I found this in another forum:
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48 RE DESIGNED TO FAIL???I have been building transmissions for over 25 years and the 48 RE transmission is definitely stronger that the 47RE as a lot of improvements have been made. However, I am not impressed. We are already seeing failures in the 48 RE's. A $7 part is going to cost you guys by the time the dust settles if you are off your OEM warranty over $2000.
As a transmission technician I have to wonder what were these guys thinking. The guys that design these transmissions are at the top of their field, you wont find any better. This is not a mistake they would make. Someone had to make the decision to engineer this change into this transmission. It is reasonable to assume that if I can for see the damage the lack of lubrication will cause these guys must also know it. .
So, why the sudden change? The existing design of this particular OEM component was not failing. Its design has been around longer than I have been building transmissions.
It makes sense that if you have a problem with a certain part of the transmission you change it. So again one has to wonder why the sudden change???
Please keep in mind this post is not intended to slam the 48RE as they have had vast improvements made to them. This is not even an expensive parts fix, the most important thing here is for the consumer to make sure that the shop and the technician doing the modification has the required expertise to fix it, or at least they are aware of it before they do the job so you have the opportunity to choose which way you wish to go.
Here is why I do not like the new design and why it is causing the damage I am seeing.
Basically the thrust washer is starving itself for oil. What Chrysler did is they drilled 6 holes at 120 thou in the rear annulus gear. What this allows to happen is as the planetary gear rotates the oil is forced out at a faster rate because it is fed by a single hole less than 60thou.
To put it simply, there is not enough oil to lubricate the thrust washer that separates the rear planetary gear and the rear annulus gear.
To fix this requires a skilled professional, about 2 hours labor once the transmission is out and on the bench and the valve body has been removed.
The way the transmission is designed now all I can say is that the approx. life is about
50 thousand miles before you are going to start seeing rear planetary, rear annulus gear and rear thrust washer failure. As we have not done a 48 in our personal shop with over 20,000 miles, the ones we have been doing are definitely showing signs of thrust washer damage already. However my dealer base, general consumers and even other vendor shops have been contacting us for assistance with this issue. I will repeat the advice that I have given them to you guys, it does not matter if your transmission vendor of choice is XY or Z, if the transmission is already out when you are doing the TC &VB, make the change then. The OEM part # for the thrust washer is 52854039AA. It's about a $ 6 from your dealership. Chances are your transmission guy will not have this part in his inventory so if you have it with you it could save you a couple of days.While it would definitely be in my best interest to not inform everyone in such a public forum, as I know my competitors do read this forum, I feel it is an important enough issue to bring to the general consumers attention.