Duramax with a 4L80E

cbarnett_2500

New member
Apr 23, 2015
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Your truck should also have a semi floating 14 bolt rear axle which is a little light duty for a duramax.

Yeah it does. It's still a strong axle though. The previous owner swapped the gears from 3.73 to a 4.10. It's a strong truck, for a gassy. Before my father installed his goosneck hitch, we used my truck for hauling a Kubota full size tractor with a front end loader and harrow. The goosneck was a 30 foot goosneck. The engine struggled going uphills, but other than that, it pulled fine. The only REAL problem was the exhaust. I was straight piped when I pulled it.
 

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
15,616
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Your truck should also have a semi floating 14 bolt rear axle which is a little light duty for a duramax.

I'd be really surprised if he could kill that rearend with a stockish Dmax. Unless he was towing stupid heavy or somehow able to launch it with a bunch of power.

Good God, I hope not. Thats what I had built for my half ton, Detroit, girdle and all.
 
Oct 16, 2008
948
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Idaho
Good God, I hope not. Thats what I had built for my half ton, Detroit, girdle and all.

If it were my ride I wouldn't worry Tom. I tend to post on the safer side than what I would actually run. I honestly don't see you having an issue with breakage beyond the norm.

Edit: To further clarify my previous post, I meant launching it with a pile of power and lots of weight might cause an issue on that 14 bolt.
 

Mikey

Drag Racer
Jun 13, 2009
560
3
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Like Mike said, the OD roller clutch is a known weak link on the 4L80E/4L85E transmissions. If you have a heavy foot and run it hard in the D position, you will probably break it eventually. What I do to help prevent this from happening is launch with the shifter in 3 instead of D. This brings on the OD overrun clutch which helps the OD roller hold and takes some of the load off of it. I have no idea who you are getting your trans from, but I bought mine from "the best in the business" when it comes to building the 4L80 and had nothing but problems out of it. I would recommend talking to Rossler if you aren't capable of building it yourself.

Should I drive MY 06 Duramax Van in 3 instead of D when Driving around town?
 

Big Chris

2 Duramaxes> 1 Duramax
Mar 30, 2010
361
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Rives Junction MI
I wasn't trying to say the 9.5 14 bolt is a ticking time bomb in this application but that it is less than ideal. I've owned trucks with them and they held up to a lot of weight and more weight then we should have been towing with a 3/4 ton truck just fine.

Also I keep forgetting the op doesn't want to modify the motor or hot rod the truck.
 

THEFERMANATOR

LEGALLY INSANE
Feb 16, 2009
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He was also under 5500K and smaller diffs.
He swapped in the 14 bolt semi floater 9.5" after he tore up the 10 bolt was what he wrote on his site. He i stil lrunning the 8.25" IFS in the front end. And I believe the weight on his truck is pretty close to 5500. The same truck as his with a 350 weighs close to 5000, so add in the extra weight of the DURAMAX/ALLISON combo, and he should be pretty close. I forget now what he posted it weighed. I know I asked him some questions about it a few years back after I did some damage to mine from a boosted launch.