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Discussion Starter #1
Every time i get going around 65-70 mph the truck gets a wobble to it. It often gets bad enough to were the back seat starts shaking and vibrating, do you guys think that it could be that the tires out of balance? the truck also has a 4 inch lift and 35x12.50x18 tires on it. Any help would be apretiated.
 

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it is possible to be out of balance. have that done and let us know what happens.
 

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Discussion Starter #3
I was looking at the driveshaft and niticed that when the lift was put on the didnt drop the driveshafts at all. should have the carrier barrings been dropt at all?
 

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yes there should have been a carrier bearing drop done. now that i think about it, you probably have some serious binding going on in the driveshafts. it will continue to bind and possibly break if you dont get the driveline geometry right.
 

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Discussion Starter #7
ya i had the lift done and it started right away. i just got done from being under the truck and the carrier berring was never touched. would i just call the lift manufacture and see if i could get drop bracket?
 

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you need to talk to whoever did your lift. that carrier bearing drop bracket or set of shims should have some with the kit. hold them responsible.
 

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I have an 8" Rize lift & have exactly 2" of shims for the carrier bearing drop.
That seams to work perfect for my set up.
Rule of thumb - for every 1" of lift 1/4" of shim for carrier bearing drop.
 

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Discussion Starter #12
so i installed the shims and it still does it. iv tried every shim width and it still wobbles. i will never again lift a new truck! Anything else i should try before i take it to a shop?
 

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I have an 8" Rize lift & have exactly 2" of shims for the carrier bearing drop.
That seams to work perfect for my set up.
Rule of thumb - for every 1" of lift 1/4" of shim for carrier bearing drop.
I agree....I have a 6" and have about 1.5" of shims....no shimmy shake or rattles.
 

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Discussion Starter #14
im going to put the stock tires back on it and see if it does it then. i cant even drive the truck it gets so bad!
 

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try that, but if the driveshaft geometry isnt just right you are gonna have shimmy. you need to have your T-case angle match the rear pinion angle and the driveshaft has to be aligned properly too. the shaft may be out of balance too.
 

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Discussion Starter #16
should a lifted truck drive like a stock truck? how would i check the angles on the tcase and the drive shafts?
 

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should a lifted truck drive like a stock truck? how would i check the angles on the tcase and the drive shafts?
Yes, pretty much.
 

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A high speed vibration such as the one you are describing is not usually a driveline. I would check the front axle components first. Trac bar bolt, pitman arm etc. A dual steering stabilizer is a definite help if running a wider wheel and tire combination. If the driveline vibrates upon hard acceleration from a dead stop, the carrier bearing is to blame. shims will help this, but i have found that it also helps a great deal to angle the carrier bearing. shims will only drop it straight down. if you look at the side of the bearing, it needs to be perpendicular with the driveline, which will mean dropping the rear of the bearing more than the front in your case. hope that makes sense. another trick to to run less air pressure in your tires, some of these trucks come with 80psi in the rear tires stock. this creates a rigid support for all unsprung weight. we usually run about 40-45 psi. if you are still getting a vibration, pull the front driveshaft out, and drive without it. front shafts are more prone to vibrate at high speeds due to the shorter lengths and higher angles than the rear.
 

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Dude, go right to the lift shop....thats what i would do...Cause you dont wanna end up with them saying YOU messed something up. The sooner you get it back to the lift shop and let them handle it, the better.

Thats what i would do!
good luck. And post up some pics!
 

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Sorry to hear you're having a problem. Some do, some dont, it seems. I am also one of the unfortunate. 8" lift (6" rear to level) and I've got the takeoff shudder. I have a fully adjustable carrier drop, and have also tried different pinion angles. Nothing will get rid of the takeoff shudder. There was also a higher speed vibration around 20-25mph and again from 43-48mph. Messing with the angles, (google "magnetic angle finder" for the tool), I found that having the carrier ujoint at almost a straight pass-through with most of the harsh angle being taken up by the tcase got rid of the higher speed vibrations. This did not fix the take off shudder and also allows a vibration that can feel like an out of balance tire at around 45mph.

Bottom line, it's easily fixed with the right driveline. I'm switching out to a new two-piece, but with a double-cardan at the center/carrier joint. Others have reported that they have NO shudder or vibration with this setup. I should know in a week or two when I get the new part.

Just sharing my experience. It's possible that some Ford drivelines are just more prone to do it because of manufacturing differences. Lots of guys have major issue and can't get rid of it, and others just add a shim and they're all set. It should be as smooth as stock, in my opinion.

Check this thread out:
http://www.powerstroke.org/forum/general-6-4l-discussion/46283-drivelines-those-who-lifted.html
 
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