Friday 15 May 2009

Lightly oiled.

A little noise in engineering is sometimes a good thing. Let me explain. Some years ago I was fortunate enough to have a flight for around an hour in a genuine 1944 Dakota. Crucially, this was not a DC-3, but a Dakota, the military variant of the vintage trooper and as such was free of virtually any frills, consisting of two engines, two wings, a tail and a fuselage. Think that was about it.
This lack of any superficial finishing was made up for in what estate agents call “character”, a character that only revealed it’s self once the aeroplane was bouncing along the runway and then shortly afterward chundering through the sky to the smell of aviation fuel and hot bakelite. And all this was accompanied by an orchestra of assorted sounds - The rush of air over the non-sound proofed fuselage, the deep growl of the engines just feet away at the root of each wing, then more discreet sounds of aluminium creaking and groaning as it eased and strained under aerodynamic load, the occasional squeak from a bearing somewhere, and an ominous compressed air hiss as the gear came up. But this was a cacophony of reassurance – all the time the Dakota was making these noises meant it was working.
Much the same can be said of aluminium cars, where the traditional engineering occasionally announces all is well with a light squeak, brief rattle or mild groan. That said, this sometimes gets to the point where the noise cannot be ignored, nor taken as the all-clear. No, it becomes what is known in technical terms as cause for concern, and this in turn gives rise to that favourite past time of aluminium car owners everywhere - the initiation for plenty of tea, the trigger for long phone calls to likeminded aficionados of hand built cars, and the cause for many a late night cramming twenty minutes of work in to four hours. It becomes the cause for an investigation.
In the case of the Caterham, this investigation was in to why the clutch was allowing the revs to noisily run away with ease every time the accelerator was floored. See? Too much noise. Over the past few months this has given rise to much debate about what needed adjusting, what was out of tune and just how entertaining it can be to overtake another car with all the right noises but none of the acceleration. The presence of oncoming traffic elevates this to being highly entertaining.
To investigate the clutch of the Seven means lifting out the entire engine and gearbox assembly but this isn’t as daunting as perhaps it sounds and is very much a case of following a logical process (and owners of aluminium cars tend to be the type who like logical processes) and simply work around the engine disconnecting anything that won’t come out when the engine is lifted. The tricky bit comes when it’s time to separate car and engine, an activity akin to childbirth but with more spark plugs and less in the way of epidurals, but having said that a little pain relief to the lower back isn’t such a bad idea after a while stooped over a live axle mother as it gives up a 1600cc baby.
Once out, the engine and gearbox could be split and the real cause of all the recent slippage was revealed, but not before Carrots and I comtemplated the idea of towing the dead Seven to the top of the nearest big hill and trying a little soapboxing.
Back to more pressing issues. The gearbox input shaft oil seal, which is an oil seal around the input shaft to the gearbox, had hardened with age and was weeping oil along the input shaft and on to the clutch gubbins. Now, some things are better when lightly coated in oil – olives, old steam engines, lap dancers and so on, but not clutches. It was a write off, which is a shame really as the friction plate still had loads of life left in it, bar the unwanted lubrication. The real snag was that although I’d pre-ordered a new clutch, to replace it without curing the actual oil leak would be pointless.
So, with the Land Rover adopting its some-time guise of Caterham Support Vehicle I scrambled in to town in search of the errant oil seal, leaving fellow ReHaBer Brent to fettle and fiddle with the clutch whilst I was gone. My local independent motor factor, who in the past have been pretty good, appear to have adopted a Halfordesque approach lately and denied knowing what an oil seal is. No matter. Taking the longest of long shots I headed for the main Ford dealership in town, and it’s a pretty large affair. They’re even described as a Transit specialist so I was half expecting to find a copy of yesterday’s Sun and a polystyrene cup wedged in the window of the parts department. What I did find was an unusually helpful German of all people, someone who knew what a Type 9 gearbox is, and crucially, stocked input shaft oil seals for them. The only disappointing bit was a price tag of nearly ten quid for the little rubber o-ring.
Oil seal refitted a minor modification was made to the input shaft shroud – a small hole (3mm I think) was drilled in the six o’clock position to allow any future oil spillage to drain in to the clutch bell housing before it reached the clutch itself.
Assembly was refreshingly quick, and before it was even dark the car was back on the ground and ticking over, if a little rapidly. The only thing that didn’t work was, in true Caterham style, the indicators. I can only assume all the huffing and puffing in and around the transmission tunnel, with its close proximity to the dashboard, had dislodged the wiring – after a quick waggle everything was fine. Job done. Although it took a little tweaking of teeny tiny brass adjustment screws on the carbs to get the car idling happily, its already been out on a few blats and it's also nice and quiet again, having had the gearbox topped up as part of the re-install, and I suspect it's been losing oil to the clutch for quite a while.
Best of all though, it now pulls like a premiership footballer in a strip joint.