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Rear driveshaft length after lift

4via4

Contributor
Newbie
Joined
Nov 10, 2011
Messages
46
I recently installed a WH 2.5" lift and upon installing the rear driveshaft, I found it to be too short. I ordered the 6 degree shims and installed them today. The driveshaft does mount up now, but it is extended all the way out and there is play where my finger is in the picture; you can move it up and down at the slip joint. The driveshaft is not the original and has a sticker from a company out of Kentucky. My question: is the driveshaft usable in its current state or do I need to order a new one? Thanks, Joe
 

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bronconut73

Bronco Guru
Joined
Aug 7, 2012
Messages
9,916
Usually you don't need a drive shaft for a 2.5" lift....
I ran my stock driveshaft with my 3.5" lift for years. It wasn't perfect but I don't recall it being as extended as yours,
In any event, there shouldn't be any play at the slip splines, so.......
 

75MIKE

Sr. Member
Joined
Aug 22, 2001
Messages
955
Loc.
NE Washington
I'm afraid with that minimal amount of engagement with the yoke and splines,It will wear quickly. It won't be long before it is doing the "jump rope thing" and it's probably doing that now. The drive line will have to be lengthen or a custom one built sooner than later for safety.
 

DirtDonk

Contributor
Bronco Guru
Joined
Nov 3, 2003
Messages
47,345
Any chance the front shaft is longer and fully compressed? Probably not, but wouldn't that be an easy fix!

I have to think it was too short to begin with, because like was said you don't need a longer shaft for 2.5, or even 3.5 inch lifts 99% of the time.
Looks like you just fell into that 1% though.

But measure the amount of lift you got as well, just to make sure you're not sizing this for springs sitting high. What you want to end up with is approximately 8.5" between the top of the rear axle and the bottom of the frame rail. Within half an inch or so.

But even if you had to get the springs to settle in first, that's still a lot of extension on the shaft. I would be curious how yours compares to others here. Anyone have measurements of their stock rear shaft in sections? For instance how long is the main upper tube.

Good luck.

Paul
 

stack

Jr. Member
Joined
Sep 29, 2017
Messages
85
Just call Duffs they will send you pdf on how to measure and build you a new one. I think it 280$
 

DirtDonk

Contributor
Bronco Guru
Joined
Nov 3, 2003
Messages
47,345
No matter who's measurements you use (you can find how we do it on the website) make sure the suspension is compressed to the expected ride height.
New springs might skew the readings if they're going to be settling out in the future.

Paul
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,833
I recently installed a WH 2.5" lift and upon installing the rear driveshaft, I found it to be too short. I ordered the 6 degree shims and installed them today. The driveshaft does mount up now, but it is extended all the way out and there is play where my finger is in the picture; you can move it up and down at the slip joint. The driveshaft is not the original and has a sticker from a company out of Kentucky. My question: is the driveshaft usable in its current state or do I need to order a new one? Thanks, Joe

That tells me that the slip joint is wore out.

I would drive it while a new one is being made.

Ideally you should have 3 lengths to send to the drive shaft shop. Compressed, ride, full droop. Ride and droop are easy. Compressed is harder. I will often cheat and measure the bump stop gap and measure to an imaginary point the same height above the yoke.
 

Pa PITT

Contributor
Bronco Guru
Joined
Jul 15, 2005
Messages
11,252
Loc.
Stephenville TEXAS
... AS Paul said check 1st & see if you can swap the front & rear shafts. We did that on Brother AL's ..
But I think our machine shop here in my town just sawed off the spline stub & drilled out the end of the tube & put in a longer stub . welded it in place , While checking for straightness . I believe he added about 2 inches to mine . After my Diesel swap.
...................
...Don't know it mine was done properly but I' live in a farm community, where thing are just fixed . But I'd sure not want that slop between the spline & the collar.
 

Steve83

Bronco Guru
Joined
Jul 16, 2003
Messages
8,980
Loc.
Memphis, TN, USA, Earth, Milky Way
Send the driveshaft manufacturer the distance between mounting surfaces at ride height, and let them create a d'shaft the correct length. Mine came from Tom Woods.
http://www.4xshaft.com/

But you should correct the pinion angle first, and the TSB in this caption explains how:


(phone app link)


I wouldn't drive that - one good bump, and it'll come apart on the road. Do you want to see a driveshaft coming up through the floor; or hear it beating the ground, frame, & gas tank as you roll to a stop?
 

bronkenn

Contributor
Bronco Guy
Joined
Apr 27, 2017
Messages
2,662
Loc.
Southeast Ohio
Send the driveshaft manufacturer the distance between mounting surfaces at ride height, and let them create a d'shaft the correct length. Mine came from Tom Woods.
http://www.4xshaft.com/

But you should correct the pinion angle first, and the TSB in this caption explains how:


(phone app link)


I wouldn't drive that - one good bump, and it'll come apart on the road. Do you want to see a driveshaft coming up through the floor; or hear it beating the ground, frame, & gas tank as you roll to a stop?

That is a very good diagram explaining the angles.
 

kaw550

Bronco Guru
Joined
Jul 4, 2007
Messages
1,133
I ran into a similar issue when I installed 2.5" springs a while back. I ended up getting custom shims made.

I am convinced the centering hole on the spring was off enough to change the distance and angle.
 
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