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6.5 to vm638

Humps

New Member
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Location
Australia
Hi everyone. Same as above am interested in how this ended up. I have a new Detroit 638 that I have fitted to a used tremec T56 transmission. Torque isn't far off the limit of the box, but wasn't to be a problem in the original truck it was to be fitted to. Now looking at slightly bigger truck, and more towing, trying to decide whether to use the Detroit or go a Cummins 6bt and Eaton 6 speed - more torque, not going to break the box.
Located Australia - these motors never officially made it here in a vehicle. Were imported in mechanical form in a Kia bus.
Mine is still bolted to the original pallet, wiring loom, ecu and electronic throttle...

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JayTheCPA

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Annapolis, MD
I have a new Detroit 638 that I have fitted to a used tremec T56 transmission. Torque isn't far off the limit of the box, but wasn't to be a problem in the original truck it was to be fitted to. Now looking at slightly bigger truck, and more towing, trying to decide whether to use the Detroit or go a Cummins 6bt and Eaton 6 speed - more torque, not going to break the box.
For towing, not sure I'd do the T56 as last I checked it did not have a low enough 1'st gear.

The Eaton 6 speed is probably the better towing choice as it has a deep 1'st gear, although it is a rather heavy transmission.

In any event, IIRC both the Tremec and Eaton have about the same torque rating, so neither might work if there is concern about pushing them over their ratings.
 

Humps

New Member
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Location
Australia
This T56 isn't rated overly high, comes standard in one of the local Holden HSV Commodores. The Eaton 6406 I was looking at was rated much higher.
The original vehicle the Detroit/T56 combo was going in was going to work OK with its diff ratio...
I am leaning towards the Cummins/Eaton combination just for piece of mind...
Now just need to find a buyer for the Detroit over here...

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JayTheCPA

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This T56 . . . comes standard in one of the local Holden HSV Commodores.
Good to know :)


This T56 isn't rated overly high, . . .
I am leaning towards the Cummins/Eaton combination just for piece of mind...
Gotcha.

Given the stated use and interest in an Eaton, consider the G56 if it will mate to the motor as the Mercedes tranny is about the same torque rating with significantly less weight. Also, the AE gear range has a taller 6'th gear (overdrive) than the Eaton.
 

Humps

New Member
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Location
Australia
Glad I joined this site. Never heard of the G56. After a little research it would seem that it is a good box until you do a lot of heavy towing.

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Humps

New Member
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Location
Australia
There seems to be a higher rated box, the G85-6, which is rated higher, but another 45 kgs(99 lbs?). Also listed as having 'hydraulic gearshift'. Haven't looked into that yet, but guessing instead of cables or linkages some sort of hydraulic system. Extra weight probably doesn't worry me too much.
Have found a second hand one here, haven't enquired on price yet...

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JayTheCPA

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Glad I joined this site. Never heard of the G56. After a little research it would seem that it is a good box until you do a lot of heavy towing.
From everything I have read, issues tended to occur when owners pushed the motor's power level well above OE which in turns translated into going over the G56's design limits. Accordingly, not sure it is fair to say the tranny is anything less than capable for towing as all of the 'failures' I had read about seemed to come from self-inflicted issues. So my read is that as long as the G56 mates to a motor that does not create *more* than 600 ft/lb of torque, it is a great tranny for towing.

And were it not for lack of an adapter / bellhousing to mate the G56 to the 6.5, I would have one in the Burb by now :)
 

Humps

New Member
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Location
Australia
Interesting. I did wonder if that was the case. From what I have read it is fairly common to push power levels over there. I will be leaving things standard, a free flowing exhaust and decent size air cleaner will be the most I will do. Has enough power for what I want to do anyway
Have emailed the business that has both boxes on prices for each. Should be interesting...

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MihaS

New Member
Messages
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Location
Slovenia
Hello Humps and others

i also have VM638 or Detroit Diesel 638LH engine. Im trying to converse it to marine engine,but i have little problem.
Can you help me with electronic throttle. I cant find anywhere what potentiometer(electronic throttle) is suitable for this engine. Please take photo and send it or write who is producer,product nr.,,,,on that potentiometer.

Also if you can photo to which wires is connected.

Please send photo and details to sotlar.miha@gmail.com

And does anybody have idea what kind of cheap diagnostic tools can I use on those engine.

thanks

Best regards

Miha
 

MihaS

New Member
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Slovenia
Great. This is like chrismas to me.

Im nervous waiting to find what potenciometer is used. That i can order it.

If anybody can help about diagnostic cable
 

Humps

New Member
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Location
Australia
Should be able to order a foot throttle, it will be used in other applications too. Although I'm guessing you would like to set up a hand throttle....

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MihaS

New Member
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Location
Slovenia
I dont know if this engine has electronic foot throttle or potentiometer is attached on engine and then driven by steel cable. Because i get with engine 2 cables.

Yes i want to set up to hand throttle. This is no problem when i get engine to higher rev.

Engine works on idle.

Thanks
 

Humps

New Member
Messages
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Location
Australia
So from what I understand there is two versions of this motor. A full mechanical pump which will have a lever on the side of the injector pump. All you would have to do is hook a cable up to that and to a throttle.
The other one is more common I think, which is electronic over mechanical injector pump. There will be two sets of wires coming off the pump from memory. This pump requires the electronic throttle, although it doesn't plug directly to the pump, it plugs into the wiring loom. Will post a pick of mine. And email you pics of the throttle.

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