T1138 transfer case question

[ccf460]

Does anyone know the specs on this case ? I am thinking about using it behind a 5.9 12 valve cummins in a ford F700 running mrap axles. My questions center around:
Max input speed?
" " horsepower?
" " torque?
Thanks

 

[simp5782]

Does anyone know the specs on this case ? I am thinking about using it behind a 5.9 12 valve cummins in a ford F700 running mrap axles. My questions center around:
Max input speed?
" " horsepower?
" " torque?
Thanks

They hold up to a BC 1 in high range. But not low. So 400hp/1250ft lbs. You wouldn't want to use low range with that power output. Unless it was very carefully done. Depending also on what transmission ratios you are running as well will determine how the case holds up.

I am sure if i used my 1st gear(14.77:1) and romped on it the case wouldnt like it for long and i am around 300hp

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[ccf460]

My first gear is in the 8.5:1 range. I don't forsee using low range except in a low speed, easy throttling crawl. My target engine output is 450 hp / 750 torque. I have heard that the t1138 doesn't like input speeds above 2100rpm, that is probably my single biggest concern. If true, will probably make me pick a different t case

 

[simp5782]

My first gear is in the 8.5:1 range. I don't forsee using low range except in a low speed, easy throttling crawl. My target engine output is 450 hp / 750 torque. I have heard that the t1138 doesn't like input speeds above 2100rpm, that is probably my single biggest concern. If true, will probably make me pick a different t case

Horsepower tends to be around 1/3 of output torque. You may want to check with adamsoffroadperformance on here. I think he makes some things for the T1138. You really wouldn't benefit from the 1138 case if you dont need the overdrive. I would go with a 138 case that is alot stronger and easier to find. The 1138s are getting slim since they tend to bust in half.

You could also look at a HEMTT case. They are cheap right now. Plus made for a high HP Detroit and CAT engine. You have a .98 high range and a 2.62 low range. Eastern surplus has the PLS cases for under $1000. Member fuzzytoaster has a standard HEMTT case.

https://www.steelsoldiers.com/showthread.php?t=162014

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[ccf460]

I am needing the overdrive. I have even considered just using the mrap t case, and finding an overdrive transmission. I have a low mileage spicer 3053A takeout from a deuce that I thought about using.

 

[simp5782]

Gerhart. One of the moderators here has a 6453 transmission from a m809 series near Jacksonville, NC he may be willing to sell. They have overdrive. That little 3000 series spicer is not going to like that power output.C

The MTVR and mrap cases tend to rely on the 7 speed transmissions that have double overdrives.

My .83 OD with a .98 ratio T case with 6.44 ratio axles on 16.00 tires will go 75mph at 2300 rpms


You were looking for the 5.65 mrap axles i believe.

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[ccf460]

Yes, I found some 5.65 mrap axles. Finalizing the deal now. He's willing to bring them for less than I can go get them for. I am waffling on getting the t600 mrap t case. My cummins has that big sae 2 or 3 housing mated to a non overdrive eaton fuller 5 spd. Even with 16.00's ,I can't get the cruising rpm range I am looking for. Got to get overdrive from the tranny or t-case some how...

 

[Jbulach]

Whats the expected weight of your truck, tire size, and max engine RPM?


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[ccf460]

Current weight is 10,500 lbs., with dual G177's. I am assuming an increase of around 1,500 lbs with the conversion. So say 12,500 safely. Tire size in the 46" range, looking at 395's on aluminum mrap wheels. Cruising rpms at 2200, max rpms at 3,000. I do occasionally pull a 10,000 lb trailer locally.

 

[ccf460]