Front Drive Shaft Help Please

CanadianCool · Feb 14, 2006

Ok Im gonna go nuts here pretty soon, I got a pretty bad case of front DS vibes, I have had the drive shaft rebuilt, just put in a set of adjustable upper and lower control arms both are set a 1/2 inch longer than stock. I have about 3.5 inches of lift with no t-case drop. I have a true trac in the front diff and trac lock in the rear gears are 4.56. If i take the front shaft out my vibes go away. Please help Im going nuts.

CMNCHE · Feb 14, 2006

If I had to guess, I'd say the problem is with the control arms. Your top one really shouldn't need to be a half inch longer than stock with only 3.5" of lift. Half an inch is a lot when it comes to alignment angles and you pinion may be rotated up just enough to cause vibes. How does your front shaft angle look.

jeepinandy · Feb 14, 2006

CMNCHE said:
If I had to guess, I'd say the problem is with the control arms. Your top one really shouldn't need to be a half inch longer than stock with only 3.5" of lift. Half an inch is a lot when it comes to alignment angles and you pinion may be rotated up just enough to cause vibes. How does your front shaft angle look.

I agree check the pinion angle.
I found this on a quick search.. Not sure how accurate they are, you may need to do some more searching on your own but hope this helps

XJ Control Arm Lenghts

--------------------------------------------------------------------------------

Control Arm Lengths

LIFT HEIGHT
LCAs
UCAs

Decimal
Fraction
Decimal
Fraction

Stock
15.75"
15¾"
15.00"
15"

2"
15.92"
16"
14.88"
15"

3"
16.09"
16"
14.92"
15"

4"
16.33"
16 3/8"
15.03"
15"

4½"
16.47"
16½"
15.11"
15"

5"
16.62"
16 5/8"
15.21"
15¼"

6"
16.97"
17"
15.44"
15½"

7"
17.36"
17 3/8"
15.74"
15¾"

8"
17.81"
17¾"
16.09"
16"

9"
18.30"
18¼"
16.50"
16¼"

10"
18.82"
18¾"
16.96"
17"

Midnight Krawler · Feb 14, 2006

Look at your pinion angle! It should be inline with the driveline. Also, climb underneath grab ahold of the drive shaft, push up and down to see if there's any play in it. Any play in your front axle pinion or slip yoke can cause nasty vibes.

CMNCHE · Feb 14, 2006

jeepinandy said:
I agree check the pinion angle.
I found this on a quick search.. Not sure how accurate they are, you may need to do some more searching on your own but hope this helps

XJ Control Arm Lenghts

--------------------------------------------------------------------------------

Control Arm Lengths

LIFT HEIGHT
LCAs
UCAs

Decimal
Fraction
Decimal
Fraction

Stock
15.75"
15¾"
15.00"
15"

2"
15.92"
16"
14.88"
15"

3"
16.09"
16"
14.92"
15"

4"
16.33"
16 3/8"
15.03"
15"

4½"
16.47"
16½"
15.11"
15"

5"
16.62"
16 5/8"
15.21"
15¼"

6"
16.97"
17"
15.44"
15½"

7"
17.36"
17 3/8"
15.74"
15¾"

8"
17.81"
17¾"
16.09"
16"

9"
18.30"
18¼"
16.50"
16¼"

10"
18.82"
18¾"
16.96"
17"

This actualy shows the measurments and you can see how the UCA length hardy changes, while the lower control arm length changes quite a bit. If you adjusted both your arms the same I would say your pinion is rotated too high.

CanadianCool · Feb 14, 2006

right now my pinion is pointing right at the t-case, and the driveshaft is good, I am at a loss, and I tired those measurments from I Love Jeeps and they point the pinion down more than it is. I will tkae some pics tommorow if i can get someone to post for me I am about to pull out my hair Thanks for the input

Front Drive Shaft Help Please

CanadianCool

NAXJA Forum User

CMNCHE

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jeepinandy

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Midnight Krawler

NAXJA Forum User

CMNCHE

NAXJA Forum User

CanadianCool

NAXJA Forum User

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