Allison behind Cummins 6.7

[coker6303]

In red it states the 3500 C&C, 4500, and 5500 use the AISIN AS68RC which is NOT the same as the 68RFE. They are COMPLETELY different trannies from each other sharing NO parts that I am aware of.

X2, they are different.

This is all making more sense. I think we are going to pass on the Allison for now. Might look into the Aisin, harder to come by and probably hasn't been pushed yet but I'm sure mike could build it!

Supposedly the Raisin will be in the 2013 2500/3500 rams but an 8 speed version. All rumors as far as I know

---------------------------------
08 LMM Chevy CCSB
Relentless Diesel trans
JoshH EfiLive tuning
554hp 1014ft-lbs 7/30/11

 

[Bryce418]

My worry about going with the Aisin would be that there is as far as I know , no hot rod support currently. You say mike could build it, I'm sure he could but I bet it may well take a few tries to get a setup that works.



I know everyone worked very hard figuring out the Allison early on and found things that worked and things that didn't.

 

[coker6303]

Very true.

I just hate for him to give up the versatility of a 6 speed for an old 4 speed

---------------------------------
08 LMM Chevy CCSB
Relentless Diesel trans
JoshH EfiLive tuning
554hp 1014ft-lbs 7/30/11

 

[Mike L.]

Very true.

I just hate for him to give up the versatility of a 6 speed for an old 4 speed

---------------------------------
08 LMM Chevy CCSB
Relentless Diesel trans
JoshH EfiLive tuning
554hp 1014ft-lbs 7/30/11

AS68RC ratio's:

1st... 3.74
2nd... 2.00
3rd... 1.34
4th... 1.0
5th.... 77
6th.... 63
Rev... 3.54

The ratio's are pretty close and geared for 4 cyl engines.

 

[Bryce418]

What's first gear ratio on an Allison?

 

[Mike L.]

what's first gear ratio on an allison?

3.10

 

[MaxPF]

I know MAXPF is working on one right now for his 12valve, but I haven't heard any progress from him lately.

It's getting stabbed in next month. Just gotta finish getting a Jeep wired and out of my way. I still need to braze a temp sensor bung in the pan and build a brace for the 203-205 combo - 230lbs of transfer case hanging off the back of the Ally is going to need some extra support to prevent breaking the tailhousing.

The thing is, I am using a TCM with an 8.1 OS to accept PWM TPS inputs from a CAT TPS. Pretty simple on a mechanically injected 12V. However, 6.7's and CR 5.9's are drive-by-wire just like the DMax. The only 6 speed setups known to work are factory setups in medium-duty trucks. In these installs, the Allison TCM communicates with the Cummins (actually Bosch) ECM over a 250kbps CAN bus. It works fine, but the software in the TCM is designed for a MD truck, so it shifts like a GM TCM locked in T/H mode. Howards Allison Conversions can set you up with a working 6 speed Ally conversion, as long as you are OK with those limitations.

 

[MaxPF]

Just an update: A guy on 4BT Swaps has gotten his 6 speed Ally working stand-alone behind a 6.7 Cummins using the setup I devised for running the TCM stand-alone behind a mechanically injected engine. It uses mostly off-the-shelf parts, including an A40 TCM (from a DMax truck no less - I wasn't sure whether a DMax TCM would work, and I had mine flashed for an 8.1 app) and a 7.3PSD TPS (I am using a TPS from a CAT ACERT app, which is nearly identical except for operating voltage range). He did some sort of bracket to actuate the TPS off of the DBW throttle pedal used by the 6.7. So far he reports that it is working well (after destroying his first Ally due to a mechanical mis-assembly when changing tail housings ). There is an issue with the TCM not reading full range from the TPS, which I believe has to do with teh fact that the TPS output isn't an open drain/collector output. Once I get a chance to verify, it will be an easy fix. For the time being it is being compensated for in software.

 

[jheyob]

Chris Watson's ford?

Sent from my DROIDX using Tapatalk

 

[THEFERMANATOR]

Just an update: A guy on 4BT Swaps has gotten his 6 speed Ally working stand-alone behind a 6.7 Cummins using the setup I devised for running the TCM stand-alone behind a mechanically injected engine. It uses mostly off-the-shelf parts, including an A40 TCM (from a DMax truck no less - I wasn't sure whether a DMax TCM would work, and I had mine flashed for an 8.1 app) and a 7.3PSD TPS (I am using a TPS from a CAT ACERT app, which is nearly identical except for operating voltage range). He did some sort of bracket to actuate the TPS off of the DBW throttle pedal used by the 6.7. So far he reports that it is working well (after destroying his first Ally due to a mechanical mis-assembly when changing tail housings ). There is an issue with the TCM not reading full range from the TPS, which I believe has to do with teh fact that the TPS output isn't an open drain/collector output. Once I get a chance to verify, it will be an easy fix. For the time being it is being compensated for in software.

Out of curiosity, did you try running the A40 TCM hooked up to the 6.7's can data bus? I know the folks at EFILIVE said tehy hooked up a 5.9L or 6.7L CUMMINS ECM on a bench harness up to an ALLISON TCM and said the data bus functioned, but they had no way of knowing if they would talk to each other or not. It would be interesting to see if teh CUMMINS CAN BUS could talk to the A40 TCM's CAN BUS with GM software in it.

 

[MaxPF]

Chris Watson's ford?

Must be. His first name is Chris. Goes by the name SuperSonic on the forum.

Out of curiosity, did you try running the A40 TCM hooked up to the 6.7's can data bus? I know the folks at EFILIVE said tehy hooked up a 5.9L or 6.7L CUMMINS ECM on a bench harness up to an ALLISON TCM and said the data bus functioned, but they had no way of knowing if they would talk to each other or not. It would be interesting to see if teh CUMMINS CAN BUS could talk to the A40 TCM's CAN BUS with GM software in it.

Well, it's not my project, so no I didn't. The gen 4 TCMs have two CAN buses. One is set for 500kbps (GMLAN) and would just cause data collisions if connected to the 250KBPS bus on the Cummins' Bosch ECM. I have heard that the other Can bus is 250Kbps, but I don't know if that is correct or not. I think Ben (DuraToTheMax) messed around with that at one time.

IF they could talk to each other, and IF they could send and accept defuel requests, it would be the better setup. Especially for a heavily modded engine - we already knows what happens to Allisons behind high HP DMax's with insufficient or no defueling. I have devised a simple method of providing defuel on a mechanically injected engine, and it may work on an electronic engine as well, but direct CAN bus comms would be the simplest, easiest, and cleanest way, thats for sure.

 

[duratothemax]

there are factory applications with 6-speed Allisons (4th gen controls) and a 6.7 cummins. So yes, the calibration does exist to make an A40 TCM talk to a cummins ECM over the databus.

The 4th gen is used on almost all current allisons, regardless of application. The GM pickup trucks are the only applications that use GMLAN (500k). All of the other applications use 250k J1939 CAN...which is what the 01-05 duramax's used.

So all you have to do "theoretically" is flash the A40 TCM with a factory 6.7/6-speed calibration, and that would make the TCM speak J1939 250k CAN and not 500k CAN (GMLAN).

 

[THEFERMANATOR]

there are factory applications with 6-speed Allisons (4th gen controls) and a 6.7 cummins. So yes, the calibration does exist to make an A40 TCM talk to a cummins ECM over the databus.

The 4th gen is used on almost all current allisons, regardless of application. The GM pickup trucks are the only applications that use GMLAN (500k). All of the other applications use 250k J1939 CAN...which is what the 01-05 duramax's used.

So all you have to do "theoretically" is flash the A40 TCM with a factory 6.7/6-speed calibration, and that would make the TCM speak J1939 250k CAN and not 500k CAN (GMLAN).

INTERESTING! In theory then, one could use the later 6.7L A40 cal file to run a 6 speed behind a 01-05 truck, or directly swap a 5 speed in behind teh 6.7L using a GM cal file(or use the SUNCOAST 6 speed conversion set-up to get a 6 speed to work.

 

[duratothemax]

INTERESTING! In theory then, one could use the later 6.7L A40 cal file to run a 6 speed behind a 01-05 truck, or directly swap a 5 speed in behind teh 6.7L using a GM cal file(or use the SUNCOAST 6 speed conversion set-up to get a 6 speed to work.

"maybe"

I kind of lost interest in the project after I got my tap-shift retrofit working (that was the main reason I wanted to make the A40 TCM work in my truck, the idea of having 6th gear didnt really do anything for me....it was the tapshift I wanted)...maybe one of these days Ill dig up my A40 TCM and the adapter harness I made (to go from 3rd gen TCM connectors to 4th gen connector) and play around with it again. Keep in mind though that the whole "TAPSHIFT" thing to begin with is a GM pickup truck specific/exclusive feature......so you are NOT going to find an "off-the-shelf" calibration that has 6-speeds, tap-shift, and 01-05 dmax J1939 CAN all rolled into one. The only A40 calibrations that have TAPSHIFT enabled are going to be 500k GMLAN only on the highspeed databus side.

The 01-05 dmax's use J1939 CAN, but I dont know if the instructions/messages are "GM specific", or if they are "standard heavy-duty-truck J1939" messages.....

In which case (if GM used their own kinds of messages on the J1939 bus), the bus would "work" and the two modules would communicate, but the ECM might be asking the TCM to reduce torque in a way that the TCM isnt used to understanding.

I guess kind of like asking a physicist to do a complex chemistry problem? They are speaking in the same english language, both scientists, understand the words, but dont really know how to fully complete the action....maybe? Im not a computer scientist so I dont know the specifics..that would be a question for Ross (EFILive) or someone else who has specifically worked with J1939 CAN on the GM duramax's/

 

[ocwelder]

I would like to thank you all for making my head hurt :thumb:
Impressive knowlege here

 

[MaxPF]

there are factory applications with 6-speed Allisons (4th gen controls) and a 6.7 cummins. So yes, the calibration does exist to make an A40 TCM talk to a cummins ECM over the databus.

Correct. However......

Keep in mind though that the whole "TAPSHIFT" thing to begin with is a GM pickup truck specific/exclusive feature......so you are NOT going to find an "off-the-shelf" calibration that has 6-speeds, tap-shift, and 01-05 dmax J1939 CAN all rolled into one. The only A40 calibrations that have TAPSHIFT enabled are going to be 500k GMLAN only on the highspeed databus side.

THAT is a key issue. Swaps behind common rail 5.9's and 6.7's have been going on about as long as the 6 speeds and gen 4 controllers have existed, but they have all used medium duty truck calibrations. The common complaints I hear about that approach is the shift strategy (it shifts like a MD truck), and lack of GM pickup features. Everyone wants an Allison that shifts and feels like a GM pickup in normal (non-T/H) mode, with the capability of T/H mode and tap-shift. The only way to get that to my knowledge is with a GM pickup specific OS in the TCM. Which, as mentioned, uses a 500k data bus.

Ben, I thought you mentioned in another thread that only one of the HS busses on a GM TCM was 500k, and that the other, unused bus was still 250k Since my goal was to use the TCM with a mechanically injected engine, I haven't explored the data bus side beyond making it functional for scanning/programming.

 

['strokeThis_'07]

Why not put a 68rfe in, like factory? Suncoast seemingly isn't having any issues out of their built 68 in their drag truck, think they are calling it the OM3GA or something.

Was this a manual truck originally?

 

[rgullett83]

Why not put a 68rfe in, like factory? Suncoast seemingly isn't having any issues out of their built 68 in their drag truck, think they are calling it the OM3GA or something.

Was this a manual truck originally?

$$$$$

 

[THEFERMANATOR]

Why not put a 68rfe in, like factory? Suncoast seemingly isn't having any issues out of their built 68 in their drag truck, think they are calling it the OM3GA or something.

Was this a manual truck originally?

Last I heard that truck was still running there new updated 48RE as the 68RFE wouldn't shift at full throttle(just revved and held there).

 

[madmatt]

Must be. His first name is Chris. Goes by the name SuperSonic on the forum.

Yes that's chris watson,, if it can be done with anything he's the man who could do it.