02 1/2 Ton Duramax Conversion

I am new to TDP and have not personaly owned a diesel. I currently own an 02 GMC 1/2 ton 2wd with a 4.8L. I have been throwing around the thought of putting a Duramax in it.

I still want to keep the driveability of the truck and obtain 20+ mpg (hopefully) after the conversion. I have also seen a duramax kick some butt in a races and that would be nice!

I was wondering what the best way to go about this would be. I was thinking about the LLY just based off of a few things I have read. Any thoughts would be great.

My main questions are will the 6.6 Dmax/ Allison fit? What kind of wiring challenges will I face? And will my 10 bolt rear axle hold up to the torque of the engine?

I plan to start looking for a roll over truck or something of the sort that is a 2wd.

Thanks for any advice in advance, it will be appriciated.

Things to consider....

1- It's usually best to install a Duramax/Allison that is the same model year as your GMT-800 (2000's) truck/vehicle, which will allow nearly plug-n-play compatibility. Any wiring changes that may have occured in newer engine/trans systems might complicate a mixed-year installation, though nearly any year/model swap is possible with a persistant and knowledgeable person.

2- You'll have to install a body lift of 2-3 inches to gain the necessary transmission tunnel and hood clearance you'll need. Of course, a lift wouldn't be necessary if you're prepared to modify the trans tunnel and hood. ;)

3- The Duramax/Allison utilize their own unique wiring harnesses and computer modules. These will plug right into your existing underhood electrical center. Your existing engine/trans harnesses and modules won't be used.

4- You'll need the diesel hydraulic brake booster and master cylinder. These should be a direct swap for your existing brake parts.

5- A diesel pickup radiator support/partition will make it easier to swap in the diesel radiator, fan shroud and intercooler, etc.

6- You may need some sort of suspension boost in the front.

7- The 10-bolt rear diff can hold up for a while, but not if you add power, tow, race..... :)

Jim

For a rear axle I was thinking a 9.5 14bolt with 3.42 posi. I don't plan on towing anything too big. At most a bumper pull stock trailer with a horse or take a couple cows to the sale in style http://www.thedieselpageforums.com/t...cons/icon6.gif. I do plan to use it as my daily driver and a part time street machine. Is it possible to order one of those axles rebuilt and set up for my truck? If so what is a rough estimate of the price and where would you suggest I go for one of those?

As for the hood and tranny tunnel how do they fit the engine and tranny in the 1ton and 3/4 ton? I would rather not put a body lift on my 2 wheel drive so I can keep the low profile for areodynamic reasons..

The rear axle. You could buy one ready to go. It will have to be from a custom shop, as 3.42 isn't an OEM ratio for that axle. Probably about $2,000+. Or, source one from a wrecking yard and rebuild it with the gears you want. That will get you in the $800-1,200 neighborhood. If you have a donor truck for your conversion with a good 11.5"FF axle, you can trade it off, and just about wash the cost of your new axle. For DD, occasional tow, occasional drag truck, I suggest an air or electric locker for the rear. Open for street driving, and spooled for the track (or if you get stuck). The best of both worlds.

Duramax trucks accommodate the engine/tranny with an OEM 2" body lift. If you want low profile, you have to modify the tunnel, make room under the hood (including the hood), and align the cooling stack and fan shroud. However (contrary to many discussions, and unique to your use), you could omit the engine driven fan completely, and use electric fan(s). This would eliminate the need for alignment of an engine driven fan. And, would free up some forward space.

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Originally Posted by tanman_2006

For a rear axle I was thinking a 9.5 14bolt with 3.42 posi. I don't plan on towing anything too big. At most a bumper pull stock trailer with a horse or take a couple cows to the sale in style http://www.thedieselpageforums.com/t...cons/icon6.gif. I do plan to use it as my daily driver and a part time street machine. Is it possible to order one of those axles rebuilt and set up for my truck? If so what is a rough estimate of the price and where would you suggest I go for one of those?

As for the hood and tranny tunnel how do they fit the engine and tranny in the 1ton and 3/4 ton? I would rather not put a body lift on my 2 wheel drive so I can keep the low profile for areodynamic reasons..

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My truck came with a 10-bolt rear axle, but I swapped-in a custom GM 9.5" semi-floater in my 1/2-ton D/A conversion. This axle is equipped with 3.42 gears, an Eaton Posi and disc brakes. Aside from the discs, Randy's Ring & Pinion built the axle for me using new gears, bearings & seals. I had custom disc mount brackets fabricated, then installed OE GMT-800 1/2-ton rear disc brake parts (like what you have now on your 10-bolt). You can read more about the axle build here.

Like DmaxMaverick said, you'll likely have to modify the trans tunnel and hood to get a D/A installed without a body lift. ;)

Jim

Thank You, for the good advice so far. I think I will give rebuilding the rear axle a shot on my own, this should be interesting seeing how it is my first conversion and my first axle rebuild, but if all else fails my brother in-law is head mechanic at the local GM Dealer and my father in-law owns a local salvage yard so I am sure one of them can set me straight. :D

As for the tranny tunnel does any one know a place in Oklahoma that can do that for me? And would some form of hood scoop give me the clearance that I need :confused:?

Now as for the front suspension would it work to just shove a set of HD Bilstien Shocks in there with OEM 3/4ton Coils off of a 2wd D/A?

Many things just aren't that simple.

The "setup" of the R&P is critical, and you'll need at least some experienced eyes on it while it's done. Bigger power makes it all that much more important. No real big deal, but it must be done right. Eventually, it will be right, but that depends on how many unsuccessful attempts you can accept.

The tunnel isn't too involved. It will involving cutting, gapping, filling welding (and/or riveting/bolting). Essentially a "tub" job. Very common in the custom circles.

The front suspension isn't that simple. You'll do better to replace the entire control arm and hanger setup than try to mix/match parts. The front hubs will need to match the rear, or the rear will need axles to match the front (lug pattern). If you keep your front hubs, HD (higher capacity) springs can be had for your chassis. LD and HD parts aren't interchangeable. Bilstein shocks are an excellent addition, but will do nothing for weight capacity or geometry.

Well so far I am used to not getting things right a few times. I assume my drive shaft, u-joints, yokes and anything else that has to do with my drive shaft will need to be upgraded, would I be wrong and what will I need for that?

I am going to stick with a 6 lug set up in the front and convert the rear end. Will I be able to get the HD springs at a GM dealer?

I have no problem with cutting and welding sheet metal but I would rather it look good so I will check around to see if I can find someone that could do it right.

BTW I won't starting the build for about a year since I am still in school, but I am going to start good looking parts pile.

If you get custom A/C lines and a cowl induction hood it should work out for you. There is said to be a newer 1/2 ton SUBURBAN in ORLANDO FL that is a 2 wheel drive with no body lift and it all fits. He does have a cowl induction hood though. There is also a guy in APOPKA FL that has just done an 02 ESCALADE, but it is a 4X4. And before that he did an 03 2500 SUBURBAN. He said that the A/C lines was what hit the hood on the SUB or else he wouldn't have added a body lift. The guy doing the conversions is ERIC of DURABURB INC. He has no website yet though, but I believe a google search will find some reading about him. He's still trying to get all of the bugs worked out of his ESCALADE at the moment as he has found that the 1500's are ALOT harder to do than the 2500's.

I just read up on the Duraburban and I will try that first. I planned on a cowl hood any ways just because it looks cool :cool:.

As for the suspension upgrade I ran across a Firestone Leveling shock with a Bilstein Monoshock made for a 1500 HD,2500,3500. It is made to account for the addition of a snow plow, Will that work? Other than that I have found Spring blocks that are either 2-3in lifts but that does not change the fact that the springs will be over loaded.

The various steel cowl induction hoods I've seen have all of the steel framework on the underside just like the OE hood, which ultimately doesn't give you any more hood clearance - unless you modify the underside framework. I don't know about the aftermarket fiberglass hoods.

Jim

I was thinking about fiberglass hood and fenders for a slight weight reduction. If I went with steel, sawing the frame work out doesn't bother me at all.

I am in the process of finding a 9.5 14 bolt right now. What year of trucks can I find one on and what kind of brakes and hubs will they have?

Also I was wondering if there were any options for a shorter radiator, would the radiator out of an HD gasser work since I don't plan on heavy towing?

Any other options would be great. Thanks for the help.

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Originally Posted by tanman_2006

I am in the process of finding a 9.5 14 bolt right now. What year of trucks can I find one on and what kind of brakes and hubs will they have?

Also I was wondering if there were any options for a shorter radiator, would the radiator out of an HD gasser work since I don't plan on heavy towing?

Any other options would be great. Thanks for the help.

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For the 1999-2007 GMT-800 models, GM used the disc brake equipped 9.5" 14-bolt semi floater in their light-duty 3/4-ton gas powered trucks - though these have eight-lug axles.

If you want to use this axle as is, just bolt it up.... You might be able to install 8-lug front hubs as well, though I don't know the particulars.

Otherwise, you'll have to customize the rear axle to accept 6-lug axles - the axles themselves will slide right in, but the disc brake components will be different....

A smaller radiator might work in a non-towing truck, but you'd still need an intercooler to realize the power potential of the engine.

Jim

Thank You for the Info.

Will the brake lines hook up to the new brake components from the 9.5 Semi-Floater? I think I can get an axle complete with brakes if the brake lines will match.