This is by way of an observation (quite rambling, sorry!) on Routemaster ownership rather than a technical query but I thought it might be useful to other owners. I’m not sure if I mentioned on this forum that I recently had to have my gearbox rebuilt by Queensbridge when third gear refused to work. It transpired that the band had been permanently locked on for some considerable time, maybe even since I bought her in 2004. Obviously it was completely worn out and substantial damage had been caused.

Anyway, she worked fine after the rebuild until a week or two later I noticed a loud hiss when parking in first gear. I took her to my local commercial garage and we found there was some gasket material protruding from the plate at the bottom of the gearbox cylinders. It seemed that, unusually I’m told, the gasket had blown. Queensbridge sent me a new one but I have yet to get chance to fit it. While checking to see where the leak was I left her in 1st, unintentionally, for about five minutes.

Later I noticed that I wasn’t getting the usual humming noise in the lower saloon which I thought was a characteristic noise of Routemasters caused by the vanes of the fluid flywheel speeding up (I rather liked it!). I was concerned that I had damaged the flywheel but no fluid seemed to have been lost. I asked “Manchester Mark” (Prescott) and Steve Anderson about this and the conclusion was that the humming had probably been caused by the brake band and was being transmitted down the propshaft. So despite what I had worried about everything was in fact now working as it should - a bonus is now that the brake and gearbox lights now go out much quicker.

Before the rebuild the flywheel used to start up very slowly and gradually speed up. Despite I and many other more technically knowledgeable people having seen this happening over my years of ownership (it had been like that for at least three years) no-one had deduced that something was wrong. Perhaps I could have been saved some of the £1400 repairs costs – and presumably lots of diesel!
My point is that I don’t think it can be over-emphasised how valuable it is to have your bus looked over thoroughly by an engineer who really does know about Routemasters and has the time and interest to check properly what needs attention – a good friend of mine was recently able to benefit from such an inspection and all sorts of previously unreported, and serious, things were found.

My bus number (if any): RML2302

Wise thoughts indeed.

I think the hardest task is now finding good engineers who really fully understand the correct characteristics of certain aspects of the vehicle.

Even in the 1970's when doing my apprenticeship some of what you describe was passed off as normal and yet several -No.- more than several RMs and RMLs made different gearbox whines or not at all and the flywheel description seems very much normal to my recollection.

There was a lot of bodgeing going on even then, and not all bad, some were innovative clever ideas others though, lazy quick fixes.
But I do remember quite a lot of mess room discussions going on over RM gearboxes and control panels so and I well, to be honest at the time preferred playing darts!

I don't think I ever heard the same explanation of what was correct from any two instructors! I am of course referring to a period when the fleet was just AEC or Leyland
RTs were similar, some came back with gearboxes or flywheels that made a kind of graoning noise when idling and in gearchange. But they worked faultlessly.
Others made little noise at all.

This area though is not my speciality on Routemasters so I think it would be a good time to compile a list of really good proven experts who are still about in both a professional and retired advisory capacity.

There's some good younger people about who are very receptive to learning and will very soon be the new generation of experts. They need all the help, information and above all correct guidance that can be offered.

Ne'er a truer word was said Jack.

Thanks very much Jack and Roy - I really intended to mention what Jack said in his second paragraph, that the big problem is actually finding that skilled engineer who has the knowledge, experience and interest to make a thorough and effective inspection. Hmm..
From what Roy said in an email to me today my flywheel appears to be a Voith - not sure what if any difference that makes.

My bus number (if any): RML2302

Brian

My understanding after reading a number of technical articles is really that the Voith coupling is a newer type, which replaced the older one originally fitted with the AEC flywheel & Llewellyn Gland. From reading what Colin Curtis had to say about it, he was not convinced that it was an improvement on the older type. It seems though that the type of coupling used in the later engines such as the refurb RML's with the Cummins, is better able to deal with the higher idling speeds. The latter reason also being relevant to the introduction of the Cummins B series engine, where the C type engine with its fluid flywheel is unable to deal with the higher idling speeds of the more modern turbocharged engine. A factor to be taken into account is the use of automatic transmissions being used in conjunction with a torque convertor as opposed to the older vane type/radial web fluid flywheel. Perhaps given the space available, it was not possible to implement the older type of Step Circuit Coupling with a reservoir, which benefitted the coupling at idling speeds by keeping the temperature level at a minimum by reducing the drag, which otherwise would have raised temperatures to an unnacceptable level. The latter being used in the Railcars fitted with Rolls Royce engines, where previously the lower powered AEC engines had been used. A further consideration would also be the very diferent traffic conditions encountered in later years, when more time was spent with the vehicle idling in gear at a standstill. Whatever we do at a given time with the mechanics of a system, it always ends up being superceded by some new technology available, fluid flywheels being no exception. Mind you I expect the introduction of fusible plugs, did not please those who had to clean the road up afterwards if one operated, better than a possible vehicle fire though.