48RE Drive Test

[ntenna]

Took the first HO/48RE at my dealer out today. Had 4 miles on it. Now it has a few more.



2500 4x4 4. 10 SB quad, black with sport/laramie package. Nice truck!



The basic impressions:



Shifts up like the 47RE, but with more power (duh!). The engine felt and sounded good; I have driven several ETH/DEE's that did not pull as well stock.



Torque Converter: It had some of the same TC slippage in 1 and 2 that I have been used to.



Valve box and electronics: Also has the same old quick multiple shifts if you put your foot in it and let off too soon... . like downshift to 3rd, then fourth and lock in about 2 seconds, making you put your foot back in it again. Never did like that on either of the 47RE's that I have owned.



But THE GOOD NEWS IS: keep your foot in it and then you notice something really different:



The triple lockup clutches snatch the Cummins from over 3200 right down to 2000 so fast you are in the next county before you know it. And it did not have any drive-train shudder when it kicked in, and I tried for that several times. Firm and quick and painless!



Those of you who have run the automatic are probably pretty familiar with the not-so-subtle feeling that the transmission is slipping as the lock-up clutches press together, especially if you are towing, and the RPM drops down over a 3-4 second period under load as the clutches take up.



THAT should NOT be an issue with the 48RE; my initial impression is that this is where most everybody will be much happier with the new transmission.



Will this truck blow past my ETH/DEE from a dead start? Probably so, because I can't shift mine that fast. Up the hill? Not likely, due to the lesser gearing options available as you deal with 3rd or 4th vs 4,5 and 6.



Did 1800 rpm at 55, 2200 at 70.



I got the impression that I had more passing power in the ETH/DEE 3500, and I can't explain that other than the fact that this was a tight new truck.....



In general, it feels like it is an improvement, and in the area of torque-converter lock-up, a vast improvement.

 

[amsoilman]

JOhn,

Does the TCC stay locked when you remove your foot from the accelerator?



Wayne

amsoilman

 

[ntenna]

Originally posted by amsoilman

JOhn,

Does the TCC stay locked when you remove your foot from the accelerator?



Wayne

amsoilman

Not certain, Wayne. Yes, there was more feeling of deceleration, but not the drivetrain snap you get on the manual if you romp on it and let up suddenly. Should have paid closer attention, although I admit I figured that the TCC lockup/lock-in on the 48RE would be tied to the E-Brake via the transmission computer, once you installed an e-brake. Sort of a sophisticated version of what we were doing with the external lock-up switches a while back.



To answer an earlier question, the dash is unchanged PRND21 and OD over-ride button. You wouldn't know it was a 48RE unless you checked the window sticker, or crawled under to see that shiny cast iron case.



As a matter of fact, the tech that PI'd it is usually right on top of the diesels, and he didn't realize he had a 48RE/HO combo.



It does get the big driveshaft and axle, though.

 

[Steve G]

Do you think the Mag-Hytec pan off 47RE will fit 48RE?



Steve

 

[ntenna]

Casual view underneath the pan looks similar, but I think some sid-by-side comparison is in order before I can really answer your question... . if I get time this week, I'll try to get under the black truck and make some measurements!

 

[Benson]

So I take it there is no external filter on this new transmission? Bummer.

 

[sag2]

Stopped by the DC training center to say hi and they were in the middle of a trans class. They had the 47 and 48 torn down, and the 48 is much heavier inside. I will try and get by again and take some pictures comparing the pieces. Might need some help posting them.

The case looks identical from the outside, and so does the pan. Will need to check for sure.