48re Overriding Clutch

[FPettijohn]

Has anyone on this forum had problems with the over riding clutch in the new automatics? I was told that if you use 1st gear that it locked it out and prevented many problems. I appreciate your responses.



04. 5 3500srwqc sltlb xzt-phantom guages pillar mount bad truck Oo.

 

[ThomasLawrence]

Overrunning, not over riding. The overrunning clutch is applied only in first gear, regardless of whether the transmission is in Drive or manual 1st. However, when in manual 1, the rear band is also applied, taking some of the load off of the overrunning clutch. For regular driving, it doesn't matter. If you're towing right up to (or over ) your GCVWR, you'll get longer life by starting out in manual 1, then shifting into Drive at about 15MPH or so. Shifting into manual 2nd doesn't buy you anything, as there's no difference between manual 2nd and 2nd gear while in Drive (deceleration is a different story - the 48RE is capable of TCC lockup while in manual 2nd, which can help with a bit of engine braking).



There's also an overrunning clutch in the overdrive unit, but this is always applied in all forward gears, except 4th (overdrive). And - if you really want to get into it - there's an overrunning clutch inside the torque converter, as well, that locks the stator for low-speed torque multiplication - but I'm assuming you're referring to the one in the main gear case of the transmission



-Tom

 

[FPettijohn]

Tom

Thanks for the explanation. I had a champion MH with a 440 and 727 and remembered someone saying it would last longer using 1st when pulling the horse trailer. Was not sure if it still applied to the new elec. trans.

 

[ThomasLawrence]

Was not sure if it still applied to the new elec. trans.

Yep. Don't get too caught up in the 'electric' term in the name, though... except for an electronically-controlled overdrive, there's actually very little difference between your old 727 and the 48RE. A lock-up torque converter was added, governor pressure is controlled electronically, the physical internals are a little beefier, and there's more clutch material, but the basic design of the transmission is unchanged.



This is not a bad thing, either. The 727 was a pretty bullet-proof design. The bad reputation of the older 4-speed Dodge transmissions stemmed from a weak and poorly-oiled overdrive unit. This was addressed with the 48RE, where the oiling was improved, and the clutches severely upgraded (from 5 to 6 discs in the overdrive clutch pack, and from 10 to 23 discs in the direct clutch pack). This is why the number of failures of the 48RE behind the Cummins are much less than those of the 47RE/47RH.



-Tom

 

[nwjetboat]

Thanks for the explainatin Tom. . I test drove both CTD and Dmax the same day pulling the same load. Though the 48re doesn't seem as sophisticated as the allison, when you stick 6800lbs behind it, the alli goes soft, doesn't like OD and starts shifting strangely. T

After 26K miles, it seems like the 48re just doesn't care if your empty or loaded, shifts pretty much the same, and likes pulling OD. .

 

[BRayls]

they also went back to the 5 pinion carrier like the old 727's had, not the 4 gear like the 46/47 had.

 

[ThomasLawrence]

they also went back to the 5 pinion carrier like the old 727's had, not the 4 gear like the 46/47 had.

Ummm... 6-pinion

 

[BRayls]

, my bad

 

[KOOPDADDY]

There was never a 727 w\ a 5 pin carrier... ... . The first 5 pin was installed on the 47RE. .