T90 Transmission Question?

I forgot where I read it but has any one blocked the oil passages between a T90 transmission and T18 transfer case? I think you cut a new gasket but leave the oil holes covered and install a sealed rear bearing with the inner seal removed so the fluid from the transmission will lube the bearing. I think the reason this was done was if there was a bearing failure in the transmission or transfer case was to keep the metal from damaging anything else.

 

Unless something has changed, that's not true. All the Borg-Warner 3-speeds pass oil between the transmission and transfer case through the bearing. It's slow, but it does transfer. Only the T-150 and the truck 4-speeds have a seal between the units.

I have not heard of sealing the back end of a T-90, but there have been plenty that have gone with a sealed bearing in the front. Leaking from the front is pretty common without a sealed bearing. If the bearing is sealed, there is no reason to oil it - it's supposed to be lifetime lubrication inside the seal.

site:earlycj5.com T-90 sealed bearing - Bing

 

Days, maybe longer.

Never owned a T-90 or a Dana 18, but I've seen oil transfer out of a T-14 into an empty Dana 20 and the T-14 end up dry. This is something that was common knowledge to me back in the 70s ... I would be surprised if it's wrong. How could the T-90 be different from the T-14? There's no seal in there. The T-150 has a seal and the Dana 20 has a matching gear with a seal surface to prevent transfer of oil - there's nothing like that in any of the Borg-Warner 3-speeds.

 

The oil migration hole at rear of T90 is at same level as the transmission fill plug.
The oil migration hole at back of transmission is about 1/4" diameter so excess oil migration from T90 to D18 is slowed down considerably.
And T90 normally stays full to that level.

The transfer case slings gear lube upward so that works to keep transmission full at all times.
That explains how the TC can low but T90 remains full.

 

Just drained my d18, checked the oil in the t90 and it was full. Left the pan off the d18 for a good 5-7 days. Never lost a drop (or anything considerable) in the t90.

just a fwiw

 

Yeah Glenn,
I was just going from old memory.
I think you're right..
That T90 oil migration hole sets at same level as transfer case oil;
Not higher up as I squimishly stated in the previous posting.
Regardless the TC does sling the gear lube toward the upper areas.
So transmission remains even if TC gets low.

 

I see no huge advantage to isolating the T90 and D18 gear lubricants
Yet a person could rather easily isolate these gear lubricants.
They would only need to plug the transmission oil migration hole and also install a sealed rear mainshaft bearing.

 

I have a M38A1 shifter tower on my T90. So all i have to do to fill it up is remove the fill plug and remove the shifter because it has a threaded cap and fill it through the top of the shifter tower till it runs out of the fill plug.

 

It's also very easy to fill D18 from the PTO port if you don't have an O.D. setting there.
But normally you could only add a tad extra oil to the D18 anyway.
If you fill too much it will slowly drip out past the speedometer drive shaft.
Perhaps an "O' ring would seal the speedometer drive shaft .
I never bothered to fill a D18 beyond that level.
Yes it's certainly important to keep D18 oil level up to snuff if you have an O.D.

 

I am installing a new t90, and the t-case is on the bench. I like your idea of extending the t-case vent. Would you have any pictures or recommendations? Is it just located higher and reusing the cap and cotter pin or did you move it somewhere else?

 

My D18 is always a little over full. It is getting oil from somewhere.