Shorten front drive shaft

[Bitch'nBronco]

After installing my long arms, I haven't used 4x4 much. After the last snow storm, I noticed what seems like the U Joints binding against the u joint housing (drive shaft side, not pinion yoke) during deceleration/ braking. I drove home the rest of the way in 2WD, but wanted to know if I can shorten the driveshaft by cutting 1/4'' off of the slip yoke spline without rebalancing, or if this is a dumb idea from the start. We're expecting more snow soon and I want to go play lol. My assumption is that the drive shaft is bottoming out on slip yoke travel when I'm on the brakes, causing the u joint to hit the u joint housing yoke. The driveline angle is a lot steeper on the front axle than it was when I had stock radius arms.

 

[DirtDonk]

Not sure I quite get what you're saying. If the joint cross is hitting the yoke, the angle is too severe for this style of joint and you will either have to grind off a bit of material from the yoke itself (where the two parts are touching), or change the angle to get more clearance.
Shortening the splines would not require any re-balancing that I can imagine, but it also would not cure this issue either, I would not think. Got pics of this interference to show us?

Non-stock arms usually add 4 degrees of caster. Pointing the pinion that much lower. If you also have offset C-bushings (using 7's by any chance?) and other caster compensators, then the shaft angle just keeps getting steeper and steeper until it's not manageable without other means.
So shortening the shaft does not initially sound like it's going to fix the issue.
If I'm reading you correctly.

Paul

 

[Yeller]

Pictures? Helps a ton.

 

[Bitch'nBronco]

Ill take some pictures tonight, I was thinking about it while I was at work. I appreciate the initial input

 

[Bitch'nBronco]

Yeah, now that I look at it closer it looks like the drive shaft yoke is maybe contacting the pinion yoke. I may shoot some black paint on it and drive around to see if the witness marks come back.

 

[DirtDonk]

You've now run head-on into the main dilemma facing lifted Broncos and trying to achieve even a reasonable caster angle with the normal methods.
As you've no doubt read here before, the ONLY way to correct caster without negatively impacting your driveshaft and u-joint angles is to "cut-n-turn" the steering yokes.
Or "inner-C's" as they are commonly called.

With your arms arms adding a hard incline, you would use offset C-bushings in reverse (to get the pinion pointed back up at the driveshaft) and then turn the yokes/knuckles to get the desired caster.

You can grind the joint interfaces for binding clearance all you want, but you will likely still have a vibration from the front shaft being out of u-joint alignment, At least at higher speeds.
You might not notice the vibration in 4-wheel low range crawling around at 2mph on a trail, but put the t-case in 4-wheel high range, or lock the hubs on the street, and it's most likely you will feel the vibration that is slowly killing your front u-joint.

Paul

 

[Yeller]

Paul is correct. Grind for some clearance and it will vibrate at speed in 4x4, it may or may not with just the hubs locked but it probably will. The vibration is a small price to pay for a nice driving bronco. Until you feel it is time to take the deep dive and do a cut and turn to correct the pinion angle and the caster angle.

 

[Oldtimer]

This is NOT the correct fix, BUT it might let you play in the snow, for now.

Super-Flex U-Joint for Front Driveshafts, 1310 Series

Check out the deal on Super-Flex U-Joint for Front Driveshafts, 1310 Series at WILD HORSES 4X4

www.wildhorses4x4.com

 

[Bitch'nBronco]

Thanks, makes sense. I guess I'll get the grinder out. Would you recommend I grind the pinion yoke? Doesn't look like i have much meat on the drivesgaft

 

[dmoses42]

How much lift do you have? Just curious, for my own knowledge as to where this problem arises.

 

[Yeller]

Yes ground the pinion yoke. There’s not enough meat on the driveshaft yoke to grind on it.

 

[Apogee]

This is NOT the correct fix, BUT it might let you play in the snow, for now.

View attachment 938179

http://[URL]https://www.wildhorses4x4.com/early-bronco-super-flex-front-driveshaft-u-joint

[/URL]

That's what I had to run on my '77 EB with CAGE long arms, which have 4.25° built-in caster, just to get my front driveshaft connected and spinning. I am currently in the process of converting over to a high-pinion D44, cutting and rotating the knuckles and wedges and setting my caster and pinion angle where I want them to actually fix the issue...it's a big job.

 

[73project]

Maybe my eyes are playing tricks on me from the pictures, but are the two driveshaft sections phased correctly at the slipyoke? It looks like they are not in the same position.

 

[Bitch'nBronco]

How much lift do you have? Just curious, for my own knowledge as to where this problem arises.

3.5" Deavers up front

 

[Bitch'nBronco]

Maybe my eyes are playing tricks on me from the pictures, but are the two driveshaft sections phased correctly at the slipyoke? It looks like they are not in the same position.

I can take another picture, I could easily have put it back in wrong when I did my clutch recently.

 

[Broncobowsher]

Just looking at that first picture, it looks like the CV is at it's limits, at ride height.
With the driveshaft disconnected at the pinion, jack the frame and let the front axle go to full droop.
Lower the driveshaft to the pinion, will it go that far without binding?
Now will it rotate a full 360° without binding at any point? There is a good chance you already mangled the CV.

 

[EPB72]

3.5 in lift trex arms, 2• bushings backwards and cut a turn 8-9 degrees ,,, caster 6-7 degrees ( using angle gauge ) but when running will check at work on alignment machine ,, getting close ,, pic shows pinion angle

 

[Bitch'nBronco]

Just looking at that first picture, it looks like the CV is at it's limits, at ride height.
With the driveshaft disconnected at the pinion, jack the frame and let the front axle go to full droop.
Lower the driveshaft to the pinion, will it go that far without binding?
Now will it rotate a full 360° without binding at any point? There is a good chance you already mangled the CV.

I'll try and do that tonight, thanks!

 

[bigmuddy]

That's what I had to run on my '77 EB with CAGE long arms, which have 4.25° built-in caster, just to get my front driveshaft connected and spinning. I am currently in the process of converting over to a high-pinion D44, cutting and rotating the knuckles and wedges and setting my caster and pinion angle where I want them to actually fix the issue...it's a big job.

Yep I have the same issue with a 2.5" suspension lift and Cage arms. The superflex u-joint is the best fix short term I could come up with years ago. I have used it quite a bit in the rocks and it was fine, but I don't do mud and snow so I can't say how longevity it would work in those applications.