Lots of discussion around here about the auto tranny for our trucks; I'm glad I have an auto for the highway mileage (spectacular so far!) and I don't tow all that much, so the convenience factor is nice too.

But lots of people don't like the newest version of the 48RE very much. What are the real weak points of this transmission? Aside from wider gear spacing due to one or two less gears than the other big 3 offerings, where does this tranny fall short when compared to the Allison or Torqshift?

I'd like to keep this discussion limited to actual technical specs or engineering facts.

 

the motor is so strong that its hard for a tranny to back it up. alot of guys are adding power and its really doing a number on them. if you can afford a TC and VB it seems to help them out

brett

 

From my understanding the 48re is comparable in strength to the allison. The downfall is the torque converter. It is made too "loose" and the clutch won't handle the power these engines make. And once the clutch is slipped once it glazes the lining and can also distort the surface of the converter where it bolts to flexplate at each boss creating high spots where each boss is as they become "twisted". That in turn allows less surface contact on the lock up clutch. But also just the fluid coupling inside the converter is not efficent and all that together creates a bunch of heat. As many of us on here that have installed a tripple disc torque converter know it drives completely different than stock. You can actually feel it shift and see the rpm's drop instead of just absorb the power and not see the rpm's drop any. But I think one of these 47 or 48 re trans would live a lot longer if there was a tripple disc installed when its new, or before any heavy towing. The other modification would be the billet shafts for a highly modified engine or pulling over 20k. All in all the chevy and ford are prone to fail with modified engines also. If you want to read a detailed letter from Dave Goerend about this go to their website. I think it's gbtransmissions.com

 

I just traded in a 2004.5 with the NV5600 6spd for a 2006 MegaCab with 48RE for the convienence factor. I live in the city, do alot of stop and go traffic, and my wife can't drive a manual, so all the evidence convinced me that getting an Auto was the way to go. Well, I never really appreciated my 6spd until I got my new truck. Driving my auto, I feel like I'm running at half HP/TQ that my engine can produce. With my 6spd, the truck felt so much stronger. While it would be nice to have 6 gears, I'm happy with the 4 in the 48RE. I just wish the shifts were better. Its hard to describe.

Now, that doesn't mean I'm unhappy with my truck. My left leg certainly appreciates the auto during rush hour traffic. Also, my wife drove my truck for the first time last week, and I was happy to see her able to do that. I'm also happy to see my RPM's drop on the highway due to the taller OD gear in the 48RE than the NV5600 and G56.

Now, the 48RE is DRAMATICALLY improved over the 47RE. Its actually proven to be a pretty decent tranny interms of reliability. The 48RE can't handle the big power like the NV5600 can without major $$$ into a rebuild, however, from what I've read adding a aftermarket TC and Valve Body can greatly improve the tranny. After 3 weeks of owning my truck, I'm already looking into one.

 

The more I read about the 48re the more it Pi***s me off,I bought a Dodge thinking it was a bomb proof truck,seems like their truck trannys are about the same as their wimpy minivan trannys ,maybe DC should let someone else put trannys in their trucks.They could of put the better TC and VB in it.What guy on this site would not of paid more to get a bomb proof tranny.I do like my truck alot,and with the auto and 3.73s get better fuel economy and decent speed,but maybe next time I might look at the GM makes a little harder!!!

 

How much does it cost to install an aftermarket TC?

 

Wow...the 48re is a very reliable transmission. Mine shifts perfectly fine. If you plan on adding big power to it then you need to upgrade it but why cry to DC about that? It is fine at stock power levels. I went from a NV5600 and I don't regret it one bit.

 

This is why I wanted to keep the discussion limited to actual engineering specs or facts. It's easy to get caught up in internet complaints; small problems get magnified, and opinion is taken as fact.

I don't care if my tranny is bulletproof or bombproof. I don't plan to shoot or throw grenades at it. I would just like to know - if there IS something that's weak on these transmissions as compared to the Allison, what is it? The answer so far seems to be the TC. Is there anything else?

If not, then there's really not that much to complain about.

Smokeman, I'm embarssed to say that I have only towed heavy once with my truck, and I did get more slippage on steep hills than I would have liked from the TC before lockup.

 

Interesting comment. I've read about the slushy TC in these trucks and I wonder if there is any good info that someone might have about what RPM drop you should see with a decent TC when it locks up. I've played with mine and under normal driving I see about a 200 rpm drop. I have towed up to 23000 lbs GCVR up and down some good British Columbia mountain passes but I cannot remember what I saw for lock up rpm drop in those conditions. I certainly never developed any kind of heating problem whatsoever though.

 

I don't have a tranny gauge yet so I don't know what the temps were, but the RPM drop was pretty large, like around 500 RPM.

This was a STEEP hill though (back country road, not interstate), and I was flogging it in the name of break in.

 

What's really wrong, it's behind a Cummins. Auto's are like sneakers, when the rubber material used in them gets worn, you throw them out.

 

Wow! That is harsh. I have sold a bunch of trucks with 48re transmissions. I have one customer who is a hot-shot trucker who has 300k on an 04' and all he has done to his 48re is change the oil in it once. And he pulls every mile, but, he left his engine stock. We have only had to work on one 48re trans sense they have been on the market, and that was on a customers highly modified truck. If the truck is left stock, the 48re is a really dependable transmission.

 

I was worried about my 48re when I first found this site soon after buying my truck. But after putting 11,000+ miles on it, 10,000 of those with my Quadzilla box, and roasting the tires while pulling a 9000-lb travel trailer I'm not worried any more. Would I like a tighter torque converter? Absolutely, but it works just fine with the one it has and I can live without one. Would I like 6-speeds? Absolutely, but again it works fine without the extra 2 gears. There's really nothing wrong with the 48re, but it could be improved. Even though, I'm perfectly content with what I have.

 

I got to say the 48RE has been a good transmission for me and I tow heavy a lot but my truck is close to stock . Anybody that thinks Dodge has a transmission that will take all the extra horsepower and torque that can be made with this engine will be disappointed down the road but a guy running close to stock should be happy for a long time . If I were to do anything to it , it would be the torque converter I guess but if that happened it would add more load on the clutches and that would require a valve body change to . My only complaint would be when backing up with a heavy load , if not for using the 4 low , the heat builds quit fast in these transmissions .

 

I've read it here before and somewhere else about the failure/problem ratings of the Big3 trannys. The 48re was the lowest at under 3% and Ford was at around 4% and the "Mighty Allison" was around 5% failure... As stated, in a stock powered Cummins, the 48re should last a very long time.