongue!

Next post beginning of April

POST 50 - MARCH 2013 - ANOTHER MILESTONE

Finally got round to bringing this blog up to date, around a week late.
Its quite a coincidence that the fiftieth post should also record a bit of a landmark event, the car more or less in one piece being driven out of the workshop and onto a trailer for its trip to the trimmers at Shildon, about 25 miles away.  Never the less its been quite a hectic couple of weeks and things have been far from straight forward.  Making the car drivable took a week or so out of the time I'd allowed to prep it for trimming, so a little help was organised for a couple of days in order to achieve the deadline.  Trimmer John is a busy lad with a queue of work lined up and if I'd missed my slot, it would have made a mess of both our schedules, hence the need to get it there on time.


The biggest single problem was the attempted fitting of the windscreen pillars (which would allow the hood to be made and fitted). The original pillars were missing but I had acquired a set of three new ones and foolishly imagined it would simply be necessary to bolt them in place.  The side pillars are bolted through the bulkhead into threaded plates, again missing, so I made these up from heavy bar, and with great difficulty and much cussing fiddled them into place using a pull cord. After endless hassle I eventually had the side pillars bolted in place and offered up the windscreen glass to check for fit.

Trial fit of screen glass (without chrome surround)

 The passenger side was not too bad, but the drivers side was way out.  This initially looked like a major disaster until I realised that relatively small tweaks of the fixing points moved the pillar significantly in whichever direction required. The rearward slope for example could be easily changed by several degrees which probably accounts for the badly fitting side screens and loose hoods I've seen on several other XK's.
I do have the original side screens which are due to be re made at the trimmers, and will ultimately dictate the correct angle for the pillars, along with the glass and hood front frame, which will then dictate final position.  The upshot of this is that the hood will have to be tailor made later once the doors and sides screens are in place.
I can remember a similar problem with my Daimler Dart (SP250).   I eventually got around to fitting the hood just before I sold it.  In the preceding twenty odd years of ownership, I often used it as a daily driver which meant that my kids eight mile trip to school was spent scrunched up under the tonneau cover when it rained.

Fitting the engine back in went very smoothly and exactly as planned but did involve two hoists and three men.

 

The pictures above give a general idea of the sequence.  Using a pair of hoists gives very precise and easy control of the angles required to install the engine with the gearbox attached.  It was also necessary to temporarily remove the round tie bar that normally sits just in front of the radiator.

The conversion to a five speed gearbox meant that the gearbox cover would require some modification to accommodate it's slightly different dimensions.  Fortunately the gear stick is in exactly the same place so nothing too major.  Playing around with cardboard, I worked out the general shape of the extra bit, then cut this out of sheet aluminum. 

Gearbox cover mod ready for folding

Check for fit

Pop riveted in place and 'Dynamated'

Folded and pop riveted to the original, then covered with Dynamat, it's slightly different shape when fitted with a leather gaiter and carpeted and  should be hardly noticeable.

Floor and boot boards were cut out from 12mm Marine Ply, given three coats of exterior black varnish on the underside, then stained and wax polished on the top side.

The original heat shields between the silencer and floor boards were made from asbestos and one of them was missing.  As an alternative I used Duratec 750 Insulation Board which is a 6mm thick asbestos free calcium silicate plate. (RS Components Stock No 248-4630)  Expensive but very high spec, which it needs to be given that the silencer is around two inches (50mm) below the marine ply floor boards.

Aluminium extrusion with Rivnuts inserted to hold heat shield

Heat shield in place - sits about an inch above silencer!

So, with numerous other small jobs completed, oil, water and petrol were added.  The ignition and choke wiring was jury rigged and the flannelette sheets stripped off.  Then finally and unceremoniously, it was started and for the first time in fifty years moved backwards and forwards a few inches under it's own power.

Just needs doors fitting

Monday March 4th - Doors were fitted and it was driven out of the workshop and and a few hundred yards up and down the industrial estate road, but with great care as only the hand brake was functional.  Geoff arrived bang on 10.30am and it was ensconced safely in John's workshop at Shildon by 11.30.

JPEG from Geoff so small image

Next Post - Mid March   (won't be late!)