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Kenworth little cat 13 speed


66dc75
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I was just wondering if anyone in here has ever run an RTO9513 behind a 3126 Cat?  KW T300 single axle 250 hp 3126 which has a fuller 6 speed which is horrible to live with. It's time for a new clutch and I have the 13 speed.

They came from the factory with 9 speeds so I figure a little bit of overdrive can't hurt.

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The Cat 3116 and 3126 were torqueless wonders. The Postal Service bought out a contract from one of CF's divisions and with it got a fleet of M2 Freightliner tractors with 3126s and 6 speeds, even pulling empty trailers they were slow. I drove a Penske rental Freightliner business class tractor with a 3126 and an RT1160 a few times, it was still a torque less wonder but at least you could keep it in the power band. Was kinda fun to drive too- the smallish engine changed RPMs quickly and the unsycronized Roadranger shifted a lot quicker than the synchronized 6 speed. But why mess with a decades old 9513 when the newer Roadrangers with all their improvements will just as easily bolt up?

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8 hours ago, 66dc75 said:

I was just wondering if anyone in here has ever run an RTO9513 behind a 3126 Cat?  KW T300 single axle 250 hp 3126 which has a fuller 6 speed which is horrible to live with. It's time for a new clutch and I have the 13 speed.

They came from the factory with 9 speeds so I figure a little bit of overdrive can't hurt.

Rich-any problem hooking that 9513 up to a mid  range engine?   It was designed for big bores.

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2 minutes ago, Red Horse said:

Rich-any problem hooking that 9513 up to a mid  range engine?   It was designed for big bores.

Hi Bob The consensus is it will work, 1 3/4" input shaft and small bellhousing., My first crane truck had a 210hp DT that had a rt910 behind it, worked great.

I've got the old timer truck mechanic doing this for me that converted my Louisville 3208 cat from an allison to a 910 and that worked out good too although obviously didn't gain any top end speed.. This one should get me rolling a little faster.

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Best laid plans.........

The 13 speed needed a few things that are getting hard to come by now that is an antique, I had 3 roadrangers given to me, one was a rtx12609 which looks to be a much better choice for this and will give me the overdrive I want so it's going in. Just need to get a new PTO though and a new driveshaft yoke. It was time to do the clutch anyway and the six speed sucked to live with, anybody want to buy it?😀

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If you use the 9513 behind a 3126 i would use a rear mount on the rear of the trans.I have seen some of the 3126 with leaking fylwheel housing to block and some with a cracked housing at the top.The trans is going to have some noise in it at idle unless you set the idle up on it.

glenn akers

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10 minutes ago, theakerstwo said:

If you use the 9513 behind a 3126 i would use a rear mount on the rear of the trans.I have seen some of the 3126 with leaking fylwheel housing to block and some with a cracked housing at the top.The trans is going to have some noise in it at idle unless you set the idle up on it.

Actually plans changed and I'll be using a RTX12609 so the noise and old age of the trans won't be a problem. It's getting a rear mount as soon as possible, we were talking about that yesterday.

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8 hours ago, mrgumby said:

Had a 3126 cat originally a6 speed put an 8LL in its place was a good little truck with the 8LL 

I'm hoping for the same results, The 9 and the 8 are pretty much the same except for the LL. I'm just sick of winding it out to 2400rpm and then having it fall flat on the upshift. It'll also be nice to be able to go a little faster than 64mph

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Yup just dropped the drive shaft and bell housing off at the machine shop. We need to use the small bellhousing but it's an early steel one that doesn't have the big enough reliefs for the later counter shaft bearings cut into it. I would rather use the the steel one than the aluminum anyway. Have to go pick up the new 8 bolt straight cut gear pto today as the 6 speed used a six bolt with spiral cut gears. Why can't they all use the same accessories ? PITA

I think I'm running out of stuff to buy ar modify for this thank God.

I'll build a rear support after its all done or see if I can find something in a junkyard. 

The twin countershafts wil eat some power to turn but I'm confident that it will be a much better setup. 

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  • 2 weeks later...

Well, tranny is in, all plumbed and was ready to go. Batteries got connected. truck cranked but wouldn't start. yeah fml.

ECM internal keep alive battery bit the dust about 2 years ago. CAT software couldn't communicate with it since but the truck ran fine just had a check engine light flashing. I guess whatever parameters and info it had left disappeared with the batteries disconnected for a week or so.

Took the ecm to KW dealer which luckily is about a mile from where the truck was, they bench tested it and yup, dead as a doornail. Off to the truck junkyard I went for a new to me ecm, back to the dealer to have it bench programmed. Of course the programming for my truck is no longer available seeing as it's old enough to drink. They installed a program that was generic 3126 software set at 250 hp. Well. the truck started but would only run for 20 seconds and shut down and  accelerator did not work. Back to KW, Now that it was in the truck they could send a guy over with a laptop and set everything up correctly. a couple of hours tapping the keyboard, calling Kenworth and Cat and the CIA for secret codes, and equations, he waved his wand, I made the sign of the cross and viola, the truck runs the crane runs and I'm broke. I guess there was no way around a new ecm anyway because the speed limiter in the computer needed to be reset for the new .80 overdrive in the 9 speed and the old ecm wouldn't talk to anybody anyway. Once I get done paying for this little debacle at least I know a whole lot more about roadranger gear ratio etc. and cat ecms. Oh and no more check engine light so that's something good I guess.:idunno:

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It’s a pita at the time but after these type of swaps you come away with a lot of knowledge about your running gear and engine. 

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The problems we face today exist because the people who work for a living are outnumbered by the people who vote for a living.

The government can only "give" someone what they first take from another.

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Got the truck back today, labor bill much higher than I was expecting.  I think they charged even for walking by it . I'll have to look ths bill over a little better.  Still need to get speedo calibrated. This thing has extra long legs now.

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