Jumping out of gear.

My 1969 S2a suddenly started jumping out of 3rd when power is removed.

Not the selector fork ball dentent springs.

Now I don't want to pull the box out, so that leaves what? - the synchro clutch detent springs?

Have seem comment that they can be replaced with box in place - BUT HOW?
I can barely see what I think are them - just flat ends (3) deep in the synchro clutch??? maybe they have vanished and that isn't them at all?

Any/all help appreciated!!!

In 4th gear, does the gear lever move as you go on and off the power?
Sometimes the nut at the back of the mainshaft can work loose, and allow the shaft to move slightly. It's the one you have to remove to fit an overdrive.

Davec - 4th gear is fine. The O/D will come off tomorrow & I will try the mainshaft nut.

I notice that when I move the selector to 3rd the selector can travel about 5mm further than the ball would normally position it. So when in the position the ball holds it there is about 5mm play either the gear or the synchro cone - so play in the mainshaft may explain it.

thanks - will let you know

on reflection there is some movement in 4th as power goes on and off - but not much ... not that it struck as wow! I did have it pop out of 4th once - some time before the problem - big downhill on overrun.

Problem solved - well not fixed, but cause determined. The spacer sleeve between 2nd & 3rd gear had disintegrated You can just see teh remains in the pic

Cheers

Sorry to Bump an old thread.

My series III 88" has jumped out of second gear on overrun as long as I have had it which is getting on for 5 years plus now.

I was under the impression that the internals of the box were to blame so I turned a blind eye to it. Last year my box failed and I had it fully rebuilt at considerable cost. The box now seems perfect bar the fact it still jumps out of second on overrun.

Unfortunately the gaurentee had run out for the work by the time I got it back on the road

Any tips I can try? The box is fitted with an overdrive which works fine if that makes any difference?

too much free play for 2nd gear can cause it it is/shoiuld be set during build but can be wrong ,loose castleated nut on rear of mainshaft can cause it (would need to be removed to fit overdrive gear)or poor dog teeth on gear and in synchro can ,but if its intermittent it may be normal as only last suffix d gearboxes had coffin shaped dog teeth which hold gear in gear during acceleration and overrun,the others are all straight ,2nd is worse for jumping out than others

The box was rebuilt off of the car so they never tested fully prior to being collected by me. It had new synchro's bearings, 1st + second gears, layshaft + more I can't remember but everything was replaced.

The fault isn't intermittent really as it'll happen on most trips if I don't hang on to the gear lever on over run.

Someone has mentioned selecter adjustment to me in the past but not entirely sure this could be the cause either.

I would hope that the overdrive gear was checked when the unit was in for a rebuild but it's something to bear in mind

loose nut allows movement in mainshaft ,but would expect it to effect others but worth looking under top cover on t/box ,2nd gear end float is set by reducing length of brass bush it and 3rd run on to give no less than 2 thou and no more than 8 thou clearance ,sometimes this is greater than should be ,parts are not quality they once where nothing you can do about it,does stick feel to go completely into 2nd ?it can be adjusted slightly if not by removing top and loosening lock screw on fork and moving it along shaft ,watch detent balls and interlocks if you remove top

As far as I can tell the stick feels like it is fully engaged. Feels very different and less positive than the slightly later 109" we have here though. Will have to investigate it further when my other car is back on the road.

the stick should move the same for 1st as 2nd

Will check later as it's not something I've ever thought about tbh. Thanks for your help.

I've just started to have problems with jumping out of third and second on overrun. I've just fitted a roverdrive. I'm confident I torqued and locked the mainshaft nut. On the roverdrive it is locked by three allen grubs. Could they be holding it off centre? It is pretty noisy but has quitened down after a run from halifax to Glasgow

i would think bush 2nd and 3rd run on is broken if single peice bush or at least very worn along with washers either end ,too much endfloat with gears lets them jump out

Have you checked the detent springs Chris, also i gues your the same ChrisCooke from SXOC so hi

Sorry for the delay in getting back on this.

There are still problems with 2nd & 3rd. Second jumps straight out on overrun now, 3rd isn't so bad but feels rough on overrun (kind of dull vibration). Everything works fine when driving/accelerating but I'm missing the engine breaking.

I'm a bit of a simpleton when it comes to gearboxes so James any explanation of what you mean would be a help. Is it the bit circled in the picture? I did just fit an over drive bit I'm pretty sure the big bolt is nipped up tight. Could something have slipped when I was messing with that?

Cheers

Dom