5 speed to 6 speed conversion.

2005_duramax_owner

New member
Apr 7, 2022
2
0
1
You sound like you work there. I tested the prototypes of that conversion and helped straighten out some flaws in it. It's still not impressive and will never hold any power. The trans starts dropping out of 6th gear under aggressive throttle and using T/H to cancell 6th gear has its own problems at about 50MPH. It will drop out of 5th to 4th causing an over reving. I do not recommend this kit. Actually, I don't recommend any of the 6 speed conversions.
:), I most certainly don't work there. The company has just treated me right in all of my dealings with them.

The conversion gives me what I want which is a quieter truck while on the highway on long trips. I don't run it hard, no burnouts, or drag racing corvettes at a red light. I have no intentions of upgrading the power of my truck so it works fine for me. I enjoy the conversion which is what counts. Plus I don't have to put DEF in the truck which is why I kept it.

I had intended on getting an L5P until I looked under the hood. It reminded me of Ford's Powerstroke in that there is an engine in there somewhere. My LLY is simple to work on, everything is easy to get to, which is why it will spend the foreseeable future sitting in my garage when I am not driving it.

Regarding your work, I have read a lot of your posts over the years, and it seems to me that you are probably one of the smartest guys in the world when it comes to the Alison transmissions, at least when it comes to the 1000 transmission series, maybe the top one or two of the lot. I believe in giving credit where it is due and you certainly have earned it. I respect your opinion. Because of that I will watch for the things that you have pointed out in your reply while I am driving the truck.
 

DAVe3283

Heavy & Slow
Sep 3, 2009
3,493
75
48
Boise, ID, USA
I have a Duramax Tuner kit, running my own tuning-- had problems like Mike mentioned with theirs they never did resolve. Once I got the tuning dialed in, having a 6th is nice, and it's holding a bit of power (my truck dynoed 660hp/1000lb-ft at the tires on the daily tune), but I have a built trans, not just their valve body. For a stock truck, I think their tuning would've been fine, for what it's worth.

My current preference (what I have in my LB7 Suburban) is get a LBZ valve body and buy the PCM Performance TCM. It's not locked, so you can adjust the shift points so 6th is more useful than how Duramax Tuner and Suncoast set it up.

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DAVe3283

Heavy & Slow
Sep 3, 2009
3,493
75
48
Boise, ID, USA
I recently bought the DT kit, but have not installed it, will it not be able to hold power? Running 369sxe, 65% SAC, and 10mm on a LB7
What all is done to the trans? If you have good clutches, I'd expect it to hold those mods just fine. My motor setup is similar (S371, SAC75, 12mm) and it holds, but I'm not on a max effort tune.

The bigger issue you might run into is their trans tuning might not work super well with your build, but yours is a bit more reasonable than mine, so it might be workable.

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bigmackmiller

Active member
Nov 30, 2008
1,046
2
38
Kokomo, IN
Evan built it for me back when he was still in Mass. his kit, with 1078 suncoast with a little higher stall IIRC, didn't know if the valve body swap would effect anything, don't want to limit/hurt the trans for sake of a 6th gear, but if all is well on yours I'll likely throw it in
 

DAVe3283

Heavy & Slow
Sep 3, 2009
3,493
75
48
Boise, ID, USA
I'm not a trans expert at all, but I was told the newer valve bodies like the LML body used in the DT kit don't need as much work as the older ones to hold power.

That all said, I don't know for sure that my trans builder didn't modify the DT valve body, but they didn't mention doing anything to it.

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turbovan

Too many toys!!!
Mar 4, 2018
74
5
8
Abbotsford, BC, Canada.
I have a Duramax Tuner kit, running my own tuning-- had problems like Mike mentioned with theirs they never did resolve. Once I got the tuning dialed in, having a 6th is nice, and it's holding a bit of power (my truck dynoed 660hp/1000lb-ft at the tires on the daily tune), but I have a built trans, not just their valve body. For a stock truck, I think their tuning would've been fine, for what it's worth.

My current preference (what I have in my LB7 Suburban) is get a LBZ valve body and buy the PCM Performance TCM. It's not locked, so you can adjust the shift points so 6th is more useful than how Duramax Tuner and Suncoast set it up.

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Interesting, so what your suggesting can work with an LB7. Hmm. I do have a LBZ valve body.
 

Cougar281

Well-known member
Sep 11, 2006
1,550
53
48
St Louis, MO
How do those running 01-05 type TCMs that have kits that use LBZ+ valve bodies account for the different trim solenoids? The 3rd gen trim solenoids don't fit in 4th gen (LBZ/LMM) valve bodies, and the connectors are different. And the 3rd gen TCM doesn't work properly with the 4th gen trim solenoids.

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Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
19,364
1,917
113
Phoenix Az
Evan built it for me back when he was still in Mass. his kit, with 1078 suncoast with a little higher stall IIRC, didn't know if the valve body swap would effect anything, don't want to limit/hurt the trans for sake of a 6th gear, but if all is well on yours I'll likely throw it in
Call Mike/Evan. There is an issue with the VB that should be checked before throwing power at it. I dont know if DT fixed it and if they didnt, im not posting it so they can fix it with free help.
 

Mike L.

Got Sheep?
Staff member
Vendor/Sponsor
Aug 12, 2006
15,686
231
63
Fullerton CA
If someone could program the LML TCM shift strategy into the early units; then you would have something special. Don't think it can be done.
 

Bdsankey

Vendor
Vendor/Sponsor
Feb 1, 2018
3,069
376
83
Neenah, Wisconsin
If someone could program the LML TCM shift strategy into the early units; then you would have something special. Don't think it can be done.
I know the PCM Performance TCM file has shift timing tables but I personally haven't been inside an A50/T87 file to know what is done in there in terms of shift strat tables.