Moke Gearbox, what to check?

[Terry]

Hi,

something else to watch out for inside the gearbox is these new baulk or synchro rings that have been heat treated on the posts only. They tend not to be very true and they wear very quickly. I got 140km out of one once.


And on the plus side if you have the last of the gearboxes which have only three holes for the double row bearing retainer they are desirable as they tended not to crack the casting from the deleted hole.


They can also be spotted from the outside by their casting number, DAM5626.


Terry

[Halfpint]

Didnt know that about the Baulk rings Terry.

As a bit of trivia I guess, these late model box's with the deleted hole in the center rib are also refered to as Twin Line gearbox's on account of the two small grooves along the teeth of the gear sets.

Bit hard to see in the pic, I didnt think to get a good shot of the grooves 


HP

[Drakman]

I think that the 2 lines of grooves on the gears denote  an "A Plus" gearbox, which has a slightly different tooth form, does anyone know if that is correct?

[Halfpint]

Now that would just make things simple Dave, and we cant have that now can we 
The A+ did have a single groove early on, but changed from about '84.

I guess the best advice is to use the casing numbers and match the individual parts from that if buying a rebuild kit.

I had a quick look around, and so we don't muddy the water too much in this thread by counting gear teeth and looking at profiles etc, some interesting trivia can be found on the Guess Works site. Im sure there are many other good sites out there.

http://www.guess-works.com/Tech/ministox.htm

Enjoy 
HP

[Drakman]

Oh good grief, now i know why they say ignorance is bliss.  Thanks HP, i didn't know these sites existed, more reading to do.

Cheers
Dave

[Terry]

Hi,

I would differ from HP and say don't go by casting numbers alone particularly if you don't know the history of the gearbox.

As an example the box I am rebuilding at the moment is the 3 hole retainer type which was A+, it has A+ drop gears but inside the box it had a 3rd motion shaft with 14mm nose, non A+, 18teeth 1st motion shaft and matching laygear all adding up to the close ratio internals from a 1275GT. And by the time I am finished the 1st and 3rd motion shafts will be the 18mm nose variety with the later close ratio parts.

I have been using these pages http://www.minispares.com/catalogues/classic/Classic~Mechanical~Parts~Manual~1959-1985/Transmission~~Gearshift.aspx?4

Terry

[Terry]

Hi,

not exactly in the gearbox but something to be aware of when you are trying to put the transfer cover back onto the gearbox.

The spigot bearing has a race or shell that fits into the transfer housing case and on the end of input shaft sits the roller bearings and if the rollers aren't in the right position the transfer case doesn't slip over them and you can end up damaging things because it can be frustrating and so after enough swearing you reach for a hammer.

There are three reasons I have seen as why that can cause the issues with fitting things together.

A mismatch in bearing and race can occur because you buy a new bearing but getting the old shell out of the transfer case is an art in itself so I remember thinking they are all the same, but they are not, and even yesterday I saw a mismatch between bearings coming out of the same brand of box but a few years apart and with different markings on the bearing itself. Sometimes the race is thicker or the rollers slightly larger. So check first before fitting mismatching pieces to the input shaft.

The most common issue I have seen is the bearing shell has a square edge on the inside which make it almost a miracle if things are lined up when you try to fit things. Some brands of bearings have a small chamfer on the edge that helps lead the rollers into place, but not the one I was trying to fit yesterday. After trying to get lucky for 20 minutes yesterday I removed the shell put it in the lathe and put my own chamfer on the shell and it fitted first time.


And the other things I saw yesterday was the circlip that holds the shell in place was not central in the casing and so with a bit cleaning of the groove and rotating the circlip around I was able to have it cause less of an obstruction in one position.


Terry