Recon gearbox

[capnblack]

Hi, I've just received a gearbox which I was sold as reconditioned, for my 71 Pickup. The box looks very nice from the outside and I've just removed the side cover to have a look inside. Question is: what should I be looking for to confirm I have what I assume I have purchased, i.e. a reconditioned box (as opposed to a nicely painted unreconditioend box)? Maybe I'm just too cynical?

[Mick_Anik]

Well, as I understand it, many parts will not be new in a recon box. Forks tend to be okay for a long time. All the bearings should be new, but looking through the side cover won't help to ascertain that they are.

There should be a space, about 1mm, between the baulk rings, which should be new, and the sides of the teeth of the gear they work on. I think you can see this through the side cover. If the baulk ring touches the sides of the teeth, there won't be much synchronising going on, if any.

Spin everything around, and you shouldn't see any cracks or pitting on any of the gear teeth. The layshaft is obscured by other things but you might be able to have a look with a torch. It shouldn't move very much laterally, just a few thou. If it moved a millimetre laterally, that would be bad news.

I can't remember exactly what you can see and what you can't. I'm sure others will be along and remind me.

The proof of the pudding is in mounting it on the car and trying it out, really.

[bmcecosse]

The main wearing point is the little 'dog' teeth on 2nd gear. looking in the side cover - you can see 2nd, 3rd and 4th gears. the dog teeth on 4th gear NEVER wear - so compare them with the little teeth on 3rd and 2nd gears - they should be the SAME. Many 'recondition' a box by fitting new syncros (and maybe some bearings) - this is useless unless 2nd gear is also replaced- it is the one taking the most abuse. If the dog teeth on 2nd gear are worn away - it will crunch - and probably jump out. Of course - the non-syncro 1st gear (and the matching teeth on the laygear) also takes a hammering, but you can't see it because it is obscured by the selector. Running the box in the car is the final test!

[capnblack]

Well...... I know it's been a while (to say the least). But today I got round to looking at installing the "new" gearbox referred to in this thread back in 2009. As I have the engine and box out of "Lilly" at the moment to replace, amongst other things, the clutch, I thought I'd get out out this lovely looking pristine gearbox from storage and put it in the pickup. Anyway, been examining the guts of the box through the side access cover and I was worried that I could not turn the input shaft in any gear, also, in "neutral" the box appeared to be still driving. This inspection was made possible as I have my "old" box lying alongside the "new" one for comparison. Anyway, the give away (having referred back to the answer I had below from Mick_Anik) is that the layshaft can be moved laterally by at least 6mm (1/4"), .... so, it would appear that, back in 2009, I was "sold a pup". As a gearbox, it will probably make a reasonable anchor!
Anyone got a recon box they want rid of? Preferably one that IS reconditioned AND has been assembled properly!
Now going to open a bottle of Proper Job and read the workshop manual section on "gearbox". Never stripped and rebuilt one before, could be a first.

[bmcecosse]

I doubt you can move the 'layshaft' from the side cover.... maybe the laygear ?? Take a couple of pictures through the open side and post them up. The box may have 'dried out' in storage - could be why it seems hard to turn etc. A spray around with thin oil may get it turning by hand.

[bmcecosse]

This a Goldseal box I have 'in stock'
You can see that the dog teeth on 2nd/3rd/4th gear are pretty much all the same. Since 4th gear pretty much never wears - it's aguide to the condition of the others. And looking down to the left - can just see the straight cut teeth on the laygear that mesh with 1st gear - and they are sharp and unbroken - as they should be! How does your box compare ?


In this picture of another (still good!) box you can see the dog teeth on 2nd gear are slightly worn, the 3rd gear dog teeth are still quite good, but not as good as 4th gear! And the laygear teeth for 1st gear are still good and sharp !

[les]

The laygear would have 1/4 inch lateral play if the shims either side were missing. Sounds more CON than recon. Good luck with your search.

[bmcecosse]

I don't think it's easy to reach down inside the box to get at the laygear to measure it's end float! But actually - it's not all that important. the angled teeth on 2/3/4 gears will push it sideways against the thrust washer anyway. Which is why the competition straight cut gear sets absorb less power!

[les]

---if there is 1/4 inch play, the thrustwashers have been left out!! --and will 'thrust' on the casing.

[bmcecosse]

Yes - I agree - if it really can slop about 1/4". I suspect it was not the laygear (or layshaft) that was being moved........

[capnblack]

Mmmmm.
I've been trying to take some decent pics of the inside of the box, without much success. What I can say is that the dog teeth on 2nd, 3rd and 4th all look fine, the bevel cut gears also look fine. The problem appears to be with the lay gear unit. There is a definite gap of about 6mm between the end gear cog and the box casing, in this space I can see what appears to be small springs, these are in line with the layshaft. The lay gear can be moved laterally by this 1/4" as described. When the laygear is moved away from the end of the box where the springs(?) are visible, the cog on the other end actually clashes with the casing itself. I'll try again for some pics. I think my best bet for now is to put the "old" box back in. At least it worked, occasionally it might jump out of 2nd (rarely) and it is a bit notchy between third and fourth, only requiring a bit of respect and timing for a smooth change (or double clutching).

[les]

The only small springs in the gearbox are in the hub and cone assemblies, these are not free to be seen! Look around the bottom of the box, you should/might see some loose, small ball bearings which would have been part of the assembly along with the springs. If you do, it will entail a stripdown to sort it out. It is not usually possible for these springs/balls to come out under normal circumstances but with the movements you speak of, who knows! Gearbox rebuilds (on Minors) are not rocket science but there are points that need special care and attention regarding washers, shims, plungers and alignment.

[capnblack]

Trying to add a couple of pics here - what do you guys make of these?
The note on the first picture reads "note offset between laygear and adjacent cog" and on the second picture "note the laygear is against the gearbox casing".
The last pic is included to show the general condition of the gears.
Will have a look around in the box to see if there are any loose bits and report back here.

[frame][/frame][frame][/frame][frame][/frame]

[bmcecosse]

I see what you mean....perhaps they forgot to put the thrust washers in.... And yes -2nd gear looks ok there. It's going to need pulling to bits - so yes if you have a serviceable box, use it meantime !

[Declan_Burns]

1/4" float on the laygear is far too much. I'm rebuilding the old gearbox that was in the TD and is very similar in design to the minor. I have a DVD from Barrie Jones on TD/TF gearbox repair and also contacted him on this issue. The end float should be 0.002" (0.05mm) on the laygear for the TD and I would think the same could apply to the minor as I can't see any specs in the workshop manual at first glance. Certainly not 1/4". I think Roy is right that possibly the thrust washers could be missing.
Regards
Declan