So im looking into converting my 2004 lb7 5 speed into a 6 speed. is it as simple as buying a 6 speed valve body and tcm? if so will any year work?
LB7: 5 speed to 6 speed
- Thread starter 20chevy04
- Start date
No it is not exactly that easy... You also need a "locked" TCM offered by suncoast to make it work.
If it was that easy NOBODY would buy the SUNCOAST kit. there is a reason it costs so much to get a 6 speed into a 01-05 truck. Valve body mods are required along with a custom TCM(that is locked and unreadeable). So unless you can get ALLISON to come off the TCM file and build your own valve body, your stuck with buying a kit from somebody.
Tuning can still be flashed onto the TCM before we lock it if the customer provides us with the file.
Okay thanks for the info ill just build my 5 speed instead then maybe dwn the road do that conversion
I have 265/75/16's and i trimmed the fuel at 1650rpm and added timing to 9deg's,i have seen a 2mpg increase at 65mph.towing seems about the same but then again i went from towing at 65mph to 75mph.
I like how quiet it is at speed,even w/ the goodyear silent armour tires.
That's what I did. Even with my 245/75/16 tires I still only turn 1900 at 70 on the GPS. The downfall is towing, it gets loaded up a bit with an LB7 towing with the 3.42's in 5th gear as the turbo comes off boost pretty easily with them. For an LLY it would be a great upgrade with the VVT turbo.
IMO, the ONLY way to convert to a 6-speed is to convert your truck to ALL 06-07 stuff. Complete LBZ/6sp swap as I did. I was messing around with the 4th Gen TCM trying to get it to work with my 04LLY ECM, as well as tried to find a 3rd gen 6sp cal that I could get to work, and finally converted over to LBZ everything (except shortblock). With the full conversion I have everything an 06 would have; Enhanced elevated idle which works much better than my LLY's winter idle ever did, tap shift, no FICM... Depending on what you were to get the parts for, you could potentially end up spending roughly the same amount on converting to a LBZ as you would on the Suncoast kit (factoring in what you would spend to get the LBZ Trans, engine and harnesses minus what you get selling the old parts). Things may have changed at Suncoast, but while there's nothing wrong with their rebuild kits, based on posts I've skimmed and conversations I've had, I wouldn't touch their 6-sp conversion kit with a 10 foot pole....
What all do you need to convert everything? What gains did you have if you don't mind me asking?
Holy old thread
I swapped.....
*Instrument cluster
*Transmission (technically you could swap the VB, internal harness, shift lever and IMS)
*TCM
*ECM
*Engine
*Body Harness (the one that runs between the ECM, TCM, Transmission, Engine)
*Shift Lever
*Some additional wires and repinning
Probably some things I'm not thinking of.
Gains? No FICM to worry about moving & cooling should I need the room. 6-Speed transmission that's controlled by a 6speed TCM that won't potentially cause the transmission to roast itself. Factory Tap shift. Better winter warm-up (not applicable in warmer climates). Anything that would make a LBZ a gain over a LLY. The 'challenge' of actually doing the swap.
If you're looking for mpg gain then this isn't worth it.
The step from 5th to 6th is .10 ratio. (someone correct me if I'm wrong)
If you want to lower your rpms then just regear the diffs. Much easier and much cheaper.
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The step from 5th to 6th is .10 ratio. (someone correct me if I'm wrong)
If you want to lower your rpms then just regear the diffs. Much easier and much cheaper.
Sent from my SM-N910V using Tapatalk