Jacks Transmissions Forums

Now that these units are getting old, it is becoming more common to see lubrication issues with the center diff in DSM AWD trannies. No matter which center diff you use (2 or 4-spider) or who makes it, the unit will eventually have wear at the cross-shaft and spider gears due to lack of lubrication. It doesn't matter which cross-shaft you have, it will have the same issue in time. I have seen all 4-spider center diffs from everyone out there and it happens to all of them. Here are some pictures of damage caused by lack of lubrication:





Eventually the scoring will get so bad that the gear will either seize in the housing, the gear will break, or the shaft will break.

Some try to drill more holes in the housing thinking that allowing more oil to escape will solve the problem, but that just makes it worse. The housing doesn't get any oil from the center, the oil comes in from the outer part of the housing. Unfortunately, the housing rotates and centrifugal force pulls the oil out of it. Adding more holes to the case will just allow more oil to leave the assembly and kill the gears faster. The only time oil can get inside of the assembly is when it is rotating at a very low speed or at a stop.

What I have done as an experiment in my own trans is add scoops to the oil holes around the outer end of the case. As the unit spins, the scoops will force oil into the unit giving the gears much needed oil. What I did on mine was add the scoops to two of the holes and leave the other two open. This allows for the oil to completely circulate through the unit and not only keep everything happy lubrication wise, but keep things cooler too!

Here are a few pictures of the simple solution:





The scoops in the case with plenty of room:







Please note this is something I made for my own trans using scrap metal. I would like to offer this upgrade to our trans customers eventually and possibly make it a standard upgrade in all of our rebuilds. I will come up with a cleaner design if this turns out to be a hit, and I can't imagine why it wouldn't be. Before I offer this to just anyone though, I would like to try a few more out in some more test units. If you are having a trans rebuilt by us, please let me know if you would like to be a guinea pig for the modification and I will do it for free.



As you can see, without the scoops oil can't get into the unit when it is rotating. Again, oil doesn't enter the assembly anywhere else and is a major design flaw. Logic would suggest that the scoops work and so far I have had no issues in my personal unit. Another way of looking at it is the faster the unit rotates, in stock form with the OEM holes, the more oil is forced out and less likely to enter the assembly. The scoops will force more oil in the faster it rotates.

Before I make it a standard upgrade though I would like to have more time running them and a few more units with it first.

Any input would be appreciated! I'm surprised no one else has tried anything like this, but it makes the most sense.

Thanks!

Jack

Really?
You couldn't have told me a week earlier?


Next time....


--Steve

Sorry! That's one of the issues when you come up with something new... We are still testing this. It may not work at all.

I like the sound of this...now how do I get it added?
Is there a comments area when placing an order?

For now, since this is still not available via the website yet, I would recommend just emailing us if you want it. I will add it to the work order to remind me to do it when we have the unit here.

Great idea Jack you guys never stop amazing me