Burning Through U-joints
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Senior User
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Burning Through U-joints
I have a '99 F-250 7.3L PSD with an 8" superlift suspension lift. The front is different springs but the rear is just lift blocks. I am going through one u-joint about every 6 months (it's the back u-joint on the driveshaft that connects to the rear axle. I know its from the steep driveshaft angle with the lift but I'm wondering what my options are to eliminate this. I've thought about trying to find someone to cut off the leaf mounts & rotate the axle up a little but I'm kinda nervous about doing that. I have also heard about angled spacer blocks which I don't know if it would be a good idea to throw more blocks in there, & also was told to use traction bars. Just curious if anybody else out there has high lifted trucks & what they ended up doing. Thanks :0)
Fleet Mechanic
Joined: Nov 2003
Posts: 1,372
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From: West Cornwall, CT
The driveshaft angles need to be matched so that they are the same at each joint. This will never be exact, but the closer the better.
You probably have a 2 piece rear driveshaft - the one with a bearing in the middle. I'd try lowering the middle bearing a bit and replacing the rear lift blocks with some that are properly tapered. If you have a single piece drive shaft, just the rear lift blocks need to be changed.
Modifying the leaf mounts is not needed. Proper angles can be achieved by using angled lift blocks. Your rear u-joints should not need replacing every 6 months! I'll bet that you feel drive-away shudder when accelerating from a stop - that's a warning sign for improperly matched angles.
Lou Braun
You probably have a 2 piece rear driveshaft - the one with a bearing in the middle. I'd try lowering the middle bearing a bit and replacing the rear lift blocks with some that are properly tapered. If you have a single piece drive shaft, just the rear lift blocks need to be changed.
Modifying the leaf mounts is not needed. Proper angles can be achieved by using angled lift blocks. Your rear u-joints should not need replacing every 6 months! I'll bet that you feel drive-away shudder when accelerating from a stop - that's a warning sign for improperly matched angles.
Lou Braun
Elder User
Joined: Feb 2006
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From: Eastern Ohio
What brand of u-joint?
My wheeling truck had the same factory u-joint for 23 years. 6 of them as a dedicated offroad truck. Drive line angles suck, t-case gears are 3 times lower then stock and the tires 10" taller then stock.
I finally had to change the u-joint because it was dry, non greasable and squeaking badly. From that point on they last, on average 2 days. After about ten of them I pulled an old factory joint out of a spare shaft. That was 2 years ago and it's still in there.
My wheeling truck had the same factory u-joint for 23 years. 6 of them as a dedicated offroad truck. Drive line angles suck, t-case gears are 3 times lower then stock and the tires 10" taller then stock.
I finally had to change the u-joint because it was dry, non greasable and squeaking badly. From that point on they last, on average 2 days. After about ten of them I pulled an old factory joint out of a spare shaft. That was 2 years ago and it's still in there.
Elder User
Joined: Feb 2006
Posts: 765
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From: Eastern Ohio
Oh wow, I missed that somehow. I'll second that.
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So would I be able to solve my problem with a good set of traction bars? & r they adjustable snuff to give me the relief I need in my driveshaft angle?
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Brett Foote
Fleet Owner
Joined: Apr 2012
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From: Spanaway
For starters skip the traction bars for now and get a set of springs that get you where you want to be.
Just get rid of the big blocks. Next look at blocks that have the right taper to get the pinion
angle set right then go for the traction bars if you still need/want them.
Some where I posted a link on how to set the pinion angle if you google it you should find some info.
Sean
Just get rid of the big blocks. Next look at blocks that have the right taper to get the pinion
angle set right then go for the traction bars if you still need/want them.
Some where I posted a link on how to set the pinion angle if you google it you should find some info.
Sean
i ain't rite
Joined: Mar 2005
Posts: 65,573
Likes: 5,609
From: Marlboro Mental Hospital.
universal joint angle should be under 30 degrees maximum. the lower the angle the longer the joint will last. i bet if you put a gauge on your universal, it will be somewhere in the 40 degree range.
get rid of the lift blocks and put a set of lift springs in. then put a degree shim in between the springs and axle to get the joint angle down. a good set of springs usually will come with the proper shim already on the bottom to compensate for angle.
get rid of the lift blocks and put a set of lift springs in. then put a degree shim in between the springs and axle to get the joint angle down. a good set of springs usually will come with the proper shim already on the bottom to compensate for angle.
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