Supporting Members don't see this Ad. Click here to become a supporting member.

Results 1 to 11 of 11

Thread: Rear Thrust Angle off question

  1. #1
    Join Date
    Sep 2016
    Location
    Nashua
    Posts
    193

    Default Rear Thrust Angle off question

    I just had an alignment done wanted to get an opinion on a fix for my thrust angle.
    Im not sure of the math to tell exactly whats off in inches vs. degrees and to which side.
    I do not have adjustable control arms yet, An have not checked bushings as of yet.

    I know my rear trackbar is pushing the axle about a 1/4"+ to the driver side. Using
    my redneck measurements...

    If i were to center this better, can any one tell me how this would affect the Thrust Angle?

    Or is this number actually referring to a combination of horizontal measurement and centering
    meaning my axle is **** eyed and not centered to boot? Meaning i have a little more of an issue?
    Time to get adjustable control arms?

    How bad is the Degree in inches?

    Thanks!
    Mark
    Attached Images Attached Images
    2016 Rubicon, RK 2.5" Lift, Metalcloak Skids, FOX 2 Shocks, 35" DuraTrac, Bushwacker Fenders, Spider Diff covers, TeraFlex HD TB's DL and TR, MORE Rear Bumper, RockHard Front Bumper, Revolution Front Axle Shafts, RI LED HL, Superwinch 9500, GMRS "WRBS559"

  2. #2
    Join Date
    Dec 2012
    Location
    Manchester
    Posts
    5,912

  3. #3
    Join Date
    Dec 2012
    Location
    Manchester
    Posts
    5,912

  4. #4
    Rubicon's Avatar
    Rubicon is offline Ex-Coordinator & Ex-Mod Certified Trail Leader
    MappingNH Trail Scout
    Join Date
    Sep 2008
    Location
    Lyme
    Posts
    14,538

    Lightbulb

    It is an angle, thus not measured in inches.

    This is showing you the rear wheels are pointing to the left and the steering wheel needs to be turned to the right slightly to compensate.

    A correct length panhard bar, relocating bracket, and/or a caster bolt kit will be needed to correct. Or just drive it, as I would, because it is not a big deal.

    The bigger concern, is it indicates that your front axle is bending. Common on JK's with bigger tires. Could get eccentric upper ball joint to compensate the camber. Or just drive it, since this is not really that bad either. Though a gusset & sleeve kit probably should be done to help prevent it from getting any worse, and the other side from starting ;)
    Last edited by Rubicon; 10-24-2019 at 05:27 AM.
    Traction, articulation, and gearing make a good off-road rig. Just a big lift, wide mud tires, and a winch simply do not.
    ~Shawn(the correct spelling ;)

  5. #5
    Join Date
    Sep 2016
    Location
    Nashua
    Posts
    193

    Default

    Thanks guys... this is what i was trying to figure out. An i'll get remeasured after wards. Am i wrong or over thinking this?

    Attached Images Attached Images
    Last edited by mjm2167; 10-24-2019 at 02:51 PM.
    2016 Rubicon, RK 2.5" Lift, Metalcloak Skids, FOX 2 Shocks, 35" DuraTrac, Bushwacker Fenders, Spider Diff covers, TeraFlex HD TB's DL and TR, MORE Rear Bumper, RockHard Front Bumper, Revolution Front Axle Shafts, RI LED HL, Superwinch 9500, GMRS "WRBS559"

  6. #6
    Rubicon's Avatar
    Rubicon is offline Ex-Coordinator & Ex-Mod Certified Trail Leader
    MappingNH Trail Scout
    Join Date
    Sep 2008
    Location
    Lyme
    Posts
    14,538

    Red face

    Quote Originally Posted by mjm2167 View Post
    Thanks guys... this is what i was trying to figure out. An i'll get remeasured after wards. Am i wrong or over thinking this?

    Maybe I am wrong, though I did work at TFT, just not an alignment tech, but I thought I still understood the methodology. What you wrote(weight) should help the axle being offset sideways that 1/4" you stated. However it should not change the thrust ANGLE, as that is an ANGLE, as in measured in degrees, not inches ;)

    This is how I read/see it, but someone please let me know if I am incorrect.
    Traction, articulation, and gearing make a good off-road rig. Just a big lift, wide mud tires, and a winch simply do not.
    ~Shawn(the correct spelling ;)

  7. #7
    Join Date
    Jan 2015
    Location
    Exeter, NH
    Posts
    942

    Default

    I'm pretty sure that thrust angle is not how much off centerline your rear axle is, rather the direction it's pointing.

    Being off centerline WOULD make it point slightly to the right or left based on the movement of the control arms, but I would think it would take a lot of side to side movement before you'd get angles changing.

    I adjusted thrust angle with my adjustable control arms on the last axle swap I did. Not the track bar.
    '99 TJ, 5.9L Magnum V8 swap, Atlas-4, Waggy 44s, Custom link susp F/R, 37" Pitbulls, etc etc etc, OMG what happened to all of my money?
    She may not look like much, but she's got it where it counts, kid. I've made a lot of special modifications myself.

    '06 Dodge 2500,
    5.7, LT315/70/17 Nittos

    '97 ZJ, 2" spacer lift on 30's, 'The Beater' - SOLD

    KC1KAX

  8. #8
    Join Date
    Sep 2016
    Location
    Nashua
    Posts
    193

    Default

    Thanks! there on my Christmas list... now for which ones. Ha-Ha
    2016 Rubicon, RK 2.5" Lift, Metalcloak Skids, FOX 2 Shocks, 35" DuraTrac, Bushwacker Fenders, Spider Diff covers, TeraFlex HD TB's DL and TR, MORE Rear Bumper, RockHard Front Bumper, Revolution Front Axle Shafts, RI LED HL, Superwinch 9500, GMRS "WRBS559"

  9. #9
    Join Date
    Sep 2016
    Location
    Nashua
    Posts
    193

    Default

    I have been looking at Metalcloaks, everyone seems to love them and no complaints with the bushings and add more flex. I am also looking at Synergy's adjustable arms while still on the rig which is worth the extra $$ to me. Im not a big fan of taking off and adjusting again. They have almost as much flex as the MC's.

    Anyone use the Synergy's? pro's and con's?
    2016 Rubicon, RK 2.5" Lift, Metalcloak Skids, FOX 2 Shocks, 35" DuraTrac, Bushwacker Fenders, Spider Diff covers, TeraFlex HD TB's DL and TR, MORE Rear Bumper, RockHard Front Bumper, Revolution Front Axle Shafts, RI LED HL, Superwinch 9500, GMRS "WRBS559"

  10. #10
    Join Date
    Sep 2016
    Location
    Nashua
    Posts
    193

    Default

    okay another question... seems like i fix one thing and have 2 more issues.

    I upgraded to Synergy Control arms to fix my thrust angel, I figured while i'm at I'll adjust pinion angle and push the axle back a hair to get a little more clearance so i'm not rubbing plastic near / on the inner rear tire well seam.

    I used this for my adjustments...

    Rear Lower Control Arms = 20 7/16"
    Rear Upper Control Arms = 18 7/16"

    My issue now is my rear sway bar links are hitting my trackbar mount, and it introduced a bit of coil roll.

    My plan is to get a 10deg coil adjustment plate, and bring the upper arms in 1/2" and use adjustable links. An depending on where this puts me, I was also think of moving the rear swaybar back a 1/2" which will require drilling and tapping a couple holes.

    Has any one else ever run into this and what did you wind up doing. I still have factory CV drive shafts so I'm still trying to be cautious of pinion angle.

    Thanks!
    Mark
    Last edited by mjm2167; 11-15-2019 at 07:41 PM.
    2016 Rubicon, RK 2.5" Lift, Metalcloak Skids, FOX 2 Shocks, 35" DuraTrac, Bushwacker Fenders, Spider Diff covers, TeraFlex HD TB's DL and TR, MORE Rear Bumper, RockHard Front Bumper, Revolution Front Axle Shafts, RI LED HL, Superwinch 9500, GMRS "WRBS559"

  11. #11
    Rubicon's Avatar
    Rubicon is offline Ex-Coordinator & Ex-Mod Certified Trail Leader
    MappingNH Trail Scout
    Join Date
    Sep 2008
    Location
    Lyme
    Posts
    14,538

    Lightbulb

    Quote Originally Posted by mjm2167 View Post
    okay another question... seems like i fix one thing and have 2 more issues.

    I upgraded to Synergy Control arms to fix my thrust angel, I figured while i'm at I'll adjust pinion angle and push the axle back a hair to get a little more clearance so i'm not rubbing plastic near / on the inner rear tire well seam.

    I used this for my adjustments...

    Rear Lower Control Arms = 20 7/16"
    Rear Upper Control Arms = 18 7/16"

    My issue now is my rear sway bar links are hitting my trackbar mount, and it introduced a bit of coil roll.

    My plan is to get a 10deg coil adjustment plate, and bring the upper arms in 1/2" and use adjustable links. An depending on where this puts me, I was also think of moving the rear swaybar back a 1/2" which will require drilling and tapping a couple holes.

    Has any one else ever run into this and what did you wind up doing. I still have factory CV drive shafts so I'm still trying to be cautious of pinion angle.

    Thanks!
    Mark
    Hi Mark,

    Not sure if it was for the rear of a JK, but I have seen offset sway-bar frame adapter mounts to cure contact issues. Might have been for a XJ?

    And if you have CV style shafts still, then pinion angle is less of a concern, as long as the Rzeppa joint is not getting maxed out. Though if you can get the u-joint on the pinion side close to 0 degrees with a CV on the transfer end, that would be the desired setting.

    Good luck!
    Traction, articulation, and gearing make a good off-road rig. Just a big lift, wide mud tires, and a winch simply do not.
    ~Shawn(the correct spelling ;)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •