CANNOT keep a rear u-joint in this poor thing
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Elder User
Joined: Nov 2007
Posts: 534
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From: Northern Minnesota
CANNOT keep a rear u-joint in this poor thing
I just now finally put some time on my truck with the new 460, I annihilated the rear driveshaft u joint already, this joint has under a 50 miles on it? It was one of the better ones they sell at the auto parts store. My buddy has the same truck as me but with a built 400, he says he's on joint number 4 in the 6 months hes been running the built 400. I admit neither one of us have tried the "best" ones, but the ones we are running are greasable and are supposed to be a good quaility part. Any one have any expiriece with a problem like this?
My truck: 78, 460, f-150, 4x4, c6, 205, posi, no lift, 33's
Buddys: 78, 400, f-150, 4x4, c6, 205, detroit locker, 4" lift, 35's
My truck: 78, 460, f-150, 4x4, c6, 205, posi, no lift, 33's
Buddys: 78, 400, f-150, 4x4, c6, 205, detroit locker, 4" lift, 35's
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Elder User
Joined: Nov 2007
Posts: 534
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From: Northern Minnesota
hmm, I know nothing about checking pinion angles, they both look ok to me, both of us are pretty good about greasing everything, I know my slip joint has a tiny bit of slop in it but barley any, don't know about his. I'm running stock lift blocks, he's running 1'' blocks without the stock ones, I would'nt think either one of these combos would have alot of axle wrap, we both have fairly new shocks also, I would think that would help axle wrap...
Fleet Mechanic
Joined: Mar 2005
Posts: 1,603
Likes: 1
From: St Louis
The pinion angle is suppose to be no more than 3, or is it 7, degrees, which when you look at the axle the drive shaft and pinion almost look flat with the a very slight bend. Axle wrap comes from when torque is applied to the axle the pinion tries to climb the ring gear and twist the rear axle pinion angle upward. Weak rear springs can cause the pinion angle to change and a lift kit can cause the angle to change if the proper wedging is not installed to turn the pinion upward to flatten the driveshaft angle.
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Elder User
Joined: Nov 2007
Posts: 534
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From: Northern Minnesota
No racing, I'm standing on mine alot I guess. So to check the pinion angle should I use one of those magnetic welders tools with a needle in it that points out the angle? I think I could dig one up somewhere.
Lead Driver
Joined: Jun 2006
Posts: 5,675
Likes: 996
From: Near Yosemite CA
Well, they are both 150's, they have a softer spring rate, and add a lift block and a nice fat 460 
and you might have a bit of axle wrap, may not seem like much, but,,,
Find a parking lot, and 1 at a time, lay on the ground a few feet away, and watch each others trucks (rear axle and springs) when you launch, easy and hard and see how much the rear ends tip up, even an inch or 2 will snap u-joints in my experience.
Your shocks do nothing for axle wrap, they are there for just the up and down of the axle, you might think about a cheap set, or make your own ladder bars, or beef up the rear spring pack. My 77 has a 351Measly and 33's and its weak little butt (the engine) can make a little tip up in the rear end, so I can imagine with some actual power (a 460!)
you might have an issue.
and you might have a bit of axle wrap, may not seem like much, but,,,Find a parking lot, and 1 at a time, lay on the ground a few feet away, and watch each others trucks (rear axle and springs) when you launch, easy and hard and see how much the rear ends tip up, even an inch or 2 will snap u-joints in my experience.
Your shocks do nothing for axle wrap, they are there for just the up and down of the axle, you might think about a cheap set, or make your own ladder bars, or beef up the rear spring pack. My 77 has a 351Measly and 33's and its weak little butt (the engine) can make a little tip up in the rear end, so I can imagine with some actual power (a 460!)
you might have an issue.
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Elder User
Joined: Nov 2007
Posts: 534
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From: Northern Minnesota
We will do this and post back, I picked up a precision super strength u-joint today, that is what I'm going to put in there.
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More Turbo
Joined: Jun 2006
Posts: 601
Likes: 0
Axle wrap can be caused by many things, mostly worn parts. Check the leaf springs for broken leaves, check the spring bushings also. Make sure all of your u-bolts are tight. If all that is good, I'd look into getting some type of traction control. Personally I'm not a big fan of ladder bars because they tend to hang up on objects when wheeling. I run a single arm (3 point tractor hitch arm) mounted on top of the rear differential, with the other end attached to a crossmember on the frame. This controls the axle wrap where it originates, at the differential. This also provides better ground clearance than ladder bars, allows the axle to pivot and the arm is adjustable. The arm also only cost around $30 at a tractor supply. We run this system on our buggies with R1 tractor tires ranging from 50" to 66", with virtually no u-joint breakage.
Post Fiend
Joined: Jul 2006
Posts: 6,948
Likes: 44
Very true. I usually run then around 15 ft lbs. Most call for just this amount (14 to 17FT lbs). I use a little blue locktite.
Overtorque turns the bearing into a bushing, and failure is in the near future.
Pretty good call. Rep given!
Overtorque turns the bearing into a bushing, and failure is in the near future.
Pretty good call. Rep given!
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Elder User
Joined: Nov 2007
Posts: 534
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From: Northern Minnesota
78smurf is my buddy I was refering to. I took what was left of my old joint to our local axle/gearing guru and he believe that over tightening of the u bolts is to blame. It only took out the two caps that were on the u bolts the other two were like new. Glad I got that solved, thank you for all your help.
More Turbo
Joined: Apr 2007
Posts: 656
Likes: 5
From: Salisbury, PA
I was blowing them up every few hundred miles in my bronco for a while. It always happened on the slip shaft side. The bearings seemed to go in slightly easier than usual. I put a different end on the drive shaft and have not had a problem since. I guess it was just a little out of tolerance.
If it is always happening on the same part...driveshaft side or yoke side I would replace the parts associated with that.
If it is always happening on the same part...driveshaft side or yoke side I would replace the parts associated with that.
Fleet Mechanic
Joined: Mar 2004
Posts: 1,398
Likes: 17
From: Hesperia, CA
Flcracker9 is right; you don't need fancy ladder bars unless you are doing some serious off-roading. Just a simple traction bar to keep the rear end from twisting is sufficient for the street. I bought a cheap set from JCW for about $60.00 a few years ago and they stopped the hopping while backing a trailer, and eliminated losing u-joints. I have at least 50K on my last set of u-joints.
