Gearbox: First motion shaft nut removal

[Osiris610]

I'm having a hard time removing the securing nut (Moss part #440-150) from my TC transmission. It occurs to me to wonder whether or not it is a standard right-hand thread. It looks like a special tool with two opposing teeth was used to put it on. I don't have one of those, but so far all other attempts to shift the nut (assuming right hand thread) haven't worked.

Any special tips or techniques?

Thanks in advance for your wisdom!

Mike

[Simon Sadubin]

Hi Mike,

Yes the input shaft nut is a left hand thread. You can use an adjustable C-spanner for this job.

regards,
Simon TC2575

IMG_3966.jpg (78.42 KiB) Viewed 3509 times

[Osiris610]

Simon, many thanks! Your advise should take care of the problem.

Mike

[ROGER FURNEAUX]

It is indeed a L/H nut: a lot of people do not have a fancy adjustable C-spanner, and use a drift on the slots.

We have made these nuts (Moss say NCA, have not checked the others), might have one left, but can easily make some more.

Roger
AKA "Mad Metrics"

[Ray White]

It would be useful to have a list of all LH threads on the T series cars.

[Steve Simmons]

Now there's a question I've never seen posed before. I'd have to think about that but off the top of my head I can only think of a few, including the one mentioned above.

First motion shaft nut
LH bearing carrier nut
LH Front hub nut
RH knockoffs (front and rear)

[ROGER FURNEAUX]

Another one is the special castellated nut on the end of the starter motor shaft.

Roger

[Duncan M]

Another place rotational forces can cause trouble is the bolts/nuts that connect the U-joint to pinion shaft flange. To avoid problems of loosening, the factory used bolts drilled for a split pin and castellated nuts. Not a place to trust Nylocks.

[Ray White]

Another place rotational forces can cause trouble is the bolts/nuts that connect the U-joint to pinion shaft flange. To avoid problems of loosening, the factory used bolts drilled for a split pin and castellated nuts. Not a place to trust Nylocks.

I have yet to have a Nylock fail...but then I always use new ones.

[Tom Lange, MGT Repair]

Duncan - I don't believe I have ever seen castle nuts on U-joint or drive shaft flanges. I always find Philidas nuts.

Tom Lange
MGT Repair

[Duncan M]

Tom-
That type of self locking nut is a good choice, and would also certainly stay tight, but were they factory installed?

Ray-
I have seen brand new (only tightened) "high quality" Nylocks fail in as little as 20 minutes of driveline use. Not on a TC. I know they were only tightened, and brand new, because I put them on-- out of a sealed pack. Short of time or other options I was able to stop the unwinding by using a properly sized split lock washer under a regular nut. That was years ago, and now I only trust nylocks to non-critical applications.

[Ray White]

I can only assume you had a faulty batch because if they had been that bad they would not be used as extensively as they are. Locnuts are, of course, temperature sensitive which is about the only downside I can think of.

My Dad was an engineer and used them extensively for years without any problems.

[ROGER FURNEAUX]

Years ago, while driving TC0978 in London, thankfully quite slowly, the rear of the propshaft detached itself from the pinion flange...I was using Nylocs, probably not new. Luckily I always carried a few spare nuts & bolts so was able to get going again. I dread to think what the effect would have been if the FRONT of the prop had come undone!

As to originality, the factory spec. book 259 says castellated nuts and split pins. In fact I have a few NOS drilled bolts, but nowadays recommend Aerotight nuts (equiv. to Philidas or Stover nuts.

Roger
AKA "Mad Metrics"

[Duncan M]

Roger-
Thank you for looking that up to confirm the castellated nuts and split lock pins were factory. I assumed they were because of all the other critical nuts with the same arrangement.

Ray- the loosening new Nylocks were on a sports racer at the axle half (prop) shaft on only one side. The rotational forces were just too much for the Nylocks. Of course we could have gone with left handed threads in that location, but finding British threaded studs of the right size and length in the appropriate strength was enough of a challenge, let along finding left handed studs to accept the nut, and right handed threads to go into the prop flange. Those nuts were several sizes larger than the nuts in question, so perhaps more prone to those rotational forces. Eventually we found that the properly sized split lock washer was a satisfactory solution after all, and it never loosened again. With the engine in front and drive wheels in back, the failing nylocks would not have been caused by excessive heat.