1912 Rex 530cc watercooled

It started with a motor, in pieces and in top mechanical condition – apart from a damaged timing side mainshaft thread, the original Bosch magneto and rear engine and magneto mounting plates still in place, the magneto still capable of a really hot spark. The motor had seen use as a stationary engine, but had survived undamaged and pretty much unworn, – much later after the rebuilt machine had been in use for some time, trouble with the big end journal showed up a badly cracked driving side cast iron flywheel, and the whole flywheel assy. was replaced with MSS Velocette flywheels, with suitable modern main bearings and a J.A.P. connecting rod, with a modern INA big end assy. replacing the original plain big end bearing.

New mainshafts were made to suit the new assembly. The 'REX' cast into the drive side crankcase, and 1912 on the magneto drive case cover, posed quite a puzzle in the identification of this substantial watercooled motor, too late to be from a forecar, – and at first glance, too large for a motorcycle!

However it didn't take all that long to come up with the answers, there is little doubt that this model was produced in relatively low numbers, over maybe 2 years, – an aircooled version of the design, probably proving more popular, – I also suspect that the original thermo syphon cooling system and radiator size may have proved inadequate in warm climatic conditions.

It became obvious early on that original parts to restore the bike would be well nigh impossible to find, – true there was a complete bike less engine, including original gas lamps in excellent condition in South Australia, but the owner was fitting a 1911 motor, and in fact there is no reason why these cycle parts may not date from 1911 – the watercooled design dates from then, when a prototype was being developed as a racer.

The only item missing from this otherwise complete bike was the rear engine plates which also did duty as the magneto mounting, and once I decided to fit a gearbox, these plates became redundant on my motor, and have gone to a good home to complete his assy.

A few facts regarding the 1911 motor are patent at this time. – It was originally an aircooled motor, but a watercooled cylinder was available, however it differs from my 1912 motor in regard to the cooling water connections on the waterjacket, – while my inlet is 7/8 inch ID, and the outlet in the detachable brass outlet plate is 1 ¼ inches, the corresponding sizes are smaller on the other barrel by almost ¼ inch in the ID, and this indicates that it is an early item that proved to be lacking in circulation capacity. While the basic design of the 1911 motor is similar, the magneto drive is completely different, using a train of gears, instead of the chain on the 1912 motor. It appears that a complete 1912 watercooled Rex exists in South Australia, but completely dismantled along with some other Rex parts, but the owner will not even allow it to be viewed, so it is apparent that at least 3 of these machines were imported and sold in South Australia – the importers being Gard Brothers, a firm very active in the importation of British machines at that time, including Douglas.

After almost 2 years of investigation, it was apparent that no parts were forthcoming, the 2 speed and clutch, or alternative 3 speed rear hub gear being the most important item. True a massive hub of Continental make, possibly 3 speed and equipped with a brake was available, but it's very rusted and siezed state did not appeal to even me! so my idea of having a nice veteran outfit had to be modified somewhat, – this decision was not taken lightly!

A suitable 3 speed gearbox of a later date was found, and it was immediately obvious that the magneto would have to be re-located above the gearbox, and when the approx. 40 degrees of rotation of the magneto drive chain covers proved possible, – the project was away! New rear engine plates with the magneto mounting on the right hand plate, actually became an improvement on the original mount, in which only the 2 drive side mounting studs were used, and could not have been all that good, – while access to the 4 bolts now used is difficult, a special spanner has been made and the mounting is now very solid.

A badly rusted frame from a 1913 (?) Humber was found, and the head stock lug being useable, this was recovered by machining out the remains of the old tubes, but the lug had to be lengthened by 1 inch to provide better placement of the radiator, and to match the front fork spindle centres, which are 1911 (?) James and were found attached to a wrecked frame at a swap meet. These were fitted to the newly built frame with new spindles, bushes, and new lower links, and a much better, ( and longer) head stem that was used after repair and modification. The biggest overall problem was to build a frame to accommodate a large heavy watercooled 530 cc motor and radiator with the necessary thermo-syphon requirements.

It was decided that a reasonable front brake was required for today's traffic conditions, and a BSA front hub was squeezed into the forks, this led to the necessity to make a 'reversed' lever from chrome steel, as normal reproduction levers bent to the bar without any sign of braking effect!
Modern sealed bearings, (suitably disguised) were fitted to all 3 wheels, the sidecar wheel hub being the only real veteran item, – the rear wheel hub was built up from 'scratch', a split rear brake drum from an early Velocette KSS being the basis for the contracting band rear brake, this is connected to the right hand foot brake pedal, which was reworked from a 1937 Chevrolet brake pedal, clevises and pins for brake and gear linkages originated in an early Ford 'Prefect' mechanical brake linkage.
A lug was fabricated from MS plate to accommodate the gearbox, which has a 2 bolt top fixing, – and this was provided with tubular lugs to match the seat down tube, and rear engine plates. The rear part of the frame was fabricated with heavy gauge 13/16th OD tube, the axle and brake anchorage lugs being 3/8th MS plate, the general design was copied from a 1913 Clyno owned by a mate. This assy. bolts up to the seat and gearbox lugs.

It became apparent that early gearbox frame designs, had a tendency to be weak in this area, – The remains of 2 James frames of this vintage had badly broken, (and several times repaired) gearbox lugs of a similar design. With this in mind I bolted an additional pair of flat braces to fully triangulate the rear of the gearbox lug to the top seat lug, and I fabricated a toolbox of modest capacity to cover these braces, and supplement the original type toolbox on the rear carrier, both these last mentioned items were the only exact replica's of the 1911/1912 frame, but the frame design was in fact as close as I could possibly get to the original, apart from the gearbox lug. In fact Rex built an almost identical frame in late 1912 for the REX/ JAP which was assembled for the Premier Company, and had a 2 speed gearbox.

The rear stand was fabricated in the style of the period, by using round tubes flattened in the press to a somewhat oval shape, pivots were fabricated from 3/8th plate, and provided with 'props', – front stand is ½ inch OD round tube. Both stands provide stays to the veteran type guards.
An early decision to use beaded edge tires on the new old stock rims that I had, was scrapped in favour of using up a supply of new 2.75 x 19 tires that I had on WM1 rims, this did reduce the ground clearance a little, but as an outfit this was not considered a problem, evidence of numerous groundings on the underside of the crankcase indicates that the ground clearance was less than adequate on the rough road surfaces of yesteryear!

A radiator of the correct square tube pattern was donated to the project by my now well known South Australian Rex owner! he has the correct radiator that fits his frame with his collection of parts, and the one that has been given to me is quite a mystery in that the maker's plate (Pendletons) identifies it as 1911 or later by it's dated patent plate, and while the core area is larger, it's unique design and dimensions and fittings certainly make it an improved REX item.

I have managed to retain most of the core area in the construction and repair of the new radiator, some core area had to be sacrificed due to damage, but so far in use the cooling is exceptionally good, deliberate attempts to raise the temperature to boiling point by running the motor at a standstill, and running with a deliberately retarded spark, indicates that the cooling system is more than adequate. The gearbox lacked a clutch, but a wrecked 50s Ariel item was in the junk box, and this was repaired and modified to fit the tapered and keyed gearbox mainshaft, this has proved to be a very sweet clutch, with a 100% no drag release, and very smooth take-up. A 7 ½ inch PCD x 1 inch width solid drive pulley was made, and riveted to the remains of the machined drive sprocket, it too retains it's original tapered shaft and 2 keys.

Cast aluminium footboards and mudguard blanks came from our VandV Club Spares scheme. I made the combination primary chain and belt cover which is in 2 pieces, an upper and a lower, the top half is easily removed in seconds by one ½ inch nut at the rear, and a ¼ inch bolt at the front, a rubber 'bung' is provided to check the condition of the primary chain. Rear wheel removal is effected by the removal of four ¼ inch bolts, 2 in the rear guard, and 2 securing the carrier, this with bike on rear stand, the contracting band brake anchorage assy. is loosened, and the wheel is then lifted out after removal of spacers and knock out axle which is 'disguised' to look like a veteran axle /securing nuts assy.

The original machine used a straight exhaust pipe flattened at the end, which is well past the rear axle, but I found that the exhaust was uncomfortably loud, especially for the sidecar passenger. Drilling 3 rows of holes in the outer rear of the pipe did little to quiet the note, so I decided to fit an expansion chamber on the inside of the pipe under the gearbox, – this is the depth of the pipe, 4 inches wide and 14 inches long, it is welded directly to the inner surface of the exhaust pipe, with 3 large holes drilled through the side of the pipe, and this has reduced the sharp crack of the exhaust under load to a quieter more subdued note.

The petrol tank is of welded steel zinc sheet construction, with a completely separate oil tank, – also welded, inside, it is retained to the upper surface of the petrol tank by riveting and soldering around the filler and oil pump holes, it's base presses against the inside bottom of the petrol tank, in several places to prevent movement and possible vibration. Petrol capacity is 2 gallons, and 2 pints of oil. The hand oil pump is new, bought many years ago from War Disposals, and could date back to the 20s or further, it is a heavy spring loaded pressure feed, regulated by an adjustable numbered valve. Although made by 'Enots', it is not branded as such, carrying only War Dept. stampings.
I have equipped the oil outlet with a sight glass made from a medical syringe. The petrol tank is made with a soldered in section in it's base for about half it's length, this to gain access to the inside should it ever become necessary. The tank is mounted on the underside by 4 bolts and 8 rubbers. The bolts are wired to prevent loss.

Handlebars are an exact copy of the Clyno's and are 1 inch OD, handgrips are made from old naturally seasoned timber. The carburettor and controls are B&B of the correct vintage, and had in fact been fitted to the 1905 Rex that I had previously restored.

Manufactured cane sidecar

The sidecar chassis was built with some recovered Vet. lugs, and some brand new old stock items as well as a couple specially made to suit the design. The springs are original Vet. but badly rusted in places, however, as they had to be reshaped, involving cutting and welding, the bad areas and welds were able to be hidden and placed where there was no strain, the design involving the straight section of the springs to be clamped rigidly to the sidecar frame tubing.

Sidecar attachment fittings and a very neat mudguard mounting bracket, are NOS from my South Australian benefactor, rear fitting is by one 5/8th. Bolt through an adjustable clevis to the bike's special rear axle lug. Sidecar wheel has a couple of inches lead on the rear wheel, and 'toe in' is approx. 1 inch at front wheel axle. Top link is a straight 1 inch tube from the sidecar axle clamp to the bike seat clamp lug area. An extra brace approx. 8 inches long from the front of the S/C chassis to a front engine plate fitting supplements the upper front anchorage below the headstock, in a similar manner to popular modification of the era.

The sidecar chassis is in fact a very close copy of the genuine Rex sidecar chassis of the period..
The sidecar body is set upon a light ( 1inch) angle iron frame, which incorporates the spring attachment points, pivoted at the front, and with shackles at the rear, which became a necessity to set up the bodywork correctly, I even found that I had to shorten my original 'shackles', when the weight of a passenger, proved too much for the 'pram' type springs.

To the frame is bolted a 5/16 inch marine ply base in 3 sections, with a built in 'glove' compartment behind the passenger's legs and under the seat, this is fitted with a sliding plywood door. The ply is drilled around it's outer edge at 2 inch intervals to take the cane 'verticals' the number of holes overall must be 'odd', – the reason for this becomes obvious when you start to weave the bodywork! To this I have constructed what is little more than an open generous reclining chair.

Weaving the bodywork was an interesting venture, but building a second would be much easier! help from an experienced cane weaver is recommended! I had advice from a husband and wife couple in their 80s, but no hands on help – but my wife did buy me a book on the subject which was quite a help. I took the finished 'chair' around to the old couple for them to see my finished effort, and it was pronounced 'very good' with a bit of friendly constructive criticism!

The upholstery is in top grade red leather, and was entrusted to a local expert, it was found necessary to provide a light steel frame inside the seat area to provide support for the upholstery fixing timber, – this would have originally been done by heavy cane sections, but none was available. The steel is much stronger, and all is hidden under the leather work anyhow! The front lower part of the body I trimmed myself, matching red plastic imitation leather glued to light aluminium panels.
After a few teething problems with carburation, the motor runs beautifully, it is mechanically quiet considering it's age, and apart from the exhaust note under heavy load (climbing hills in top gear!) there is no complaint, and it is obvious that the 4.8 to 1 top gear gives the motor no problems, and an extra tooth on the engine drive sprocket could be easily tolerated, especially when ridden solo, when the gearbox is never needed! The machine was a bit unwieldy when ridden once solo, but this wouldn't worry a younger rider, and I did get used to it after a while, but was glad to re-attach the 'chair' and it has remained a combination ever since! Handling both solo and with the chair is excellent, in fact as a combination it is by far the easiest that I have ever ridden, but a bit of ballast in the absence of a passenger is a must for riding peace of mind in modern traffic conditions, without it the chair will elevate far too easily even though the bike is set up vertically.

Starting is incredibly easy, – cold, – a slight 'tickle' on the carburettor float, set the throttle and no air, and spark lever correctly to avoid a kick back which can be considerable! almost always a first kick start, and the motor will immediately settle down to a slow idle. After a short warm up, it will start first kick, even with the controls set a low idle, – once under way with motor under load, the air and throttle levers are advanced together, with very small variations to the air lever to 'sweeten' the motors running.

Paint scheme is silver tank and tool boxes, with dark red petrol tank side panels that match the sidecar upholstery and lined in gold and red, toolboxes and guards lined in red, and frame and chassis and fittings are black. With REX and 1912 cast prominently on the engine, only small Rex transfers adorn the tank and frame headstock. Polished brass and copper are a feature of the engine, and nickle plate has been kept to a minimum, the taillight and additional driving lamp, ( which can be detached and used as a hand held lamp) still has acceptable plating, but the headlamp and some fittings have been restored and plated.

Dry weight of the Rex is 285 pounds, wheelbase is 57 inches, overall length is 85 inches with a seat height of 30 inches. Gearbox ratios are 15 to 1 bottom, and 7.3 to 1 second. Despite the fact that a gearbox has replaced an unobtainable geared rear hub, I feel that the end result is not such a blasphemy as some would consider, I am well pleased with the general appearance, riding comfort and manners of a machine that while not original, is a representation of a machine, that is as far as I know an only survivor of it's marque, the Rex company ceased production after this short model run, but it did continue to provide cycle parts to the trade, and the name lived on in other motorcycle companies for many years.

Origin of parts used in construction

• Frame lugs, 2 early veteran Humber, others manufactured.
• Frame tubes, 16 gauge, and heavy tube sections made from modern fork staunchions machined to correct OD.
• Mudguards and cast al. foot boards, VandV Club spares scheme
• Handlebars, 1 inch OD 16 gauge, bent. ( a copy of 1913 Clyno bars)
• Front brake hub, modified BSA.
• Side car hub, period veteran.
• Rear hub, fabricated, brake drum from split ( and welded ) early Velocette KSS
• All wheels modern sealed bearings ( concealed), with knock out axles, modified to appear as 'nutted' axles
• Wheel rims, ex. BSA 'Bantam' ( 19 inch WM 1)
• Rear wheel drive belt sheave, new unused, courtesy good friend, Wes Vickers.
• Hand oil pump, 'Enots', ex. War Dept surplus, could be WW1. ( feed sight glass made from medical syringe)
• 1912 BandB carburettor, ex. Alec Milledge (incorrectly fitted to 1905 Rex that I restored for him).
• Radiator core (only – damaged), 'Pendletons' 1911 patent, courtesy Chris Harley South Aust. Rex owner.
• Various NOS sidecar lugs and attachment fittings, rusted out sidecar frame and springs, also ditto part of veteran Humber frame. Peter Allen South Aust. Enthusiast and friend
• Front forks, 1911 (?) James. ( Bendigo swap meet)
• 3 speed gearbox, mid 20s Humber. ( deceased collector sale)
• Clutch 50s Ariel, – modified.
• Rear brake foot pedal, 1936 Chevrolet brake pedal, – modified.
• Gearshift and brake rod clevises, Ford 'Prefect' mechanical brake fittings.
• Other parts fabricated.
• Gearbox mounting lug.
• Various frame and sidecar lugs and fittings.
• Frame with bolted up rear section, including axle and brake anchorage and sidecar attachment lugs.
• Petrol tank and radiator mounting lugs.
• Chrome Van. 'reversed' front brake handlebar lever.
  Rear carrier, – exact copy of original item.
• Petrol and oil tanks and filler caps and necks and fittings.
• Radiator tanks and fittings.
• Head stem, lower fork links and spindles.
• Tool boxes.
• Front and rear stands and fittings.
• Exhaust pipe and expansion chamber and fittings.
• Engine and magneto mounting plates.
• Rear brake contracting band assy.
• Gearbox 'V' drive pulley.
• Gas lighting mounting brackets.
• Engine decompressor assembly.
• Inlet induction manifold.
• Primary chain cover.
• Gearshift 'gate' and linkages.
• Brass clamps for water hoses. – copied from Rolls Royce fittings!