Vibration Starting at 70 MPH After New Parts

MaximusLJR06

Jeep Green LJR Addiction
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Figured it’s time to start a thread for this one. Been chasing vibrations for over a month now.

Started out with no vibrations, but the bushings in my lower RE control arms went out. Ordered some Savvy lower arms. Before the Savvy lower arms showed up my Adam’s Off-road Front driveshaft started making the angry sparrows noise so I pulled it out. Still no vibrations.

Savvy lower control arms arrived. I installed these and set the length to match the RE arms I removed. I believe they were all 16”. A new Tom Woods front driveshaft arrived and I installed it. Had vibrations starting at 65mph. Brought home and checked the pinion angle, it was around 5-6 I believe and the driveshaft angle was 10.5. I shortened The front lower control arms to try and gain some pinion angle and ended up with the arms set at 15.75” and the pinion was at 7-8 and driveshaft 10.5. Still had vibrations but they started at 70mph now. Pulled the front driveshaft and the vibrations go away. I email Tom Woods and they sent out a replacement shaft that is triple check for balance.

Fast forward to current. I now have savvy front upper control arms installed and the new Tom Woods driveshaft. My pinion is at 8 and the driveshaft is at 10. Caster angle is approximately 4.5. I still have vibrations at 70mph and faster.

It is smooth as butter from 0 to 65 and then at 70 is starts, you can feel it in the whole jeep and see it in the rear view mirror. The vibrations aren’t as bad now with the second shaft from Tom Woods but still there. I’ve driven it enough with the front shaft out to be pretty positive it’s coming from the front end. I’ve had some private conversations with a couple members on here and we are pretty stumped currently. Attached is my most recent alignment reading and the previous alignment reading. The only thing that was adjust between the 2 was the caster angle, shop was trying to get my pinion up higher. Hoping maybe @mrblaine will give some insight.

First alignment

2A2AD695-5A3D-4188-BAAD-3F73038BCBF2.jpeg

Second after adjusting caster
7D2F7C2E-852E-4290-894E-379C25601C4F.jpeg
 
I assume you've already ruled out tire balancing? Any change if you rotate the tires?

Your pinion angle relative to the DS seems to be fine.

Also, did you make sure the ujoint surface was clean and the joint itself is fully seated?
 
Your pinion should really be even to above the driveshaft in the front. I try to keep mine within a degree of each other. Accelerating will cause the pinion to lower.
 
I assume you've already ruled out tire balancing? Any change if you rotate the tires?

Your pinion angle relative to the DS seems to be fine.

Also, did you make sure the ujoint surface was clean and the joint itself is fully seated?
Tires are all but brand new, they have 4,000 miles on them and I didn’t have any vibrations before with them.

Ujoints are all seated properly and the checked the phasing on the new front shaft and it is good as well.
 
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Your pinion should really be even to above the driveshaft in the front. I try to keep mine within a degree of each other. Accelerating will cause the pinion to lower.
That’s what I was hoping to achieve but if I make it match or a degree high my caster is going to be like 2 or 3 then which is way out.
 
Try something for me. Jack the psi up to 32 psi and report any change. I've been playing around with this.
 
Get the front shaft balanced to higher speed also and make sure it isn't bent ...takes a dial indicator.
 
Get the front shaft balanced to higher speed also and make sure it isn't bent ...takes a dial indicator.
I will have to contact Tom Woods about that. This is a replacement shaft that they triple checked before sending out after the first one had vibes
 
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Can you put the adams driveshaft in, and the other control arms to measure your angles? When I'm troubleshooting something like this, I like to return to the last known good state (if possible), then change one thing at a time, until the negative result happens.

You changed a whole bunch at once. Hard to know what's going on and what is interacting with what.
 
Can you put the adams driveshaft in, and the other control arms to measure your angles? When I'm troubleshooting something like this, I like to return to the last known good state (if possible), then change one thing at a time, until the negative result happens.

You changed a whole bunch at once. Hard to know what's going on and what is interacting with what.
I have thought about installing the Adam’s driveshaft again. Can’t install the old arms though. I had to cut the bolts to get them off. Bolts were seized to the bushings. And they went in the trash as well
 
I have thought about installing the Adam’s driveshaft again. Can’t install the old arms though. I had to cut the bolts to get them off. Bolts were seized to the bushings. And they went in the trash as well
If you are positive that the only thing that changed is a pair of new driveshafts, then the rule, "the last thing you touched" applies.

Get the old driveshaft rebuilt with a new centering ball and run it. If you are indeed correct, the vibes will return to their previous state of non existence.
 
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If you are positive that the only thing that changed is a pair of new driveshafts, then the rule, "the last thing you touched" applies.

Get the old driveshaft rebuilt with a new centering ball and run it. If you are indeed correct, the vibes will return to their previous state of non existence.
I think this is what I will do this weekend. I figured I could throw it back in as is, to see if the vibrations are gone. The angry sparrows noise wasn't bad when I removed it, just would happen for the initial 1/4 mile after sitting over night. If the vibrations are gone then I'll have that shaft rebuilt.

Control arms all changed to Savvy except rear uppers. I would say if anything the pinion angle should be better than what it was with the lower RE arms that were installed previously. Never had adjustable upper arms until this past week.

If the vibrations are present with my old shaft installed, would this point to the control arms not being adjusted properly?
 
After you get your new, old driveshaft rebuilt and reinstalled (or while you wait for parts) try an old fashioned toe in check. It looks like yours is just inside spec. And some can be very touchy. 1/8 to 1/16 inch is the rule, but some appear a bit more touchy than others. Mine was poor at 1/8". It wasn't until I hit just past 1/16" before it settled down nicely. That was adjusting one flat at a time to find where the toe wanted to be.
But, as MrBlaine said, if it was fine until the driveshaft change, then that should be the culprit.
 
After you get your new, old driveshaft rebuilt and reinstalled (or while you wait for parts) try an old fashioned toe in check. It looks like yours is just inside spec. And some can be very touchy. 1/8 to 1/16 inch is the rule, but some appear a bit more touchy than others. Mine was poor at 1/8". It wasn't until I hit just past 1/16" before it settled down nicely. That was adjusting one flat at a time to find where the toe wanted to be.
But, as MrBlaine said, if it was fine until the driveshaft change, then that should be the culprit.
Will toe in cause vibrations? Obviously with the new control arms installed the pinion and caster angle have changed and toe in could be different from where I was originally. I'll need to figure out the best way to measure toe in as well so I can check it this weekend.
 
Get the front shaft balanced to higher speed also and make sure it isn't bent ...takes a dial indicator.
I mentioned something to Tom Woods about this and they pretty much said that the driveshaft was setup to the best of their abilities and that they will provide me with either a full refund if i want to send it back or $100 refund if i want to keep it and have another shop work on it. Said they balance to 3,300 RPM which is equivalent to 80 MPH in most vehicles.