Different size driveshafts

[CSDMAX]

Hey guys and girl(that would be you Diva),

After reading DMAXDiva's message about her new exhaust and checking out her new pics, one of the pics mentions "monster muffler - monster driveshaft". This reminded when, back in March, I was shopping for my new truck, I noticed that two different 2500HD Duramax GMC's had different driveshafts. (Yes, NutNbutGMC I was looking at GMC's....but Chevy stole my heart and pocketbook!) Anyway, one driveshaft was the same as what I have in my vehicle now and the other had a significantly larger circumference. Do any of you know why there would be a difference? I asked the salesman about it but he just gave me a dumb blank look....then looked underneath and said yeah your right...hmmmm. I don't recall if one was an automatic, the other a 6 speed.

[SoCalDMAX]

Well, the answer is:
(get your mind out of the gutter!)

GM originally designed/installed 2 piece driveshafts for these trucks due to the length, especially CC LBs. The execution left a lot to be desired, the carrier bearing has a huge rubber donut with (IMHO) too much slop, especially for something getting torqued like it does. It twists, whips the 2 shafts around and can cause a shudder.

So they came up with a one piece driveshaft to replace the 2 piecers that were causing shuddering on take off, especially on certain models. This very long shaft has to be a large dia. hollow aluminum shaft to take the load. Instead of tossing out the existing stock, GM continued to use 2 piecers until they ran out, then installed 1 piece shafts, but different assy lines ran out at different times, and some models are still built with 2 piece shafts.

They won't replace your 2 piece shaft unless you complain and you have the affected model.

Hope this helps. Steve (with a 2 piece) tongue.gif

[FRMLPLR]

Don
My work truck with the piston slapping 6.0 has the smaller version. Assume the larger is reserved for the Dmax setup. Did watch a 1500HD twist his off at the the rearend at one of our last tractor pulls!!! :rolleyes: Kids out to show off their fancy rides!! Didn't have enough sense to slide shaft out of transfer case, so it just slapped around under there as he limped to the pits!!!

Scott

[CSDMAX]

Thanks Steve,

What mind....what gutter? The only gutter I can think of is the one on Alli-Maxes machine. :D

I just did a search for old threads about driveshafts and came across the subject you just mentioned about the two piece driveshafts. I remember seeing two pieces but... At least I have the single driveshaft and NO vibration or shuddering.

FRMLPLR,

My DMAX has the smaller of the two driveshafts with a big doughnut behind the U-joints as compared to the huge driveshft I saw on one of the GMC's. It did appear to be brighter like aluminum or at something similar, and it did not have the doughnut. Maybe there is yet a third driveshaft style for those piston slapping 6.0's

[Idle_Chatter]

Well, in addition to the two-piece shafts, there are two different one-piece shafts. My late-build 2001 (Aug) has a *steel* one-piece. It's only about 5" in diameter and rusty brown. I was shocked at the size of the aluminum "torpedo" one-piece when I saw it for the first time under Nels truck. That thing's got to be 8" or more in diameter!

[CSDMAX]

Thanks for the confirmation Idle chatter. "Torpedo" is right! That thing was huge. It stood out like a sore thumb.
Anyone have any problems with this HUGE diameter driveshaft, other than those with the two piece jobers?

[Nels]

Tom got my curiosity up, so I went out and measured it (It's a guy thing -- Gals measure their chest, guys measure their shaft :D ). With the tape wrapped around the circumfrence, I got just over 18-1/4". That puts the diameter just under 6". My truck was built in March of 2001, just after the two piece shaft shudder problem came to a head. It was among the first to get the one piece aluminum shaft from the factory. The first comment from the service staff while prepping the truck was, "Look at that aluminum telephone pole!"

The diameter actually has more to do with resonant properties of a rotating mass of that specific length (and other engineering-type stuff) than it has to do with the torque of the Dmax. Also keep in mind that the body style of the truck will dictate differences in the length of the drive shaft. My truck is an extended cab 4WD long box with the Allison. 2WD would be a different length, short box would be a different length, crew cab owuld be a different length, etc. On some of these configurations, the two piece works just fine, and others always came with a one piece (possibly with a different diameter or of a different material). IIRC, most of the launch shudder issues were with 2 piece shafts on Ex cab long box and crew cab short box models with 4WD and Allison, which have similar length shafts. I believe these are now all being made with the big one piece shaft.

[DMAXDiva]

Nels:

I ain't touchin' THAT one with a 10 foot pole, or an 18-1/4 inch driveshaft for that matter!(but then again, I think Freud would have a field day with me over my fascination with really big, really powerful, really masculine trucks...hmmmm... :rolleyes: )

[csimo]

Yes there are two different one-piece driveshafts. My truck (2002 CC D/A) has the huge aluminum one piece shaft, but my nephew just picked up the identical truck as mine yesterday (color is different) and it has a one piece steel drive shaft.

The steel shaft is "normal" sized, much, much smaller than the aluminum one I have.

I guess GM finally gave up on the two piece design.

[JasonsSS]

I have a 2001 4x4 x-cab with the 6.0, and it also has the HUGE aluminum single piece driveshaft. I looked at some 02's at the dealership, and there were some of the 8.1's that had the smaller single piece steel driveshaft. There didn't seem to be any rhyme or reason as to which vehicle gets what size/material driveshaft.

Jason

[NutNbutGMC]

^..I have the big drive shaft and it works perfect. No complaints yet, after all these miles and smiles. :D
DMD... Freud?? What about me???? LMAO... :D

[ 07-15-2002: Message edited by: NutNbutGMC ]</p>

[DMAXDiva]

NutnButGMC:

What, me worry? You're only interested in dumb blondes... tongue.gif

[ 07-15-2002: Message edited by: DMAXDiva ]</p>

[GMC-2002-Dmax]

My truck has the one piece Torpedo aluminum driveshaft. The build date is 01/27/02 and is a CC short bed. No problems at all.

find out when I get "juiced" from the brown truck ( when it get's here !!!!)

GMC :D

[NutNbutGMC]

^...DMD... LMAO... You rock..... :D