Swapped Allison to 13 Speed In My GU713, But Truck Will Not Start

[Joey Mack]

So Is it working now??  

[KKRT]

Yes Jojo. Everything is working now. I'll update when I start pulling some hills next week.

I'll later summarize my process for folks who may be interested. Since the gray engines went away in 2007 with start of the CTP,  there are hundreds of red engines out there (MP7 and MP8). We all have to be creative with our red engines, if we want to do some different things (just one guy's opinion,  Jojo).

[Joey Mack]

I agree.. that's why I suggested a starter button..  sometimes we just have to make it our own...  

[KKRT]

THE PROCESS: The manual work of swap (Allison to 13 spd) is relatively simple. My challenges came with the reprogramming and starting, which I believed my dealership could easily handle.

Anyone who can change a Mack transmission can swap the transmissions in 2 days. Plus, another day to change the 2 engine cooling parts for the manual (Thermostat Housing-PN 21905526, Connection Pipe-PN 21394446). Bottomline, all this can be done in one week to 10 days. You only need a good transmission jack, a few basic shop tools, and some skill; and of course another pair of hands: -Remove driveshaft, -Remove Allison (don’t forget bolts holding flex plates), -Change the flywheel, -Install heavy duty clutch, -Install the Eaton, -Install clutch cable & clutch pedal (all GU cabs are set up for clutch cable and pedal), -Reconnect driveshaft. DONE.

I didn’t need to change flywheel housing or modify the driveshaft (you may have to lengthen driveshaft if you use a shorter manual tranny like an 8 or 10 speed). You also need 2 manual transmission quick connect cooling lines from the dealer (PN 21866804 and PN 21866806). Quick connect fittings were already at bottom of the radiator (PN 21866813); I bought 2 fittings for the Eaton (PN 21866811). PTO pump turns in opposite direction for the Allison, so you need a PTO for a manual or get a hydraulic shop to change the pump’s rotation.

LESSONS LEARNED:

-Parts: I got a strip yard to send me a trans, clutch pedal and flywheel from the same truck (I didn’t need a flywheel housing; I would have gotten it from the same truck).

-Reprogramming: Inform your local dealer a week before the project to request an E-Service for a manual program. I also found tuners on the internet who said they could reprogram the truck, but I stuck with the local dealership, because I could go there and talk to them.

-Starting Problems: Thanks to Mackpro for telling me about the transmission harness (Part # 21902987). Once I mentioned to the dealership tech to install the harness the speedo, PTO, backup light/buzzer and trans temperature all started working. After a lot of trying to start my truck from the ignition, Joey Mack (Jojo) suggested a starter button; with that idea I ran a direct line from ignition ground to starter solenoid. Truck starts and runs fine.

-Cost: If you do the mechanical work yourself (trans swap), and you can get ahead of the programming and starting problem, it’s cheaper than a remanufactured Allison. Dealer charged 2 hours for the reprogramming, extra dealer costs came from them trying to figure the speedo and starting.