Is my unit bearing bad?

L

lonewolf

New member
My passenger front tire has a noticeable 0.020" play if I grab the tire underneath and try to pull it out. Pulling it from the top or sides produces no play. Pulling straight out on the tire or the hub directly doesn't give me any play either. The bearing feels fine, no noise coming out and rotates smoothly.

The lower ball joint has 0.009" up/down play. And the upper has 0.002" side to side play. They are Synergy ball joints and have about 30K miles on them. The Jeep has 53K miles, with 35" tires.

I'm thinking it's my unit bearing, but I'm not 100% sure and don't want to replace it just to end up with same play. What do you guys think?
 
jeeeep

jeeeep

Hooked
Take the tire off so you can rotate the hub assembly by hand. If the unit bearing is bad you'll be able to feel it as you rotate it. It should be a smooth rotation, when you're doing it by hand you'll feel if it has any resistance or a gritty feeling
Unless it's really bad if you try to do the same thing with the tire mounted you won't feel a thing
 
Spazbyt

Spazbyt

Hooked
Just out of curiosity what are you using to measure in the thousandth of an inch. I wouldn't think anything out side of the motor couldn't be +/- .020". I'm not a mechanic so I may be naive but .001" and .009" is vary small and .020" is less space the the space between these two o's oo (unless you have a huge monitor of coarse). Im guessing you put a dial indicator on you axle tube? Is that a common method for checking bearings? Sorry I couldn't help with the OP.
 
L

lonewolf

New member
Spazbyt said:
Just out of curiosity what are you using to measure in the thousandth of an inch. I wouldn't think anything out side of the motor couldn't be +/- .020". I'm not a mechanic so I may be naive but .001" and .009" is vary small and .020" is less space the the space between these two o's oo (unless you have a huge monitor of coarse). Im guessing you put a dial indicator on you axle tube? Is that a common method for checking bearings? Sorry I couldn't help with the OP.
Click to expand...

I'm using a normal dial indicator, based on the axle C, and the needle horizontal on the wheel.

Lots of things outside of the motor can't be +/- .020" (for example, differential gears). This is big enough to feel by hand or see with a naked eye. Obviously, it's not critical (yet), but I'm trying to tighten up my handling and braking, so need to go over everything.
 
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Spazbyt

Spazbyt

Hooked
I just got done reading Eddie's write up on unit bearing replacement and wow what an eye opener! Eddie's were only out by 0.010", Lonewolf said noticeable movement and Eddie said your wheels would look like they have camber to them. I would have never guessed that just a few .010 would do that. Next time my wheels are off the ground I'm checking mine. Well you learn something every day thanks guys.
 
L

lonewolf

New member
UPDATE:

Installed a brand new bearing - nothing has changed. My lower ball joint must be bad then. I was in denial, because I thought there is no way the Synergy ball joints could wear out so fast, way before my stock ones did.

Ordered the Teraflex ball joints, however, they won't be going into my current D30, because it took a dump yesterday on top of a mountain:

IMG_20160612_201634.jpg

IMG_20160613_010548.jpg

Drove like this down to a differential shop for about 40 miles, with part of it being on a rough dirt road.

A PR44, regear, and lockers are going in next.
 
JeepJeep75

JeepJeep75

New member
^^^^^Daaaaaaaaaaaaaaammmmmmmm!!! That sucks! At least you weren't completely stranded. Any idea what caused the axle tube to fail?
 
L

lonewolf

New member
I had no idea I'll be able to make it down to pavement at least. Any moment I was thinking the wheel could fall off.

It broke right after I hit a rock with the rim of my passenger wheel. The rock was hidden in the bush so I couldn't readily see it. I was maybe going 10 mph. It dented the aluminum rim (on the outer edge) some, and there was a loud "bang" when it happened. The Jeep continued to drive, so I thought it's just another rock hitting my Jeep. But after a bit I felt how it severly pulls me to the right.

I suspect the tube was compromised prior to the complete breakarage. The shop I brought it to had the same thoughts. I inspect my axle often, and never saw any visible cracks on the outside.
 
Ddays

Ddays

Hooked
Holy shit! That photo should be in Dynatrac's brochure. I've seen bent tubes but I've never personally seen a tube snap like that. Bet that was a thrilling ride
for 40 miles. Glad you made it safe.
 
Recurve

Recurve

New member
My synergy ball joints lasted me all but 6 months.... I won't be buying another set that's for sure.
Stock ball joints last longer.
 
Sullivan

Sullivan

New member
Synergy has some issues with ball joints. Buddy just replaced his last week and has a bad one already. Had to have been a bad joint from the start.

That's what happens when you use 35's on a Dana 30. Especially when you smack a rock. Very common that the tube snaps. Even D44 will do that if its not trussed or sleeved.

Go PR44 like you said. Best upgrade I've done. I've drilled the front end on accident a few times and it held up great. Any other stock axle would have snapped for sure.
 
WJCO

WJCO

Meme King
Sullivan said:
That's what happens when you use 35's on a Dana 30. Especially when you smack a rock. Very common that the tube snaps. Even D44 will do that if its not trussed or sleeved.

Go PR44 like you said. Best upgrade I've done. I've drilled the front end on accident a few times and it held up great. Any other stock axle would have snapped for sure.
Click to expand...

You can't be serious, lol.
 
jeeeep

jeeeep

Hooked
Damn! that sucks but at least you made it out. I saw a D44 break like that on a 2013-2014 :thinking: I forgot what year the guy told me, I was surprised how it broke - very similar to yours.

he was on the same trail not going fast but just lots of larger rocks to maneuver through.

you're going to like that PR44! :thumb:
 
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Jackal01

Jackal01

New member
Sullivan said:
Synergy has some issues with ball joints. Buddy just replaced his last week and has a bad one already. Had to have been a bad joint from the start.

That's what happens when you use 35's on a Dana 30. Especially when you smack a rock. Very common that the tube snaps. Even D44 will do that if its not trussed or sleeved.

Go PR44 like you said. Best upgrade I've done. I've drilled the front end on accident a few times and it held up great. Any other stock axle would have snapped for sure.
Click to expand...

So far I my D30 with 35s and 3.73 has been great. It has been off road a couple times ("mild"wheeling). Granted I will not be surprised if it craps out before I replace it next year but still.
 
swampdog

swampdog

New member
Jackal01 said:
So far I my D30 with 35s and 3.73 has been great. It has been off road a couple times ("mild"wheeling). Granted I will not be surprised if it craps out before I replace it next year but still.
Click to expand...

I have 35s and 4.88s in my D30 and have been pretty hard on it so far with trips to Windrock and Uwharrie. No issues yet.
 
Hammmerhead

Hammmerhead

Member
lonewolf said:
UPDATE:

Installed a brand new bearing - nothing has changed. My lower ball joint must be bad then. I was in denial, because I thought there is no way the Synergy ball joints could wear out so fast, way before my stock ones did.

Ordered the Teraflex ball joints, however, they won't be going into my current D30, because it took a dump yesterday on top of a mountain:

View attachment 208228

View attachment 208229

Drove like this down to a differential shop for about 40 miles, with part of it being on a rough dirt road.

A PR44, regear, and lockers are going in next.
Click to expand...


That housing got really hot during that drive or it has been heated with a torch in the past....or maybe its just a camera reflection or somehthing
 
cozdude

cozdude

Guy with a Red 2-Door
Hammmerhead said:
That housing got really hot during that drive or it has been heated with a torch in the past....or maybe its just a camera reflection or somehthing
Click to expand...

Well he did drive 40 miles on it like that he said so I'm going to say the metal to metal made it get super hot
 
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