271 output Yoke strength... Upgrade?

stubz616

stubz616

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So I finally got around to putting the 271 out of an '03 Superduty into my truck after freshening up my trans last week, and also installed a detroit locker with a new flat pinion flange from yukon. So i found a driveshaft flange on Fort Wayne Clutch and Driveline's website that i believe i will be able to utilize all 8 threaded holes in the companion flange at the pinion because the new yukon flange has a 2.954 pilot.
So my question is, Is there a need to upgrade the output on the 271 to be able to do something similar or is a factory ford style driveshaft end (Utilizing 4 bolts) strong enough to deal with copious amounts of torque that these trucks are able to produce? If an upgrade is needed, where could i get a new output flange for the transfer case? The one on the T-case now has a 2.68" pilot with 8 Holes (Not threaded). Is there a better option for the driveshaft side that will work with this yoke besides going to just a bigger U Joint?

Also, while I'm asking some people that might know, what is a good option for a slip yoke thats incorporated in the driveshaft that will stand up to the abuse of a high horsepower truck?
 
I think you'll be fine with four bolts. Have you ever looked up the shear force needed to break grade 8 bolts? Four of them, extended out from the axis, and probably at least 1/2" right?

I don't have any experience with breaking them, and I'm sure shock loads are pretty high, but here's a chart for you:
Screen-Shot-2013-09-24-at-11.56.23-AM.png
 
You'll be running one or two piece rear drive shaft??

My truck originally had 47re, NP241DLD, D70U which had 2 piece steel rear drive shafts with stock 1410 joints.

I'm running NV4500, NP271D (Dodge), and D80 with one piece aluminum rear drive shaft with 1480 joints.

IMO slip yoke is where it's at for simplicity and still plenty strong.

My rear one piece drive shaft which consists of 2 1480 yoke ends, 2 1480 joints, 5"x.120" tube, and the slip yoke, that's it. Light, simple and works. 6 parts total.

If you stay with the fixed output and I'll assume you'll go with one piece rear drive shaft, you'll need at least 2 companion flanges (to bolt on the t-case & axle), 1 yoke end, 1 slip yoke end, slip sleeve for the slip yoke end, 2 joints and the tube. That's around 8 parts and I'd image it ain't gonna be light and will need to maintain/grease the slip yoke.

I know eliminating the slip yoke in the t-case may looks attractive but IMO it's something that really don't need to be concerned about on our trucks. It's more of a jeep thing only since their wheel base is super short so they do this to gain some more length to improve their drive shaft angle and it'll give them the option to remove the rear drive shaft if it should fail to drive home in FWD.

After the NP271D swap I drove my truck to my driveshaft guy in FWD to have the new rear drive shaft built. I used a Gatorade bottle which is prefect size to be cut down and taped to the rear output housing to keep the oil in.

My driveshaft guy said for pure strength for something like sled pulling, he recommended 2-piece steel rear driveshaft. FYI if you're going with 1480 joints, you can't really re-use any components off your original drive shaft because the tube size is too small and not standard. The 1480 joints is way more stronger than tube so it will fail way before the joint will.

Whatever route you choose to take, stay with Spicer!

By the way, NP271D made my old NP241DLD looks wimpy. Pure beef.
 
I've done silly things to my 271F behind my dodge, 1st gear locked 25 psi launches with 6 tires grabbing traction.

I like the fact that my transfercase is sealed when its not in the truck, slip yoke is simple, but when you dump the oil out on the driveway, its a pain.
 
I have a fixed output also on my NV271. I think the fixed output shafts are even bigger than the slip shafts.
 
It's 34 spline. My NP241DLD's slip yoke can almost go into NP271's slip yoke. It's that much bigger and highly doubt that it'll be a weak link.
 
Thanks for all the replies guys!

I ended up getting both flanges with four bolts and 1480 joints. Ordered some ford bolts to make life easier since I have the special swivel socket to install them that I barely ever get to use. Haha. Using those two flanges my driveshaft is only 48 3/4" C to C on the U joints. The driveshaft guy is gunna put a beefy slip setup in the driveshaft and said it should all total out to around $500-$550 with everything being brand new (all spicer parts) We'll see how it holds when I get it in there
 
I have a 271f in my 2.5 puller with the ford yoke, no problems, hopped it a couple times without a issue, I'm running a shortened 08 dodge 1480 2 piece rear shaft


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