’99 Ram manual transmission - rebuild or replace

[Gearclash]

If I was swapping in a G56 for towing I would want the AD ratio behind a 5.9. Aside from 5th the ratios are all lower than AE and better suited for towing, especially with a 3.54 rear end.

Each to there own, but having pulled the ever living guts out of my truck I don’t agree. For what I do with it I see the AE being the better set of ratios.

 

[AH64ID]

Each to their own, but having pulled the ever living guts out of my truck I don’t agree. For what I do with it I see the AE being the better set of ratios.

Yes, for sure to each their own. I would still really do the math and consider the AD. While there were some AE’s behind the 5.9 at the very end of the 5.9 the AE ratio was better for the 6.7 because of how much lower of a rpm power band it has over the 5.9.

Having used both a NV5600 and G56 AD the AD is much better suited to the rpm band of the 5.9, plus it’s added ~6% rear wheel torque in 1-4th and 6th. I really couldn’t tell too much difference in 1-4, but 6th was a major difference towing. Truck ran cooler and pulled harder, and that’s with 3.73’s. Just my 0.02 based on having used both for heavy mountain towing.

 

[Gearclash]

better for the 6.7 because of how much lower of a rpm power band it has over the 5.9.

Just curious, as I have not run a 6.7 Cummins in a pickup, where would you say the power band is on a 6.7 vs a 5.9 in the pickups? My ’99 really needs to be above 1900 and below 2400.

 

[AH64ID]

Just curious, as I have not run a 6.7 Cummins in a pickup, where would you say the power band is on a 6.7 vs a 5.9 in the pickups? My ’99 really needs to be above 1900 and below 2400.

They pull very hard from 1500-2500, and don’t mind towing all day below 1800 even on decent grades. It’s probably 400-500 rpms lower than my 5.9 was when towing. It doesn’t pull as hard above 2700, but the 5.9 was also built/tuned differently.

The added displacement and variable turbo really help the low rpm performance.

 

[Gearclash]

I always scratch my head about the advertised peak hp of the 24 valves being at 2900 RPM. The ability of mine to pull hard falls off fast after 2400. The 5.9s as found in ag tractors usually are set for a max governed engine RPM of 2400 give or take a little.

 

[AH64ID]

I always scratch my head about the advertised peak hp of the 24 valves being at 2900 RPM. The ability of mine to pull hard falls off fast after 2400. The 5.9s as found in ag tractors usually are set for a max governed engine RPM of 2400 give or take a little.

Those engines also likely have different cams, which will have a big effect on peak hp rpms.

My stock 5.9 was also rated at 2900 and while it didn't seem to like the higher rpms when loaded down it did make more power and pulled hard thru redline. With my upgraded cam and turbo it really didn't complain about the rpms as much, but still was happier at lower rpms.

 

[petersonj]

Most all engine horsepower ratings are at or near the top of their respective maximum engine rpm bands. That is because it is where the highest horsepower will occur.

If an engine's horsepower was rated at an rpm where you would actually spend time driving the truck, then nobody would buy the truck.

There is a reason I own a truck with Cummins engine - Lots of engine torque available in the 1400 - 2000 rpm range, the range my truck spends 90% of its time on the road.

- John

 

[AH64ID]

Most all engine horsepower ratings are at or near the top of their respective maximum engine rpm bands. That is because it is where the highest horsepower will occur.

If an engine's horsepower was rated at an rpm where you would actually spend time driving the truck, then nobody would buy the truck.

There is a reason I own a truck with Cummins engine - Lots of engine torque available in the 1400 - 2000 rpm range, the range my truck spends 90% of its time on the road.

- John

Yes, rpms are very important for the relationship of hp and tq.

One of the reasons modern diesels do so well is they really have upped the lower rpm horsepower. The current HO makes 368 hp at peak torque, and it’s very noticeable when towing. They are “down” to 787 lb/Ft at peak hp thou.

 

[NIsaacs]

I always scratch my head about the advertised peak hp of the 24 valves being at 2900 RPM. The ability of mine to pull hard falls off fast after 2400. The 5.9s as found in ag tractors usually are set for a max governed engine RPM of 2400 give or take a little.

The high RPM is a Dodge/Ram thing, you won't see that RPM in a Cummins in any other application. Most pickup customers want a gasser performance, that's what they are used to. Plus, with 4 and 5 speed trannys, you kinda need that RPM. 6spds and above, will perform fine with less.

 

[AH64ID]

The high RPM is a Dodge/Ram thing, you won't see that RPM in a Cummins in any other application. Most pickup customers want a gasser performance, that's what they are used to. Plus, with 4 and 5 speed trannys, you kinda need that RPM. 6spds and above, will perform fine with less.

Many other ISB/QSB applications are rated lower, but not all. There are some variants that are rated higher, as high as 3400.

 

[NIsaacs]

Many other ISB/QSB applications are rated lower, but not all. There are some variants that are rated higher, as high as 3400.

I assume marine, they get some serious power out of those with the unlimited cooling. I would also assume, intermittent use at full power.

 

[AH64ID]

I assume marine, they get some serious power out of those with the unlimited cooling. I would also assume, intermittent use at full power.

Yes the highest rpm and highest power are marine engines, but they aren't the only ones with higher rpms. It's also more than cooling, it deals a lot with the constant load which is easier on the engine than the variable load that vehicles put on engines. Marine engine also rarely make 100% of their power until they are at rated rpm, unlike vehicles.

The QSB 6.7 can have a 550hp rating at 3300, that would be a fun engine in a jet boat. Who knows, maybe that's what Ram will use to compete with the HO Furd.

 

[NIsaacs]

The QSB 6.7 can have a 550hp rating at 3300, that would be a fun engine in a jet boat. Who knows, maybe that's what Ram will use to compete with the HO Furd.

Then there is the Ram 2500, still running 370hp 10 years after the fact, woo hoo, it did jump 50 lbs tq, ten years later

Whining aside, still wouldn't trade it for my '01.

 

[slowmover]

5.9L is one happy camper when highway cruise rpm kept between 1,700-1,900. Longevity & MPG (thus reliability).

Need more?

Cancel cruise control, drop a gear, and she’ll do the necessary with near-minimal throttle-input degree or duration.

Event over, re-engage CC . . and note that the fuel tank stayed sound asleep. Never noticed.

.

 

[Regcabguy]

The 2-3 shift never bothered me. Enough power there that being out of the peak power band wasn’t a handicap. 3-4 was a different deal though.

6 speed anything seems hard to find.

For those that have G56 6 speeds - a question. I have a 3.54 axle ratio. Which G56 ratio will play nicer with my axles? I would like the highest OD ratio I can get. If I am towing heavy I want to stay in the 1:1 direct drive gear anyway, 5th on the 6 speeds.

You would want my early ratio G-56 with the 3.54's. Better for towing and running taller tires.

 

[SAndreasen]

The NV4500 on my 1999 2500 let go this week. Most likely a bearing out on the input shaft, or possibly the counter shaft. Looking for experiences. I could rebuild this transmission, or replace it with another NV4500, or replace it with a one of the various 6 speed units. Whatever I do I will be doing myself. The only complaint I have about the NV4500 is the 1000 engine RPM jump between 3rd and 4th, which is why I’m considering a 6 speed. Lack of oil ultimately killed this NV4500 so it is not that the NV4500 isn’t tough enough. Are parts still really hard to find for the NV5600 or has that changed?

I vote rebuild it unless you have an extra 5 or 6 grand laying around . Stay out of 5th when towing . I just blew mine up it’s been noisy for a couple years I plan to rebuild it and run another 100,000 miles if the truck is still around that long.

 

[Gearclash]

I vote rebuild it unless you have an extra 5 or 6 grand laying around . Stay out of 5th when towing . I just blew mine up it’s been noisy for a couple years I plan to rebuild it and run another 100,000 miles if the truck is still around that long.

Cost and time is probably going to force me to rebuild the 4500. I have a practice of not towing hard in 5th, been doing that ever since I had the trans opened up 15 years/100,000 miles ago when the 5th gear nut came loose. Easy to see then that 5th gear has no business transmitting very much torque.

I did have the experience of running my nephew’s 6 speed Dodge Cummins (2012 I think?) this fall, pulling my own 20’ deck over GN tandem axle with a 7500 lb load. Must be a later G56. Gear ratios are right where I would like them. Not very nice shifting though, compared to my 5 speed. Terribly hard to get it into first gear. Hard to go between 1st and reverse. Not easy to shift between gears after that either, although at the end of the trip I began to double clutch it and that really seemed to help? I think this truck had the dual mass flywheel eliminated. Definitely not a stock truck.

 

[SAndreasen]

I have not driven anything that new maybe someday.

 

[bcbender]

Terribly hard to get it into first gear. Hard to go between 1st and reverse. Not easy to shift between gears after that either,

Seems like its a truck to truck thing,... my NV5600 was always hard to shift compared to 2 other NV5600 trucks I've driven. Had it rebuilt and it was still not the easiest thing to row. That and the stiff clutch helped me decide to move over to the AISIN.

 

[Gearclash]

Pictures of my nephew’s truck, my trailer and load. 250 mi one way run. Truck handled the trailer and load easily; however, running loaded in 6th gear produced a head splitting drone for the front seat passenger so I was forced to run 5th when loaded. Otherwise it was really quiet in the cab, lot better than my ‘99 Cummins.