4l85 trans to Allison

JoeyD

JoeyD

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Apr 21, 2008
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Want to swap allison trans into my Express van. I have the D max already but the 4l85 is not up for what I want. I can't make the van lighter, weighs around 8500-9000lbs. I want to run more than stock power, want 400rwhp.
Fitting the trans is not an issue just making it work. I have EFI live so I can make my truck think it's a stick and I could buy a stand alone for the ally but would like to make it work together. Any insight on this
 
JoeyD

JoeyD

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Apr 21, 2008
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chevyburnout1 said:
Couldn't you just get a complete harness from an Allison equipped engine then just flash in the ECM an Ally operating system?
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Thats my question. I know the ally uses it's own TCM but does it just wire to the trucks ECM? There must be more to it as that sounds to easy.
 
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lotsofmiles

Father of the Van
Dec 4, 2008
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JoeyD said:
I have done that with not much luck. I think the van is just to heavy for how i drive and at what power i want to have.
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I still think thats why i went thru 3 transmissions at stock power.

Pulled my equipment out, ran EFI tune, and beat the Crap on the empty van and no problems.


Fwiw , my 4l80 in gas van is starting to cry too. :(
 
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lotsofmiles

Father of the Van
Dec 4, 2008
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JoeyD said:
Thats my question. I know the ally uses it's own TCM but does it just wire to the trucks ECM? There must be more to it as that sounds to easy.
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Have you searched on 'pussow's posts on Dp from a few years back. Seems to me iirc there's some wires that have to change.
 
malibu795

malibu795

misspeelleerr
Apr 28, 2007
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~40,000 mile at 20-25,000lb for 99% of them.. only problem was the flex plate. swaped in an allison flexplate and no problems. all orginal 6.5 4l85e setup.
06 van dmax efi live tuned as well added timeing boost and pulled defueling out remaped the part throttle area.... set line pressue at 145psi for the tranny.

built? as in what has been replaced?
 
THEFERMANATOR

THEFERMANATOR

LEGALLY INSANE
Feb 16, 2009
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It can be done by swapping over to an LBZ OS in the ECM, adding in the GEN IV TCM, cluster swap if your worried about the tapshift display, and teh shifter handle. Yes you have to swap around I think 8 or 9 wires at the ECM as GM purposely wired the van and trucks differently so that a van owner couldn't swap in a truck ECM for more power(at least that seems to be the only logical explanation for it). Also you will have to wire in your lift pump to run with the key on as teh van OS is unique in the fact it runs the vans lift pump(van uses a lift pump whereas trucks do not). It's a doable swap though by all accounts.
 
JoeyD

JoeyD

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Apr 21, 2008
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malibu795 said:
~40,000 mile at 20-25,000lb for 99% of them.. only problem was the flex plate. swaped in an allison flexplate and no problems. all orginal 6.5 4l85e setup.
06 van dmax efi live tuned as well added timeing boost and pulled defueling out remaped the part throttle area.... set line pressue at 145psi for the tranny.

built? as in what has been replaced?
Click to expand...

All steels and clutches with red alto's, billit converter, shift kit.
 
JoeyD

JoeyD

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Apr 21, 2008
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malibu795 said:
Nothing done to the pump or sprag on direct drum? My question is why is mine holding with 3x the weight and yours aint
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All parts inside were upgraded that needed to be. The 4l85 had the HD sprag and drun and the hardened input shaft already.
I can only guess because mine puts down more rwhp than double your flywheel power. The 1st thing to go was the converter in each case.
I am not against the 4l85 but at this point if the 6spd ally is an option I will go that route
 
JoeyD

JoeyD

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Apr 21, 2008
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THEFERMANATOR said:
Fixing the converter shouldn't be an issue as I believe precision will build you a triple disc for it if you ask them to.
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That is who I used, after seeing how they last I don't think I would use them again. This is based off the trans guy giving me a run down on how the trans died and what was found inside vs the condition of the parts inside
 
malibu795

malibu795

misspeelleerr
Apr 28, 2007
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JoeyD said:
All parts inside were upgraded that needed to be. The 4l85 had the HD sprag and drun and the hardened input shaft already.
I can only guess because mine puts down more rwhp than double your flywheel power. The 1st thing to go was the converter in each case.
I am not against the 4l85 but at this point if the 6spd ally is an option I will go that route
Click to expand...

at most im doing is ~300fw.. i do have 4.63:1 gears vs 3.73? that you have..
eveyone i talked to stays a stock 85 can handle 500-550tq and i have done my best to keep it under that.. WOT for 9 miles up 5-6% and it holds..
im guesing your runing a decent tune that would prob limp a stock 6 speed?

what actually is slipping first? TCC? OD/OR clutch pack? direct, forward, intermediate clutches?
i ask cause i havent seen any one come forth and say what went wrong in their tranny.. mike L has said many times the od/or clutches are weak link.. but i havent seen anyone post up burnt od/or clutch packs or say that was their problem..
hughes make a billet both single and tripple disc xfm convertors..

i want to be able to drop down to 4.10 or 4.30 gears but to keep my 65mph on a 5% grade @ 26k im going to need ~400fwhp

also notice our driving style most likely are completely different guesing you work out of your van much like i work out of my truck.. taking that my fuel cost is probaly higher % over the over then your is.. that be correct?
 
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JoeyD

JoeyD

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Apr 21, 2008
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malibu795 said:
at most im doing is ~300fw.. i do have 4.63:1 gears vs 3.73? that you have..
eveyone i talked to stays a stock 85 can handle 500-550tq and i have done my best to keep it under that.. WOT for 9 miles up 5-6% and it holds..
im guesing your runing a decent tune that would prob limp a stock 6 speed?

what actually is slipping first? TCC? OD/OR clutch pack? direct, forward, intermediate clutches?
i ask cause i havent seen any one come forth and say what went wrong in their tranny.. mike L has said many times the od/or clutches are weak link.. but i havent seen anyone post up burnt od/or clutch packs or say that was their problem..
hughes make a billet both single and tripple disc xfm convertors..

i want to be able to drop down to 4.10 or 4.30 gears but to keep my 65mph on a 5% grade @ 26k im going to need ~400fwhp

also notice our driving style most likely are completely different guesing you work out of your van much like i work out of my truck.. taking that my fuel cost is probaly higher % over the over then your is.. that be correct?
Click to expand...
Just remembering the last trans, the converter was toast and the clutches inside the trans looked good, except for the trash from the converter itself.
This is based off the trans guys opinion and what he showed me.
I don't baby my van driving it and drive a lot of city miles.
 
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lotsofmiles

Father of the Van
Dec 4, 2008
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1 st trans for mine had a spun bearing in the tail.
2nd blew out reverse (band and piston iirc).
3rd they wouldn't tell me maybe due to me filing the lemon law suit.

All were at stock power/tune/completely stock van.
 
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