Gear jumping ?

[F6frogie]

Hi all, I just wondered if anybody had any clues on why my gearbox likes to jump out of first gear every now and then when setting off - even when the gear is held in it sometimes pushes my hand away !

I have heard it might be some sort of ball and spring which gently locks in the first gear which might be getting a little tired?

Any help would be great - Thanks

 

[angel]

On my '75, I had some problems some years ago with the fourth gear jumping off, exactly like yours does, on overrun.
On removinf the top cover I discovered that an oil leak had drained the oil completely... :-( :-( then upon dismantling the gearbox I found that it had caused the 4th selector fork to wear considerably at the two "paws" that slide into the groove of the 4th gear selector hub. Therefore, there was so much play that allowed the selector hub to disengage.
Another problem could be excessive second motion shaft endfloat.
Balls and springs seldom wear, but you can check them with the gearbox on the car only by removing the top cover. If they are OK, you have to take the gearbox apart to check its innards...

 

[F6frogie]

Thanks for that Angel.

I did take the top cover off to check the detent springs as I heard that they can loose there tension a little -I added a bit of tension to the 1st/2nd selector shaft spring by means of placing a small stainless screw head of the correct size into the top of the spring where it comes into contact with the lid (yes, :shock:I know!! but I could not get hold of any new springs) and it jumps out of gear a lot less now so am pleased.

I will leave the dismantling of the gearbox for another day