Notchy gearbox and humming diff, change to a different oil?

[RichardsonStag]

Hi Guys,

So the gearbox on our Stag is showing its age, its a Manual Overdrive (J Type) with signs that the syncro has gone on second (hard and crunchy to get in without double de clutching, pops out on overrun).
This is the top of the to do list for next winter but until then we plan to use it, currently all the other gears are notchy, which we are putting down to the clutch slave seeping (it recently had a new clutch and the bite is about a center meter from the floor currently).
I'm hoping a new slave will sort the other gears, but this has got me thinking about oil types, it currently is full of the correct grade oil, however is there a different grade which could help the situation? Or am i better just giving it an oil change with fresh standard grade oil again?

And then the same question for the diff, the diff hums on the motorway, it is full of oil thats not that old, but are there better grades?

Finally something slightly less important, i cannot find what size screws are needed to secure the centre console down to the transmission tunnel, Rimmers diagrams don't seem to display them. Its the two machine screws that go through the woodwork fastening bracket, through the centre console and into the tunnel. I just need a thread size (UNF presumably?) and i can get some ordered.

Thanks,
Mat

[richardthestag]

Hi Matt

Tired gearbox, noisy and baulking. old fashioned bodge was to install ladies nylons or sawdust.

BUT that might just make things worse for the rebuild at the end of the year.

Jumping out of gear and crunchy gears are something that will probably need to be lived with. I run mine of 20/50 multigrade which is thinner than oe spec oil, an expert will be along shortly to advise whether a heavier oil might help?

Changing the oil, unless it is full of shrapnel or hasnt been changed in years I am not sure I would bother. good money after bad.

Master that DDClutch for added grins and hold it in second like Steve McQueen would have done in Bullett

re clutch bit point. provided all is standard, the only adjustment is / should be on the clutch crossshaft which the slave pushrod attaches too. iirc mine has three holes. I am fitted to the middle hole and biting point is just below 1/2 way.

Does the bite point rise if you pump the clutch? yes = common fault air in the system. undo bolts securing slave to engine adapter. swivel it so that the bleed nipple is right at the top and bleed it again.

Pretty sure the clutch drags if the slave is on the wrong side of the engine adapter plate but check that also. The slave mount should be on the gearbox side of the hole, not the engine side.

again experts will be along re heavier grade oil or additives for humming diffs.

re the screws, you mean the ones that are under the coil tray? I will go measure one now

[richardthestag]

screw is cross head 3/16 NF32

[Guest]

Hi Guys,

So the gearbox on our Stag is showing its age, its a Manual Overdrive (J Type) with signs that the syncro has gone on second (hard and crunchy to get in without double de clutching, pops out on overrun).

If you carry on driving a car with knacked out syncro rings you will destroy the drive dogs on the gear, as well as damage the syncro hub.
I see this all the time, but people carry on driving this stuff regardless.

[RichardsonStag]

screw is cross head 3/16 NF32

Thanks Richard, thats all been really helpful, i'll get some ordered!


Regarding the clutch, the bite has been low for a while, all gears have been crunchy for the past couple of hundred miles (whereas it was only second before), and my dad is adament the bite used to be higher.
The pointer has been that when driving out of the garage last week, i stalled it (the choke cables ended up being removed whilst sorting the interior out), the engine turned over a few times before starting and whilst doing so, with the clutch fully down, handbrake off and in first gear, it creeped forwards, this is on a flat concrete floor. So the clutch wasn't fully disengaged.
Tonight we have fitted the new slave, drained the system, and bled with fresh fluid. Although we ran out of time to drop it on the floor and test. The old slave was seeping rusty coloured fluid from the piston.
I know the clutch lever you mean, ours is set on the top hole, which perhaps is something i should play with, i imagine the hydraulic system is self adjusting to although for clutch where, much like the brakes self adjust?


Down the plughole, what do you recommend then? Stop using it and remove the box? Or is there anything that can be done to minimise damage? (Whilst still using it).

[Guest]

Down the plughole, what do you recommend then? Stop using it and remove the box? Or is there anything that can be done to minimise damage? (Whilst still using it).

I am handling more and more gearboxes which have been rebuilt multiple times by other people, - usual stuff no-name chinese bearings and nasty bits of all shapes and sizes.

I don't mind doing this, and the word in the trade is, GREAT, we make loads of money out of other people's junk rebuilds....
The problem is, lots of these gears are getting in really bad shape, and they are NOT getting younger.

I decided, once this summer 2018 is over, I don't want to keep trying to chase down NOS or good s/h unobtanium any more.

Simple thing, carry on driving a flaky transmission with dragging clutch and bad syncros, don't be suprised if some day, it becomes yet another flaky rebuild that's notchy, nasty, noisy and plain sounds like "it's been to the moon and back".

The impossible can be done immediately.
Miracles take a little longer....

[mole42]

Simple thing, carry on driving a flaky transmission with dragging clutch and bad syncros, don't be suprised if some day, it becomes yet another flaky rebuild that's notchy, nasty, noisy and plain sounds like "it's been to the moon and back".

The impossible can be done immediately.
Miracles take a little longer....

Love it.... :-)

I once drove a Triumph 2500S with a noisy diff, day after day, until one day it exploded on the M6, the remaining hot oil catching fire - underneath the fuel tank! A passing Good Samaritan stopped with a fire extinguisher and both the car and I lived to fight another day.

[Kithmo]

Depends what you call noisy with a diff. I had old Fords back in the 70s that had whiny diffs at 60K miles and went on for another 50-60K miles without a problem (apart from the whine)
Now rumbly, that's different, it may be a bearing that's breaking up and could let go at any time, needs sorting asap..