Any one running 496/Ally in a buggy?

[PSYCHOFAB]

I just picked up a 2002 GMC 2500 4x4 with a badly bamaged cab and Im wanting to use the moter and tranns maybie in a buggy. I was wondering what would be needed to run it. If theres some stand alone stuff or if the factory stuff is the way to go? I have a good 5 hours in surching this and I find stuff for the 8.1L but not for the Allison. Thanks.

[chevy_man]

With the number of guys using the factory computer/wiring in all these 6.0L swaps, I'd say that would be the easiest/cheapest bet.

Should just need to eliminate un-needed sensors, BCU, etc. and strip the harness down. Get a custom tune for your setup and be done. Now, this is easier said than done but since you have the complete truck it's not that bad since you have every part there.

You could also probably sell the allison and put a 4L80/85E behind it without losing too much $.

[PSYCHOFAB]

Why would I want to down grade?

[herkdriver007]

is there a stand-alone controller for the Ally?

[MaxPF]

Just use the stock Ally controller that came in the truck. Make sure the wiring between the PCM and TCM all stays intact, and it will work perfectly fine.

Heres what you will need to add:

ODLO mod and switch (ODLO=Overdrive lock out - it's not necessary, but it's nice to have)

T/H switch (tow/haul mode seems to work better off road, as it holds a lower gear longer before shifting, and locks the TCC in 2nd gear and higher))

4-lo input - tells the TCM when you are in low range, and has compensation for low range ratio. This can be eliminated by putting the OSS before your t-case. If you use a t-case setup with multiple low ranges you will need to run the OSS before the t-case setup anyway since the Ally TCM cannot accomodate multiple low ranges.

Allisons have no sprags or roller clutches, so they won't overrun on decel even when shifting automatically. T-case selection is limited due to the 29 spline output shaft. I solved that issue by turning mine down to 1.350" and resplining to 32 spline. I also hardened the shaft to 40HRC to make up for the loss in strength caused by reducing it's diameter. According to my math, it is now stronger than the stock 29 spline shaft which is only hardened to 28HRC:







The round pattern on the Allison is the same as any other GM round pattern. With the 32 spline shaft I can bolt up a round 205, 208, 241, etc. I am actually going to bolt a 203-205 doubler up to mine, but you get the idea.

IIRC, the Atlas can be had with a 29 spline input, so altering the Ally's output shaft wouldn't be needed if you went that route. You could also use the 261/263 that came in the truck, of course.

Here's a link to wiring for 2003 trucks: http://www.gmupfitter.com/publicat/2...lectric_CK.pdf I believe the engine and trans wiring is the same as a 2002. It really isn't any harder than an LS/4L80E swap - you just have one more box to bolt into your chassis somewhere.

More Allison info can be had here.

I hope you actually do this. I think it would be an absolutely bulletproof setup for a rock rig

herkdriver007: Yes, there is a standalone solution. You use the Allison TCM and wire it up stand alone. This is how I am getting a 6 speed Ally to work behind my mechanically injected Cummins

[PSYCHOFAB]

Thanks. I seen your shaft on the other thread. Im planig on puting my 203/205 behind it but dont have acsess to the the tipe of machineing to build a new out put. Ill probly just be going with the 29 to 31 spline stub. I will make this happen.

[MaxPF]

Originally Posted by PSYCHOFAB

Thanks. I seen your shaft on the other thread. Im planig on puting my 203/205 behind it but dont have acsess to the the tipe of machineing to build a new out put. Ill probly just be going with the 29 to 31 spline stub. I will make this happen.

Find out how much the stub costs. I might be able to hook you up on resplining the stock shaft for not much more, and it would be a cleaner setup.

EDIT: I forgot to mention that the Ally tailhousing can be broken if the t-case isn't properly supported. The best fix is a truss that mounts to the tailhousing-to-case bolts and attaches to the t-case assembly. That way it takes the load off the Ally's tailhousing This is absolutely mandatory as heavy as a 203-205 is, even with an extra crossmember supporting the t-case assembly.

Here's a pic of one going to the stock Gm t-case, just to give you an idea of what I am talking about:

[jays68yak]

I love my 8.1. But I went manual tranny for simplicity.

[DieselS10]

Originally Posted by PSYCHOFAB

Im planig on puting my 203/205 behind it but dont have acsess to the the tipe of machineing to build a new out put. Ill probly just be going with the 29 to 31 spline stub. I will make this happen.

I just swapped out the input gear in my front 241 to the 29 spline from the 261 that was behind the Allison. It goes right in the 241, but the shaft diameter at the front of the 241 shaft has a smaller diameter than the bearing in the 261 input gear, so I welded it up and turned it to the correct size. Just throwing out another option.


And Max that's some good info on the Ally!

[DieselS10]

Sorry about the highjack, but Max, I was reading through that link where you were talking about the 241's. Do you believe the 241C will live behind a moderately tuned Duramax/Allison?

[MaxPF]

I have no idea. The only part I worry about is the range coupler; the teeth are awful small and they are on a small base circle. OTOH, I have never heard of anyone stripping them and I've been beating on one behind my Cummins, so Id say go for it. The 241s used in the 90's Dodge Cummins apps and the 241 sets used in the 4 speed Atlases are the HD variety which supposedly have more teeth on the range coupler, but I have never seen one to compare. Dodge guys run em behind some pretty bombed Cummins' though. As for the regular 241, I'd run it - heck, I AM running it... at least till I get the 203-205 ready to go

[PSYCHOFAB]

Originally Posted by DieselS10

I just swapped out the input gear in my front 241 to the 29 spline from the 261 that was behind the Allison. It goes right in the 241, but the shaft diameter at the front of the 241 shaft has a smaller diameter than the bearing in the 261 input gear, so I welded it up and turned it to the correct size. Just throwing out another option.


And Max that's some good info on the Ally!

I already built my rocks for pasenger side drop and my 203/205 to match.

[PSYCHOFAB]

Originally Posted by MaxPF

Find out how much the stub costs. I might be able to hook you up on resplining the stock shaft for not much more, and it would be a cleaner setup.

EDIT: I forgot to mention that the Ally tailhousing can be broken if the t-case isn't properly supported. The best fix is a truss that mounts to the tailhousing-to-case bolts and attaches to the t-case assembly. That way it takes the load off the Ally's tailhousing This is absolutely mandatory as heavy as a 203-205 is, even with an extra crossmember supporting the t-case assembly.

Here's a pic of one going to the stock Gm t-case, just to give you an idea of what I am talking about:

Ill get a price and get back with you on that shaft for shure. I have herd about the tail housing and seen some beffy replacements but there big bucks. Im planning on bracing the shit out of it and hope for the best.

[MaxPF]

Yea, if it's braced up good you'll have no worries.