RESTORATION OF SMITHS HEATERS AS FITTED TO A 1960 TRIUMPH TR-3A Triumph offered Smiths heaters as an optional accessory in all side screen TR’s. The diagram below shows a schematic of the heating circuit, which is fed from the cylinder head through valve (7) through the heater core, then returning to the water pump through fitting (12). These heaters were fairly trouble free when coolant was changed on a regular basis, and if the cooling system and heater were flushed annually. Most problems involve a plugged core or some type of electrical malfunction. This article will provide a simple step by step procedure for (1) checking the heater for proper function, (2) dismantling the heater for examination of components and (3) refinishing and reassembly.

Smiths heater as installed in TR-2, 3, 3A, 3B and 4

Smiths heater as fitted to my 1960 TR3A

Smiths heater and interconnecting system as fitted to Triumph TR3A

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It really helps to have access to a blasting cabinet / compressor. I invested in one a couple of years ago, and believe me it gets plenty of use. For these heaters , disassembly is very easy as no special tools are required. The biggest challenge is finding parts if you need something that's missing. For example, the little plastic handles on the doors are not available. One of mine was chipped badly. Luckily, I had a second heater unit that had one perfect handle. So, like many restoration challenges , sometimes it takes two or more units to make one good one. Begin disassembly of the heater by removing the 3 spring clips as shown below. These clips hold the top and bottom end units in place, with the core clamped between them.

spring clips bottom housing – cast alum. frame - steel

Top plate - steel

Inlet and outlet tubes

Left / right duct diverter

Right-angle duct cast alum

heater vent doors - closed

heater vent doors open

5 Once you remove the three spring clips, the bottom blower housing lifts off easily. This will reveal the core, fan blade and motor

1 2

3 4

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by simply removing three nuts the mounting frame easily lifts off providing access to fan motor

frame attachment studs

these bolts attach fan motor housing to end plate

motor end plate

6 screws - motor end plate to motor housing

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11

6 7

8 9

4

motor – fan end shown (fan removed)

13

12

motor with end plate removed

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Brushes and commentator

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17

These wires need to be un-soldered In order to remove rotor.

14 15

18

Rotor removed from motor and mounted in lathe for skimming of the commutator

BRUSHES

BRUSH HOLDER

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Restored Heater ready to be mounted in TR3A

New Smiths nameplate available from internet suppliers

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Photo 18 shows the rotor mounted in my lathe. It was necessary to skim the commutator to restore the surface and improve operation. This operation was not done with a cutting tool. I used medium crocus cloth, which is an iron-oxide coated abrasive cloth, used as a polishing agent. This is a good time to examine the motor brushes. These are made of carbon and wear down in normal use. In this motor design it is not possible to inspect the motor brushes by unscrewing a cap on the out of the motor. Unfortunately you must remove the entire motor housing. Visually, a brush that needs replacement will show a dramatically uneven face, with discoloration in one spot, and, more likely, chipping on an edge. It's important to note, however, that it's usually not ideal to remove and reinstall brushes without good reason. However, since most of these heaters were built over 40 years ago, it’s a good idea to replace the brushes now. I could not find a direct source of original Smiths motor brushes. I ended up removing one of the brushes and taking it to a motor repair shop. He sold me a couple of brushes for a few dollars. These were slightly oversize in all three dimensions, so I simply filed them down to size. After attending to the commutator , the rotor can be inserted back into the motor housing. Now the field winding wires need to be re-soldered to the commutator. This is followed by a test of the motor before you completely re-assemble the heater. I temporally reconnected the fan and connected the motor to a 12 volt DC power supply. You can use your car battery but be sure to put a fuse in series. I recommend a fuse size no larger than 5 amps. With the fan attached and with new brushes the motor was connected to a 12 volt DC supply. I measured just under 2 amps. In actual operation you may measure higher current because the fan will have more load when shrouded by the heater core. Reassembly of the heater is simply the reversal of disassembly and is very straight forward. Prior to mounting the heater back in the TR I added an in line fuse (10 amps) for added safety. Be sure to replace all hoses and hose clamps. There are documented reports of serious burns (to particularly sensitive areas of the human anatomy) that occurred when an old hose burst or clamp let loose. For added authenticity ribbed heater hoses are available from a few of the major suppliers. In addition you can replace the old faded nameplate of your heater with a new one. I found a supplier of these nameplates on eBay. I am often asked if new replacement motors are available for these heaters. The answer is no. So unless you have can cannibalize another heater you have problems. However, I have yet to find a motor which was not repairable. Usually a skim of the commutator and new brushes will bring these units back to life. In the event that the motor is a total loss and a spare is not available, it may be possible to find a modern replacement unit that fits. I am currently working on a retrofit unit based on a modern permanent magnet DC motor similar to those used to cool portable electronic equipment. I hope to have a report on this in the near future. I hope you found this article helpful. If you have any questions I can be contacted at trtags@comcast.net. Best regards, Frank Angelini