What's up everyone? So a while back I put a 4 inch suspension Lift on my Jeep. Also put on a SYE, new Adams rear drive shaft, adjusted rear pinion angle, and re-geared to 4.10 since I have the 3 speed auto. Since then I haven't had chance to drive it much. Took it out on the highway yesterday and I'm getting a vibe that shakes the steering wheel at 60 mph, so I'm thinking that I need to adjust the front pinion. Angle. Other than that the jeep drives great. My question is, do I just need adjustable front upper control arms to do that, or do I need uppers and lowers?
Front pinion angle
- Thread starter Pugaroo
- Start date
Odds are very good that the front pinion angle is still fine even after a 4" lift, your shimmy is very likely just one (or both) tire is not perfectly balanced. Speed-sensitive shimmies and vibrations are nearly always tire issues, sometimes from a bent wheel.
The pinion angle itself is irrelevant, what is relevant is the angular difference between it and the driveshaft. Ideally the difference is 0 degrees. But again, the front pinion angle should be fine as-is. The front driveshaft is way longer than the rear driveshaft so it is not nearly as affected by suspension lift height as the rear axle's pinion angle is.
Your speed sensitive shimmy is no doubt a tire problem, very likely simply not well balanced enough.
Your speed sensitive shimmy is no doubt a tire problem, very likely simply not well balanced enough.
Ok thanks for the info. I'll leave it alone and have my tires and wheels checked first.
Also takes only a couple minutes to unhook the front shaft and tie it up and out of the way. Go for a spin and see if the vibe is still there
Now that I think about it,It's actually been a long time since I've done anything with the tires so I'll try that first. If that's not it, I will definitely try the drive shaft and see what happens. Thanks for the replies everyone.
@Jerry Bransford if there is no major issues with the front pinion angle, do I need the adjustable upper front control arms? or a regular standard sized ones would do the trick? next question.... do the front uppers really matters for flexing purposes? do they limit the amount of flex or lower the stress in the components? I'm planning to add a Johnny Joint end to my Core 4x4 lower control arms in a few weeks but not sure if I should consider to add a JJ in the upper front as well... I currently have a poly bushing in the upper front CAs.. (I do have a JJ in the upper rear control arms)
4.5 Rubicon express springs with Core 4x4 LCAs and 1.25 body lift... but the RE springs runs usually a bit taller... so I would say about 5 inch lift and 1.25 body lift (all the stuff for the lift already done, DC driveshaft, tummy tuck, rear upper adjustable, rear shock relocator, extended brakelines etc...)