How to source a transmission upgrade

[cadillackid]

it seems that getting the proper bits to mate a 643 to a 5.9 seems to be difficult, i think it was Kubla I was talking to about doing the same thing on his latest bus, he mentioned that it seemed the converter ring adapter was tough to source..

lets talk Overdrives.. the mechanical advantage of swapping in a 1000 or 2000 is that both can be had with SAE3 bells.. the converter bolt pattern and offset are identical to the AT545.. so its pretty much just unbolt the 545 and bolt up the 1000/2000.

buying a 1000 and the associated electronics is going to be your most expensive option out there.. my 1000 in the red bus operates absolutely Fantasmical (is that a word?). but it was also well into the 1000s to source it, the TCM, (I also chose to buy software to tune it as well).. that nets me 6 gears. with a final OD of 0.61:1 from the trans..

Sourcing a used 2000 (esp if you can source one from a used Thomas freightliner. with a 5.9).. would be a lot cheaper. and you could also have the necessary bits with it to bolt it right up to the engine.. the wiring harness you may need to source elsewhere unless you can find a bus junkyard that actually was nice enough to properly remove the TCM and harness from the bus intact. I have copies of the allison pinouts for all of their TCM's so if you were able to snag one , we could look up the wire colors to tell you what to hook up to what..

if you need to source the harness then CAC, or jason@transmissiontuner.com can make them for you.. they will cost a few hundred bucks to source new..

if your 5.9 is the newer 24 valve, we can grab you throttle data right off your ECM, otherwuse we have to find you a throttle box that will take the cable input and turn it electronic for the OD trans to recognize. CAC makes those and they work well.

this would be significantly less cost then a full new trans and would net you a 0.75:1 ratio with 5 gears to work with..

just tossing some ideas out there..

the only reason i went with all new parts on mine as I drive LOTS of miles on my bus. and wanted to start fresh.. my bus has been on the road a little less than 10 months with its new trans and ive run over 20k miles on it...
-Christopher

[natedlee]

Originally Posted by cadillackid

it seems that getting the proper bits to mate a 643 to a 5.9 seems to be difficult, i think it was Kubla I was talking to about doing the same thing on his latest bus, he mentioned that it seemed the converter ring adapter was tough to source..

lets talk Overdrives.. the mechanical advantage of swapping in a 1000 or 2000 is that both can be had with SAE3 bells.. the converter bolt pattern and offset are identical to the AT545.. so its pretty much just unbolt the 545 and bolt up the 1000/2000.

buying a 1000 and the associated electronics is going to be your most expensive option out there.. my 1000 in the red bus operates absolutely Fantasmical (is that a word?). but it was also well into the 1000s to source it, the TCM, (I also chose to buy software to tune it as well).. that nets me 6 gears. with a final OD of 0.61:1 from the trans..

Sourcing a used 2000 (esp if you can source one from a used Thomas freightliner. with a 5.9).. would be a lot cheaper. and you could also have the necessary bits with it to bolt it right up to the engine.. the wiring harness you may need to source elsewhere unless you can find a bus junkyard that actually was nice enough to properly remove the TCM and harness from the bus intact. I have copies of the allison pinouts for all of their TCM's so if you were able to snag one , we could look up the wire colors to tell you what to hook up to what..

if you need to source the harness then CAC, or jason@transmissiontuner.com can make them for you.. they will cost a few hundred bucks to source new..

if your 5.9 is the newer 24 valve, we can grab you throttle data right off your ECM, otherwuse we have to find you a throttle box that will take the cable input and turn it electronic for the OD trans to recognize. CAC makes those and they work well.

this would be significantly less cost then a full new trans and would net you a 0.75:1 ratio with 5 gears to work with..

just tossing some ideas out there..

the only reason i went with all new parts on mine as I drive LOTS of miles on my bus. and wanted to start fresh.. my bus has been on the road a little less than 10 months with its new trans and ive run over 20k miles on it...
-Christopher

So much good info here - I really appreciate it.

So KC has already found a couple used options for me (with 1-year warranty), starting at $900 + $150 for shipping. I sent her my drivetrain specs (gearing, tire size, etc) and she's going to run some numbers to determine if I'd be better off with 5 gears or 6. The previous owner upgraded rear to 4.78. Also my 5.9 is a late '97 12 valve (ISB), which apparently makes this all the more easy. ¯\_(ツ)_/¯

I know I'll be happier with this option - just need to get rolling. I'll source the harness through KC and just pay it.

[Booyah45828]

I don't think cummins made an electronic (isb) 12v engine. If they did, I've never seen one so I'd assume they're pretty rare.

You can still use the newer allison, you'll just have to create a throttle position signal for it to read.

[Twigg]

Originally Posted by Booyah45828

I don't think cummins made an electronic (isb) 12v engine. If they did, I've never seen one so I'd assume they're pretty rare.

You can still use the newer allison, you'll just have to create a throttle position signal for it to read.

They went from the 4B mechanical engine to the ISB, changing the number of valves in the process.

Same with the bigger brother. That went from 6C to ISC.

[Booyah45828]

Originally Posted by Twigg

They went from the 4B mechanical engine to the ISB, changing the number of valves in the process.

Same with the bigger brother. That went from 6C to ISC.

Yeah, I know that. He'd have a 6bt btw, not a 4bt. Which is why I asked the question about having electronics on a 12v because I've never seen it.

[Tango]

True. Cummins went to the 24 valve configuration & electronics at the same time in mid 1998. Also went to the suck-o rotary pump but it only lasted a few years before they replaced it with the much better Bosch common rail.

Long story short...if it has 24 valves...it is electronic...and visa versa.

[cadillackid]

Originally Posted by Booyah45828

I don't think cummins made an electronic (isb) 12v engine. If they did, I've never seen one so I'd assume they're pretty rare.

You can still use the newer allison, you'll just have to create a throttle position signal for it to read.

the throttle is easy, cable-type TPS;s are all over.. CAC makes one that they put on 4BT's and older dodge cummins trucks all the time to run the modern transmissions..

the only advantages an electronic engine gives you is more precise control of the transmission.. the engine data often contains information about its Load factor, cruise set points, turbo boost, and torque data.. all in a J1939 data stream that the allison TCM can read and apply the best use of TC engagement and gear selection for what the driver is trying to achieve.

the allison TCMs are able to perform some learning by using just throttle input, and of course they also have RPM at the converter as well as the main turbine of the trans.. allison can approximately determine torque when the TCC is unlocked.. this data coupled with throttle data is saved. and utilized as a reference when the TCC is locked and various RPM / throttle conditions are observed..

while my allison operated nicely with just a throttle i can say it operates even better once I established the J939 link to my computer..
-Christopher

[NovaTRON]

I wondering if you ever figured out the speedometer issue?

I ask this, after having my transmission upgraded (on a 5.9 12v) from an AT545 to a MT643. The shop connected the sender unit of the 643 to my existing speedometer and now my speed and distance (odometer) is reading double (x2).

I keep reading that the 643 has a mechanical output, but the sending unit does not use a cable- it's a plug with 4 wire- though my bus's speedometer uses 2 wires - one is power and one is signal. So 2 of the 4 wires are not connected.

Anyone have any insight into a fix for my issue?

[Yukon Cornelius]

Great bit of info here