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Daniel Wilson
Daniel Wilson,
Category: Medium and Heavy Trucks
Satisfied Customers: 1634
Experience:  Owner at DJ Wilson
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Have a 9 speed transmission in 2012 587 Peterbilt has a

Customer Question

Have a 9 speed transmission in 2012 587 Peterbilt has a Cummings motor in it we want to change it to 13 speed what will be the out come of that move?
Submitted: 8 months ago.
Category: Medium and Heavy Trucks
Expert:  Jim replied 8 months ago.

Hi, Welcome to JA! my name is ***** ***** I Will try to Assist you with this.

The first Thing that we need to do is to get the number off of the serial plate on your transmission.

The number usually starts out with FRO or RTO, RTLO, something like that, this number is ***** important in choosing what transmission to go with, secondly I would like to know what is the ratio of the rear.

Expert:  Jim replied 8 months ago.

Just so You know, before we go any further, you will have to cut your driveshaft down to make this work. The 9 speed is a shorter trans and the 13 speed is about 9 inches longer which means that your drive shaft will have to be shorter to accommodate a larger trans.

Customer: replied 8 months ago.
My understanding Peterbilt has a kit 250.00 dollars to convert into 13 speed using the same transmission small job not to cut the drive shaft out or anything like that good transmission is made to accept it 2 converted into a 13 speed then run the air holes up and put on The Flipper just a simple I was just wondering what kind of fuel mileage and low-end and top end results
Expert:  Jim replied 8 months ago.

there is a kit available to convert a 9 to a 13 but only on 1 specific model trans made by eaton fuller.

This is why I was curious about your trans number.

Expert:  Jim replied 8 months ago.

The Fuller Convertible manual transmission operates as a simple 9-speed transmission, and can then easily be converted to a 13-speed to increase vehicle versatility and resale value at trade-in time

Depending upon your diff ratio, average cruise speed lets say 50 mph you would probably be at about 13 to 1400 rpm?

The 13 would bring you down to about 1150 to bring in fuel $$ savings.

Expert:  Jim replied 8 months ago.

you would loose a little bit of torque on the low side, but have plenty of top end in hills and pulls