Engine/Transmission (1994 - 1998) Just the facts please.

[CBlack]

I was thinking about this today but I don't truly know the answer.



Why is a 6 speed transmission more durable on our trucks than a 4 speed?



Why is a manual more durable than the automatics?



I think I understand why, but I notice a lot of people upgrading to the NV5600 or the G56.



Is it something with the torque at low RPMs and lowering gearing?



I've read that the Gear Vendors OD units can be shredded with added power to the engine.



Can someone give me the low down on this, please.



Thanks.

 

[GAmes]

For what it is worth, I went to the G56 for two reasons. 1st, the NV4500 was put behind an engine rated at 215 HP and 440 TQ. It makes sense to me that with the higher HP and TQ ratings of the '06 engine that the transmission would be rated higher as well. 2nd is the added 4th gear, really nice for what I do.

 

[hsmith]

The GV units are rated at around 1000 hp if I am not mistaken. I have been through a couple of them with considerably less hp. He He. Go figure.

 

[CCiatteo]

I was thinking about this today but I don't truly know the answer.



Why is a 6 speed transmission more durable on our trucks than a 4 speed?



Why is a manual more durable than the automatics?



I think I understand why, but I notice a lot of people upgrading to the NV5600 or the G56.



Is it something with the torque at low RPMs and lowering gearing?



I've read that the Gear Vendors OD units can be shredded with added power to the engine.



Can someone give me the low down on this, please.



Thanks.

I'll take a stab at this based on my own experience in my truck.....



The upgrade path for from the 5-spd to the 6spd is probably more for the better gear splits than any thing else. If you have ever towed or hauled anything substantial in a 5spd truck you'll quickly discover (as I recently did) that the 3 - 4 gear split and 4 - 5 gear split are less than optimal. You really have to wind 3rd gear out so when you shift to 4th you don't completely bog down. Then you often find yourself in no-man's land if you are cruising at 55 mph. Kinda at the top of 4th gear, but not enough engine speed to make it to OD without the RPM's dropping below 1750, which causes 2 things. First your just outside the engine's sweet spot from an efficiency standpoint and you are begging for the 5th gear nut to work loose. When my clutch goes, I'll do everything in my power to swap in a G56 box.



The ripple effect of the 5spd to 6spd box is the inherent strength gain. The new box physically dwarfs the old one. Not all that room is for the one extra gear. The internals bigger and stronger to better handle the output of the newer engines. So its a double bonus.



I don't know too much about the auto's, but the older units (like what would have been stock in my 97) just can't handle the power in stock form, are very expensive to have rebuilt/upgraded properly and you still don't have the control that manual box allows for. The newer auto's might be completely different??



My 38 cents.

 

[SRath]

Short 'n sweet enough?

NV4500 = @200 pounds of steel and iron

NV5600 = @500 pounds of much beefier steel and iron with no 5th gear nut issues



Neither is made by Dodge.



Automatic = made by dodge = crap



Dodge never has built a decent automatic; why should adding the torque of a Cummins and heavy loads make it any better?



No automatic besides an Allison should ever go behind a strong diesel motor.

 

[fest3er]

... Automatic = made by dodge = crap



Dodge never has built a decent automatic; why should adding the torque of a Cummins and heavy loads make it any better?



No automatic besides an Allison should ever go behind a strong diesel motor.

Ah, my good man. There are plenty of people who would disagree with you on this point. The 47RH/47RE grew out of the venerable Torqueflite. Granted, it ain't the greatest in stock form; the TC is especially lightweight and is usually the part that fails. Up to 600-800HP, autos from Goerend, SunCoast and ATS hold up very well and put the power to the ground. SunCoast, locking up moments after a 4WD 1/4 mile launch, hold up nicely at 1000HP. And that technology has trickled down to the products we mere mortals use.



That said, if your towing heavy, the close ratios of the G56 are well worth the extra weight of the transmission.

 

[SRath]

I honestly don't think mopar has ever built an auto trans, even the 727 Torqueflite, in the same league as a TH400, much less an Allison. Many, including myself, consider the venerable TH400 to be the high standard, aside from an Allison, for 'reliable, strong, and durable' in production cars, pickups, and motorhomes. Dodge and Ford automatic transmissions could not compare to either.

That's what kills me here: why people drop thousands upon thousands of dollars into dodge autos when they could swap to an Allison instead? Allisons have been handling heavy commercial use behind diesels in buses and motorhomes and straight trucks for decades.

I'm a manual transmission guy, but the two TH400-equipped vehicles I own never give me transmission trouble, and they have seen much heavy use. The one in our old Class C is 27 years old and a bone-stock 98k virgin that's never been out of the vehicle, and it handled everything from the Nevada desert to the 8% & 10% grades of the Bighorns last summer flawlessly. I would trust no mopar or ford slushbox to do that.

 

[CBlack]

I honestly don't think mopar has ever built an auto trans, even the 727 Torqueflite, in the same league as a TH400, much less an Allison. Many, including myself, consider the venerable TH400 to be the high standard, aside from an Allison, for 'reliable, strong, and durable' in production cars, pickups, and motorhomes. Dodge and Ford automatic transmissions could not compare to either.



That's what kills me here: why people drop thousands upon thousands of dollars into dodge autos when they could swap to an Allison instead? Allisons have been handling heavy commercial use behind diesels in buses and motorhomes and straight trucks for decades.



I'm a manual transmission guy, but the two TH400-equipped vehicles I own never give me transmission trouble, and they have seen much heavy use. The one in our old Class C is 27 years old and a bone-stock 98k virgin that's never been out of the vehicle, and it handled everything from the Nevada desert to the 8% & 10% grades of the Bighorns last summer flawlessly. I would trust no mopar or ford slushbox to do that.

I started this thread because I am considering an Allison swap.



I was researching it and it is cheaper to put a stage IV Allison in my truck than a built Goerend/Suncoast/ATS with Gear Vendor unit.





Thanks for the input from everyone.

 

[SRath]

That would get my vote if an auto is what you need or want!

 

[JMcCoy]

If you could swap in an Allison at a good price, do it.



I went with an ATS and it is night and day from stock form. The problem is not with the 47re. It's that people (myself included) tow beyond the capacity of the vehicle, increase horsepower, and DON'T CHANGE THE FLUID. Mine lasted 180,000 miles until water intruded through the B&M pan plug (JUNK), and I towed regulary. Who knows how long it would have lasted. I did not start upgrading power until I installed the ATS transmission. The 47re is an excellent transmission for what it was designed, 180 hp and 420 lbs of torque.



The 727 was an excellent transmission for the old mopars, just a little dated for what we now ask of our vehicles. Same goes for the ford C6



As far as the TH400 goes, it was a great transmission for trucks, hot rods, and buggies. It was worthless around the circle tracks. They ate 30 more horsepower to run over the TH350 (also an excellent transmission). Not all divisions allowed the install of manual trannies. Does this mean there was anything wrong with the TH400? Of course not. If I were to build another swamp buggy, I would install a TH400, because it is strong and I wouldn't need the extra gear. You cannot argue the fact that the TH400 is super strong, but that doesn't make it the best auto transmission ever built. I would take a built 47re anyday. Chevy guys want to talk about there 383 stroker with a TH400, Ford guys with their 9" rears, and Mopar guys with their 426 Hemi (most have never even seen one). All great pieces of equipment for there time. All are technologies of the past. Not trying to offend anyone, just put into perspective.



All that said, If I were to do it over again, I would have converted to G56. Good luck

 

[CBlack]

A 6 speed Allison Auto would provide close to the same benefits of a 6 speed manual from what I've read.

Currently I just haul a lot in the bed, but when I start my business I will be towing anywhere from 3500# on up to whatever it takes.

I'm almost ashamed to admit that I have never driven a standard. My family has never owned one and I've never seen the benefit with previous vehicles I've owned.

I am a quick learner though!

 

[AClayton]

NV4500 = @200 pounds of steel and iron

NV5600 = @500 pounds of much beefier steel and iron with no 5th gear nut issues



Neither is made by Dodge.



Automatic = made by dodge = crap



Dodge never has built a decent automatic; why should adding the torque of a Cummins and heavy loads make it any better?



No automatic besides an Allison should ever go behind a strong diesel motor.

The Torqueflight 727 was a very good trans... ..... the 47RH and RE are less desirable at stock form.

 

[GAmes]

NV4500 = @200 pounds of steel and iron

NV5600 = @500 pounds of much beefier steel and iron with no 5th gear nut issues



Neither is made by Dodge.

New Venture used to be owned by Chrysler. New Venture Gear - Dodge Wiki

 

[KOG]

In its day the 727 was considered to be the best automatic in the world. Period. It was never designed to take anywhere near the torque of the Cummins.

The GV OD has the same problem. Transmissions aren't really rate by HP, they're rated by torque. And diesels typically runa at about half the speed of a comparable HP gas engine, thus producing about twice the torque for a given HP rating. That takes transmissions and other drive line components apart in a hurry.

The Allison 1000 is about the minimum transmission capable of handling the torque of a serious diesel and even they have problems. One of my cousins had the Allison in his Duramax come apart at about 30K after towing a 5th wheel rig from Atlanta to Alaska and back. Died in Chattanooga on the return trip. Took a week to get a warranty unit shipped in. That one made it all the way from Chattanooga to Atlanta before it died. The second replacement has made another trip to Alaska and back without coming apart yet.

I should mention that this guy is extremely meticulous about servicing equipment and treating it gently.

 

[NIsaacs]

I will give the O/P's original question a shot. The big and medium duty truck industry had the same issue to overcome. The engine power development evolved at a faster rate than the transmission builders could keep up with.



They finally moved away from slow axle gears and overdrives and went to high axle gears and direct drives. This system works. Direct is straight thru the transmission and acts like a carrier bearing. There is no torque/stress/heat applied to any gear or bearing. Overdrive uses almost all parts of the transmission. So does any of the underdrive gears. If you had a rear axle fast enough and used one gear under direct, it would act just like overdrive does. It would also use all parts of the transmission and also over time fail.



Disclaimer... I am only discussing manual trannys. Autos might suffer the same way however I don't understand them enough to say for sure.



Nick

 

[SRath]

In its day the 727 was considered to be the best automatic in the world. Period.

:-laf :-laf :-laf :-laf :-laf :-laf

 

[mickeyblueyes]

So what would it take to put a Allison in a 3rd Gen Dodge? How could the two computers take to each other? All of the Fed Ex trucks have either 2nd or 3rd Gen Cummins with Allisons(1000). Its no secret that the transmission shop was kept busy also.

 

[CBlack]

So what would it take to put a Allison in a 3rd Gen Dodge? How could the two computers take to each other? All of the Fed Ex trucks have either 2nd or 3rd Gen Cummins with Allisons(1000). Its no secret that the transmission shop was kept busy also.

Call Brayden at Fleece Performance.

 

[AABEN]

So what would it take to put a Allison in a 3rd Gen Dodge? How could the two computers take to each other? All of the Fed Ex trucks have either 2nd or 3rd Gen Cummins with Allisons(1000). Its no secret that the transmission shop was kept busy also.

If I was you I would look hard at the new auto trans that dodge is using in there new trucks 08 and up. You need to talk to some one that has the new trans in a 08 up. === GOOD LUCK ---

 

[LVJUNIOR]

So what would it take to put a Allison in a 3rd Gen Dodge? How could the two computers take to each other? All of the Fed Ex trucks have either 2nd or 3rd Gen Cummins with Allisons(1000). Its no secret that the transmission shop was kept busy also.

I have a Goerend transmission in my truck and while it is much better than stock it will never match an Allison in any category. Even Dave Goerend will tell you a built 47re or 48re will never be able to compete with a built Allison.



That being said you can not just drop an Allison behind Cummins. The duramax is programed to defuel right before the Allison shifts therefore softening the blow to the transmission. A Cummins does not defuel so there are a few upgrades that need to be made to an Allison to make it live but they are very minor and inexpensive.



As far as the electronics, Destroked.com has a stand alone controller for both 5 and 6 speed Allison transmission as well as billet adapter plates to mate it to a Cummins. You will also need to source a different transfer case as the stock Dodge unit will not mate to the Allison. You will also have to build a custom shift linkage to make it work



I priced it out and an upgraded Allison with computer and adapter plate comes in right around the same price as a built 47re and billet converter. If I didn't already own the billet converter and wasn't unemployed when I upgraded my trans I would be driving with an Allison instead of this 47re.



And as far as the new dodge 6 speed auto goes, I have driven them and towed with them and they are definitely not an Allison. They shift as eradicly as the 47re and still turn 2100rpm at 75mph in overdrive keeping you out of the optimal fuel economy range.



Good luck sorting through all of the info. If you do decide on an Allison swap make sure to post lots of info and pictures for the rest of us.