ISX Posted January 12, 2014 Share Posted January 12, 2014 Been wanting to do this for a long time and finally did. Basically its my truck with 245/75/16 Tires and 3.54 rear with Nv4500 Vs Nv5600. The chart shows me shifting at 2000RPM in every gear then picking up the next gear at the same MPH that the last gear was going at 2000RPM. The numbers between show the RPM drop between gears, as in 4th to 5th on the Nv4500 drops 500RPM. Its interesting because the 3rd to 4th gap on the Nv4500 is actually less of a jump than 2nd the 3rd, but because it is still jumping a vast RPM at a higher speed, the truck can't cope with the lower RPM and high load of high speed that it encounters, so it "feels" like a huge gap. When you compare it to the Nv5600, it definitely is a big gap. From 15-50 there is exactly 2 gears worth on the Nv4500 and exactly 3 on the Nv5600. Quite a difference. However, I am not sure but based on the chart do you guys with Nv5600's feel a slight "gap" between 5th and 6th? Link to comment Share on other sites More sharing options...
rancherman Posted January 12, 2014 Share Posted January 12, 2014 "felt" is a good term... at least with my bone stock cummins. But, I've been driving this 00 for 10 years too. Now that I think I have the 'feel' for this truck, both overloaded and empty, I'd say it's about perfect for the way IT HAS TAUGHT ME HOW TO DRIVE IT. My first experience with a diesel pickup was a 1996 dodge 5 speed, I guess at the time I didn't 'dread' or despise the transmission, I just learned to operate the vehicle so it wasn't dogging it.. When the 2000 came along, I found quickly that the cummins didn't have to be pushed quite as hard to progress through the gears.. without much thought. but that is ME. Others will have different results!! If the od is used as a gear 'after acceleration is done' then the 'jump' isn't nearly as noticeable. But, put a guy or gal behind the exact same truck and if they short shift into od whilst still going up a hill, loaded, into a nasty head wind.. and they'll cuss the very transmission as being 'way to wide'. As for me, I got the nv5600 almost ready to put into the 97. I don't hate the 4500, but I am spoiled by the first 5 gears of the 5600! Link to comment Share on other sites More sharing options...
dorkweed Posted January 13, 2014 Share Posted January 13, 2014 After having both……………..I like the NV5600 better for towing by far. Empty, it doesn't matter. 2 Link to comment Share on other sites More sharing options...
dripley Posted January 13, 2014 Share Posted January 13, 2014 (edited) I have liked my 6 speed since day one and 6th gear always just felt like another gear to me, though I try to run it at no more than 50% throttle with the 5th wheel on(15k #). The only experience I have with the 5 speed was on my 96 with the V10. It would only pull my other 5th wheel(12k #)on dead flat ground in 5th and I hardly ever used it while towing. Not sure that s a fair comparison. 5th on the gasser always felt like an OD, where as on the Cummins 6th just feels like another gear to me. Edited January 13, 2014 by dripley Link to comment Share on other sites More sharing options...
Staff AH64ID Posted January 13, 2014 Staff Share Posted January 13, 2014 There are times with I want the NV5600 6th to be a .85:1 and times I wanted it to be a .70:1, or higher. It's why I really want a 7 speed with a .85:1 6th and .70:1 7th. With my current 245/70R19.5 the .73:1 is great empty at 70-75, but it would be nice if it was a little lower with a camper hooked up. 5th with these tires is improved for pulling big grades. Link to comment Share on other sites More sharing options...
ISX Posted January 13, 2014 Author Share Posted January 13, 2014 Mine as you see in the chart is around 68 at 2000 rpm. Its perfect pulling the trailer since at 70 its at 2050 so I never have to downshift no matter the hill. Bad thing is that means I run very excessive rpm when unloaded. The Dana 80 has the option for 3.31 gears, nothing lower but that would make it much better unloaded. Link to comment Share on other sites More sharing options...
Staff AH64ID Posted January 13, 2014 Staff Share Posted January 13, 2014 Yeah I like 2000 for hill pulling, only the steepest of grades on high(5-6K+) and hot (75+) days require a downshift if I am towing the TT, which puts me at about 18K GCW and towing a big barn door. Link to comment Share on other sites More sharing options...
Ilikeoldfords Posted January 13, 2014 Share Posted January 13, 2014 I really do enjoy pulling with the six speed. I towed a couple of times with a buddies 97 cummins and NV4500. It felt like I was always shifting because of that gap between 4-5. Couldnt find the sweet spot at some speeds. I have to agree with AH64ID about the 7th gear. I really like the six speed for towing but I wish I could have an extra OD for just cruising empty. Maybe a gear vendors someday.... 1 Link to comment Share on other sites More sharing options...
dorkweed Posted January 13, 2014 Share Posted January 13, 2014 The lower rears don't always result in improved mileage. Even with the lower rpm's, there are other factors involved………….gear leverage, electronic timing at certain rpms, etc. IIRC, AH64ID, I believe, said the 3rd gens "stock" retard the timing around 1800-2000rpm. Link to comment Share on other sites More sharing options...
Staff AH64ID Posted January 13, 2014 Staff Share Posted January 13, 2014 Timing starts to fall off at 2,001 rpms, and is really low by 2,200 in the cruise region. 1 Link to comment Share on other sites More sharing options...
ISX Posted January 14, 2014 Author Share Posted January 14, 2014 I really do enjoy pulling with the six speed. I towed a couple of times with a buddies 97 cummins and NV4500. It felt like I was always shifting because of that gap between 4-5. Couldnt find the sweet spot at some speeds. I have to agree with AH64ID about the 7th gear. I really like the six speed for towing but I wish I could have an extra OD for just cruising empty. Maybe a gear vendors someday.... That's weird since the 4th to 5th shift is the same mph and stuff as the 5th to 6th shift yet even smaller gap, so you shoulda experienced the opposite. The od on the 5600 is also numerically lower which would make it even worse. Link to comment Share on other sites More sharing options...
Ilikeoldfords Posted January 14, 2014 Share Posted January 14, 2014 (edited) Maybe it was the difference of rear ends??? Mine is a 3.55 and my buddies was the 4.10 gearing. That alone would not make my example very good because the trucks were not consistent that way. I cant really explain it but I just very much enjoy towing with the NV5600 over the NV4500. Feels like I have more control over acceleration and deceleration. Maybe I am just crazy too Who knows!!?? Edited January 14, 2014 by Ilikeoldfords 1 Link to comment Share on other sites More sharing options...
rancherman Posted January 14, 2014 Share Posted January 14, 2014 I just realized, my Toyota pickup 5 speed has dang near a perfect gap all they way through the gears.. ring ding ding all they way up to 5th. I have just over 2000 miles on it since I bought it last month.... I now know why the clutch pedal pad is missing! ha... worn off! I truly believe the starter motor has more torque than the actual engine! but, it's perfect for what I need it for! Link to comment Share on other sites More sharing options...
dorkweed Posted January 14, 2014 Share Posted January 14, 2014 I just realized, my Toyota pickup 5 speed has dang near a perfect gap all they way through the gears.. ring ding ding all they way up to 5th. I have just over 2000 miles on it since I bought it last month.... I now know why the clutch pedal pad is missing! ha... worn off! I truly believe the starter motor has more torque than the actual engine! but, it's perfect for what I need it for! My first ever new vehicle was a 1987 Toyota pickup. Regular cab, 5 speed, 2WD and no air conditioning!! Come hell or high water, that little truck with the 22R four-banger always got me 30-32mpg on the highway. Sold it with 180,000 miles on it to an amigo that did part time landscaping. Never saw it after that. Just prior to selling the Toyota, is when I bought my '99 Dodge Ram 2500 with the Cummins. Link to comment Share on other sites More sharing options...
Recommended Posts