Considering an 05 LLY Duramax 2500hd

[BR3W CITY]

Anyone own one of these, or have experience with em? Need to replace my current daily, and have seen a few of them popping up more reasonably priced than before.

I avoided the Lb7 (i think) due to the injector problems but the LLY seems to be a happier motor in general. I like the Allison trans, and being able to get one with leather and options etc for under $20k is a plus.

But of course, I haven't owned a duramax truck before, so I have nothing to compare it to but regular NBS trucks. I work from home, so the truck either gets used for errands, truck stuff, or occasionally to pull my '66 when I have a buddies open trailer I can use.

I'm considering going to the 2500 so I can tow the 66 more frequently, and possibly have something large enough to haul an enclosed race trailer.

[95 S_Trucker]

If it were me, I would look at an 06 or an 07 with the LBZ. The Allison got another gear in 06.

They did have the injector issues sorted out by 05. The 05 would be a good truck too, it would just have a 5 speed auto.

Aside from that, its regular chevy truck stuff. pretty normal maintenance. Nothing to crazy. I would inquire about the brake lines, or crawl and look and see if it has the updated coated brake lines. If not, they will need replaced. You can get a complete pre bent kit with coated lines for $80-100, but it takes 5-8 hrs to install them.

[BR3W CITY]

Thanks for your input man. Finding that gen with the LBZ is a little tougher in my area, and they are commanding a premium right now.

If I see one, I'll look at it.

The 05 I'm looking at seems to be fairly priced at ~16k for 90k miles. Its a 2wd which is ok with me. Owner does say its had intermittent gauge cluster failures. I'd have to plug my HP Tuners into it and see if the odo or anything was tampered with.

Funny how confident I am with LS motors, but ya toss a diesel in front of me and I look like a 12 year old lol.

Heres the ad
http://milwaukee.craigslist.org/cto/5297711821.html

[clinebarger]

Originally Posted by BR3W CITY

Thanks for your input man. Finding that gen with the LBZ is a little tougher in my area, and they are commanding a premium right now.

If I see one, I'll look at it.

The 05 I'm looking at seems to be fairly priced at ~16k for 90k miles. Its a 2wd which is ok with me. Owner does say its had intermittent gauge cluster failures. I'd have to plug my HP Tuners into it and see if the odo or anything was tampered with.

Funny how confident I am with LS motors, but ya toss a diesel in front of me and I look like a 12 year old lol.

Heres the ad
http://milwaukee.craigslist.org/cto/5297711821.html

Stay away from "Tuned" trucks, You will find the owner has "Limped" the trans & trying to off-load it while it doesn't slip under normal driving.
If the owner will not let you make a full throttle up-shift into 5th gear on the Hottest Tune....Walk away!

A 5-speed can be converted to a 6-speed without transmission removal (TCM & Valve body swap)

Look up LLY overheating issues, If you don't tow at/near GCWR....This may not be an issue for you?

Also look up Injector wire rub problems, Easy fix!

[BR3W CITY]

Thanks Cline. We've got EFI Live, BS3 and the HPt suites, so the plan is to drag out the laptop and take a look at command vs actual shift timing to see if the transmission has any issues.

I would only tow a 1-up race trailer (20ft ish), so no where near the 5th wheels and construction loads some guys are hauling. Looks as though I can change out the radiator or upgrade the trans and oil cooling to help that issue.

I didn't know you could make it a 6spd without actually putting a 6spd in it. How do you add a gear, without actually adding a gear?

[clinebarger]

Originally Posted by BR3W CITY

I didn't know you could make it a 6spd without actually putting a 6spd in it. How do you add a gear, without actually adding a gear?

The Allison 1000 was designed from the beginning with the ability to have 6 forward gears, Don't really know why GM didn't spec a 6 speed from the start?

5 speed clutch apply chart, Has 5 Clutch Packs C1-C5

1st gear, C1 and C5 Applied, 3.10.
2nd gear, C1 and C4 Applied, 1.81.
3rd gear, C1 and C3 Applied, 1.41.
4th gear, C1 and C2 Applied, 1.00.
5th gear, C2 and C3 Applied, .71.

The 6 speed has the same Clutch Pack apply sequence for 1st through 5th gears & C2 and C4 are applied to achieve a .61 to 1 6th gear.

Suncoast & PPE both sell the TCM & Valve body for this.....Not cheap, About $2000.

[BR3W CITY]

Wow, I really did not know that. Are those specialty parts, or can it be done using GM stock? I've got access to the entire GM catalog pretty much, I pay around cost.

[clinebarger]

Originally Posted by BR3W CITY

Wow, I really did not know that. Are those specialty parts, or can it be done using GM stock? I've got access to the entire GM catalog pretty much, I pay around cost.

Yes & No...

The Valve body is modified just for this, I have not actually reverse engineered the few Sun Coast conversion Valve Bodies I have installed, But it looks like they use a '06-'09 "LBZ/LMM" Valve body & modify it to use '04/'05 "LLY" Electronics, May be more to it???

A 6 speed TCM & a 5 speed TCM are radically different, LBZ & newer are GMLAN, LB7/LLY use Serial Data. There is not a factory GM OS to enable 6th gear operation in a 5 speed TCM, Sun Coast sends a TCM with the kit, And, Yes it is LOCKED, Probably an Allison OS of some sorts???

Valve Body differences.

[BR3W CITY]

"Locked" lol thats cute. Nothing in the TCM would be different hardware, so its all software..which means we can break it.

I guess I'll have to actually get the truck home before making a project out of this Looks as though using the LBZ valvebody is key #1, the rest is time consuming but not "hard"

[BR3W CITY]

Was able to pull a 6spd allison 5000 valvebody off the shelf, and it looks virtually identical to the 5sp valve body except for a single pressure tube. Looking at some internal documentation encourages the possibility of just drilling out the boss and installing the tube as a DIY. Got a wealth of other info in the process from a few folks in the know.

When GM or the big's contract for a transmission form a 3rd part like Allison or ZF, they don't do any of the control logic themselves. The TCM programming for all GM transmissions was done by GM, which means that there aren't any specialized protocols or hardware being used from outside the GM brain-trust (meaning it can be accessed, read, or written by tools available to me).

It was hinted to me that the Allison 5k was only released as a 5speed for those couple years for 3 primary concerns;
#1) GM wanted to have another selling point on the LBZ trucks, and waited to release it as a 6speed until that product cycle.

#2) The ECM's and TCM's were improving by leaps and bounds from 03-06, so its possible that the units being used didn't have enough onboard memory or a fast enough com speed to control the 6spd to a satisfactory level or lacked the resolution to do so properly.

#3) Partially related to #2. This period included GM's extended warranty on HD trucks to buy back faith from the LB7 years. The application of c2-c4 puts a large amount of load on the trans internals, especially when considering the possible loads the vehicle would see and the potential for heat (bearing in mind the LLY's overheating concerns that were addressed when the LBZ debuted). Keeping the truck a 5speed gave the some room to work, and helped minimize the potential for slippage (and thus warranty claims) on a trans early in its product life.

My interest is piqued to say the least. We're going to look at the TCM controls for the 6speed and see whats actually happening thats different.

[john@thepier]

I have an 05 GMC Duramax/Allison its the LLY now has 28,000 original miles and had 2 dash clusters before 10,000 miles, no other issues as of then, nock on wood, I like it.

[clinebarger]

Originally Posted by BR3W CITY

Was able to pull a 6spd allison 5000 valvebody off the shelf, and it looks virtually identical to the 5sp valve body except for a single pressure tube. Looking at some internal documentation encourages the possibility of just drilling out the boss and installing the tube as a DIY. Got a wealth of other info in the process from a few folks in the know.

When GM or the big's contract for a transmission form a 3rd part like Allison or ZF, they don't do any of the control logic themselves. The TCM programming for all GM transmissions was done by GM, which means that there aren't any specialized protocols or hardware being used from outside the GM brain-trust (meaning it can be accessed, read, or written by tools available to me).

It was hinted to me that the Allison 5k was only released as a 5speed for those couple years for 3 primary concerns;
#1) GM wanted to have another selling point on the LBZ trucks, and waited to release it as a 6speed until that product cycle.

#2) The ECM's and TCM's were improving by leaps and bounds from 03-06, so its possible that the units being used didn't have enough onboard memory or a fast enough com speed to control the 6spd to a satisfactory level or lacked the resolution to do so properly.

#3) Partially related to #2. This period included GM's extended warranty on HD trucks to buy back faith from the LB7 years. The application of c2-c4 puts a large amount of load on the trans internals, especially when considering the possible loads the vehicle would see and the potential for heat (bearing in mind the LLY's overheating concerns that were addressed when the LBZ debuted). Keeping the truck a 5speed gave the some room to work, and helped minimize the potential for slippage (and thus warranty claims) on a trans early in its product life.

My interest is piqued to say the least. We're going to look at the TCM controls for the 6speed and see whats actually happening thats different.

Makes sense., Good luck on the project. And keep us posted Brew....

I would recommend a Trans-Go shift kit, Good Converter & Refresh the Frictions....C1-C4, C5 Never gets burned/hurt, The Good news is these are real easy to build. And easy to pull on a 2wd truck.

[biketopia]

The 6speed upgrade is sweet, but unless you drive A LOT you wont gain enough from the possible fuel savings to really offset the cost. Besides a lot of guys with the 6 speed find them selves locking out 6th while towing to keep the RPM's in the sweet spot for power, and keep the temps down. Look into the LBZ mouth piece mod regardless of if you tow or not, or just pick up a whole LBZ intake, filter to mouth piece and be good to roll. They use the Donaldson filter. The injector harness rub at the alternator bracket is another point to check and keep an eye on. Other then that they are great trucks, check out duramax forum and snoop around there and all your questions and will be answered, even the ones you didn't know you wanted to know haha.

[Too Slow '90]

I have one and have had no issues. I read volumes on the possibility of overheating. I never had any issues but when I decided to haul a fifth wheel I decided to put an auxiliary radiator to be safe. Just under 100k on it and no problems. It's a great truck.

[71veronica]

Well in case you need more opinions, I bought mine from my uncle who bought new in late 04. And he has only had to replace the tcase. I just replaced stepper motors in the dash cluster. does have the lbz mouthpiece. Has 145k so kinda low miles. great truck plenty of power for me, motor is stock.