New guy with van addiction

[the_engineers]

Greetings all!

My name is Brooks and I have a van problem. We have a 2002 GMC Savana Hightop Explorer conversion van with a 5.7/4L65E swapped to 6 lugs. The 5.7 is very worn after ~190k and just doesn't have the power to pull our 20' enclosed car trailer.

We kicked around swapping a HT383E, but in the end decided we'd always be on the ragged edge of properly towing (and stopping) the 7,000 lb load. After a year of searching, we bought a 2006 Express 2500 with a Duramax to use as a donor chassis. The plan is to get the '06 into shape (head gaskets, injectors, etc) and swap bodies. I'd like to swap to the Allison as part of the switch. The ability to swap to the truck tune, more reliability and lower highway rpms are all of positives. I understand the floor needs to be cut, which is not a big deal as the conversion van has a loose center console that will hide the majority of the change anyway.

I've read a lot of starter threads here, and elsewhere, about people starting the Allison swap, or hearing about the Allison swap...but I have yet to see proof that someone has done it successfully. FWIW, I'd like to do the 6-speed to see the full benefit.

Anyway, I've rambled plenty. Thanks for having me and feel free to point me in the direction of a successful Allison van swap if you know of one.

Thanks!

 

[the_engineers]

The donor vehicle

 

[zf>allison]

That is awesome, I want a van to pull the racetruck.

 

[Poltergeist]

:welcome8:

 

[the_engineers]

I guess I should clarify...a success thread about an Allison swap in a van seems to be elusive. Sorry for any confusion...

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[TheBac]

Since it looks like you're going to use this thread to describe your build, I moved it into Repower/Transplant section.

Nobody on here has swapped a van 4L80 to an Allison that I know of. JoshH is the only guy I can think of still here who even messes around with a Dmax van.

 

[036.6turbo]

We kicked around swapping a HT383E, but in the end decided we'd always be on the ragged edge of properly towing (and stopping) the 7,000 lb load

I can't help with the van dmax swap, but I did put a 383H.T. motor in a TBI GM truck. Many, many moons ago, back before GM even offered the "E" model.

I can tell you it did tow well, but the 4L60E I had behind it was never happy.

On it's best day, it was not on par with a Dmax.

 

[036.6turbo]

The plan is to get the '06 into shape (head gaskets, injectors, etc) and swap bodies.

I just reread your post, my mother drives a 2003 Chevy full size conversion van. If memory serves, it is a Uni Body, not a body on frame configuration?

I'm not sure about a body swap?

 

[the_engineers]

After 1995, they are all body on frame. There's actually a great YouTube video showing the body being lifted off to replace the motor, rather than pull it out through the front.

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[JoshH]

I have played around with the Duramax powered vans a little, but I've never really even considered swapping in an Allison. From what I remember, there is quite a bit of clearance around the transmission to the floor. I wouldn't be surprised if you could fit it without doing any cutting. It might get a little tight around the bellhousing though. Wiring probably shouldn't be too complicated since the TCM and ECM will be speaking the same language. It will take a little bit of wiring, but if you have access to wiring diagrams and know how to read them, you shouldn't have too much trouble.

 

[Tothemax]

how about a 6l90 they came in 11 and up duramax vans and had a 14k gvw

 

[the_engineers]

The reading that I've done makes it sound like the electronics on '10 and newer would be an extremely steep hurdle. I don't recall seeing a stand-alone for the 6L90...

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[the_engineers]

Busy day today...good news and bad news.

Good news:
I talked to Jason at TransmissionTuner.com. He figures the best route is to run the ECM, TCM and BCM from a donor truck. I'd automatically have the truck tune and all three would be automatically able to talk to each other. He suggested keeping my current BCM and figuring out which BCM pieces need to talk to the GMLAN...AC, cruise, etc.

Given that info, I saddled up the trailer and headed to pick up a '06 Allison that i found at a nearby salvage yard. Trans, torque converter and 90 day warranty for $660 plus tax.


Bad news:
I finally got a chance to really give the donor van a good once over. Aside from having a body that's been beaten like a rented mule, the doghouse is much larger than my current. We'll have to see how much is necessary.

Oh well, I'm in it now...

 

[the_engineers]

So, looking at the Allison yoke, I have a noob question about driveshafts...do all Allison-equipped trucks have a slip, or 2-pc, driveshaft? I'm used to the standard slip-yoke arrangement for most transmissions.

 

[CarolinaHD]

2wd was slip shaft and 4wd was slip yoke, both 2 and 4wd trucks came with 2 piece steel driveshafts, some had single piece aluminium shafts on 4wd shorthe bed trucks.

 

[the_engineers]

Any issues with cutting down a slip shaft, or should I plan on ordering custom? I'll be around stock'ish power levels. If I can cut one, I'll start searching for a crew cab long box 2wd driveshaft...should be enough material to cover my 135" WB.

 

[the_engineers]

I thought I posted this previously, but don't see it.


Intended recipient (or victim).

 

[bmc1025]

Check with duramax tuner ( nick with Calibrated Power) I think they swapped their mobile tuning van to an allison.

 

[the_engineers]

I spoke with Chris at Calibrated Power (Nick was busy). Their recommendation is to grab a TCM for my Allison. They can tune the rest into place.

Now for the next challenge...I'm struggling to find a wiring harness. I'm guessing I'll be building one? Anybody have any preferred suppliers/awesome success stories?

 

[the_engineers]

Found a TCM and harness to order on Monday...hadn't looked deep enough at car-part.com...

Also, I picked up the gauge pack and steering column from a 2013 Express ambulance. The 2013 has the PRNDM1 display and the shift lever has the +/- controls. Not sure what will be required to make them talk correctly with the rest of the van, but I'm almost done buying hard parts at this point...