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Fixed rear pinion angles, now noisy?

9

93gc40

NAXJA Forum User
Location
Visalia, California
96, 4.0, AW4, 231, 3.5", 30 BFG, 1" TC Drop.....

I added 4 deg shim under the spring yesterday. Pinion angle now perfect, match TC vs Dif, both at 5 deg sitting in my drive way. All vibes Gone. were only very slight before. I could feel them, but others couldn't.

Thing is now my rear end seems to be humming under power. I'm thinking I get the angle ,TOO, close. I do need to change the axle bearings could this be the noise? Should I remove the TC drop, will raise the TC 2 degs or so?
 
Whats the angle between your TC and D-shaft? Over 10°?

Yeah, its good to leave the pinion pointed up 1°-2° to account for some axle wrap on power. I'd dump the TC drop and put in a SYE kit...
 
Right, time to Log Out for the night...
 
fool4wheelin said:
Whats the angle between your TC and D-shaft? Over 10°?

Yeah, its good to leave the pinion pointed up 1°-2° to account for some axle wrap on power. I'd dump the TC drop and put in a SYE kit...
Click to expand...

First, I'm not asking to adress the merit of SYE vs TC drop. As I have no vibes now with the TC and Diff in/out puts parallel. Yes my DS is too steep and will do a SYE at some point. Will too steep a DS cause rear end groan? U-joints are NOT binding. Slip yoake NOT over extended.

Question is regarding, GROANING noise, after correcting the input/output angle relationship. I go measure all three angles and post this morning.
 
Measurements

Before TC = -4, DS = ??, Pinion = +11, slight Vibes, slight groan when only in curves at speed.
Now TC = -4, DS = +12, Pinion = +6, Added 4 deg shim, Vibes gone, but Groan is anytime under power, not when coasting.

Do I need to go with a 6 deg shim, should bring pinion to 3-4deg?
Remove TC drop that angle will go to about -2 deg?
Concern either way is the DS angle will increase.

YES I will do a SYE, but can't afford it now. I don't have a job. House payment comes before Jeep mods.
 
By the math (unless someone says I am wrong) your off 2*. If it was 1* that would be ok. If it was me, I would remove the TC drop brackets and re-measure. You might be ok after.

Also, I know two people including myself who thought the DS wasn't pulled out much after the lift and were wrong! Cost me a new TC. The oil was dry. Bone dry. Check your oil in the TC just to make sure since your under there.
 
I realize that you're asking about your rear pinion/axle, but I had problems with my slip joint making noise because it couldn't take the extra DS angle, so just don't rule that out.
 
JeeperYJ said:
By the math (unless someone says I am wrong) your off 2*. If it was 1* that would be ok. If it was me, I would remove the TC drop brackets and re-measure. You might be ok after.

Also, I know two people including myself who thought the DS wasn't pulled out much after the lift and were wrong! Cost me a new TC. The oil was dry. Bone dry. Check your oil in the TC just to make sure since your under there.
Click to expand...

Agree on the angles, and am going to pull or adjust the TC drop.
I Know the the TC has oil, just changed it. I also lubed the slip joint when I installed the shims. I'm pretty OCD about that stuff and change all fluids yearly, Coolant, trans, brakes, tc, power steering, both difs and oil every 2 months or 3000 which ever comes first. Everything get a check if I plan to go more than 50 miles from home or before and after wheeling, that can be 2-3 times a week. I do not want to break because of a lack of simple preventitve maitenance. Boulders are a different matter, all together.
 
fool4wheelin said:
I realize that you're asking about your rear pinion/axle, but I had problems with my slip joint making noise because it couldn't take the extra DS angle, so just don't rule that out.
Click to expand...


That wasn't because of the angle, but it would have been due to being over extended. Excess angle causes U-joints to bind.
 
how about a worn ujoint?? I have seen mine have little groves in the cross where the little needles run on. change the angle and you change the spot where the needles run and you get the noise.
 
ceb0217 said:
how about a worn ujoint?? I have seen mine have little groves in the cross where the little needles run on. change the angle and you change the spot where the needles run and you get the noise.
Click to expand...

That makes sence. I forgot about the wear pattern affect on the U-joints. I guess it's time for new u-joints.
 
93gc40 said:
That wasn't because of the angle, but it would have been due to being over extended. Excess angle causes U-joints to bind.
Click to expand...

It could be because it was over-extended, but I doubt it with only 2" of lift. The stock DS angles are pretty low, and making them any steeper will put more stress on the slip yoke. Slop in any slip-yoke is bad. IMHO, a slip yoke on the TC is more prone to causing problems than when on the DS.

Why do you think they didn't use a TC slip yoke on the front DS?
 
fool4wheelin said:
It could be because it was over-extended, but I doubt it with only 2" of lift. The stock DS angles are pretty low, and making them any steeper will put more stress on the slip yoke. Slop in any slip-yoke is bad. IMHO, a slip yoke on the TC is more prone to causing problems than when on the DS.

Why do you think they didn't use a TC slip yoke on the front DS?
Click to expand...


Because it is a Chyco product and they tended to do a lot of things on the Cheap in the 80s and 90s.

It's Got 3.5" of lift.
I'm going to change the U-joints and wheel bearings, past due anyway, and look at the slip joint again. Everything seems tight. But in-case you haven't noticed, every single mod done to an XJ, exposes at least 2 new problems to fix.
 
Sometimes changing the angle of a u-joint from where it has been running for some time, to a different angle, will cause the u-joint to become noisy. I wouldn't rule out that you may need to change your u-joints to address your problem.
 
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