Hi, I'm hoping someone can help. For reference my current setup is 3.8 auto with 5.13 gears and stock drive shafts, 4" lift and pinion angle set the same as t-case (7 degrese). I usually run 35s when I go wheeling and my stock wheels tyres driving around town, this isn't much of an issue for me because I never need to go faster than about 90kph / 56mph. However since I had my gears done I have noticed a very mild vibration when travelling at 80kph / 50mph or faster only when I have my stock wheels tyres. Is this because the drive shaft is spinning to fast?

 

Ever sense I installed the new control arms, I have had this issue. In theory I was going to set the axle back a 1/4 in. so the wheel would be center of the bucket. Think the axle is to be set 1 degree lower for be under load (torque).

PS: Im in hunt for a accurate angle gage, 1/2 degree increments would be nice

 

You should have the pinion -2° lower than the driveshaft.

 

I'm still running a stock drive shaft, is that measurement still applicable or only if you have a double Cardin shaft?

 

Double carden but helps w/ the stocker also.

 

Vibration in the rear end! You're putting it in the wrong hole!😜😜

 

Do you have vibration with both sets of tires? I know you said with stock at a certain MPH, but I want to make sure. (eliminate a wheel being out of balance)

Are you positive it's in the rear? (maybe a front driveshaft ujoint going bad? May be hard to tell front/rear. 4" lift with a stock front DS it's just a matter of time before you throw a Ujoint) I'm guessing you have an exhaust spacer...

Have you checked your rear driveshaft for signs of damage? Could possibly be ever so slightly bent.

Also, check the torque on the driveline parts. While you're under there, retorque everything just because. LCA, UCA's, track bars, etc...

Lastly, it could just be a driveshaft out of balance. With everything rotating faster, Where you may have had the vibration at say 65 before, it may be prominent at 50 MPH now. This is honestly what it sounds like since it only does it with the factory size wheels and tires. However, it could be any of the above.

 

From my experience so far it doesn't seem to come from the 35s and at first I did put it down to a wheel balance issue but usually wheel balance issues are within a speed range so when you get past it it then goes away where as my issue seems to get worse the faster you go.

I know it is definitely not a front drive shaft issue because my stock front finally exploded and I was running without one for about a month while I was waiting for my new one and the vibe was still there.

The only sign of damage on my rear is a slight rub mark where it touches the fuel tank at full flex, it is possible that this could be an issue.

I'm leaning towards your last suggestion that the drive shaft is out of balance as everything else seems good.
Do you think it will help if I set my pinion angle closer to inline with the drive shaft as mentioned in the above post?

 

It's worth a try, but if you've got a DS out of balance, I don't know that it will solve the problem. Based on your input, I think you've narrowed it down to an out of balance DS>

 

So I'm thinking that it was out of balance before I did my regear and now the shaft is spinning much faster I'm now noticing it. This is annoying, would it be worth having it rebalanced or just get a new one?