48RE Questions

[DaveHess]

I am new to TDR and I apologize if I am regurgitating something old. I am also slightly technilogically challenged when it comes to posting so feel free to correct me. I have a 2003 "555" that is my first CTD. I love the truck but have noted an annoying tendency for the 48RE to perform a very harsh upshift into overdrive. Sometimes it is difficult to tell what happened after the 3rd gear shift in that the OD shift and lock-up happen so rapidly (less than a second). This only occurs while unloaded. I pull two different trailers, one a flat bed with race car weighing about 4500 pounds loaded and the second a travel trailer weighing about 7000. It shifts very nicely when loaded. Took it to the dealer who thinks I am an idiot and they told me I am feeling the 3rd gear shift. No, I am not. They also told me I am driving too light on the throttle and the truck may not be able to correctly determine which gear to be in because of that. I do baby the truck. Recently, we have noticed a low buzz sound coming from the rear of the transmission audible in the cab during the OD shift. Anybody else have this happen to them? I should also note the harsh shift does not occur all the time. Best guess, light throttle with slight hills seem to be the ticket for the harsh shift. Any help here would be appreciated.

 

[CLAYTON]

A good synthetic oil in the transmission will help with that a little. Other then that I don't know what would help... that is unless you go with a good aftermarket transmission

 

[Dieseldumb]

Happens to me before and after rebuilt 48RE-just the nature of the beast, thinks me! Can use tow haul to control shift into OD-does not happen when loaded. Enjoy!

 

[Dosdon]

Happens when unloaded but only on occasion. I haul a 14,000 lb 5th wheel with no problems at all, actually this transmission kicks the livin bejesus out of that load, quite impressive.

 

[bchesley]

the culprit is the torque converter. I just had a tighter aftermarket TC installed and my harsh lock up is totally gone. The big problem is the factory one is so inefficient that in order to lock up it has to drop 300-400 rpm. I could actually bark my turbo under normal driving conditions when I hit lockup. If I was on the throttle a little or towing it would not do it. I am just so amazed after driving with the new TC why the factory cant put one in like it. The difference is night and day.



Brad

 

[Texasrattler]

Hey bechesley,



Where did you get your DTT transmission, somewhere in Texas? Is your new TC part of the DTT transmission upgrade?



Thanks

Pete

 

[bchesley]

Relentless diesel in Willis Texas did my upgrade and yet the tc was part of it. I was really skeptical on how much difference a tc could make, I am now a believer. The tighter converter actually puts the power to the ground. After I had it installed it felt like I picked up another 30hp. It was well worth the money!! Also relentless is a certified DTT installer, heck he lived up there for 3 months for training to build these trannies. I highly recommend them.



Brad

 

[DaveHess]

Brad, Could you explain the "DTT trans with 89%"? Also, I read some threads where it is talked about the TC being a 3 disc or 5 disc. Thanks for all of your time in answering the thread I posted.

 

[MikeBeggy]

I agree 100% with the lower stall convertor. I bought mine fron Precision Industries... they are a manufacturer that supply many of the trans companys that we read about. I also used Dunrites trans upgrade kit. It contains many seals that are necessary for the trans clutch pistons and various accumulators along with spring, shims etc to raise the system pressures to go along with the higher performance shifting. Anyway, my truck shifts and drives way better and stronger. I've never been too concerned about fuel mileage but I did pick up about 1 mpg for overall driving.

 

[bchesley]

The DTT trans with 89% means that I have a DTT built transmission with a torque converter that is more efficient. The 89% number reflects how efficient it is. You can get a tighter converter with 91 or even 93%. How it all works, you need to go to the dieseltrans.com website and read up. It is interesting reading. I never knew much about trannies until the bomb bug bit me. I was forced into upgrading for peace of mind and future bombing.