FRO-15210C Tranny question

You would need to change transmissions to increase torque rating.

 

the truth is I do not believe that!!! you will break the transmission.with 320hp I does not matter what horse power you put on it. If you do not know how to use it correctly it will break. If it cooled down by water, change it for it can be cooled by air. I do not believe much torque advertised . Never in my lifetime i have seen a transmission breakdown on a hill.(for hp) Years ago the largest motor in cubics for its time was the cummins KTA(800hp), in addition the rto12513 was also large for its time. If you can see they do not match. Never have I read or heard of someone break this transmission before ,In some contest of dyno there are people who have more than 1200 hp that participate with this transmission. So do not worry keep your transmission.5 down 5 high is the best, super 10 is to much chimichanga!!!!! just take out a gallon of oil and put 1 gallon lucas.be cool!!! just my 2cents

 

Download from the roadranger site your trans and a higher rated torque.
You'll find 90 percent of the parts are the same part number. You should then realize your trans will hold much more torque than what it is rated for.

 

Warranty would be my only consideration. Cummins won't do it but you can do the increase through other sources. If you know how to drive and have a temperature gauge on the transmission, the rest is common sense.

 

I remember reading that some of the guys running souped up Big Cam Cummins by Pittsburg Power putting out 700hp or better were running their original transmissions and those old boxes were only rated for around 1250lb/ft. It was a matter of smart right foot useage. But I think due to liability issues most shops won't uprate beyond what the drivetrain is rated for. They don't want to get sued if you leave your transmission all over the interstate!

 

Ok now let me see if I have this right You have a Cummins ISX 450 ST and you are saying that it is under powered due to the trans Right ? Just how much power are you wanting ?
We have a Cat 6 NZ rated @ 435 with the same tranny you have pulling a 35 end dump and in TX we are pulling on average of a 26 ton payload . In ARK we average 24.5 tons and I do not have a problem with the way the truck performs . we have 3.73 ratio in rears. What gears are in your truck