gearbox

Post by **mixerman** » Sat Nov 27, 2004 12:53 pm

i have a 1960 minor names suzie and it is not very well it seems to be jumping out of 2nd gear any ideas all your mechanical mined people

Post by **Willie** » Sat Nov 27, 2004 2:09 pm

A common symptom of a worn gearbox usually I am afraid.

Post by **Multiphonikks** » Sun Nov 28, 2004 8:15 am

Jumping out of 2nd gear is probably the first sign that the gear box is on it's way out. My car jumps out of 2nd gear if the engine is too high-revving when I change down. The solution i'm using at the moment is to watch my rpm as I change down (made a lot easier of course if like me, you have a rev-counter!)

The only real soultion though is to change the offending gear cogs. Nasty, and rather time consuming I've been told by several. If you want the gearbox servicing/rebuilding then there are several companies who will do it for you. Where are you based?

Of course, it may be cheaper and easier to buy a new box because you don't know what the other gears are going to be like when the box is dismantled....

Post by **newagetraveller** » Sun Nov 28, 2004 7:32 pm

If your car jumps out of gear it is usually due to one of two reasons;

Firstly if the particular selector fork is worn then the gears are not engaged properly. Selector forks wear as a matter of course to some extent. The wear is accelerated if the car is driven too fast in low gears or the oil level in the gearbox gets too low.

Secondly when a gear is engaged the selector fork holds it in position by means of various small springs, ball bearings and plungers. If the springs etc get dirty or worn they will not hold the selector fork in place.

The most likely reason is a worn selector fork.

Post by **ianselva** » Mon Nov 29, 2004 9:07 am

I think you're wrong there . The gears hub is held in place on the gear by friction as of all the synchro teeth only 3 or 4 are actually taking the load . The rest are slightly relieved when manufactured. When the teth wear down to the level of the rest the force is spread over all and is thus too little to retain the gear in place.

Post by **lowedb** » Mon Nov 29, 2004 9:34 am

I can't speak from experience on the mog box, but other boxes I've come across it's been the bearings on the input and output shafts. As these wear the increased play in the shafts is what pops it out of gear.

I didn't think the selector fork held the gear selected, just pushed it in. Once it's engaged the springs and balls in the synchro hub hold it engaged. If the fork was constantly trying to keep the gear engaged, the wear and friction losses would be very high.

Post by **rayofleamington** » Mon Nov 29, 2004 11:47 am

Once it's engaged the springs and balls in the synchro hub hold it engaged.

That's certainly my experience too. The worn selector fork can still be the problem as it might not push the synchro hub far enough so that the spring-lock will engage - however i'm no expert regarding gearbox failures.
Worn brearings are the most likely cause of failure on the average gearbox, but I suspect that the moggy box has some peculiarities that cause jumping out of gear even if the bearings are ok.

Post by **Kevin** » Mon Nov 29, 2004 2:52 pm

it seems to be jumping out of 2nd gear any ideas

Live with is as long as you can and then get a recon box if you cant rebuild your own, they can go on with your symptons for quite a while.

Post by **Willie** » Mon Nov 29, 2004 7:18 pm

RAYO'... I agree with that. I had my own gearbox rebuilt on my
2 door and,despite having new everything it persisted in jumping
out of 1st gear from day one. The 'expert' had it back twice but,
eventually admitted that he had no idea why!!