the only concern that i see often is some governor pressure concerns which is a computer concern when DC put the electric throttle servo on the TRS valve, and some converter concerns on fleet trucks. other then that not many failures

 

no flashes availiable, yet

 

what type of "governer pressure concerns" are you talking about???

 

How is the 48 DRAMATICALLY improved over the 47? Six pinions in the planetaries as opposed to 4 or 5? Most people don't break them? The rear planet is steel and not aluminum?? Most don't break, the 1 extra clutch in the direct drum?? A bit better, but......These two are nearly identical.

The NV 5600 needs a multi thousand dollar clutch to handle big power, not "that" much cheaper IMO.

 

I think the biggest improvement made in the 48re was the valvebody. I even think in later years DC went back to the 5 pinion, don't know what years though.

 

The 2005 I had apart a couple of weeks ago still had six.

 

What I found interesting is that DC went away from the 23 single sided OD clutches and reverted to the old 6 double sided units.

 

single side clutches are said to be very much strong for reasons i am looking into at time.

 

Six pinion steel plantaries that don't break under high TQ loads, yes they break, and/or wear so bad they shed metal into the trans. Heavier planetary in the OD section and more clutches. Better lubrication in trouble spots. Higher flow pump that will generate more pressure at low rpm's. Heavier converter parts and lockup clutch. They took a lesson from the aftermarket on the last two.

The trans holds up pretty well to higher power and weight rating than the 47RE. The proof is in the repair records. Of the big 3 the 48RE is by far the least problematic.

Yeah, DRAMATIC is pretty close to the truth.

 

Lets see here....I have had 2 47re's and now a 48re The 47's were great no problems even with a "small box" and a lot of heavy towing. The "06" 48re seems to be a bit more thought out than the older version. Holds lower gears running down hill. Approved for a exhaust brake. The tow haul mode fits its intended use well. I seems to me any of the big 3 have auto transmission have issues when they are behind a "heavly modified" engine. I like my 48re (so far)!

 

I am no transmission guy but the constant hunting for a gear drives me crazy. Haven't tried an '06 with OD LO but whoever decided to leave it out in the '05s was an idiot. Around town its a bit better but often it seems the tranny can wait to get to 4th gear. Never had a vehicle where the tranny lugs the motor more than the 48re.

...and don't talk about T/H, it doesn't help much at all. Without OD LO, it heads to 4th as fast as it can.

With that said, I love my truck and 4 gears are fine just wish it would lockout OD.

 

That number is about 10%

Running at 2000rpm unlocked will drop 200rpm when locked

 

the governor concerns are: the hunting through 1/2 gears with or without T/H, this is a computer concern, the way i was explained about is that the governor logic and scheduling is not correct, but you cannot just change it because of emission standards, that is also the reason it wont to go to 4th gear so fast, EMISSIONS F**** everything up!

 

Thanks bigdav...now is that a running empty or loaded figure? Or should it differ?

 

Awesome information.

Aside from repair records, do you know of how the internals stack up against the Allison?