This item is for a 38" length Rev Clock Cable - of the (now extremely rare) pre-war type, that were rubber sheathed - for the ultimate in originality on your pre-war Inter or competition bike, if fitted with a Smiths Chronometric Rev Clock.
We take as a starting point, a good quality proprietary (UK manufactured) rev clock cable - of the type we also sell seperately for Post-War modelds, but then carefully add an additional sheathing of oil resistent black rubber covering over the original cable outer, with stainless steel ferrules on either end of the rubber - which just overlap the normal alloy cable end fittings - to give a really smart and genuine Pre-War look.
For anyone with an eye to originality, and owning a Pre-War competition or sports motorcycle, you may have noticed that pictures of early competition bikes fitted with Rev Clocks (which commonly seem to have become optional extras from approx 1935 onwards, but can occasionallly be found on earlier bikes) - often seemed to have rev clock cables thicker than later cables. This was normally because those early cables had a rubber outer sheathing to protect them (rather than waterproofed cloth covering, common on other cables at the time). Unfortunately almost none of those original cables have survived in their original condition - because the old 'natural rubber' sheathing has now perished and dropped away. I have seen a couple of original cables which look like they may have been of this type - but now just have the bare metal flexible coil outer remaining - which loses the original effect!
Therefore we decided to make the tooling and parts to allow us to make a batch of these.
The starting point is to take a good quality (post-war type) rev clock cable of the correct length, but then remove the fittings on one end, then add a section of oil resistent hosing over the original cable outer covering. However, to make this look smarter and more professional - we have added close fitting stainless steel ferrules, lipped on one end, that are pressed onto the end of the rubber sheathing on each end. We have carefully trimmed the rubber to the correct length - so that once fully pushed the cable on one end - we can then add new crimped fittings on the open end, before sliding the rubber back down again over the fittings - so none of the original covering is showing and the lipped ferrules overlap the alloy cable fittings. The final effect is to give that final pre-war look, but still maintain the original fully functional cable.
Sorry, but these cables are priced accordingly to the time and effort spent to assemble them - as well as cost of materials. The sheathing is a high quality oil resistent pipe and we CNC manufacture the stainless steel ferrules from solid 3/4" stainless bar - as no good quality commercial ferrules are available. We also re-manufacture the cable fitting on one end (again CNC), to allow the fitting of the sheathing. Therefore, not cheap to produce - but they do look very original, and should generate comments when fitted to your pre-War bike!
In the accompanyning photographs you will see photographs of two period pre-War racing Norton M30 models (i.e. pre-War Manx's). The first picture is of a 1937 'Big Plunger' Manx, and the second photo is of a 1939 Gardengate Manx (which looks brand new out of the showroom in the photo). Both bikes are fitted with rev clocks and similar type rubber sheathed cables.
Final Note: - the stainless ferrules are manufactured to be a close/tight fit over the rubber sheathing - and therefore I have found crimping or punching the ferrules to keep them in place is unnecessary as it will damage and mark them - however, a customer could use a single centre punch to do at a later date, should they think this extra security wothwhile. Likewise, we have found the rubber sheathing (which is not glued to the cable, as it needs to be slid after fitting to abut the alloy cable fittings) does not need any additioinal retention - but if it a later date that is required - a small loop of stainless lockwire tightened around one end of the rubber sheathing would further retain it.
FYI, when I have fitted rev clock cables to Norton singles in the past - I find that they normally just touch the exhaust pipe (and can burn) with their natural bends - therefore you may want to check this when fitting, it is not unusual to use a small clamp (or lockwire length) to hold the sheathing back from touching the exhaust and burning - which would be a shame! I notice there are photos of the Works Norton singles in period, where they also did this.