Rcw big/wide center gearbox

[Wayne]

Hi AllThe Following may be of interest (or not)Below shows the mythical big gearbox sometimes called the wide centre gearbox. the gearbox was developed in 1988 and fitted to the Rc588 at some point. The box was fitted to all Rcw engines, the ratios are believed to be the same as the std Interpol and commander boxes just bigger and stronger. The unit forms a casting where as the earlier boxes were cut down std units, the right hand end plate also had to be modified to accommodate the big box. The gears and shafts are believed to be all marked NRS, I have a new lay shaft and bushes for the gears they are all marked NRS, the selector setup differs from the std setup in several ways as the cam plate has pins rather than teeth also the clutch centre spider I possess is made of aluminium. ( I don’t have a main shaft or any gears or the selector mechanise if any one has them)One point worth noting is the F1 Nrs588 also had a unique gearbox, the gears and shafts are also marked NRS the Owo1 gearbox was used on the Duckhams F1 engineRegards Wayne

[Wayne]

Hi AllBefore any one asks the gears and shafts for the big box will not fit a std road gearbox and the Rcw nrs gears only fit the above box, F1 nrs gears can only be used with the corrisponding Nrs bushes they have extra clearance on some gears.Regards Wayne

[ZFD]

I think we (Andover Norton) have parts for these still, but you will have to check with Pete Morris via Phil in Hungerford.Joe

[Richard Negus]

I don't think so!Or, to put it another way, oh no you don't! Parts for these boxes were never part of the regular stock and, like this box and cover, were 'saved for posterity' by race team associates in 1989/90 when the RCW's were superseded by the NRS.Wayne has a challenge, but advertising often pays. This is the sort of thing he's looking for:-

RCW_pinion.JPG

They would almost certainly be etched 'NRS......' and don't fit anything but the 'big' RCW box.Perhaps RAR can contribute information, as I believe he designed and got it made.

[Bob]

Hi,I did not know the wide centre was in the public domain!.The NRS Wide Centre gearbox did not have the same ratio's as the standard, a closer ratio I will look out for the Data sheets. (in the loft)My part in all this apart from running the Inspection Department, helping to manufacture 7 different engines and 2 different Motorcycles variants was also the Transmission and Gearbox, primary belt drive, slipper clutch, this also included air bleed off from high pressure zone to the clutch. Our Tuning Guru was Brian Creighton, and the Original (and best engine builder) was David Evan's, for my part I taught myself gear design and went on to design a beefed up but a bit illegal, 5 speed gearbox for 1988 myself and the pattern maker (Kings Heath Patterns, Mike Lemon) used the old fashioned fast track method, cutting and chopping existing castings, filling with Plasticine to blend the shape, any way within 3 weeks we had castings for the gearbox made.Richard Negus, Loaned me Doug Hele to draft my design, still have some drawings (in the loft). I engaged a Local gear making company, Marklew and Sons, Jack and Dave, Tamworth and I designed the gears around what tooling they had in hand, the only exception being a 22.5 deg Pressure angle full tip cutter for the gear shapes, to suit the Sunderland cutter that they had, and Jack had said would produce good accuracy and it did. As it was a secret and we could have been banned outright from Racing I could not give or accept any credit for this splendid work, within 6 weeks I tested the first drop centre gearbox at Mallory Park circuit, and whenever scrutinising took place until we changed to the F1 engine around 1991 I would be praying that an observant official would not notice the deeper gearbox case.The background to the gearbox story is that it was originally designed for 54 BHP T160 Triumph Triple the standard Rotary produce 78 BHP and on test the gearbox was fragile and in later Service also, it was the old story, we had over 500 gear cluster in stock from the old BSA Triumph stores, and development centred around them, the Race engine due to bigger Ports but predominately due to the air going into the Carbs gave additional 30 BHP on the test bed, perhaps with a gain of double that to the Ram air effect.It was proved by test that Norton achieved more HP than Mazda race engine, and that was the basis of a Joint technical venture meeting held in Japan at Mazda, in which I tabled Quality control questions and Gear questions in relation to the Rotary (another story). For the FI we used at first 6 speed Yamaha gear clusters, but the Ratio's did not suit the Rotary power delivery and we had some gears breaks, so I was asked to design a new 6 speed cluster with Ratio's to suit the Rotary and also if possible strengthen them.I talked to our riders and from debriefing notes an with help from Chris Mayhew deduced what they wanted with regards to Ratio's, I had the benefit of being able to ride the bikes myself and under stand from a riders prospective, in any event I designed and ordered £26,000 worth of clusters 4 off first batch, and even though not perhaps needed I talked to some people at Rolls Royce and they put me in touch with a division that did Shot peening and I elected to have this done in the high stress areas of the Gears, the spirit of help given to us when we mentioned JPS Norton was just amazing, things that took weeks took days.Bob

[Bob]

BTWThe gear in the picture that Richard posted, is 2 nd generation, made by Staff's Silent Gear Co, if you look closely you will see the Lightening slots to reduce inertia and speed up the gear changes.Bob

[Wayne]

Hi Bob, Jo and RichardJo, The Nrs big gearbox bushes I obtained from Pete at Andover and as far as I am aware he has no further race stuff apart from moulds for the 89 jps bodywork and Duckhams front mudgard, you also have the patterns for the big gearbox. Richard,thanks for the picture of the gear to show what we are talking about and encourage ment, some one has gone one further and said I will never put a big box together? Bobthanks for the detailed reply, I have unearthed quite a lot of Rc, Rcw, Nrs and some Duckhams stuff. Your detailed reply on the big gearbox is very welcome as I am trying to build a full works Rcw engine to go in a replica 89 twin shock bike, hopefully everything apart from the main frame and wheels will be works stuff on the finished bike .On the f1 gearbox I have a very useable Nrs input shaft and gear cluster, the output shaft and gears I have has suffered a seizure and is beyond use, Dave Evans and Pete Course both immediately think its ex Robert Dunlop as he was the only racer to size a F1 nrs gearbox.Bob you may also not be aware I am trying to rebuild SPE/NOR/A/387 a 1988 Rc588 back to its former 88 glory, I started with the suspension linkage and the rolling chassis is almost complete, any advice, technical information, pictures of parts or even left over parts avalable(parts are wishful thinking, but if you don’t ask you never know) . I am very interested in finding out when the race shop started feeding oil direct into the rotor bearing, (my eccentric shaft from Rcw 3 has this facility and I believe was used to the end in 94, My Nrs eccentric shaft also has this facility. I also have a Rcw eccentric shaft just marked TB in felt tip, both Dave and Brian have confirmed it’s a race shop unit but have no idea what TB stands for.Regards Wayne

[Bob]

Wayne,All NRS boxes machined and raced from castings not cut and shut, the sample that the pattern maker followed was a cut and screwed together cut road bike casting. The Drive end plate was cut and welded on, the gearbox sandwich plate being machined from solid The design brief set was 24 hour life, my logic in case we did a 24 hour race, first gear having to live for 30 minutes full power, out of the 24 hour, the time spent in each gear for each race venue, TT included was estimated and a utilization profile was found for each gear. The first person to ride the design was yours truly at Mallory Park, Simon Buckmaster working on handling and set up on another standard machine. The first person to race on the NRS Wide Centre was Trevor Nation at Brands Hatch (Easter match race?), in practice the engine smeared and he had to go out with a standard engine and gearbox, it lasted around 7 laps, the gearbox that is, I think that after that TN & SB always used wide centre, I know becuase when or if they missed a gear ( a lot in the early days), I was always the one to blame, ask Trevor he will tell you.The Gear selector forks was made to suit and looked like bigger versions, I think that the peg type camplate that you have is a dev one, the idea being that the selector would block the camplate from overtravel by flicking on the peg, as tuning the dentent plunger was hard to optimise.I will think about the TB mark, at least 7 main items had serial numbers, does it have an stamped or vibro etched number near the Main rotor Journal air holes? It could simply be the initials of a fitter or race mechanic?Bob

[Wayne]

Hi BobThe rcw eccentric shaft has direct rotor bearing oil feeds spark eroded, but no usual etched markings between the rotor bearing journals just TB in faint felt tip, Dave Evans had a good look and said its 100% race shop unit. On markings my rcw big gearbox right hand endplate has no markings but plenty of damage where the primary drive chain let go, fortunately it can be repaird. Dave informed me racing took place over markings and its from Steve Spays rcw bike at the Assen meeting as it was the only time this happened.I do have a Std works race box shell that will be fitted to the rc588, I have other strange stuff, a steel clutch chain drive primary from Nrs-1-8 the clutch drum, spider and centre retaining ring are all lightened and its modified so there is no starter mechanism, I have two of these clutch drum and centres, I also have a new norton slipper clutch but not the belt drive aluminium clutch drum and pulleys to go with itRegards Wayne

[Wayne]

Hi BobThe rcw eccentric shaft has direct rotor bearing oil feeds spark eroded, but no usual etched markings between the rotor bearing journals just TB in faint felt tip, Dave Evans had a good look and said its 100% race shop unit. On markings my rcw big gearbox right hand endplate has no markings but plenty of damage where the primary drive chain let go, fortunately it can be repaird. Dave informed me racing took place over markings and its from Steve Spays bike rcw at the Assen meeting as it was the only time this happened.I do have a Std works race box shell that will be fitted to the rc588, I have other strange stuff, a steel clutch chain drive primary from Nrs-1-8 the clutch drum, spider and centre retaining ring are all lightened and its modified so there is no starter mechanism, I have two of these clutch drum and centres, I also have a 92 on slipper clutch but not the belt drive aluminium clutch drum and pulleys to go with itRegards Wayne

[Wayne]

Hi BobMy Rc588 was deliverd to Norton from Spondon in april 1988 the sixth race frame made, it currently has offset bearing cups fitted but the head stock dose not have the pinch bolts of the latter 4xx frames fore easy bearing cup replacement. Currently Stuart at Spondon wants to replace the cups to central ones, however I am against this until its proved the current set up is non original, I have obtained the correct bearings to go with the offset cups and would just need a new yoke stem at 26.5mm.The frame dose not appear to ever have had the battery located at the headstock as the frame has never had the battery strap anchor fitted just below the tank strap anchor point. I assume the battery was placed under or in the seat unit. Rear shock I have the works 88 Ohlins unit marked SPE and a WP marked SS2 (etched) spamped 18/89 NO500A, my second WP shock is stamped TN5 I have to look at the date stamp ect, when I get the bike back from Spondon I will do however believe its an earlier unit than the 89 oneOne area of confusion is the intermediate plate/exhaust vacuum adapter. The 87 bike appears to have a unit that comes up through the air box in front of the carbs, I have seen a picture in Perkins book that looks like its made from a tube cut at an angle at the front and blanked off on a mid 88 rc bike. Then there’s the Rcw type thin at the front curving up to the rear. Any picture or information on the 88 adapters would be og grate help.So far I have not been able to determine any race history of the bike other than it’s a genuine example, Brian and Dave believe it was raced (stuart at Spondon thought it was the show bike due to the frame and swinging arms condition) this week I read in a Bonham’s catalogue that 347 became the show bike in 88 so this may dispel Stuarts theory. If you look in the sale/wanted section of the forum there’s a picture of the bike with a dummy engine fitted. Any info you can provide I would appreciateRegards Wayne

[Bob]

Wayne,I found this for the 5 speed, I would have done a similar one for the 6 speed.BobUtilization RatioPower Race Motorcycle 100%Road Going Machine 30% of Peak Power 70% for cruiseExpected Life Miles Race Road3000 70000Gear 1st 2nd 3rd 4th 5th Life to failureRace 2% 15% 34% 33% 16% Bending L50 Pitting L10Road 1% 12% 25% 32% 30% Bending L100 Pitting L20 To find Hours for each gear find Miles per each ratio then use average final drive ratio.You could simplify this by estimating the total time based on running average, for instance for UK Mainland race tracks we could say the average lap speed is 95MPH 3000miles/95mph =31.579 Hours total life Gear 1st 2nd 3rd 4th 5th Hours 0.63 4.74 10.74 10.42 5.05 When you consider that 1st gear is mainly used for starts on most circuits the 0.63 hours is not unreasonably low.Lets say that the average that a road machine will be 45mph then 70000/45 = 15555.6 Hours of which 30% is at peak power 467 Hours say & 1089 say at cruise loadBob Rowley

[Bob]

WayneOf course I spotted the 24 year old typing error, just as I hit the submit button, Lets say that the average that a road machine will be 45mph then 70000/45 = 1555.6 not 15555.6 Hours of which 30% is at peak power 467 Hours say & 1089 say at cruise loadBob

[Wayne]

Hi BobThanks for the info, looks like the std gear box may have a hard time, also i don’t have a air-cooled right hand end plate for the big box, (one exists but not in my possession) the current plan is to use the std race cut down box in the picture and use the wide centre box on the rcw.Incidentally I don’t have any of the wide centre selector mechanism or gears I just have an idea of what to look for from the descriptions of ex Norton people like your self. Any copies of drawing or sketches would be useful, as things can always be remade. The only paper info I posses, is a sketch of the rcw/pvm wheel spacing, Nrs wiring loom dimensions and plug pin identification, Nrs588 gear ratios and sprocket selection chart, I also have the fork utilisation and yoke geometry for Nrs 004 and 005 (Haslams machines) in 92 for each race and rider.Regards Wayne