Driveline Vibrations

[Whipped96]

I think I have thought and searched this do death so I'm just gonna ask.
Truck is an OBS extended cab short bed.
I have a Belltech 3/4 drop on my truck that consists of 3" coils in the front and shackles and hangers in the rear.
I have also installed the Belltech #4981 driveline alignment kit.
I am getting vibrations from the rear starting at about 30mph and progressivly get worse.
I have new U-joints and new tires that I have had rebalanced.

These are the items that are included in the kit.

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The carrier bearing is spaced as shown.

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The instructions state to install the shim with the thicker portion toward the front so that is the way I did BUT, the picture shows otherwise.

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I measured the pinion angle with an angle finder and it shows +3 coming out of the carrier bearing and +2 at the yoke on the rearend.
I think from what I have found is the pinion should be negative the same amount as the carrier bearing. Mine obviously is not.

Could I achieve this by moving the shim to have the thicker portion in the rear as the picture shows?
Should I rotate the carrier spacer so the carrier is only raised 1"?

 

[TylerZ281500]

what are your angles? check your rear pinion and ujoint for slop. over the counter u joints even though new can have alot of play in them. also are your front and rear sections in line with each other? carrier bearing spacers arent recommended in most cases because they put the two sections at different angles which may cause a vibration.

is your trans bshing or bearing wearing out? could just be the driveshaft in itself, unbalanced tires, pinion tons of stuff. i work in a drivline shop so theres tons of stuff to check for.

as for if moving the shim might help youd heave to check with your angle finder or just drive it and see what it does.

 

[Whipped96]

I measured the pinion angle with an angle finder and it shows +3 coming out of the carrier bearing and +2 at the yoke on the rearend.

U-joints and pinion have no slop.

Carrier bearing was inspected when I had the driveshaft out.

Trans bushing is new.

Tires are new and I have had them rebalanced.

 

[magimerlin]

Just for S&G's... Unbolt you driveshaft at the rear end and rotate it 180 degrees and bolt it back up. See if that changes anything!!


Sent from what use to be a great country.

 

[Whipped96]

Just for S&G's... Unbolt you driveshaft at the rear end and rotate it 180 degrees and bolt it back up. See if that changes anything!!


Sent from what use to be a great country.

Worth a shot!

 

[TylerZ281500]

was the drivehsaft marked at all as to which way goes where if it was balanced and straightened a certain way moving it 180 could throw it off entirely.

 

[magimerlin]

^^^^^ that's why I suggested to turn it 180 and see what happens... Had the same thought...


Sent from what use to be a great country.

 

[someotherguy]

Memory could be fuzzy but most likely the shaft is keyed at the slip yoke, preventing misalignment of the two pieces. Generally though driveshaft shops will mark them anyway as it's kind of their business to know that things like that are important, and they balance the shaft as an assembly.

The pinion angle shim position may be the issue, and honestly I can't recall because I'm usually doing a 4/6 or more; I thought with a 3/4 you weren't really in the situation where you needed the spacer kit you installed?

Richard

 

[TylerZ281500]

Memory could be fuzzy but most likely the shaft is keyed at the slip yoke, preventing misalignment of the two pieces. Generally though driveshaft shops will mark them anyway as it's kind of their business to know that things like that are important, and they balance the shaft as an assembly.

The pinion angle shim position may be the issue, and honestly I can't recall because I'm usually doing a 4/6 or more; I thought with a 3/4 you weren't really in the situation where you needed the spacer kit you installed?

Richard

i work in one of those places. you learn crazy like how a moog ujoint wont feel bad while its in the truck but your chasing balance from every degree while trying to balance it due to so much slop.

 

[someotherguy]

It's extremely misleading when the shaft is in the truck, especially if there's any tension at all on the driveline. I block the tires and kick the trans in neutral before checking; anything less is a waste of time.

Had kind of a surprise a few months back; wrecker got crashed and it split the driveshaft (dude that hit me bounced off the truck a few times while grinding down the side of it, ending in smacking the rear tires so hard it broke the U-bolts so the axle came right off the leaf springs, burying the tires in the bed corner) - driveshaft's rear yoke got all beat up on the pinion yoke dampner, crushing the ears around the joint's bearing caps. Had a driveshaft shop cut the yoke off and weld on a new one, install all 3 new joints, new carrier bearing, and balanced the assembly. Was fine for a little while then started vibrating again. New carrier bearing was toast (the rubber web had broken apart, not all of it, just most of it)...they replaced it and re-balanced for free, but couldn't offer any ideas on why it failed.

Richard