Re-geared and free-spinned the 3500 4x4 diesel

[gumby79]

Sounds like you need the under/over drive box back to get back to target rpm . A 285/75 r17 Vs 235/85r16 is were i got the outside diameters from.
Edit : or is the rpm stated with the smaller tires?

[skyking]

It is! I have plenty of choices now.
One of the plusses of the new transmission is in gears 1~4. They are all a bit closer together now, which is nice for the shifts while towing. Often you get in a spot where you really have to rap out a gear to make a shift, so closing up that spacing by any amount is welcome.
The jump to OD being greater is not really an issue while towing. I won't use it on a hill, only on the flats or downhill. The OD gears are not as strong and when you run in them, it induces a side loading in the transmission that builds heat and wear. My rule of thumb is no more than 10 PSI of boost in 6th.

[skyking]

I have the engine back from the rebuilder. I will probably wrap the manifold and blanket the turbo. I took it apart and there is little to no port matching needed between turbo and manifold, just a minor cleanup of a casting ridge.
Looks like I will start engine re-assembly Wednesday next week, and get it ready to go by late Friday.

[skyking]

I put it back together over the last two days and started it this morning. After a short test drive and fixing a loose connector, I got the trailer ready, hooked on and towed it home through 90 miles of semi-crappy traffic.
The cam has made quite a difference. It builds boost at a much lower RPM now, the throttle response is much better. Where I used to kick out a chunk of smoke that was mostly but not all due to the rings, now there is a small puff. I am sure the new reman nozzles have something to do with that.
The cam is noisier at cruise. The engine sounds more like a VP44 24 valve now, with a distinct crackle that was suppressed by that timing overlap.
The rings did a great deal of breaking in during the initial cam break in. You run the engine at 1800 RPM for 20 minutes, and even after it warmed up we kept giving it less and less throttle to achieve the 1800. The Smarty Touch has pedal position as one of the options. IT started at 15% and dropped down to 5% by the time we were done.
As predicted 60 MPH is right at 1600 RPM with these tires. It is lugging with the trailer on with any grade, but rolls nicely on the flats and downhill. It shows a marked increase on the MPG gauge, but that is only for the "feels". I will do a proper observation after break in is done.

[DS98HX]

You could swap 88-95 balljoint Ford F-350 outers, knuckles, and brakes for a DIY free spin kit on the Dodge axle.

[skyking]

It is done already, and I retained the same brakes.

[gumby79]

?Dose the smarty show EGT? What is it ?
Did tou do the wrap. Or are you getting a bace line first?
Are you using synthetic oil for brake-in , Trans ? Motor?
The mpg is up on a fresh engine. Awesome. It should climb as it gets closer to 50k mi .and things start to wear-in.

[skyking]

Smarty does egt with optional probe. I installed it but need to wire it.

[slowmover]

I'd love to see 1600 at 60-mph for solo!

As is, the NV5600 6-speed man trans with stock tire size and standard 3.73 gearing I see 1625-rpm at 54-mph on the city freeways here in Fort Worth. (RPM is from Ultragauge OBD reader).

These trucks are set up to run and "work" 55-65/mph maximum, IMO.

As per the Dodge Owners Manual I've always used First to get it rolling. The shift to Second is almost instantaneous. (Normal rate of acceleration for one of these is best described as ponderous: it's a medium duty synchro trans behind a medium duty engine. Design life is far longer than the V8 diesel drivetrains, and this is part of the tradeoff). So when I've considered the 3.42 swap it was in the knowledge that I'd have to stay in the lower gears longer, and to a higher rpm before shifting to bring it back in above peak torque. Especially when loaded. (I've also used these trucks on the oilfield hauling 20k+ trailer and load; but in 4.11/DRW configuration ).

But these HPCR Cummins trucks are already overpowered straight from the factory for their intended use. So the "compromised gearing" vis-a-vis a decent load is more about better skills at the wheel to get up and go. Into traffic, across highways (I already avoid left hand turns solo, and REALLY hate them when with my trailer and stretched out to 63'; the trailer momentarily stops across all lanes in a left while it pivots; why trip planning is an FE requirement for working trucks, not optional), and down the highway entrance ramp. May take well over a mile to reach cruising speed.

So, FWIW, I spent nearly all this past year entering highways in my work truck at anywhere from 25-40/mph. It's just not a concern given some ability to read mirrors and interpret. It's why we have a wide differential between lower and upper speed limits.

For what the OP and I both want (I'll state it as better, full-er use of each gear plus a relatively low top end speed while working; relative to the moronic masses travel speed), it's a win. It'll take some adjustment as I've been driving this pickup about ten years now. I've wanted to do this gear change for several years but it's still not at the top of my long list.

I know I'll be in Direct more often, but Overdrive isn't a "strong" gear in the first place. Downshifting more often is a penalty offset by better flatland and solo MPG. Granted that as a commercial driver I don't give much thought to having to shift more often. Nor do I spend any time anymore in trying to improve MPG as the percentage gain on a stock truck is too small beyond my current efforts (I've experimented), so I know I'm ready for truck specification changes.

And those experiments in driving technique show me that I'll willingly (I hope it's also happily) compromise heaviest load towing ability as my truck and travel trailer are considered by me to be a matched pair. Their combined weight is less than those oilfield loads. Thus, not hard work for a Cummins.

I'm looking forward to what the OP has to say about the camshaft change with this gearing. (And as a note I can't always sign in depending where I am, but I always read the posts/threads).

Any plans for a data reader so to re-program on a custom basis?

.

[skyking]

After every one suggested NOT wrapping the manifold due to cracking problems in the late 3rd gen, I opted to leave it off. I did wire brush it and the turbo casting and elbow, and painted with high temp rustoleum . Only 8 bucks at Home Depot.
Engine has the usual Rotella T conventional oil. It will get changed out at 500 miles. The transmission has Lucas Oil 50W synthetic. Not too pleased with the transmission, it is quite notchy in R,1,2 in comparison to my old transmission. I hope the synchros break in some.
There is little break in left to do, in reality. There was virtually no oil consumption in the first 100 miles, and no visible blowby either at the tube or oil cap. Next time I start it up I will put a cork on the blowby and video the oil cap to show the totality of the blowby.
The rebuilder's recommendation was to go out with the trailer on and climb some hills
That's what I did, and the truck will sit until the next time I want to go out and camp. I think next weekend is out due to subfreezing temps, but I hope to go the following weekend. I am definitely champing at the bit but want to be practical about it.
Slowmover,
right now the wallet is sucked flat, so I will stay with what I have as far as instrumentation/tuning. The Smarty Touch I have will do UDC tuning but nobody has pursued it much since the advent of EFI Live.
The built in MPG gauge is quite confused, so all it is good for is to reset it often and see what different gear/speed combos do relative to each other. I sure wish we could calibrate that overhead!
I see a future with possibly less towing MPG, due to not being able to use OD as often. To amend that situation I will have to be diligent in upshifting whenever the opportunity arises.
All this changes with the future trailer design, which will have a lower CDA than the solo pickup , coupled with a target weight of less than 5000 pounds.
The engine will be able to handle a moderate grade at 1600 RPM with those lighter loadings.
Starting out in first, it has enough gear for most any situation with the trailer. In the extreme case I can crawl out of a bad spot in 2wd low.