TECHNICAL TIPS - TRANSMISSION

TORQUE TUBE PINION NUT: If you’ve tried undoing the nut on the pinion inside the torque tube to remove the bearings, you will know how difficult it can be.  Not only have you to remember that the nut is usually a left hand thread but usually it will not budge no matter how much effort you apply to the spanner. To overcome this problem place the pinion in a wide vice as close to the nut a possible and tighten as much as you can.  Heat the nut quickly and as much as you can without heating the pinion unduly.  Then quickly apply a chisel to the corner of the nut and give it a hard hit with the hammer.  “One hard hit is worth a thousand soft ones”.

 
REMOVING REAR HUBS: Austin " Seven " rear hubs may be removed without the use of a special extractor. The procedure is fairly well known, but is worth repeating, and is shown in Fig. 7. The wheel is removed, and the three counter­sunk screws which secure the brake drum are taken out, but the drum is left in place. The split pin is removed from the hub nut and the nut unscrewed until it is almost at end of the shaft. A second nut is affixed to the end of the first with the aid of a blob of thick grease, and the wheel replaced.  The three wheel nuts are then tightened evenly in rotation, and a smart tap on the centre of the wheel, which should be suitably protected from the hammer, will loosen the hub.
REAR AXLE OIL: Do you struggle filling your rear axle with that thick 140 oil? Do you keep saying I must get a proper pump? Well, Sandy Croall down in deepest Cornwall has passed on this oh so blindingly simple solution. Next time you go to an autojumble or event where cheap tools are sold, get an oil can like the one illustrated with a flexible plastic pipe attached. They are 'as cheap as chips'. Cut off the brass nozzle, (don't try and pump the oil with the nozzle attached it will take for ever), and hey presto, job done. Sandy says he painted the side AXLE OIL, and found that a tyre valve cap fits the end of the pipe to keep the oil clean.
REAR AXLE OIL: When was the last time you checked the oil level in your back axle? Regular checks ensure that the bearings and gears will not fail you. Remember to use D140 grade oil; do not use EP140 as it has a detrimental effect on some of the components within. Whilst you are under the car make sure that you have greased the universal joints (both ends on later cars). Excessive backlash (rotation of the propshaft without rotation of the half-shafts, and front to back movement of the pinion) is indicative of worn pinion bearings. Too much movement will lead to catastrophic failure of the teeth on the crownwheel and pinion. Check it now – especially if your back axle is noisy, best to replace the bearings, both new and second-hand crown wheels and pinions are very expensive.  “Bumbling” (A7OC) with many thanks
CHECKING REAR HUBS: When did you last have a peek at the relationship betwix your ‘Seven’ hubs and shafts? Any sign of wear, marks on the key surface, sloppy fitting in the keyway are evidence of movement however small, between the shaft and hub, the cause more often than not being an insufficiently tightened nut. It may also be that the hub has been riding on top of the key. To check, remove key, fit hub and tighten nut as hard as possible with a socket and a substantial lever with a suitable length of bar placed between a wheel stud with wheel nut fitted (to prevent damage to thread) and the hub centre extending to the ground. Carefully note position of hub nut, i.e. marking face etc, remove nut, fit key if completely sound, and re tighten. Whatever else you do, do not fit a sloppy fitting key. Tightening to a different position indicates a need to file down the surface of the key until it tightens exactly to the position achieved without the key. Unless you’re fitting together the two components which have never previously met, proceed with caution down the road of ‘lapping’ the hub on to the shaft with grinding paste about which much has been written. After seven decades or more, it surely is reasonable to assume that any lapping that’s been needed, has already been done, who knows how many times. Over doing this lapping lark can only eventually lead to the risk of the nut tightening against the shoulder on the shaft beyond the threads, instead of against the hub. It is known to have happened! For additional confidence in a secure shaft/hub drive, the oft times repeated advice of re-checking the tightness of the hub nuts after a couple hundred miles or so is worth considering. And at the risk of stating the obvious, if, on the final tighten-up, you find that the cotter pin hole is not lined up to enable fitting the cotter; resist any temptation to slacken off to accommodate it, no matter how little. Either fit a suitable shim washer or grind down the nut surface just enough for the nut to be fully tightened for the cotter pin to be fitted. Incidentally, an old wheel that has seen better days, and with the centre removed, fitted and lowered to the ground is ideal for securing the hub while giving the nut that final tightening heave. John McKay Scottish A7C Meshing Point June ‘09 with many thanks.
 
CARDEN BLOCK COVER: The rubber boot cover for the Carden block on the earlier propshafts from the usual suppliers is very insubstantial and has only ever lasted a few weeks for me. A much tougher option is the Mini Mark 1 cv joint boot (Delphi Lockheed part reference TBJ2197) which has lasted now for over 4 years and is available locally from the likes of Autoquip at about the same cost.  Eddie Eddles Devon A7 Club with many thanks.  (Also available through Mini Spares on the internet but I notice there are “inner” & “outer” boots so be careful—Ed)  CARDEN BLOCK UPDATE:  I have bought and fitted several Mini Rubber covers from our cherished suppliers and they are useless! They are too big on the middle diameter and rub one side of the tunnel until a hole appears and the grease comes out!! I've read your article and looked at the Mini Spares website and I see the cheap ill-fitting boots that have previously failed. Now on the same page they show a superior boot at £14.95 - is this perhaps a better fitting boot and smaller in the middle.  Bryan Downes PWA7C
TIGHTENING REAR HUB NUTS:   Glyn and I use a 4 foot gas bar on the end of a socket bar when tightening the rear hub (taking care not to damage the hub threads with the socket). If not kept really tight, the hub works on the axle shaft key instead of the taper as it is not tight on the taper and eventually, at the very least, the key breaks but more often or not the half shaft shears off at the key.  Does your Austin clonk at a back wheel area when drive is taken up between going backwards and forwards? BEWARE!!! Gary Munn
FLYWHEEL OIL THROWER: Having to tighten the flywheel on my Box, I noticed the thin tin-plate oil thrower between the rear bearing and the flywheel was just spinning loosely around and incapable of throwing oil anywhere! A quick call to Vince Leek solved the problem—the oil thrower is just pinched by the flywheel boss and will always be flattened out when the flywheel is put on. The solution is to lightly crimp the inner edge of the thrower with a pair of pliers, preferably pointed, and then fit the thrower over the sticking out end of the crank, concave face outwards, and replace the flywheel—simple! However, I did notice a scratching noise when I first turned over the engine by hand but this disappeared when I pressed in the clutch for the first time. David Whetton

HARDY SPLICER PROP FLANGES:  Hardy Spicer propshafts can only connect in two positions. It is not possible to release the bolts and turn through 90 degrees as the fixing holes permit only 180 degree rotation on the flanges. To set the splined sleeved end at 90 degrees different to the fixed rear requires removal of the sleeved unit and refit at a new position by disengaging from the splined shaft and re engaging at the desired position.  George Mooney DA7C
INPUT SHAFT BEARING: 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.

GEARBOX DRAIN PLUG REPAIR:   Damage to the thread of the drain plug can be a cause of oil leakage. The casting in this area is not very thick and the thread can easily be stripped. Here is a simple repair.
1. Open up plug hole to ¾ inch,
2, Tap new thread ¾” BSP being careful to hold the tap square with the case.
3. Fit ¾” BSP blanking plug with ¾” Dowty seal.
Obviously this is easiest done with the gear box out of the car, but it can be done with the gearbox in situ. Just make sure the car is safely jacked up on tall stands. If you do not have a ¾“ drill carefully open up the hole with careful use of a round file. Suitable plugs are available from plumbers merchants.. Taps from Tracy tools. Vince Leek DA7C