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Sway Is My Fan Club.
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Discussion Starter #1
Welp, apparantly Brutus has a minor issue in the drivetrain. I broke another u-joint.

Last time was after my dyno pulls, about a week or so after the fact, with no notice, I pulled out on the highway with a massive vibration and the driveshaft fell out due to a busted joint.

This time it happened almost a week after the bad ass burnout and 3 passes at the dragstrip. This time it didn't leave me stranded. I had a vibration that increased with speed and stopped with letting off the throttle. Dad checked it last night while I was at school and yep, another busted u-joint.

Dad and JT think an angle or something is wrong somewhere to cause this to happen. Dad said it's the same size joint as what we run in the race car - and the Duster has way more HP and steeper rear end gears. But I don't see how it could be an angle problem because the entire thing is stock. The only thing not stock is the engine and some stuff in the C6.

So what do you think is causing this? Both times it happened after driving it really hard. On the dyno it was a slow speed increase up to about 130mph. The second time, I was launching it pretty hard, but really not much harder than when I get on it sometimes. So I dunno. :shrug

Oh and this is not a greased issue, I keep them greased.

Oh and here's a pic. :toothless
 

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FSB warrior
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I would say probably 75% that its an angle problem, I would think power would be a problem with just straight snapping them, not wearing them down like they are 15 years old. Is your DS balanced?? The rear end pinion is supposed to be pointed at the same degree that the T case is pointed, I think I remember that from a 14 bolt thread. I hear one of those magnetic angle finders is only like 20 bucks, but may want to let a few more peeps chime in.

BTW the Blazer I just bought burns them up pretty quick too, the P.O. thought it was because of the insanely hard shifts the tranny does.
 

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Which trunions broke? The ones on the drive shaft or the ones on the pinion yoke?

Guess #1...The yoke on the end of your drive shaft could be slightly ovaled

Guess #2...Your pinion yoke is deformed

Guess # 3...since all is stock but the motor and tranny...you might be getting axle wrap on harder then "normal" starts and binding the drive line at the pinion.

Be sure to get a new set of U bolt for you pinion yoke. If you've been having these issues they have more then likey been over stressed.
 

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Lick my balls
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I'm gonna take a wild guess and say it is because of this :toothless
 

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dogonmut said:
Which trunions broke? The ones on the drive shaft or the ones on the pinion yoke?

Guess #1...The yoke on the end of your drive shaft could be slightly ovaled

Guess #2...Your pinion yoke is deformed

Guess # 3...since all is stock but the motor and tranny...you might be getting axle wrap on harder then "normal" starts and binding the drive line at the pinion.

Be sure to get a new set of U bolt for you pinion yoke. If you've been having these issues they have more then likey been over stressed.
Very good guesses IMHO. Guesses #2 and #3 have caused me more driveshaft u-joint failures than any other cause...#3 VERY recently when I let some drunken idiot drive my rock crawler - was only supposed to be a few hundred yards to the next house - and he mashed the skinny pdeal on dry pavement.



Both can be hard to spot because #2 can be very subtle and #3 you cannot see happen unless you happen to own a 2000 fps FastAction portable movie camera.
 

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Sway Is My Fan Club.
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Discussion Starter #6
81Bronk36 said:
Is your DS balanced?? The rear end pinion is supposed to be pointed at the same degree that the T case is pointed, I think I remember that from a 14 bolt thread.
Yes, the driveshaft is balanced. The only thing I forgot to mention is the fact I swapped from a NP203 to NP205, but if I remember right, the first time it happened was with the 203, and this time was with the 205.

I think dad has all that stuff to set the angle right, he did all the work to narrow the rear end in the Duster and reset the leaf spring perches on it.


dogonmut said:
Which trunions broke? The ones on the drive shaft or the ones on the pinion yoke?
The pinion yoke side. He said the first time was the same way.
dogonmut said:
Guess #1...The yoke on the end of your drive shaft could be slightly ovaled
Guess #2...Your pinion yoke is deformed
How do I find out if this is it?
dogonmut said:
Guess # 3...since all is stock but the motor and tranny...you might be getting axle wrap on harder then "normal" starts and binding the drive line at the pinion.
Yeah, could be...but I dunno, doesn't feel like it launches all that hard to me, but I'm used to driving the race car, too. It's only got 3.55s in the rear.
dogonmut said:
Be sure to get a new set of U bolt for you pinion yoke. If you've been having these issues they have more then likey been over stressed.
Ok, I'll do that Scott, thanks for your reply. :thumbup


waltman said:
I'm gonna take a wild guess and say it is because of this
I keep comparing it to the race car and I don't think that one burnout could have fubar'd it that fast. Not if we're running the same u-joints with more torque in the race car and haven't broken one in it yet.


Guess it's a good thing I don't have a 4-speed or I really would be breakin' some shit. :toothless It's only makin' like 330 ft lbs of torque.
 

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-How do you tell if they are deformed?

Unless it's clearly bent it's hard to tell. If there is any slop or a feeling of "looseness" or it feels like it can rock a little and it can be felt by your hand when you hold the U joint in the pinion yoke then it's deformed.

If I were you I'd go to a 1350 pinion yoke and run a combo U joint to adapt it to your drive shaft or go big with a 1410 yoke and get your drive shaft reworked to accept a 1410 as well.

Even if you do either one of those...which you "should" do...I'd be willing to bet you have axle wrap issues that should be addressed.

Just because your Bronco doesn't "jump" out of the hole like a light weight race car it still has tons...litterally...of weight all pushing back onto your rear axle. All that weight is being transfered threw your (i'm assuming) 15+ year old stock springs with old rubber bushings.

The first thing I'd address is the pinion yoke. Then keep your right foot dipped in feathers instead of led until you can address the rear suspension. For that you might want to consider new leaf packs or first try installing new bushings and maybe even new hardware. Don't forget to relpace the bushings in the shackles as well.

If you don't want to go the "replace the springs" rout, you might want to consider an anti-wrap bar but by all means replace the bushings before you install one.
 

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How are the rear springs??Definately sounds like your having axle wrap issues.But have your driveline angles squared away first.Also check to make sure the pinion is tight.Rinnin anything other than the factory spacer block?The bigger the block the easier it is for wrap up.
 

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Sway Is My Fan Club.
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Discussion Starter #9
dogonmut said:
Unless it's clearly bent it's hard to tell. If there is any slop or a feeling of "looseness" or it feels like it can rock a little and it can be felt by your hand when you hold the U joint in the pinion yoke then it's deformed.
I've had what I suspected to be a mild slop in the driveline for awhile. It was giving a pretty good clunk in the rear end when shiftd into reverse.
dogonmut said:
If I were you I'd go to a 1350 pinion yoke and run a combo U joint to adapt it to your drive shaft or go big with a 1410 yoke and get your drive shaft reworked to accept a 1410 as well.
Where can I read more on this? I had considered going to bigger joints one day - even before I'd had this breakin' joint problem.
dogonmut said:
Even if you do either one of those...which you "should" do...I'd be willing to bet you have axle wrap issues that should be addressed.
I wouldn't be surprised now after reading this post and thinking about it, if it is indeed axle wrap. Maybe time to research ladder bars as well?
dogonmut said:
Just because your Bronco doesn't "jump" out of the hole like a light weight race car it still has tons...litterally...of weight all pushing back onto your rear axle. All that weight is being transfered threw your (i'm assuming) 15+ year old stock springs with old rubber bushings.
Yup, hadn't considered the weight issue. There's a good 2,000 pound difference between the Duster and the Bronco...and the Duster has stiffer springs and slider links, compared to as you said, old leafs and bushings in the Bko. Guess I need to remember to consider these things before comparing the two.
dogonmut said:
The first thing I'd address is the pinion yoke. Then keep your right foot dipped in feathers instead of led until you can address the rear suspension. For that you might want to consider new leaf packs or first try installing new bushings and maybe even new hardware. Don't forget to relpace the bushings in the shackles as well.
I really try to stay outta the skinny pedal...but I'm not always successful, I've got a competitive streak. The the new leaf packs, and bushings sounds like something that will get done when I get the lift. I'll do it all at once, as the front end needs tightening up as well.
dogonmut said:
If you don't want to go the "replace the springs" rout, you might want to consider an anti-wrap bar but by all means replace the bushings before you install one.
Wow, thanks for the great post. :)


Billz4x4z said:
Rinnin anything other than the factory spacer block?The bigger the block the easier it is for wrap up.
Nah, it's all factory.
 

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BroncoBabe said:
I've had what I suspected to be a mild slop in the driveline for awhile. It was giving a pretty good clunk in the rear end when shiftd into reverse.
That could have been after it started having missing metal in there.
 

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Sway Is My Fan Club.
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Discussion Starter #11
81Bronk36 said:
That could have been after it started having missing metal in there.
Nah, it's had driveline slop for awhile. Even before my u-joint issue. But it did clunk harder than normal a couple days after my passes at the dragstrip.
 

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green ones make me horny
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it still sounds like pinion angle is bad. or possibly a transmission mount or something could be bad cause it undo stress as well. worth a look

ken
 

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you are overtightening the u bolts on the yoke and crushing the cap, then the needle bearings bust up quick, then once there gone it starts hammering away like a loose rod bearing.
 

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BurnedB said:
you are overtightening the u bolts on the yoke and crushing the cap, then the needle bearings bust up quick, then once there gone it starts hammering away like a loose rod bearing.
Very true. All the above are possible, but this is simple...what are you torquing your U bolts to? I don't believe you need any 1410 yoke to fix this. Your springs, axle wrap, proper U bolt torque...what U joint brand are you using?
 

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Lick my balls
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BurnedB said:
you are overtightening the u bolts on the yoke and crushing the cap, then the needle bearings bust up quick, then once there gone it starts hammering away like a loose rod bearing.
I highly doubt the cap, which if I'm not mistaken is case hardened, would warp like that. More likely the u bolts would break long before that would ever happen.
 

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Babe, while you have this joint out do yourself a favor.

Beg, buy, or borrow a quality measuring instrument and measure how ovaled the yoke is.

A set of dial calipers is usually good for 0.001" and should be all the precision you need there.
 

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waltman said:
I highly doubt the cap, which if I'm not mistaken is case hardened, would warp like that. More likely the u bolts would break long before that would ever happen.
I have broken may U joints free from their U bolts and then found the caps feet away in perfect shape.

BurnedB said:
you are overtightening the u bolts on the yoke and crushing the cap, then the needle bearings bust up quick, then once there gone it starts hammering away like a loose rod bearing.
I doubt you'd be able to over torque the U bolts with a boxed end wrench unless you used a 5 foot cheater bar.

I've never put a torque wrench on a pinion U bolt. I don't have one small enough to fit in that little space. If you do, I'd like to see a picture of it.
 

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Quote:
Originally Posted by dogonmut
If I were you I'd go to a 1350 pinion yoke and run a combo U joint to adapt it to your drive shaft or go big with a 1410 yoke and get your drive shaft reworked to accept a 1410 as well.

*Where can I read more on this? I had considered going to bigger joints one day - even before I'd had this breakin' joint problem.
----------------------------------------------------------------

Call the guy's at Randy's ring and pinion for a larger pinion yoke and any drive line shop will have combo U joints.

If you go to a 1410 U joint you'll need to replace both the pinion yoke and the slip yoke on your drive shaft. The slip yoke would be available at a drive line shop as well.

I don't really feel you "need" to go the 1410 rout unless you really want to. Correcting the other issues should hopfully solve your problems.

Here's a pic of my front drive shaft. The yokes on it are 1350. The yoke on the front ouput shaft of the T case is 1330. I used a combo U joint (1330/1350) on the T case side. You can (kind of) see the size difference of the caps on each side...if you squint a little. I'm sorry I don't have a pic of a combo U joint by itself.


FYI-1300 series U joints have the same size trunions. The major difference is the size of the cap size but that makes all the difference in strength.

FYI 2-In general a U joint with a smaller cap has the abaility to work at a greater angularity especially when used in a double cardan.

FYI 3-To my knowledge, there are no series difference combo U joints. As in there are no 1350/1410 combo U joints.

FYI 4-Neapco brand U joint are in general to most common brand U joints out there. They are a good brand. Neapco and Spicer are the best 2 brands in the drive line U joint world.
 

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shibby
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Hmm, looks like there was either a lack of lubrication or the needle bearings couldn't roll properly.

Here's mine from a few years back, no grease and needle bearings gone.



Compare your pic to mine.



Wore right through the CV head-

 
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