Clutch Pedal Adjustment - a modification

 If the gearbox has been removed from the car for some reason this modification might be worth considering whilst the cross-shaft is accessible.  Don’t even think of doing this with the gearbox in the car by the way - it’ll end in tears and frustration!

An Austin Seven 4 speed gearbox, whether crash, 2 synchro or later 3 synchro, has on tClutch adj 1he nearside end of the clutch cross shaft, a slot to enable some sort of screwdriver blade to be inserted to place the release bearing in the right place on or very close to the clutch release fingers.  When the release bearing is in the right position, the clamping bolt on the clutch pedal can be tightened.  Once done up correctly the operation of disengaging the clutch by pressing down the pedal can be achieved.  

With the right type of screwdriver, a comfortable environment, and a sound slot in the shaft, the job would appear straightforward.  In reality it is seldom the case.  Austins are invariably filthy and oily underneath just where you need to work, and it’s a very cramped space with the chassis obstructing your activities.  If you’ve got a cranked screwdriver and you can see clearly what you are doing and the slot isn’t too worn, then the job can be achieved with only a slight rise in blood pressure, but in reality, it is difficult.

The procedure is only applicable to 4 speed gearboxes where the clutch pedal is secured to the cross shaft by a pinch bolt arrangement.  Earlier 3 speed boxes have a securing cotter pin, making the fitting procedure different.

One of our members suggested a procedure which solves many of the difficulties by substituting the screwdriver slot with a hexagon head, on which can be applied a convenient ring spanner to move the cross shaft into place. It can then conveniently be held in position while the clamp bolt is tightened.  

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Firstly the cross shaft is drilled and tapped along its axis and this can be done in two ways.  If the cross shaft can be removed from the casing, and you have the equipment and ability, then using a lathe to drill the hole and tap the thread is preferable.   Otherwise it is possible to do it without dismantling the cross shaft assembly.  I did it this way because the taper pins that lock the release bearing arms resisted all attempts to remove them without resorting to extreme violence.   I set the gearbox firmly on its side so that it could not move, marked the position of the hole with a punch and drilled vertically using a drill guide, aka drill jig, of the correct size.

The result is best seen by studying the illustrations. The hole should be about 11/4” deep. The bolt used was the 1/4” BSF thread clutch cover bolt available from several A7 parts suppliers and must be tightened right up to the head.  Use a high strength locking compound such as LOCTITE 601 or 648 because it needs to resist the undoing torque (anticlockwise) when making the adjustment.

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A 1/4” BSF ring spanner makes the adjustment a 2 minute job, with the 5/16” BSF spanner you are using on the clamping bolt.  I don’t know why Austin didn’t use this method, but since starting this article I have heard that it has been used elsewhere.

 

 

 

The original article, with acknowledgement to  Alistair Wreford, was written by Bob Kneale and appeared in Seven Focus, December 2021 pp9-11  



See also:

Clutch Pedal Adjustment

Clutch - Keeping Friction Surfaces Dry

Clutch Overhaul

Jamming Clutch






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