MM gearbox tailshaft/flange loose

[RobThomas]

Like the title says, I've just had a look at the box out of HFH 200 and the flange that is bolted to the output shaft is loose. I looked at another box in the garage and it is the same. Is it a known issue? I'm aware of the advice regards speedo slippage in the factory manual but wondered what has caused it in the first place. Has anyone stripped an MM box before?

[mike.perry]

Can you post some photos?
Or phone John Evans 02392 465256, 07776 381520. He is repairing an MM box at the moment

[RobThomas]

Sure, but there isn't anything to look at. If I grab the flange on the back of the gearbox I can pull it about 5mm rearwards. It doesn't appear to wobble on the splines but just pulls in/out. (See section F.6 of the manual?)

PS Does anyone still sell the top water elbows for USHM3 and also the blanking plate for the side when a pump has been added?

[ian.mcdougall]

Hi Rob
ESM do both the blank for block has to have a drain tap can't remember where I got the tap but can look when I get home
This is the link to the blank and elbow http://morrisminorspares.co.uk/shop/ind ... 37ce4b240a
Regards Ian

[mike.perry]

The tail shaft flange should tighten in with the nut on the end of the shaft. Is there any lateral movement or oil leak? If so then the bearing and/or oil seal need replacing.
The flange on my spare box moves fractionally but the nut is loose
The block drain tap castings are still available from John Vine, Minor Developments 01562 747718. Not sure about the brass tap, you may try ESM

[MMaurice52]

Like the title says, I've just had a look at the box out of HFH 200 and the flange that is bolted to the output shaft is loose. I looked at another box in the garage and it is the same. Is it a known issue? I'm aware of the advice regards speedo slippage in the factory manual but wondered what has caused it in the first place. Has anyone stripped an MM box before?

Rob,

I rebuilt a spare gearbox for my MM last Spring. If the flange nut is tight, the cotter pin still intact, then I would suspect a worn "mainshaft intermediate" bearing (see Fig. F.13 of the WSM). The bearing inner race is held in position on the shaft by a cir-clip. The nut, if tight, would hold the Speedo. gear, spacer and tailshaft bearings at zero clearance. I have numbers for the
three bearings if you need replacements. BTW: the tailshaft bearing is metric the other two are inch size.
If the nut is loose, I would suspect damage further in on the mainshaft which would require dis-assembly.

Marc