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Question about trans and rear swap


masterwelder
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Pulling out the T2070 from my 690s and swapping it for a RTO 12513 and changing my 5.73 rears to 4.64s. That later combo was in my cousins R modle with a 237 and seemed to work well. I figure with the extra power of my 300 it will be even beter.

My question is what can I expect for a top speed? I have 22.5 rubber. The speedo in my cousins truck didn't work well but I know it wasn't going 90 mph topped out!

Any other coments about this set up?

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don't think a 12513 will hold up to the torque of a 300. max torque output of a 300L is 1425ft at 1250 rpm. I think.

Ok. I was thinking a E7 300 was right around 1200 ft pounds of toque. I'm the only driver of the truck so I will treat it as good as possible. Its a roll off truck that I use for roll off, 4000 gallon tank, flatbed, dump and this winter I'm going to fit up the boom so it can slip on the roll off chassis also.

I wonder if there is any way to "beef up" a 12513?

I also have a Eaton 9sp in my cornbinder dump with a 300 Cummins- I'll go take a look at that trany to see what model that one is.

I almost wish I had back the carriers that I sold to 84 Superdog this spring, but I'm pretty sure I don't have enough motor for that- but if I did I could go about 100mph!!

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With 11r22.5's you'll make 65mph @ 1785 rpm, the Eaton has a .74 or. If you swap to 11r24.5's you'll get your rpm down to 1704@65 so you would be able to make 70mph just over 1830rpm. I would go with a 4.42 or 4.17 if you want to get your rpm down at interstate speeds and still keep good torque multiplication. If your not running too heavy you could swap to a 3.86 and the 13spd and keep your 22.5's and be geared ok, bout 1600rpm@70, if your close to gross 4.17 would be better making about 1730rpm@70mph with the 22.5 talls.

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  • 2 weeks later...

With 11r22.5's you'll make 65mph @ 1785 rpm, the Eaton has a .74 or. If you swap to 11r24.5's you'll get your rpm down to 1704@65 so you would be able to make 70mph just over 1830rpm. I would go with a 4.42 or 4.17 if you want to get your rpm down at interstate speeds and still keep good torque multiplication. If your not running too heavy you could swap to a 3.86 and the 13spd and keep your 22.5's and be geared ok, bout 1600rpm@70, if your close to gross 4.17 would be better making about 1730rpm@70mph with the 22.5 talls.

Thanks Ryan. I think I can live with the 4.64s. Setting cans at a residence can get tricky so I would like to keep some low gearing. I don't do allot of interstate driving so the top speed isn't that crucial, just didn't want to top out at 55.

I'm hoping that the EM7-300 will work well with the 13sp. From searching old posts it seams that the 350s were more common with a bigger transmission. I'm not against turning my 300 in to a 350 or 400, just not now if I can help it.

Whats you thoughts on the torque of the 300 being to much for the 12513? Do you or dose anyone know about beefing up the 12513? My mechanic mentioned something about changing the yoke on the trans to make it stronger. Is there a lot of difference between a 12513 and the 14613?

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To my understanding yes there is a lot of differances between the 12513 and 14613 internally. Gears and ratio wise, and torque rating. If your going to put one of them in with the 300 the 14 series be my choice. If you wanted to be sure of reliability then go with 18913.

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I have a RTLO 14713A behind a 2200lb tourque hauling lowbed. Regulary gross around 130,000. Sometimes up around 150,000. Truck has @ 680,000 on it. Point being, as long as you use youre head you will be fine. Stop and think, back in the day they KT's 1100 ci with 12513's behind em. Also keep in mind there are lots of 12513 trannys out there and there a lot cheaper to fix/replace. Just my 2 cents worth. 12513 also shift nicer than a 14613

Remember if it's got a hood it's no good!

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