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Funny vibration/noise after eliminating transfer case drop

clandr1

clandr1

1/2 ton status
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Ok, so I replaced my worn out transmission mount and the PO had done the transfer case drop using the factory spacers placed between the crossmember and frame. When I reinstalled the cross member I put the spacers back on the bottom of the crossmember where they belong.

Now, when I let off the gas and coast there is a sort of grinding or rubbing noise coming from underneath the truck that wasn't there before. Any idea what it could be?

All u joints have been replaced and I only have a 2.5" lift on it. I'm not sure if eliminating that extra inch of drop caused my driveline angles to be bad? But it doesn't make any sense because if I keep my foot on the gas (even slightly) the noise goes away/doesn't happen.

Thanks in advance!
 
Sounds like a driveline vibe. Placing your foot back on the gas rotates the pinion up and the vibe goes away. Easiest way to check is throw an angle finder on there and see.

Are there shims under your rear springs? 2.5" really shouldnt matter much, but everybody has different results.
 
The PO dropped the t-case for a reason, make some solid spacers (same thickness as the stock spoacer you moved) and place them between the frame and crossmember to make your problem go away. DO NOT put the small spacers back between the frame and crossmember as that will make the frame crack.
 
Would it help to have the rear axle reshimmed? I was just under the impression that a transfer case drop wasn't necessary with such a modest lift height. I'm trying to keep it tucked up as much as possible and don't have access to a welder (nor the knowhow to run one).

Any suggestions on where I could get square tubing cut and just drill my own holes?
 
take an angle finder to your back shaft... check top and bottom joint angles and get back to us... probably need a shim...
 
do you have blocks in the rear or leafs?...can you add a shim with blocks?

On my old jimmy I made some t-case spacers out of flatbar and just drilled 2 holes, worked great.

btw...my new jimmy is bone stock and my pinion angle looks terrible
 
clandr1 said:
Would it help to have the rear axle reshimmed? I was just under the impression that a transfer case drop wasn't necessary with such a modest lift height. I'm trying to keep it tucked up as much as possible and don't have access to a welder (nor the knowhow to run one)?
Click to expand...

Exactly, you're on the right track. Shim the pinion to get it to go away, no reason to drop the t-case.
 
folkenheath said:
Exactly, you're on the right track. Shim the pinion to get it to go away, no reason to drop the t-case.
Click to expand...


Ditto. Theres really never any reason to drop the transfer case if everything is setup correctly because if your to the point where you think it NEEDS it you need a cv shaft.

I still stand by my saying that spacing the transfercase is a half ass fix...
 
Ok, looks like I'll have to get the axle shims done/replaced. If I can give you all the angles of the front and rear of the driveshaft can you tell me what type shims I'll need to buy?

Thanks for all the advice so far.
 
here's a pic to show you.... as long as the angles (noted as 3 here) are within the operating angle of your series joint, your good... it's usually best to have the pinion down a degree or 2 to allow for torque...

degree.jpg



get yourself an angle finder...


Johnson.jpg
 
clandr1 said:
Ok, looks like I'll have to get the axle shims done/replaced. If I can give you all the angles of the front and rear of the driveshaft can you tell me what type shims I'll need to buy?

Thanks for all the advice so far.
Click to expand...

do you have rear blocks or leafs?
 
88jimmy4x4 said:
do you have rear blocks or leafs?
Click to expand...

Blocks. The kit was supposed to have leafs only in the back, but the place I had install it said they had to use blocks because the tail was sagging after installing the new leaf springs.

I'll see if I can pick up an angle finder this weekend and report back with some numbers.
 
clandr1 said:
Blocks. The kit was supposed to have leafs only in the back, but the place I had install it said they had to use blocks because the tail was sagging after installing the new leaf springs.

I'll see if I can pick up an angle finder this weekend and report back with some numbers.
Click to expand...


How tall of a block? A degree milled zero rate may be a much better solution for your situation.
 
It's a 2-2.5 inch block -- I haven't measured it but that's about right.

Can I put two zero rates on top of each other, or are they only a one at a time deal?
 
clandr1 said:
Now, when I let off the gas and coast there is a sort of grinding or rubbing noise coming from underneath the truck that wasn't there before. Any idea what it could be?

All u joints have been replaced and I only have a 2.5" lift on it. I'm not sure if eliminating that extra inch of drop caused my driveline angles to be bad? But it doesn't make any sense because if I keep my foot on the gas (even slightly) the noise goes away/doesn't happen.

Thanks in advance!
Click to expand...

This is EXACTLY the issue I am having after my 4" lift kit gave me 6"+ of lift. I am exploring the tcase drop as a temporary solution. I know the CV shaft and relocated spring perches is the BIG FIX...but my wallet needs small for now.
 
dieselndixie said:
This is EXACTLY the issue I am having after my 4" lift kit gave me 6"+ of lift. I am exploring the tcase drop as a temporary solution. I know the CV shaft and relocated spring perches is the BIG FIX...but my wallet needs small for now.
Click to expand...

could be gear mesh, balancing, etc. You can try the drop, do it cheaply with some square tube and longer bolts. Don't pay for a T-case drop that is going to be temporary
 
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