Drive Shafts - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Mattman2010 · 01-03-2011, 02:41 PM

Here is the deal, I just converted my 2wd Crew Cab Dually to a 4x4 Single Rear wheel. I need to get a drive shaft shortened or lengthened to make me around an 88 inch rear drive shaft. Here is my delima, I have a k20 drive shaft with a slip yoke that fits into the rear of my transfer case, it is 59 inches long, and then I have a two piece drive shaft with the carrier bearing that is 38 inches from the end of the transmission to the carrier bearing, and 65 inches from the carrier bearing to the rear axle.

Which drive shaft would be better to shorten or lengthen? Would the k20 drive shaft be to long at 88 inches? Or is it worth shortening the front drive shaft of the two peice to 21 inches and put the slip yoke on the end of it?

The k20 has the 32 spline slip yoke and the correct size U-Joint to fit to the rear axle (The rear axle came out of a k20 as well) I am sure I would have to get conversion U-Joins for the two piece to get it to mount up to the slip yoke.

So what do you think would be better? To run a long drive shaft, or to run the two peice? I know the shorter it is the stronger it will be, but I dont think that the longer one would be to bad.

Thanks, Matt

KQQL IT · 01-03-2011, 02:57 PM

Im pretty sure 88'' would be to long, unless it was 4'' diameter or more. Go two piece. Shorter is usually cheaper that a re-tube for lomger.

swb85 · 01-03-2011, 03:00 PM

You cannot lengthen a drive shaft, only shorten or have a new shaft made. I would run a 2pc drive shaft with carrier bearing. Once they start getting long like that they become harder to balance and they'll wobble......and that's a situation you want to avoid.

Mattman2010 · 01-03-2011, 03:33 PM

Pretty sure I know some people that have had their drive shafts lengthened. I think I will probably go with the two piece, as it will probably work best to use a shorter one for pulling stuff.

swb85 · 01-03-2011, 05:18 PM

Quote:

Originally Posted by Mattman2010

Pretty sure I know some people that have had their drive shafts lengthened. I think I will probably go with the two piece, as it will probably work best to use a shorter one for pulling stuff.

You can't lengthen (add some tubing to make it longer) a drive shaft, but you can re-tube it (cut off weld yokes and weld to new tube) to make it longer, but that's basically building a new driveshaft. Technicality.

355GoldieGM · 01-04-2011, 11:57 PM

id go with the two piece drive shaft as i had mine rebuilt longer for a moncie trany and at just over 6 feet i had to hunt down a bigger drive shaft balancing machine, and it was harder to balance down to 0
88 inches justs seems like alot, but if you do decide to go that route, id advise to go for thicker and bigger diameter tubing.

01-03-2011, 02:41 PM	#1
Mattman2010 Registered User Join Date: Jun 2010 Location: Pittsburg, KS Posts: 953	Drive Shafts Here is the deal, I just converted my 2wd Crew Cab Dually to a 4x4 Single Rear wheel. I need to get a drive shaft shortened or lengthened to make me around an 88 inch rear drive shaft. Here is my delima, I have a k20 drive shaft with a slip yoke that fits into the rear of my transfer case, it is 59 inches long, and then I have a two piece drive shaft with the carrier bearing that is 38 inches from the end of the transmission to the carrier bearing, and 65 inches from the carrier bearing to the rear axle. Which drive shaft would be better to shorten or lengthen? Would the k20 drive shaft be to long at 88 inches? Or is it worth shortening the front drive shaft of the two peice to 21 inches and put the slip yoke on the end of it? The k20 has the 32 spline slip yoke and the correct size U-Joint to fit to the rear axle (The rear axle came out of a k20 as well) I am sure I would have to get conversion U-Joins for the two piece to get it to mount up to the slip yoke. So what do you think would be better? To run a long drive shaft, or to run the two peice? I know the shorter it is the stronger it will be, but I dont think that the longer one would be to bad. Thanks, Matt __________________ 1980 K10 - 6.2L Diesel/SM465/NP205 Build Thread 1984 K30 CC Dually - "The Tank" 12V Cummins/Nv4500/Np205/D60/D70HD 4" lift & 37's Build Thread 1960 C-60 Dump Truck Make it road worthy! Thread

01-03-2011, 02:57 PM	#2
KQQL IT At the body shop. Join Date: Aug 2009 Location: Land of fruits and nuts. Posts: 5,200	Re: Drive Shafts Im pretty sure 88'' would be to long, unless it was 4'' diameter or more. Go two piece. Shorter is usually cheaper that a re-tube for lomger. Last edited by KQQL IT; 01-03-2011 at 02:58 PM.

01-03-2011, 03:00 PM	#3
swb85 On a budget like Fred Sanford Join Date: Oct 2005 Location: Topeka, KS Posts: 2,031	Re: Drive Shafts You cannot lengthen a drive shaft, only shorten or have a new shaft made. I would run a 2pc drive shaft with carrier bearing. Once they start getting long like that they become harder to balance and they'll wobble......and that's a situation you want to avoid. __________________ '85 Silverado swb: 383 stroker, 10.5:1, vortec heads, 232/238 roller cam, RPM air gap, performer 750 carb, stainless longtubes, 3" duals/super 44's, T56/4.11 383ci build / exterior refresh thread '98 Camaro z28: 370ci twin turbo 370ci build '01 Tahoe LT 4x4: 5.3, longtubes/ory, magnaflow duals, custom tune....wife's DD Last edited by swb85; 01-03-2011 at 03:00 PM.

01-03-2011, 03:33 PM	#4
Mattman2010 Registered User Join Date: Jun 2010 Location: Pittsburg, KS Posts: 953	Re: Drive Shafts Pretty sure I know some people that have had their drive shafts lengthened. I think I will probably go with the two piece, as it will probably work best to use a shorter one for pulling stuff. __________________ 1980 K10 - 6.2L Diesel/SM465/NP205 Build Thread 1984 K30 CC Dually - "The Tank" 12V Cummins/Nv4500/Np205/D60/D70HD 4" lift & 37's Build Thread 1960 C-60 Dump Truck Make it road worthy! Thread

01-04-2011, 11:57 PM	#6
355GoldieGM Registered User Join Date: Dec 2010 Location: Estrie Quebec Posts: 59	Re: Drive Shafts id go with the two piece drive shaft as i had mine rebuilt longer for a moncie trany and at just over 6 feet i had to hunt down a bigger drive shaft balancing machine, and it was harder to balance down to 0 88 inches justs seems like alot, but if you do decide to go that route, id advise to go for thicker and bigger diameter tubing. __________________ BAM BAM My Project: http://67-72chevytrucks.com/vboard/s...ghlight=goldie



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