Reasons NOT to buy a 6spd Manual Cummins?

SilverSurfer15 · Sep 29, 2015

Ive been thinking that a 6spd cummins with 6-8in lift would be a blast to drive.. any reasons not to do this? Not too many people seem to have the manual trans, I read a few threads on other forums and just curious if any one here has any information I haven't seen.

I know:

TQ is less (but I would be deleting and running a +30~ tune)
Some lifts are better than others for the manual trans
stock clutch prob needs to be replaced with 37s and full 900tq

This is strictly a "have fun" truck. No towing, nothing substantial anyways.

Thanks!

DannyMK2 · Sep 29, 2015

automatics have come a long way so less people are buying manuals. with that said the biggest disadvantage to the manual in the cummins is that every time you shift you lose boost and the turbo has to spool up again, whereas the automatic stays in boost. aside from that i would say personal preference.

avolnek · Sep 29, 2015

As you already mentioned the biggest issue to me would be detuned engine, but with a delete and tuner that is corrected...

second would be as Danny said and having the turbo spool just to let off, albeit a short time, the turbo will spool down and have to spool back up... not a huge deal...

Honestly I'd love a fun truck like that!

darthdzl · Sep 29, 2015

You'll get sick of shifting if you have to drive in the city for any length of time.

Other than that, I can't see a compelling reason not to. Go for it!

SouthTexan · Sep 29, 2015

The power rating on the Cummins mated to the G56 manual transmission are the way they are due to the limits of the clutch and transmission. If you go to the Cummins forums you will see that even adding a little more power will have adverse side effects to the transmission in those trucks. Most have had to upgrade the clutch and transmission internals to allow it to handle extra power.

You also do not have to delete your emissions just to add power. My basic fuel economy tune adds 25 horsepower and 70 lb-ft of torque while the driving tune adds 50 hp and 120 lb-ft of torque all without deleting anything. If you do delete, which I am completely against, then be sure to save everything you took off. You most likely will not get popped by for not having your emissions devices on when you have the vehicle, but you most likely will when you sell it. Here in Texas it is $27,000 on top of the federal fine for selling a vehicle with the emissions system tampered with. The amount could be more in other states. This not he a big deal if you plan on selling it to a buddy, but most likely will be if you trade it in.

SilverSurfer15 · Sep 29, 2015

My main reason for doing deletes is strictly to get the sound and experience. Not so much the power, as I mentioned I would only run the small tune anyways. I am intrigued by the warranty on the new models, so staying stock could be an option if I bought a new tradesman. And my vehicle is registered in FL, no emissions. And you can go on cars.com or autotrader and find diesels where the dealer is ADVERTISING emission deletes on their used inventory. It doesn't really seem to be as big a deal as they want it to be. But that's a whole different debate.

If I buy an automatic, I am just going to get a 6.4 and do a big cam/converter

theviking · Sep 29, 2015

I drove a family member's 2012 G56 Cummins around town a bit. If definitely didn't feel as quick as some of the newer 68RFE trucks I test drove. As others said, it's hard to keep the turbo spooled as you really can't shift it fast enough.

I wound up just getting the 6.4 on my new truck. Haven't had it long enough to comment on durability but it is quicker than the Cummins, stock vs stock. Haven't seen or heard or any sort of truck 6.4 cams available anywhere. I can't even locate specs on the stock truck cam. So curious if you came across anything. I think there are 11" converters available through Edge, etc.

Good luck, don't think you could go wrong with either combo.

SouthTexan · Sep 29, 2015

As I said, I am 100% against deletes because I know how much damage the emissions can do to a person in the long run and seeing someone die of lung cancer is not a pretty site. I am of the nature that it should be person that buys the diesel is the one who has to pay for all the responsibilities that come with it and not the 72 year Vietnam vet with respiratory issues. If you don't think that unfiltered diesel emissions does not effect anyone, I can show you data from my time working at Cummins proving otherwise.

Again, that is just me and my opinion. I respect others too much to have my selfish actions affect others in a a negative way. From what I just read in Florida's legal code, it is first degree misdemeanor punishable by one year in jail and a fine to sell a vehicle with a tampered emissions system.

Jimmy68 · Sep 29, 2015

I had an 07 Cummins and 6 spd manual, Thought way cool. ****, hated it. Wanna play? Shift, shift, shift, shift, shift, going 40, shift, shift, damn gotta slow down, shift, shift, shift, floor it, shift, shift, shift, wheee, damn, shift shift, shift, slow stupid traffic, yay, shift, shift , shift, red light, shift, shift, clutch, coast, stop, green, shift, shift, shift, shift, slow down shift, shift, going again, shift, shift, shift, shift, omfg I shift hate this truck shift shoulda shift bought an shift automatic, shift, DAMMIT shift, I'm going shift home shift truck pi(shift)ssing me off shift.
Get it?

Hootbro · Sep 29, 2015

Jimmy68 said:
I had an 07 Cummins and 6 spd manual, Thought way cool. ****, hated it. Wanna play? Shift, shift, shift, shift, shift, going 40, shift, shift, damn gotta slow down, shift, shift, shift, floor it, shift, shift, shift, wheee, damn, shift shift, shift, slow stupid traffic, yay, shift, shift , shift, red light, shift, shift, clutch, coast, stop, green, shift, shift, shift, shift, slow down shift, shift, going again, shift, shift, shift, shift, omfg I shift hate this truck shift shoulda shift bought an shift automatic, shift, DAMMIT shift, I'm going shift home shift truck pi(shift)ssing me off shift.
Get it?

+1

Cool for about a month, then you are wishing for the automatic.

Stangshcky12 · Sep 29, 2015

Can't say I've ever wished I had an automatic
Having had 1 nv5600 and 3 g56 trucks my only complaint is traffic but they are so easy to drive its not that terrible. Find a gear that you can just roll, if other people want to try to cut you off, let them
The stock clutch does ok at 75 hp over stock and even 100 hp over stock if you drive it right.
Had an 09 with a dual disc in it, hated driving it cause the clutch was so stiff. If you arent looking for alot of horsepower (750+) stick with a single disc

I usually only use 3 or 4 of the gears anyway

Jimmy68 · Sep 29, 2015

Stangshcky12 said:
Can't say I've ever wished I had an automatic
Having had 1 nv5600 and 3 g56 trucks my only complaint is traffic but they are so easy to drive its not that terrible. Find a gear that you can just roll, if other people want to try to cut you off, let them
The stock clutch does ok at 75 hp over stock and even 100 hp over stock if you drive it right.
Had an 09 with a dual disc in it, hated driving it cause the clutch was so stiff. If you arent looking for alot of horsepower (750+) stick with a single disc

I usually only use 3 or 4 of the gears anyway

And you use them a lot. :roflsquared:

Plus my stocker governed out at 170kmh. That's 106 mph for you folks in the past. Had to leave early for work to get there on time.

Hemifatboy · Sep 29, 2015

I think u missed a shift jimmy

Jimmy68 · Sep 30, 2015

Hemifatboy said:
I think u missed a shift jimmy

Stangshcky12 · Sep 30, 2015

I can leave my truck in 6th gear from 30/35-100+mph, especially with as flat as Wisconsin is I usually shift 2-4-6 or 5th if I'm in town

Something else to keep in mind is the gear ratio difference between 1st gear in a manual vs 1st in a 68re when considering the difference in torque ratings.

Pulling 12k-14k bumper pull trailers in western PA I always prefered manuals, even my old 6.uh0 powerstroke had a zf6

Jimmy68 · Sep 30, 2015

You know it. If it's a hauler on a regular basis a manual is perfect. I heard manufactures are going away from manuals because of low sales.
Mine was my daily driver. Pulled nothing. Was going to buy a 5th wheel camper but... life happens.

crash_eco · Sep 30, 2015

My car is a standard, I commute 200km each day in it. with 80% being highway and 20% being a horrible stop and go in the city.

if you dont mind having more to do than just hitting the gas.. go for it!

Jimmy68 · Sep 30, 2015

crash_eco said:
My car is a standard, I commute 200km each day in it. with 80% being highway and 20% being a horrible stop and go in the city.

if you dont mind having more to do than just hitting the gas.. go for it!

Car is different too. The Cummins low rpm drove me nuts. How do you "race" with 2800rpm? It's a quick shift and lose power between shifts.

If it's a work truck pulling a wagon, awesome.

I like 5000rpm and more. My Ramcharger with a heavily modded 360 pulled 8500rpm. THAT WAS FUN.

Diesels have there place. I need the fun factor of higher RPM.

A V8 gas engine and a 4spd in a 66 Coronet. Oh yeah.

I think it's the open 4BBL through headers and dual exhaust that gets me.

drittal · Sep 30, 2015

Either you don't mind shifting or you do. Empty you rarely use 1st. When you get good you find you rarely need the clutch unless starting from a stop or you messed up and missed your rpm.

SilverSurfer15 · Sep 30, 2015

Yea guys, the shifting is not a concern. I've driven standards my whole life in all kinds of conditions. Twin disc cars, triple disc vette in traffic, a solid axle Tacoma with a blower and unbalanced 40s and bead locks, Etc. I'm used to dealing with all this.

It's more so about the truck itself. Sounds like everything is fine with them. I need to drive one thiugh, I drove a 06 years ago and didn't really like it. But it was jacked up with stock gears, and sucked bad. Typical redneck scenario lol.

Reasons NOT to buy a 6spd Manual Cummins?

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