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Discussion Starter #1
ok, this is gonna be long,,,

Situation/what happened: traveling with cruise control set at about 73mph, empty i heard a terrible noise start. i had enough time to turn radio down to determine the issue when all of a sudden a loud bang and i was powerless. pulling over and observed NO driveline anywhere to be found.(had to walk back about 100yrd and out in farm field to retrieve)

Lead Up: after installing a 4" four-link BDS suspension lift in the front and 2" taller blocks in the rear and about 3/8"(per instructions) spacer in the carrier bearing i had a slight vibration/shimmy under Moderate to Heavy acceleration. (also running 35"tires MT tires)

Followup: Battling with Ford we agreed to split the bill 50/50 since i had barely 5,000 miles since mod and only 30,000 on truck total. and it was a minor size lift. they had to replace the complete rear driveline and yoke. Now i do still have a slight vibration/shimmy under hard acceleration.

The BIG QUESTION: what is the cause of this?? about 1/2 people say its axle wrap, other 1/2 say it isn't.. pics to follow..
 

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Discussion Starter #2










 

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Discussion Starter #3
 

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Discussion Starter #5
ha, at least you saw the problem right away,, when its completely missing,, little harder to notice,,haha

maybe we need to start a support group,,,:hehe:
 

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Two piece drive shafts suck. I had the same problems tryed all kinds of stuff, bottom line lose the 2 piece and have a custom 1 piece no vibes pricless.
 

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Discussion Starter #7
pursued that idea pretty hard also,, but everyone says thats too long for a one piece. so does it have that double u-joint thing at one end?
thanks
 

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Your truck is the same as mine ccsb right? You should have no problem local shop did mine, just cut of the ends on my stock shaft welded them to a one piece shaft. High speed balanced done cost me like 300 bucks I think, best money spent. A lot of places I called told me the same thing it was to long, as long as its not a cclb that a different story. Not sure where you are but try any local big rig truck parts store that carry drive line parts etc. Thats who did mine.:thumb:
 

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Here few pics


 

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try a 1 inch shim in carrier, I have 6 inch block in rear and 1 inch shim and no vib at all. Shaft is straight.
 

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Discussion Starter #11
try a 1 inch shim in carrier, I have 6 inch block in rear and 1 inch shim and no vib at all. Shaft is straight.
so is the over all lift that you did to the rear then? Mine was 4" front and right close to 2" rear for a level look,,
 

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so is the over all lift that you did to the rear then? Mine was 4" front and right close to 2" rear for a level look,,
I removed the factory 2 inch and replaced with home made 6 inch
 

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Ouch! You're lucky it didn't beat the snot out of the rest of the truck when it came loose! The u-joint looks like it failed first, then beat it's way out of the caps before detaching itself from the truck.

Now what caused the u-joint to fail is the question. I would guess at improper driveline angles. If you blew out the driveshaft doing a burnout then I would say axle wrap, but seeing as it did it just cruising along I doubt that's the issue. I was trying to find an article on driveline angles but couldn't find it. Really though you don't want to much extreme angle on the driveline. It's just like your front 4 wheel drive u-joints. Turning sharp puts alot of strain on them. That's pretty much what having the wrong driveline angle does to the rear joints, only it's constant and it's only a matter of time before they fail.

Really I'm suprised Ford helped you out at all. Good for them. Seeing as it's lifted it's changed the stock driveline so how can they be responsible? And nothing against you, but it didn't wear out all at once. You can see from the u-joint that it's melted/worn down bad. This doesn't happen all at once. I'm sure it started wearing more and more, but with a lift/noisy tires/engine noise it was hard to notice till it blew out. Did you happen to hear any clunking noise before it blew out when going from drive to reverse, or vice versa? You'll usually hear this with extremly worn u-joints.

You might try more carrier bearing spacer to try and reduce driveline angle, especially if you still have a vibration.
 

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Discussion Starter #14
Ouch! You're lucky it didn't beat the snot out of the rest of the truck when it came loose! The u-joint looks like it failed first, then beat it's way out of the caps before detaching itself from the truck.

Now what caused the u-joint to fail is the question. I would guess at improper driveline angles. If you blew out the driveshaft doing a burnout then I would say axle wrap, but seeing as it did it just cruising along I doubt that's the issue. I was trying to find an article on driveline angles but couldn't find it. Really though you don't want to much extreme angle on the driveline. It's just like your front 4 wheel drive u-joints. Turning sharp puts alot of strain on them. That's pretty much what having the wrong driveline angle does to the rear joints, only it's constant and it's only a matter of time before they fail.

Really I'm suprised Ford helped you out at all. Good for them. Seeing as it's lifted it's changed the stock driveline so how can they be responsible? And nothing against you, but it didn't wear out all at once. You can see from the u-joint that it's melted/worn down bad. This doesn't happen all at once. I'm sure it started wearing more and more, but with a lift/noisy tires/engine noise it was hard to notice till it blew out. Did you happen to hear any clunking noise before it blew out when going from drive to reverse, or vice versa? You'll usually hear this with extremly worn u-joints.

You might try more carrier bearing spacer to try and reduce driveline angle, especially if you still have a vibration.
yeah i was shocked it didn't beat up truck also,, couldn't find a single scratch, especially with the dent that was creased into it(see pic). i was very fortunate that ford was willing to work with me at all also. but i was pursistant enough that it was in the shop less than a month prior and had a full inspection with no problems. and that there was only 30,000 total on truck with about 5,000 after lifting. ford and myself both agreed that it looked like the ujoints let go first. they also found a tsb that showed a vibration/shimmy issue under acceleration. all this added up is how i was able to get 'half' covered (still cost over $750 myself). the tech that worked on it is an avid 'crawler' builder with about 30yrs experience at dealership(great guy, who also helps me tune Glock pistols,,haha)

problem i am having now is: i know he is experienced and knows what he is talking about, but he thought i put rear blocks in backward. reversed them, then said they were right and put them back. shimmed the rear axle and now have something like 1/2 degree difference between ujoints. however i am still getting a bit of vibration/shimmy under hard acceleration. i am nervous that next time it wont be so gentle on the body work. what is your opinion of a one piece shaft? like i said before almost everyone says too long to do it. this is could be axle wrap that is causing vibration and then just let go when cruising? or think its the 'MT' tires?? (pro comp extremes)...

thanks for any and all help everyone,,,,
 

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Discussion Starter #15
anymore input is appreciated, thanks

bump....
 

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The vibration on hard acceleration could be from axle wrap. It goes away when driving normally? Usually with axle wrap though it will be just on initial take off, especially from a dead stop. Now if you had 10" of blocks under your rear springs, but with only a 2" difference it shouldn't be that crazy.

If your just cruising along and mash on it do you feel the vibration then?
 

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Discussion Starter #17
i will double check when i get home sunday, but i do believe the vibration is there, but ever so slight for a second. seems like just when the power hits hardest then tapers off i think??
 

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I can't believe Ford actually agreed to pay half. Good for you!
 

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Discussion Starter #19
i will double check when i get home sunday, but i do believe the vibration is there, but ever so slight for a second. seems like just when the power hits hardest then tapers off i think??
just checked it out and sure enough,,,as described^^

anyone think it could be tires??:dunno: really hate to throw money at it for new springs and not fix the problem,,,,
 

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If the issue is axle wrap then I would look at a good set of traction bars, not springs. This should pretty much eliminate axle wrap.

If the noise is only there under hard acceleration then it might be an axle wrap issue. Seems to me if it was tires or a drive line issue you would be hearing or feeling something under other conditions also.
 
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