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Is my pinion too high?

P

PapaGeno21

NAXJA Forum User
Location
Rhode Island
Ive got vibes from 55-80 and its from accel and decel and just coasting.

I get NOTHING under 55.

I rebalanced the tires, got a brand new driveshaft rebuilt and balanced.

Heres my rear pinion angle.

RE 4.5" Superflex

d3ee71f7.jpg


104dfa93.jpg


887ef517.jpg
 
Could you snap a few of the angle by the t/c?
 
What are your gears/tire size,and what are your angles?
 
That looks like a stock front shaft. So, I'm assuming you have an SYE. The pinion angle is fine, maybe a hair low depending on how old/flexy your springs are. Are you sure the vibes are from the rear end? A buddy of mine searched for vibes for a while, turned out BOTH driveshafts were wore out, so when he pulled one, the vibes were still there. He'd replace it and pull the other and still had vibes. Chased the vibes for a while until he realized both shafts needed to be repaired. Just food for thought, it's not always as it seems. Do you have a photo handy of the front pinion angle?
 
Only had the lift 4 months, its the RE 4.5" Superflex but I have 4.5" rear packs vs the 3.5" and shackles.

I have the SYE, and that is a rebuilt, balanced front shaft from a driveshaft shop.

My tires are 35" Km2's that have been re-balanced twice with different shops.

4.56 Gears

the front shaft seems fine as when I remove it nothing changes.

I installed a T-case Drop and its welded to the frame so that cant come out, a few of my bolts snapped when removing the crossmember so I had no choice.

The springs in the rear are stiff as hell, actually the trucks 1" higher in the rear so im debating on removing the baby leaf on the pack.
 
Yeah ok, well like I said the T-case Drop cant come out.

Its triple welded to the frame. (The dude who did it didnt want it coming out on me, so he REALLY welded it in there)

Plus ive got 3 broken bolts stuck inside the frame rails. SO the t-case drop has to stay.

Taking it out makes no sence as to how that would fix anything, maybe I should lower the pinion angle 1-2 degrees. By the pics it looks to be perfectly inline with the shaft, which means under accel it might be torqing up?
 
TheArsonist21 said:
By the pics it looks to be perfectly inline with the shaft, which means under accel it might be torqing up?
Click to expand...
Ya, the pinion should be pointing slightly lower than the t-case outuput, so when the axle torques, it is then inline. I would lower it a bit.
 
are you using the hack and tap sye? i noticed that when i installed mine the spicer yoke had some play on the hack and tap flange. i unbolted the four bolts and tried eye ball centering the yoke. i had vibes around 45mph before and i don't get anything until the speedo hits 100mph(4.56 no speedo gear so about 70mph) thats good enough for me, i don't need to go any faster. maybe thats something to check if you have the hack and tap. also make sure all the u-joints are properly seated. and as others have said, with a shaft extended that far, you have less spline contact inside the shaft so it has more freedom to wobble/ vibrate. i'm guessing you've got a 5-speed since the shaft is so extended... grab onto the shaft near the slip splines and push up and down on it. see if there's any play there. i wouldn't rule this out just because it's rebuilt. thats a lot of shaft exposed...
 
No it doesn't have to stay! grind it out, the bolts are simple to get out! you spent all this time and $ and it's still not right. buy a new crossmember at the boneyard.do it right and be done with it. you dont need a T/C drop with a sye. and are you sure you have the right length shaft in there? it does look a little short!
 
BADaXJ said:
and as others have said, with a shaft extended that far, you have less spline contact inside the shaft so it has more freedom to wobble/ vibrate.
Click to expand...

You will always have the same amount of spline contact under any condition(extended or collapsed).
 
What Deg shims are installed?

The drive shaft looks a little extended, I would swap in a front shaft from a 96 GC, They are about an inch longer.
 
You will always have the same amount of spline contact under any condition(extended or collapsed).
Click to expand...
yes you are correct, i worded my response incorrectly... you do have the same amount of spline contact but you DON'T have the same amount of stability at the slip joint. the more the shaft is extended, the less resistance the joint has to orbital movement...
 
The slip joint is FINE. Its a brand new shaft, just got rebuilt and fully balanced and whatnot. There is NO play in it.

I had the perches re-welded in there, and we set them too high so its got negative 6 down right now. I have to have them cut off and rewelded again to get this thing any lower as I am not putting in 8 degree shims.

Theres no need to take out the t-case drop, once again, im not going to get it out. You dont understand how welded in place it is, its not going to be just a grind away procedure, then I have bolts broken inside.

No need for a new crossmember, mines fine.

Im just going to try the pinion a little lower this time.
 
Ok well my friend is the guy who welded it in place.

I only have one bolt broken in there.

We are gonna cut that thing outta there so after doing that, my pinion angle should be lower. Should be perfect.
 
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