Jumping out of First and Reverse Gears

[Chipper]

I currently have two ribbed case gearboxes (one in the car) that both have a problem where they jump out of first and reverse gears.

Today, I took the side cover off the one that's out of the car for a look-see, but couldn't see anything obviously wrong, apart from some swarf at the bottom of the gearbox - all gear cogs looked in good condition, and the gears all selected OK but would nevertheless jump out of 1st and reverse gears when the input shaft was turned.

Does anyone have any pointers on where the problem might lie?

[biomed32uk]

If its 1st and reverse then the first gear ring and corresponding gear on the laygear are common to both of these gears, the large gear at the rear of the box. It's also the one that takes a hammering due to no synchromesh.

If the laygear bearings have broken up the box will normally howl like a goodun all the time, you can feed a hand in (just) to try and assess it, but its looking like a strip down on the way, which really is not difficult at all.

Unlikely to be any of the detents and plungers, as two gears are affected.

What colour is the swarf or bits, if its silver then its probably gears or bearings.

[bmcecosse]

Bio - can you please post a link to your gearbox rebuild guide ? I missed it first time round.... Thanks Roy

[biomed32uk]

No problem, I am working on V2 of it, I want to add in re assembling the 1st / 2nd hub with the detents, a ty wrap and its easy.

There are also some gramatical corrections to be made and some general tidying up. On the last push to get the car mobile now and then I can get on with extending the garage / workshop so next winter she has a nice garage to live in, and of course enjoy the car over the coming months.

https://dl.dropboxusercontent.com/u/509 ... ebuild.pdf

Hope its of use, waiting for someone to donate me an old box, will do the stripdown then.

Geoff

[bmcecosse]

Thanks Geoff - I missed the earlier posting when I was in hospital. I'll have a good look at it tomorrow. My 'box is lying in bits waiting to be re-assembled, and of course I have long forgotten where the interlocking slugs and balls go...... All it really needed is a new 1st motion shaft bearing, after years of storage 'nose down' so all the crap fell into the bearing.... Roy

[bmcecosse]

Many thanks ! Amazingly comprehensive document...now printed off for later consumption.

[biomed32uk]

I tried to do it step by step with pictures, most of it is really straightforward but all those balls and slugs for the detents and interlocks have to be right.

My box seems to work well, not driven it yet on the road but I do have a little bit of whine now when ticking over, one problem with used parts, I now have a mix of three boxes. Its quietened down a lot since I first started it and hopefully some driving will get the gears to know each other, settling down some more.

Good luck with the rebuild.

[bmcecosse]

Thanks ! My wife want's to know what's happened to the printer ink.......

[biomed32uk]

Oooops, sure that would chew through quite a bit of ink, fortunately I am far enough away that Mrs BMC can't have a go at me.