Wish I had 4.10's

[jimnance]

I have found that the 3. 54's and my auto trans work great on the flats pulling my 19,900 GCVW. It cruises at 60 MPH at about 1750 RPM's which is a nice sweet spot.



In the hills though the 3. 54's are too tall to pull big hills in fourth gear (out of O/D), and in third I'm turning 2800 RPM at 45 MPH. Because I'm beyond the best torque curve, on some hills I have to slow to 40 MPH to get to an RPM where the engine pulls better.



If I go to 4. 10's I fugure 60 MPH on the flats at about 2000 RPM and I think I could pull most hills in fourth at a more comfortable RPM.



Anyone out there with 4. 10's and the auto that can tell me if it works better pulling large loads?

 

[Pit Bull]

I'm going close to 65 mph at 2000 rpm. The sweet spot on the 24 valve is 2000 rpm based on torque and HP. Don't know about pulling mines a daily driver (road queen)

 

[cullyguy]

Well if the "transmission Kit" is good and solid aka DDT stuff TC & VB Then add some stage 2 injectors + good air supply to your proposed bombs and you won't need 4:10's. However you might want to make sure you got good brakes Caution! If you are just doing a VB Trans kit DO NOT ADD THE LARGER INJECTORS Unless you want to fry it fast. You need a good solid TC also, my choice DTT stuff.

 

[jimnance]

I am happy with the power. Don't want to go any farther bombing the truck. I figure if I can step on the throttle with an auto and dry pavement and spin the tires with a 7,000 lb truck I've got enough power.



I just think maybe my gearing could be better.

 

[Cummins Corvette]

If you are in third gear, with the tcc locked, then 2800 rpm=~65mph. You must be in second to get 2800 rpm at 45 mph. If you are running with the tcc unlocked, that could be a big part of your problem.

 

[jcosola]

Re: 4.10's

Hi Jim,

I agonized before ordering my truck regarding the 4. 10 vs 3. 54. After talking to many I opted for the 4. 10. Am I glad I did. But I am going to remain stock for a great while. When I pull I haul a 10,000# 5th wheel. There are only a couple of grades that I have had to shift out of drive. Of course I have sacrificed 2-3 MPG on the hwy's when not pulling a load. I had a 96 with 3. 54 and two wheel drive and now I have a 2001 and 4. 10 and also 4X4.



John C.

 

[barryg41]

I pulled out of O/D at 68 mph with a RPM at 2750. It did quite a good job of pulling at that speed and rpm. The MPG's suck but it pulls the hills good (Colorado, South Dakota) It takes a long time for the overdrive to lock in. I dont know how long, but someone will chime in how long it takes to lock in. I wrote Cummins about the RPM at constant speed. They said 2750 rpm all day and night. Auto of course!



I added the PE EZ but have not pullled the Camper since then. I am hoping that I dont have to drop down (out of O/D) to maintain speed on simple hills. Most folks have told me that this is all that I need to keep up with the Jones'. I have had some tell me to put iin the shift kit (TransGo) and it will be even better. Really looking into that! But most stand tall and say go with DTT. But I would wait till the Auto is toast and then go with DTT or ATS. Your Choice!!!



Hope this helps!

 

[LSMITH]

If the line pressures match the power being made the TCC will not slip even with the factory TC. You do not need a super TC to drive with modest power while towing. The DTT convertor lock up clutch is not much if any stronger than the factory clutch from what I was told, DTT uses a much more efficient fluid coupling rather than lockup to put the power down. Will the DTT convertor work better in this situation? Absolutely. Is it necessary? No. CAnderson is right though, if locked up the RPM for speed will be a lot lower than originally posted. Let it lock in drive and then apply the power slowly, it will pull. If you pin it to the carpet it will kick down to second and stay there, 2800 at 45 and no lock up and the temps going through the roof. It will likely shift to third and with no lock up will slow down till it goes into second again, it is a vicious cycle. MHO.

 

[chuck3]

I'm with CAnderson, at 2800 rpm in 3rd lockup my truck is pushing close to 70 mph and I have the 3. 54 gears.

 

[Briar Hopper]

jimnance, drop Steve St. Laurent a line, he'll be glad to swap out rear gearsets with ya! He has 4. 10, wants 3. 54.

 

[obert]

I have a '98. 5 2500 quad 4x4, but it has the 5-speed. I am more than satisfied with 3. 55 (acording to the spec decal under hood),

Even at pretty much stock. A big load will cause extreme fuel usage- like 10 or worse. At 37k gross, it did take a mile or so to get to 60mph, but had no trouble keeping it there.





P. S. -- If yer still young & stupid, that 7000# bullet will run about 110 mph Acceleration drops terribly @ that rpm, but if you hold it (on a track, unless you got deep pockets for Smokey) the mechanical limit is 115mph.

 

[jimnance]

Locked up

It won't stay locked up going up the hill. As soon as the pull starts the auto drops out of lock up. I have a transgo transmission kit and am happy with it. I suppose if I could get some sort of box that will let me force the T/C to stay engaged it would be good, but I'd be a little concerned that with the stock T/C clutch, even with the higher line pressure I might get slipping pulling this big a load up these 5-6% grades.

 

[LSMITH]

Jim, forcing lockup is the wrong way to go about this. If you cannot use 3/4 or better of your throttle without unlocking the TC there is something wrong with the VB setup or the kickdown cable. Take it back to the shop that put the kit in and have them fix it. The last little bit of travel on the pedal is what should unlock your TC and kick the trans down a gear when it is time, I would bet you that the kickdown cable is a bit tight to get gov pressures a bit higher. Don't force the lockup unless you are prepared to learn exactly when and when not to use it and follow those guidelines as if your life depended on it. If you do not follow those guidelines exactly everytime on time you will be buying a transmission rebuild. Hope this helps. You are on the right track, just need to finish the race right now. Stay with it, accept nothing but the right result.

 

[jimnance]

Lock up

I'd say I'm using 80% throttle or better to keep the speed up and as I lose speed at some point the T/C unlocks. From what you said I'm thinking the transmission is working as designed.

 

[Charley]

jimnance:



I'm pulling a 15,000# HR, fifth wheel with a box stock 2001, 4X4, auto, 4:10s and it does the job fine. I cruise on the level at 65/68. Have pulled a few 8% grades and I do have to go down through the gears but manage OK. Have been down to 35/45 mph but in the total trip it doesn't make much difference in total time. I won't add any power to this truck as I did to the 97, 5 spd which would do a much better job of pulling the same trailer as I only pull about 2% of my total milage and am happy with the commute as is. If I were pulling the rig most of the time I would opt for the HO 6spd and mild bombing. Changing ratios would cost you around $1400 if you had a shop do it. I did that to a half ton Ford 302 V8 pulling a 9000# trailer and was very happy with the change but it was still too much trailer on too little truck.



Charley

 

[LSMITH]

I forgot to mention, I would prefer the 4. 10 gears in my truck as well. The gears I have are too tall for my power, tires, and use of the truck. Forget about bothering Steve, we have the Dana 70 axle, he has the 80. if it would work I would have had his 4. 10s in mine a LONG time ago.

 

[juicedcummins]

If you bought yourself a fuel-box with the timing you would have the best of 2 worlds. You would have better mpg empty maybe pulling. All fo less hassel than switching diffs. If youre tc goes out it didn't belong behind a CUMMINS in the first place!

 

[RobG]

On my truck (which is a 6-speed), I prefer to keep the RPMs at 2000-2200 on flat ground when towing, but when I have a big hill to pull, I need the rev's up to 2500-2800 to keep my EGTs down given my mods.



Rob

 

[LSMITH]

juiced, put the pipe down man!!! If you need propane to light it DO NOT SMOKE IT!!!!! JK, he is running an EZ, with both timing and fueling. Parts do break from abuse , wear and exceeding design limitations as well.

 

[juicedcummins]

OOPs I must of missed that on his sig.