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Driveshaft Options for lifted truck

fbane

fbane

Member
Joined
May 11, 2024
Member Number
7797
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9
Been racking my brain on how to approach my situation and thought maybe could get some advice from around here.

Currently have a 2007 Chevrolet 2500HD Classic 4x4 ECSB with the 6.0/4l80e/NP261HD combo and the truck has a ~6 inch lift under it. The problem I am running into is that the current driveshaft I have in the truck is too short by almost 3 inches and its currently 69 3/8 center to center of ujoints so a new driveshaft setup is necessary. Also this truck is running 4.10 gears with 35 inch tires and sees speeds regularly of up to 60-75mph as I do a lot of highway driving.

Now I've been doing a lot of research about this and it seems most driveshaft shops don't like to exceed a certain length with steel shafts so that generally leaves aluminum in play, but I've heard I would need to be probably close to a 5" diameter shaft to make up for the possibility of driveshaft whip.

So a couple options I had going around was..

Option 1: See if adding a double cardan could make up for the extra inches needed; but this adds a ton of extra weight to the back of the transfer case
Option 2: Get an aluminum shaft made; but this cost is probably going to be astronomical
Option 3: Install a 2 piece driveshaft; easy to do and plenty to find

I don't think option 1 is a great idea as I'd like to not destroy my transfer case if possible. Option 2 is viable but going to hurt the pocketbook (Canadians get ripped off).

Option 3 is very doable and while I don't do any extreme offroading I would like to have the option and not sure how good running a 2 piece offroad with the carrier bearing does and if there is any caveats about this setup someone should know. Or am I just overthinking this and the 2 piece with a carrier bearing will be fine offroad?
 
Unless the rear section is brutally short (steep angle), I'd stay with the 2-piece.

The one-piece has the caveat that if you lose/remove it, your tcase juice is leaving the building.
 
Let’s not forget Cadillac put 81” driveshafts in their cars during the late 70s yet 50 years later most shops shy away from it.
 
Call the shop you are going to deal with and ask them.

I've got a few regulars that order up steel shafts in the 70"-73" range. It will be a 4" tube, and they do get heavy.
 
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Steve300xcw said:
Call the shop you are going to deal with and ask them.

I've got a few regulars that order up steel shafts in the 70"-73" range. It will be a 4" tube, and they do get heavy.
Click to expand...
Is there a disadvantage to smaller od and thicker wall? Will it be heavier than the 4" thinner wall?
 
M92PV4U said:
Right, but those appear to be the same wall thickness.
Click to expand...

Play with this one a lil. It'll let you pick the driveline style, length, and whatever tube you want.

spicerparts.com

Spicer Critical Speed RPM Calculator

Calculate the optimal operating revolutions per minute of your driveshaft based on the style of the driveshaft and specific measurements with the Spicer Critical Speed RPM Calculator.
spicerparts.com spicerparts.com
 
Steve300xcw said:
Call the shop you are going to deal with and ask them.

I've got a few regulars that order up steel shafts in the 70"-73" range. It will be a 4" tube, and they do get heavy.
Click to expand...

Steve300xcw said:
Play with this one a lil. It'll let you pick the driveline style, length, and whatever tube you want.

spicerparts.com

Spicer Critical Speed RPM Calculator

Calculate the optimal operating revolutions per minute of your driveshaft based on the style of the driveshaft and specific measurements with the Spicer Critical Speed RPM Calculator.
spicerparts.com spicerparts.com
Click to expand...

So my thinking of running the 2 piece is mostly because I have it sitting on my shop floor and its only a bit of fabrication to make the bracket to bolt it too and it gives a better option for a driveshaft while I remedy the issue of the long one.

Using that spicer chart it doesn't say what material its made out of but I assume steel and if I was to choose a 4" diameter with a 0.83 @ 72 inches center to center, puts me at a 1/2 true critical speed of 2565 and my truck on the highway at speed is riding right around the 2100 RPM and according to that site it says if its close to increase the diameter or run a 2 piece setup. If I accelerate on the highway while doing 110km/h (68 mph) that will put me way over the critical speed rpm.

Now I'm not the driveshaft expert but it seems that for the length I want, a one piece will always be putting the driveshaft into the 1/2 critical range during cruise which from what I can tell is not what you want.
 
Yes that calculator is for steel. Its handy for when you are trying to see what you can get away with. Although I have no doubts that their numbers are on the reserved side of things, not that that is a bad thing... Also why you are finding most shops are pushing aluminum drivelines at around that length

If you already have the 2 piece driveline an its in decent shape...I'd run it, just because I'm cheap:laughing:
 
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Another vote for 2pc.

And if it's still fucked after you install it you've got more options for getting it right by doing shit like dropping the carrier bearing and whatnot.

total newb said:
Those were low rpm cars with turbo fast gear ratios. 2.41 with 30".
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In a time when normal people weren't pushing a 90mph cruise speed on the interstate light traffic conditions no less.
 
Well got around to working on this more. Its definitely a too short driveshaft and being out of balance. Had some quotes for a new shaft and will be over $1000 CAD so will be going the 2 piece route.

Just for reference my transfer case is 5.3 down with the driveshaft at 7.1 degrees with my pinion at 5.8 down. Which is an angle of 1.8 at the case and 1.3 at the axle which is well within the 3 degree realm usually asked for.

I have tried to look at see what stock angles are but can't really find much but debating if when I switch to a 2 piece if maybe going to 4 degrees at the transfer would be a better angle. I know I would have to get shims for the rear to match or maybe with the 2 piece it will be ok.
 
I reread your post but didn't see an answer to this. So yes it's too short. Does it currently vibrate with your lift height, speed, ratios, etc? If no...then I'd take whatever you have to a local reputable shop, have them go through and replace all the parts including the center bearing if it's a 2 piece, and extend it to the proper length. It works now so don't re-invent the wheel.

If it vibrates then I'd ask that reputable shop about what options you have and what they recommend.

I run a 1 piece CV on my Suburban with what is about 5"ish of lift. Shaft is super smooth. Now the old 205 slop/noise is another problem but that shaft is pretty long and steep for what it is and does not have any issues.

But with a slip yoke case your options maybe limited for an inexpensive CV solution so then maybe a 2 piece is more economical then getting the tcase to a fixed yoke.

Whatever the solution I doubt you are in an uber expensive aluminum solution.
 
How much does the angle change under load?

I know it's not something you can easily measure, but consider that the pinion lifts against soft springs (axle wrap) and most of the angle will be at the tcase. To counter that, angle the pinion lower.
 
if it was mine i would be calling a shop like Adams drive shaft and see what they recommend but I'd imaging having a longer shaft made is the ticket.
 
fbane said:
Well got around to working on this more. Its definitely a too short driveshaft and being out of balance. Had some quotes for a new shaft and will be over $1000 CAD so will be going the 2 piece route.

Just for reference my transfer case is 5.3 down with the driveshaft at 7.1 degrees with my pinion at 5.8 down. Which is an angle of 1.8 at the case and 1.3 at the axle which is well within the 3 degree realm usually asked for.

I have tried to look at see what stock angles are but can't really find much but debating if when I switch to a 2 piece if maybe going to 4 degrees at the transfer would be a better angle. I know I would have to get shims for the rear to match or maybe with the 2 piece it will be ok.
Click to expand...

I'm cheap and lazy. Bolt the 2 piece up, shim the carrier down a lil if it needs it and go for a hot lap. Some guys get away with a lot:laughing:
 
Skinny said:
I reread your post but didn't see an answer to this. So yes it's too short. Does it currently vibrate with your lift height, speed, ratios, etc? If no...then I'd take whatever you have to a local reputable shop, have them go through and replace all the parts including the center bearing if it's a 2 piece, and extend it to the proper length. It works now so don't re-invent the wheel.

If it vibrates then I'd ask that reputable shop about what options you have and what they recommend.

I run a 1 piece CV on my Suburban with what is about 5"ish of lift. Shaft is super smooth. Now the old 205 slop/noise is another problem but that shaft is pretty long and steep for what it is and does not have any issues.

But with a slip yoke case your options maybe limited for an inexpensive CV solution so then maybe a 2 piece is more economical then getting the tcase to a fixed yoke.

Whatever the solution I doubt you are in an uber expensive aluminum solution.
Click to expand...

I can't drive on the highway as it vibrates too much to a point where I don't want to risk it breaking stuff especially since its too short.

Aluminum 5" at the length I need was $1300 CAD

wvracer821 said:
if it was mine i would be calling a shop like Adams drive shaft and see what they recommend but I'd imaging having a longer shaft made is the ticket.
Click to expand...

McBastard79 said:
Call Tom Woods Drivelines or whatever they go by nowadays
Click to expand...

Not an option being Canadian

Steve300xcw said:
I'm cheap and lazy. Bolt the 2 piece up, shim the carrier down a lil if it needs it and go for a hot lap. Some guys get away with a lot:laughing:
Click to expand...

That is my plan just was thinking of angle of the transfer case and rear axle.
 
Well everything is money. If your expectations are a cheap solution that actually works you probably will never get a good solution.

Every truck I've built that wasn't just a simple small lift has ended up with $1500 usually if shaft work. Gotta pay to play if you want it to go down the road smooth.

I've also built trail trucks with receiver hitch tube or poop pipe but it's a different case there.

If someone quoted you that money I'd shop it around but it's probably where you will land if you want it done right. Sure someone may try to get you in at a cheaper price point but they may also give you thinner wall or smaller diameter tubing. Or cheap Chinese joints. It all costs money and there is a minimum price point to make it all work correctly.
 
Skinny said:
Well everything is money. If your expectations are a cheap solution that actually works you probably will never get a good solution.

Every truck I've built that wasn't just a simple small lift has ended up with $1500 usually if shaft work. Gotta pay to play if you want it to go down the road smooth.

I've also built trail trucks with receiver hitch tube or poop pipe but it's a different case there.

If someone quoted you that money I'd shop it around but it's probably where you will land if you want it done right. Sure someone may try to get you in at a cheaper price point but they may also give you thinner wall or smaller diameter tubing. Or cheap Chinese joints. It all costs money and there is a minimum price point to make it all work correctly.
Click to expand...

Oh I'm aware of all this, but if these trucks came with 2 piece driveshafts and I can install one and get rid of the vibrations then why not? Its only a few minutes to throw it in and ensure it all fits and angles are good then weld in a quick bracket to hold the carrier bearing.

I went against my own advice when I bought this truck but unfortunately during the time I didn't have many options and would have preferred a stock truck but alas here I am and now have to work it out.
 
Skinny said:
Well everything is money. If your expectations are a cheap solution that actually works you probably will never get a good solution.
Click to expand...
:shaking:

This is fundamentally a simple problem. He absolutely can create a very cheap solution that works at the cost of his time. Or he can spend half a grand or more paying someone else to build him something that just works.

Just because the former isn't an option you care capable of doesn't mean it's not an option for him
 
Head down to pick and pull and start measuring 1 and 2 piece drive shafts. I'll bet you find something that works needing a conversion joint at the most
 
Sure

Or you could waste a bunch of time taking a shaft out of a truck that's in a junkyard, weld a bunch of shit to make it work, fingers crossed it solves your problem or you could be chasing something else down that may never work.

Not sure what your time is worth but that sounds like a bunch of noise and resources to dump into a very large question mark.

Not that a trust what a "lift kit" manufacturer says but did you reach out to them to see what they recommend? I'm sure you are not the first person with this combination of truck and lift amount.
 
M92PV4U said:
Be careful though, those assholes bend and dent them with the forklift.
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I spent years looking for an Aerostar aluminum shaft for my ranger, i found a dozen in my efforts, every one was ruined.


Crying about a $1200 driveshaft? How much was the last set of tires you bought For your big gay brodozin highway cruiser? :flipoff2:
 
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