TECHNICAL TIPS - CLUTCH & GEARBOX

CLUTCH OIL LEAK: As the input shaft bearing of an Austin 7 3-speed gearbox wears, the oil returning quick thread gets damaged in the nose piece, allowing oil to leak onto the clutch. A simple and cheap way to overcome this problem is, firstly, to renew the bearing and then insert a modern oil seal in the nose piece between the input bearing housing and the roller bearing.  This stops oil from reaching the worn quick thread.  There are 2 types of seal: either Payen NA080 or Payen NA092 will do the job and they are simply a press fit in the housing, It is a good idea to grease the new bearing as hopefully no oil should now reach it.
CLUTCH THRUST BEARING: One of the most unreliable aspects of the 3 speed gearbox cars is the slotted collar clutch thrust bearing. The clutch levers have a nasty habit of wearing through the collar at the most awkward of moments, necessitating removal of the engine to restore the mess. Instead of re-cutting 3 new slots, a far more reliable alternative is to fit a 4 speed gearbox type clutch thrust, which simply slides on in its place.  When the gearbox is bolted up to the engine, make sure there is clearance between the race and the levers and that when the pedal is depressed the clutch disengages fully. If not, bend the 3 levers with a long pipe accordingly. Once bent make sure all 3 are exactly the same distance from the centre plate to avoid premature wear and judder. 

The pedal rod end spring can now be dispensed with as there is no need to keep the race in constant contact with the levers as there was before.  Mouse trap springs need not be fitted, nor the 4 speed box race return spring but, if preferred, the later wide foot clutch levers may be used. The above simple and unseen modification should result in a more reliable set up and a smoother clutch operation. Mine has been fitted for about 40,000 miles, so far without any problems.  (PS: 2007, still fitted! If you use late levers you will have to heat them cherry red before bending as I believe they are cast. Of course there are other methods of adjusting the levers if you so wish, on this there are several articles. Munwellyns and now GM Autoservices always heat and bend all. Some people prefer to fit mouse trap springs, (not easy), but Glyn and I have never found it necessary.)  Gary Munn

CLUTCH LEVERS: Whilst rummaging through a whole load of clutch levers I noticed that they aren’t all the same!  To be precise, the pivot point (marked) on some of them was much closer to the round pin hole than others.  Clearly, the nearer the pivot is to the pin the lesser is the movement of the lever pin, resulting in a soft pedal with a lot of travel, and the further the pivot is from the pin, the greater is the movement of  the lever pin giving a hard pedal with a short travel.  Roger Ballard

CLUTCH SPRINGS: Next time you work on the clutch it may be worth checking the springs have not become compressed and not working correctly. The photo below shows some clutch springs from a recent clutch refurb, the spring on the left is new for comparison. The other three springs are from the same clutch which not only had become compressed, but also by differing amounts. New springs are 11/2” thanks to www.a7c.co.uk for confirming the correct length. Douglas Alderson DA7C