Jeep Wrangler Forum banner
21 - 40 of 135 Posts
You're still dealing with that? The JKS blocks worked for mine. It was tight not having a body lift but certainly doable. No interference issues at all afterwards and best of all, no more vibrations.
Yes I am. What a PITA. I'm looking at doing a MML now to hopefully cure the issue once and for all. I have my TC dropped about 1/2" I'd say but I hate the way it looks and to lose clearance.
 
Yes I am. What a PITA. I'm looking at doing a MML now to hopefully cure the issue once and for all. I have my TC dropped about 1/2" I'd say but I hate the way it looks and to lose clearance.
A MML with rubber bushings (avoid polyurethane which transmits vibrations) would be the next best step then. :)
 
Discussion starter · #24 ·
Changing the rear pinion angle is not the answer with the stock single-cardan driveshaft. In fact, don't do it. The pinion angle needs to remain parallel to the tcase output shaft angle as the factory set it.

You say you dropped the tcase 1/2-3/4". That's normally enough for a 2" SL, if that's what you actually ended up with. But if you stacked washers between the frame and the skidplate, you didn't get as much drop as the washers were tall. Like if you stacked 1/2" of washers, you only actually got probably less than 1/4" of drop due to the indentation the stack of washers sits in.

How much actual tcase skidplate drop did you get, measuring the gap between it and the frame? You may just need to add a little more drop. My first TJ lift was also 2" and 5/8" of tcase drop from perhaps 7/8" stacks of washers completely eliminated the vibrations.

Here's a quick question... did a previous owner install cam bolts on the upper rear control arms at the frame side? It almost looks like the rear pinion angle is a tad high which would explain most of the vibrations coming during acceleration.
I dropped it a complete inch today and my pinion angle is at 10 degrees, Somehow it raise up after the space lift which im confused on why it changed my angle that much. TC shaft is at 7 degrees after dropping it an inch.
 
A MML with rubber bushings (avoid polyurethane which transmits vibrations) would be the next best step then. :)
The exact reason why I went with the MML. Cost more than some washers but in the end it was well worth it.
I'm thinking either the JKS blocks or the Brown Dog mounts. Leaning towards Brown Dog because they're made in the USA.
 
I dropped it a complete inch today and my pinion angle is at 10 degrees, Somehow it raise up after the space lift which im confused on why it changed my angle that much. TC shaft is at 7 degrees after dropping it an inch.
Your pinion angle changed because by pushing the Jeep up it rotates your axles inwards. By doing that they pivot and your angle increases. I think this is what you're talking about.
 
Discussion starter · #27 ·
Changing the rear pinion angle is not the answer with the stock single-cardan driveshaft. In fact, don't do it. The pinion angle needs to remain parallel to the tcase output shaft angle as the factory set it.

You say you dropped the tcase 1/2-3/4". That's normally enough for a 2" SL, if that's what you actually ended up with. But if you stacked washers between the frame and the skidplate, you didn't get as much drop as the washers were tall. Like if you stacked 1/2" of washers, you only actually got probably less than 1/4" of drop due to the indentation the stack of washers sits in.

How much actual tcase skidplate drop did you get, measuring the gap between it and the frame? You may just need to add a little more drop. My first TJ lift was also 2" and 5/8" of tcase drop from perhaps 7/8" stacks of washers completely eliminated the vibrations.

Here's a quick question... did a previous owner install cam bolts on the upper rear control arms at the frame side? It almost looks like the rear pinion angle is a tad high which would explain most of the vibrations coming during acceleration.
No cam bolts are installed. It was completely stock when I got it. The rear pinion angle measures 10 degrees. The tc output shaft measures 7 degrees. I'm confused on why it was a dramatic change in the angles after such a small lift. Where should I go from here?
 
Discussion starter · #28 ·
Your pinion angle changed because by pushing the Jeep up it rotates your axles inwards. By doing that they pivot and your angle increases. I think this is what you're talking about.
yes but most others aren't having this issue with just a 2" spacer lift. Did I install something wrong? I mean 10 degrees is a ton man
 
I dropped it a complete inch today and my pinion angle is at 10 degrees, Somehow it raise up after the space lift which im confused on why it changed my angle that much. TC shaft is at 7 degrees after dropping it an inch.
You only have 3 degrees difference between the t-case output and the pinion. You need to have equal joint angles with the t-case output and the pinion.

The top drawing here is what you need. You can have as much but not more than one degree lower on the pinion compared to the t-case output. Most suggest 1/2 to one degree lower on the pinion.
Line Parallel Transmission part Auto part Cylinder
 
Discussion starter · #30 ·
First thing you want to do is figure out if it's front or rear. Bad u-joints or centering ball, or worn slip yokes, make sure the slip yoke aren't frozen or very stiff to slide. If all that checks out then adjustable upper control arms will fix it even without a SYE. The little bit you'll have to rotate the pinion won't require any kind of TB bracket or adjustable TB.
Its the rear. I pulled rear shaft and drives great.
 
Discussion starter · #31 ·
Changing the rear pinion angle is not the answer with the stock single-cardan driveshaft. In fact, don't do it. The pinion angle needs to remain parallel to the tcase output shaft angle as the factory set it.

You say you dropped the tcase 1/2-3/4". That's normally enough for a 2" SL, if that's what you actually ended up with. But if you stacked washers between the frame and the skidplate, you didn't get as much drop as the washers were tall. Like if you stacked 1/2" of washers, you only actually got probably less than 1/4" of drop due to the indentation the stack of washers sits in.

How much actual tcase skidplate drop did you get, measuring the gap between it and the frame? You may just need to add a little more drop. My first TJ lift was also 2" and 5/8" of tcase drop from perhaps 7/8" stacks of washers completely eliminated the vibrations.

Here's a quick question... did a previous owner install cam bolts on the upper rear control arms at the frame side? It almost looks like the rear pinion angle is a tad high which would explain most of the vibrations coming during acceleration.
Also Jerry I want to state that the vibe is felt more like a hum and it starts exactly at 50 mph rather i'm on the throttle or coasting. I verified this today driving the jeep.
 
Nothing wrong with that direction. I went with the blocks mostly for cost plus my mounts are in great shape.
My mounts look totally fine too. I'm worried they're dry rotted though because my Jeep is 12 years old and wasn't driven much until I got her last year. I'll have to look into the options.

How hard of an install is it?
 
Bump need help here troubleshooting my problem
First thing you want to do is figure out if it's front or rear. Bad u-joints or centering ball, or worn slip yokes, make sure the slip yoke aren't frozen or very stiff to slide. If all that checks out then adjustable upper control arms will fix it even without a SYE. The little bit you'll have to rotate the pinion won't require any kind of TB bracket or adjustable TB.
This will eliminate your vibrations.

https://www.core4x4.com/products/wr...justable-rear-upper-control-arms-w-rubber.php

MML may or may not give you 3 degrees, don't know never tried one.
 
To correct the angle he would have to shorten the control arms, no? I don't think that these arms are designed to go shorter than a stock arm, but I could be wrong.

Originally I was thinking the same thing but many said that is not the solution because of what I just said.
If the pinion needs to go up or down that depends on which side of 0 the readings are.

My front pinion needed to go lower to get the yokes inline and still have 6 degrees of caster.
With the Core arms had no problem shortening the uppers enough to do that with a little more to go.

If the pinion needs to go down then it's possible there is too much t-case drop.

If the pinion needs to go lower you could do lower arms, lengthening them would also bring the pinion down.
 
BTW OP, your angles are not off. I have a 2" suspension lift and this is what I had measured with 4 washers of drop.

Transfer Case Output - 6.4°
Driveshaft - 16°
Pinion Angle - 9.7°
 
Discussion starter · #40 ·
Update. I put the jeep on jackstands and drove it. The driveshaft wobbled so I removed the shaft and noticed my tcase output shaft has about 1/8" of movement maybe less but I can see the wobble on it. What's acceptable movement on the shaft? What are my options?
 
21 - 40 of 135 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top