Allison 6 speed into 7.3 Excursion

Thanks in advance for solving all my problems, and helping with all the labor, over the internet.

I drive an '00 Excursion, 7.3 4x4 currently with a 4R100 and 283k. 3.73 gears, 285s (32"), nothing too modified.
Duties are primarily a daily, with plenty of highway heading to jobs, kids sports, and it's the vacation rig. Sold the camper, but not saying I won't get another. Any towing would most likely be under 12k.

With that out of the way, I want a taller overdrive, and I need a trans built to handle my injectors that are waiting to go in. 230/100s. With those injectors and my KC38R it should put me, in the hero tune, between 500/1000 and 575/1200. I know, some will laugh at that.

I understand that an Allison with a basic rebuild with aftermarket clutches, a good billet stator converter and good tuning should be good for 750/1500.

Biggest questions come from adaptors and controls.
My top 2 adaptor options are SAE3 from a school bus or MD truck, or DeStroked adaptor and flex-plate.

Not sure if the SAE3 setup fits in the tunnel, downpipe (4" Diamond Eye), what starter? This would be the lesser cost, but how well does the flex-plate hold that power? This would mean SAE bellhousing, which I understand all have the speed sensor, so any '06-09 GM trans would work.

DeStroked adaptor is more money, but makes for a shorter driveline. Flex-plate is plenty strong for my use. This means '06 GM trans, maybe some '07. Rest up to '09 can be used with a bellhousing with the sensor, which is available.

Next is controls. Jason at transmission tuner with his MD kit. I've heard nothing but good, although he himself cautions over 500 hp. Biggest downside currently is manual shifting is you only get to select highest gear, not select the gear. If I want to make a dyno pull from 1200 RPM, it'll downshift. Not sure this is really a big deal, but I'm a control freak maybe?

DeStroked uses a GM TCM, and manual mode is whatever you select. Apparently that's how the GM trucks are. Less expensive possibly, and either tuning from them or any D-Max tuner can EFI Live tune it.

NP273 adapter should be a clocking ring, GM 40 tooth tone ring with a sensor in the adaptor housing, and a 29 tooth input in the transfer case. I don't think there's surprises there.

I have a local driveline shop that can adjust driveshaft lengths and balance.

Sorry for writing a book. Thanks for reading!
I'm in for any feedback. Although 'just build the 4R' isn't necessary...

I swapped an allison out of a 2006 duramax behind my Cummins, using Jason and couldn't be happier. After seeing how crucial the tuning is and how easily it can destroy the trans, I'd steer clear of destroked etc but that's just me. Jason puts a lot of time and effort into getting things right, and cares a lot about his work.

thatguy69 said:

I swapped an allison out of a 2006 duramax behind my Cummins, using Jason and couldn't be happier. After seeing how crucial the tuning is and how easily it can destroy the trans, I'd steer clear of destroked etc but that's just me. Jason puts a lot of time and effort into getting things right, and cares a lot about his work.

Click to expand...

Jason is on the short list for sure. I've used him in the past to tune a 5R110 in a 12v Fummins. A friends truck, not mine. He was fantastic. I'm on a list for a harness and control currently.

I have reservations about DeStroked tuning also, just because I've heard nothing of it. But, any DMax tuner can tune it, which opens the possibilities to some really experienced guys. That's my understanding anyways. I did get confirmation from one big tuner that they can.

Another thing to keep in mind you need to build the transmission so it can take full power shift. There will be no fuel pulled back for the shift. This also means the guy doing the tuning should know and understand this. Jason has been very helpful. If I was not wanting tap-shift Jason would be doing my tuning when the time comes. If he gets his controller working for tap-shift before I am ready I will more than likely go with him.

California Conversions has a complete 7.3/Allison option.

Cowboys4Christ said:

Another thing to keep in mind you need to build the transmission so it can take full power shift. There will be no fuel pulled back for the shift. This also means the guy doing the tuning should know and understand this. Jason has been very helpful. If I was not wanting tap-shift Jason would be doing my tuning when the time comes. If he gets his controller working for tap-shift before I am ready I will more than likely go with him.

California Conversions has a complete 7.3/Allison option.

Click to expand...

I plan on fresh rebuild, aftermarket clutch kit and billet stator converter. My understanding that's a 750/1500 recipe unless you're drag racing and sled pulling. At the same time maybe?

I thought CA conversion wasn't tunable? Also trying to stay on budget.

How stout is that Bus flexplate? Aren't you shooting for 800+ hp? I'd like that route if it'll hold my power, just not sure it will. Or is there a stronger flexplate option with that sae 3 setup?

BrewTown said:

I plan on fresh rebuild, aftermarket clutch kit and billet stator converter. My understanding that's a 750/1500 recipe unless you're drag racing and sled pulling. At the same time maybe?

I thought CA conversion wasn't tunable? Also trying to stay on budget.

How stout is that Bus flexplate? Aren't you shooting for 800+ hp? I'd like that route if it'll hold my power, just not sure it will. Or is there a stronger flexplate option with that sae 3 setup?

Click to expand...

I will never know what the stock Allison shafts can hold with full power shifts. I am going all billet for peace of mind. In the GM aplication they pull fuel for the shifts. There's a lot less stress on internal parts that way. So in the stock aplication I can see the shafts holding it. But not under full fuel shifts.

I thought the CA conversions was tunable? But only by them.

Yes, 800 is the goal, if it does not happen, o well.

No, the buss flex plate will not hold 800+ hp. It cracked with a stock 7.3. No way would I trust it. Billet or bust for me. There is no other factory option that is stronger that I am aware of. Hence going with a custom made billet flexplate.

It was my understanding that the Cummins guys were having the same luck with shafts as the GM twins. Maybe that's bad info. Either way, I'm going to send it with my milder build.

Who's making you a flexplate? Should be a basic piece, with no gear for the starter. I'm still unsure which way to go here, sae 3 or destroked adaptor.

BrewTown said:

It was my understanding that the Cummins guys were having the same luck with shafts as the GM twins. Maybe that's bad info. Either way, I'm going to send it with my milder build.

Who's making you a flexplate? Should be a basic piece, with no gear for the starter. I'm still unsure which way to go here, sae 3 or destroked adaptor.

Click to expand...

Hopefully that is the case. I might be remembering those details correctly. Hopefully a cummins/Allison combo guy speaks up on this.

I have not pinned down who is going make the flexplate yet. My flexplate will need the gear for the starter. The factory T444E/Allison setup I have has the starter gear on the flexplate.

After I nail down how much it's going to cost to get a one off flexplate built, I might end up selling my parts and going destroked. That all depends on the price for a one off flex plate.

Cowboys4Christ said:

I have not pinned down who is going make the flexplate yet. My flexplate will need the gear for the starter. The factory T444E/Allison setup I have has the starter gear on the flexplate.

Click to expand...

I was under the impression that those were separate parts with a hub/spacer in between. I stole some pics of the parts from an old post on PSA.

It appears that the thick mass that has the starter ring gear, mounts direct to the crank, then the hub/spacer, then the flex-plate for the converter. Please let me know if this is what you have and how it mounts. I haven't gone to grab any of this stuff to know what's correct or how it mounts.

BrewTown said:

I was under the impression that those were separate parts with a hub/spacer in between. I stole some pics of the parts from an old post on PSA.

It appears that the thick mass that has the starter ring gear, mounts direct to the crank, then the hub/spacer, then the flex-plate for the converter. Please let me know if this is what you have and how it mounts. I haven't gone to grab any of this stuff to know what's correct or how it mounts.

Click to expand...

I will have to take a look at my box of parts again. I might getting the dt466 setup and the T444E setup confused.

On EDIT: I bought the parts last January and put them in storage. So There's a good chance I am forgetting.

That's more than likely the 444 setup. The few 466/A1000 combos I've worked on have an awful huge adapter ring on the front of the converter, as well as another bell housing adapter

JWhite said:

That's more than likely the 444 setup. The few 466/A1000 combos I've worked on have an awful huge adapter ring on the front of the converter, as well as another bell housing adapter

Click to expand...

Have you, or anyone you know actually used the T444E adaptor in an SD? Or an OBS for that matter? I'd like to know if there's clearance issues, like downpipe, starter, firewall or floor etc...

I have not

I know a guy that had in a SD. He claimed no clearance issues. I have never got the chance to look at it though.

Cowboys4Christ said:

I know a guy that had in a SD. He claimed no clearance issues. I have never got the chance to look at it though.

Click to expand...

Great! Assuming you mean an SAE 3 adapter.
Looking forward to you heading there and taking pictures. Tonight...
I am wondering what he used as a flexplate and what kind of power he's putting through it. It would be awesome if there was an off the shelf part, like off a DT570 or something...

Does sarcasm come through in plain text?

BrewTown said:

Great! Assuming you mean an SAE 3 adapter.
Looking forward to you heading there and taking pictures. Tonight...
I am wondering what he used as a flexplate and what kind of power he's putting through it. It would be awesome if there was an off the shelf part, like off a DT570 or something...

Does sarcasm come through in plain text?

Click to expand...

Yes, that would be correct. He used the SAE Set-up from a IH T444E Allison combo. As far as I know he used the stock flexplate that was from the IH/Allisonrig.

I agree it would be nice if there was an off the shelf part that would work. But as you pointed out this should be a an easy flexplate to build.

I would if I could I am in MT and he is in Washington. Kind of hard to do.

And yes, loud and clear, loud and clear.

I might need to gather parts quickly. The 4R100 was applying the converter clutch in reverse when I was plowing the driveway. Temp hit 220° twice, maybe 3 times. At least I can count on the supply chain for timely supplies...

I have not made it to where my parts are stored to get part numbers. It's a 36 mile round trip and I have not needed to head that way yet.

To bad you transmission is giving you trouble. I had a 4r100 that would lock the converter in reverse. Drove it for years that way and even towed with it.

Oh I'm driving it. I figure it will last a while, but this thing is our road trip vehicle. Wife, 3 kids and 2 Great Danes take up space. It doesn't seem to have gotten worse, and I thought it was acting up at least 10k ago.

If it's a rig for trips, I'm not sure I could trust it.