Squeezing oil into a T-50 gearbox....

[jondee86]

Changed the oil on my car today and found that after draining the T-50
I could only get about 1.1 litres in the fill hole before it started running out
Now I know that the FSM says 1.7 litres and I know that there will be a bit of
old oil left inside, but 1.1 litres is well short. And if there is 600 ml of old oil
left inside and I am changing grades, that's gonna fcuk with the expensive
new oil I put in !!

Car was near enough dead level. Is there some trick to getting the oil in/out
that I might be missing, that would account for this strangeness ?

Cheers... jondee86

[assassin10000]

Fill through shifter hole.

Trans isnt level in the car. Rear needs to be slightly higher.

Andrew

[jondee86]

Thanks Andrew... I drained it again with the back 3" higher than the front.
Still didn't get much more than a litre out, so maybe that is what it has been
running with ? Anyway, this time I will fill it thru the shifter hole and stick
in 1.5 litres. Should be good

Cheers... jondee86

[jondee86]

Just to tidy this up... I measured how much oil drained out...
1. With the car level drained 1150 ml
2. With the back of the car 3" higher drained 1150 ml
So it seems that draining and then filling until oil spills out the level
plug will only allow 1150 ml of fresh oil to be filled into the gearbox.

Now I have added 1500 ml thru the shifter hole, and there is a BIG
reduction in gear noise inside the cabin. Therefore it is reasonable
to assume that filling until oil spills out the level plug DOES NOT add
sufficient oil. Adding 1500 ml is better, and maybe adding 1700 ml
would be even better for hard use. I'll try that next time

Cheers... jondee86

[AE82 FXGT]

Careful with adding too much oil in gearboxes.

They're supposed to have the bottom half of the countershaft in oil and it's usually supposed to sling the oil to the top input/output shafts.

If you drown the box in oil I guess you slow it down/ add resistance.

There must be a reason the manufacturer put it at that level, mind when it's not brand new, it's another ball game so I'm probably talking out my ass.

[jondee86]

Yeah... I sort of took the oil level into consideration. It is possible to
overfill a gearbox, and it could result in oil churning and drag. But then
the factory recommended fill of 1.7 litres is most likely based on filling
a dry gearbox... and I don't know how much oil is left inside when its
drained on the car. So I settled on there being maybe 200 ml left inside
and added 1500 ml.



Looking at this there seems to be a reasonable amount of clear space in
the bottom of the box. And going by the reduction in gear noise the teeth
must be meshing in oil now, or have a lot more oil on the tooth contact area
than they had before. The noise it made before always bothered me... it
was just too loud for a happy gearbox.

Now it sounds happy, and until someone can tip up a "drained" gearbox and
tell me how much was left inside, I'll take a chance with adding 1500 ml.

Cheers... jondee86

[MAC_HATER]

Its been an interesting read this! thanks for that

my old Corona's T-50 was always a noisy old wench - it would scream on decel also, we just did the usual "fill to overflow bolt level" and left it, perhaps adding a bit more would have silenced it a wee bit, or it was already too far gone and no amount of oil would quiet it haha

[85AW20v]

It's not a case of fill it till it comes out the output shaft end rather than the "filler hole" is it seeing as the rear is slightly higher as suggested by assassin10000? Would it take 1700ml if that was done?

[assassin10000]

Even complely drained from the plug, when I tipped a t50 up on end I still got a small puddle of oil out of it IIRC. Not including what was stuck to the surfaces inside...

Putting 1.5-1.7L through the shifter hole is good imo. Its not enough to overfill the trans afaik.

Andrew

[jondee86]

It's not a case of fill it till it comes out the output shaft end rather than the
"filler hole" is it seeing as the rear is slightly higher as suggested by assassin10000?
Would it take 1700ml if that was done?

I drained the gearbox with the rear raised, and no more oil drained out than when it
was level. And considering the small angle/change in slope of the gearbox by raising
the rear wheels 75mm, I really don't see any realistic chance of getting more oil in.

I believe the real difference between the recommended factory fill and the amount you
can squeeze into the fill plug, is explained here...



When the gearbox cases are together, the assembly bolt locations at the bottom form
a series of small "weirs" retaining puddles of oil. These will always hold some oil when
the gearbox is drained. In addition to which the drain plug is not at the bottom of the
box, but in the side, and located above the top of one of the "weirs".

This glass holds 7oz or 200ml....



... and it is not difficult to visualise that amount of oil being left in the gearbox after
draining. What I have more difficulty with is figuring out why I could only fill 1150ml
into the gearbox ? Either a lot more than 200ml stays inside, or the positioning of the
fill hole is too low. Whatever the explanation, I'm going to stay with filling 1500 ml

Cheers... jondee86