Singer Owner September/October 2007

Roadster Repairs - Getting the engine and gearbox in place

Ashley Crossland

You will recall that I have another "back garden car" on the go (see previous article), and now it's the time to get an engine and gearbox into the chassis without any lifting tackle. This is not impossible; you just have to do it in manageable bits if you want to avoid having a hernia. You will also remember from last time that I said that it was a 1500cc engine that I was fitting into a 4AB chassis which would therefore originally have taken the 1074cc 9hp engine. First of all I hacksawed off the front engine mountings, and then I checked where the new 1500 cc front engine bearer was to fit. One set of tapped holes was already present on the chassis for the engine bearer (you will remember that I mentioned last time that the front engine bearer sits on the suspension tower, and shares some of its mounting bolts). However, when I got the engine bearer on I saw that there is the second set of holes already drilled in the chassis but just needed completing with a captive nut. Mig welder out again!

Perhaps a small digression is needed here to explain why I should want to divert from keeping the car an original 4AB. Suffice to say that what was sports car performance in the 1950 is only average motoring now, and hence a more powerful engine is an attraction. I suspect that 1500cc engines are now slightly more plentiful than 1074cc engines, and the 4AB chassis was basically identical to the 4AD chassis in terms of brakes, steering, etc. and thus I don't see there being any compromises in safety when the bigger engine is fitted. In any case this 1500cc engine came with the project because it been the intention of the previous owner to put it in the chassis but he didn't actually complete that bit. Actually it is an engine that I overhauled myself some years previously and so I knew that it didn't need any further attention.

The availability of engines is another thing of course. I suppose it's to the advantage of Roadster owners, and unfortunately to the detriment of corresponding Singer saloon cars, that various Saloon car bits have been used to keep our favourite Roadsters going. I suppose everybody knows that the 1500cc 4AD Roadster engine was also used in the Singer SM1500 saloon, the Hunter, and indeed the Mark 1 Gazelle. (There are some important differences - some quite significant for Roadsters - but we will skip over that for the time being.) Needless to say that when these saloon cars gravitated to the scrap yard, then it was fair game to salvage their engines as essential spares for Roadsters. Equally the Super 10 Saloon engine was the same shape and size as the 9hp Roadster engine but just a bit bigger in the bore size, and Roadster owners would be keen to get hold of one of these engines to secretly use the "extra" horsepower in their car. This harks back to the days when UK cars were taxed on RAC horsepower, but which was discontinued (I assume) around 1951 as it was blamed for fostering the inefficient "long stroke" engines which allegedly were poor at "revving", and which was allegedly loosing sales, worldwide, for British car manufacturers. As we have heard many times before, RAC horsepower bore no direct relationship to actual horsepower, but was a function of the bore of the engine - thus engines had small bores and long strokes to get a higher cubic capacity, without owners having to pay unduly for tax and insurance. The British motorist still remains heavily taxed so there's no change there! However, there are a good many supposedly 9 hp Roadsters running round with 10 hp engines in them, which won't matter much until you need a cylinder head gasket or some pistons for an engine overhaul. The 1500 cc engine design benefited from the abandonment of the RAC rating.

Now don't blame me for saloon cars getting scrapped off sooner than sports cars, for regardless of the marque it seems that people traditionally have been keener to hold onto their treasured sports cars. So the survival rate of Roadsters is relatively high, and mechanical parts being donated by scrapped saloons has helped this. The Super 10 is the one car that has helped the 9hp A, 4A and 4AB cars. As already mentioned, the engine is essentially a direct replacement, albeit with larger bore, which owners of the day would welcome. Also the 4speed gearbox in the saloon is an added attraction to supplant into the 9hp, 3-speed car. I understand that post-war Super 10's had a gearbox identical to the 4A and 4AB Roadster, whilst earlier 10 Saloons had a sort of different "cast" remote which was not quite as neat looking in the Roadster. Nevertheless, over the years one or two 3-speed Roadsters have gained a 4-speed box courtesy of the Saloon. I suppose when Roadster owners went to the scrap-yard and saw the complete engine and gearbox unit, the temptation was too great.

Unfortunately I seem to have waffled on longer than intended. Back to the story. The garage where I am building this car has deliberately got no electricity, and neither does it have lifting beams in the roof. So installing the 1500cc engine has had to be done in stages. The prime lump at the start of this exercise was a basic bottom part of the engine, i.e. no ancillaries like starter motor, and indeed no cylinder head. And neither any water pump which weighs enough on its own. I recommend that two people lift the first lump onto the chassis, after that it's a one-man job. Then it's just down to building up the engine in situ. The first thing that I bolted on was the water pump, which as mentioned weighs enough on its own, as does each of the bits that follow. The water pump takes the rubber mounting which sits on the front engine bearer, and thus the engine is now located at the front. After that the flywheel can go on. When I offered up the flywheel, I noticed that the two dowel pegs were missing from the end of the crankshaft. A different flywheel (which itself sounded cracked as it doesn't "ring") had 2 dowels present that were persuaded out with a pair of Stillsons. The size of these dowels is a bit unusual - something like 0.395" dia x 0.60.0" long. Then when the locking plates go onto the flywheel bolts, they cover the dowels and stop them coming out.

I had refurbished a clutch plate by fitting a new facing only on the driven plate side, as the flywheel side didn't seem to have worn. The new facings I had were 1/8" thick, and as the one facing still measured the right thickness, I thought that I would only do the worn facing. One thing to check on clutch plates is that all the springs are still "tight" i.e. under compression, or otherwise it's not worth refurbishing the clutch plate. Line up the clutch, and then fit the cover assembly. The cover assembly was a genuine Borg & Beck with the number 45688/24 painted on (twice) and a number that looks like GH7. The pressing was stamped 42460.

The gearbox that I have is a 4ADT box and surprisingly it went on OK - usually with other cars I have struggled to get the input shaft lined up with the splines on the clutch, but there was no problem this time. Oh, yes and at this point it is useful to have someone else handy to fasten up a nut or bolt whilst you are supporting the gearbox. Did I say previously that you didn't need anyone else?

I could now see where the gearbox feet came. This was the another unknown when deciding to fit the 1500 cc set-up, although I'm sure there have been other contributors to the magazine who have described this. Fortunately the feet come over the 4AB cross-member not exactly on the centre line and the mounting holes are slightly different. This 4AB cross-member is a bit different in shape than the 1500 cc cross-member largely I suppose because of the difference in accommodating the relevant rubber mountings. The 4AB uses a rubber horseshoe arrangement, whilst 4AD's use two separate mountings (almost like an engine mounting). However, since the 4AB and 4AD prop shafts are the same length.......

Again time for a small digression. There is a lot of similarity in the actual gearboxes (not the clutch and bell housing, or tail end) of all of the four speed Roadsters - there might be a few odd gears that are different, and indeed the SM1500 and Hunter Saloons share a lot of the guts of the Roadster box although they are in a different case. Anyone in need of a gearbox overhaul should be pleased with anything they can get as a donor - even a SM1500 and Hunter Saloon box should not be discounted.

These digressions seem to have taken up a fair amount of space so I will finish here. I've yet to finalise the rubber mounting arrangement for the gearbox, so more about that later.