Fine vibration in the front end under load, on throttle from 55-75. Smooth at 80. Out of ideas...

[whatsvanos]

I searched.

Correctly executed 2.5 lift which has been on the truck for years. Diff drop, SPC upper arms present. The axles are brand new Toyota oem which have been on the truck for over a year. They are both seated correctly to the front diff. Brand new toyota OEM front and rear prop shafts which were installed correctly. This slight, fine vibration begins at 55 on throttle all the way to 75 and then gets smooth as glass at 80. If I hit overdrive and push the pedal down this vibration really wakes up from these speeds.

When not on throttle it's smooth as glass.

What should I do here? Is this a pinion bearing / carrier bearing issue in my front diff? I have heard they can wear out and cause vibration etc. Front diff has a fresh fluid flush and the drain plug wasn't covered in metal etc.

 

[MycoManiac]

I searched.

Correctly executed 2.5 lift which has been on the truck for years. Diff drop, SPC upper arms present. The axles are brand new Toyota oem which have been on the truck for over a year. They are both seated correctly to the front diff. Brand new toyota OEM front and rear prop shafts which were installed correctly. This slight, fine vibration begins at 55 on throttle all the way to 75 and then gets smooth as glass at 80. If I hit overdrive and push the pedal down this vibration really wakes up from these speeds.

When not on throttle it's smooth as glass.

What should I do here? Is this a pinion bearing / carrier bearing issue in my front diff? I have heard they can wear out and cause vibration etc. Front diff has a fresh fluid flush and the drain plug wasn't covered in metal etc.
View attachment 2943189

U-joints new all around? Wheel bearings and related service. Tires, probably not the issue but always could be.

Check rear control arms, can present an issue like this with wear.

 

[OEMGUY0720]

I would say pinion bearing yes it could be the culprit as the vibration only wakes up when there is load on the pinion gear to turn the ring gear.

 

[whatsvanos]

U-joints new all around? Wheel bearings and related service. Tires, probably not the issue but always could be.

Check rear control arms, can present an issue like this with wear.

all four u joints are brand new toyota. rear control arms have never been touched, vibration is coming from front end though.

i remember someone else having a similar issue and it was wheel bearing related but mine are brand new and torqued correctly (with correct preload etc).

 

[whatsvanos]

I would say pinion bearing yes it could be the culprit as the vibration only wakes up when there is load on the pinion gear to turn the ring gear.

this is my main concern...

Its just not "as" common of a job on 100-series cruisers so I would want to make sure that's the issue before i rip out the diff. Seems like more people would have this issue.

 

[whatsvanos]

bump.


I know many people here have had this issue...

 

[ibrahim83]

Another bump for you in case this hasn't been resolved.

 

[East100Cruiser]

I have a similar issue, but mine is the front diff "wandering" around / vibrating / wobbling. I replaced the bushings because I thought this would fix it, but it did not fix the issue. I pulled the SPC ball joint as far out on the a-arm as possible, which helped. The front diff does not wobbly/vibrate when it's on jackstands anymore, but still does it by 10mph at moderate acceleration. I put a gopro to find this out. I have the upper a-arms adjusted all the way out.. no the alignment is far off, but I found that the CV joint was being "pressed" together too hard at full droop.. only moving the upper a-arm out helped. My issue is-- now that I've adjusted everything out (and it is obvious i have negative camber), it still vibrates (just not as bad). Only under load.. i checked the driveshaft and it's tight..

This truck was smoothe as glass before I lifted it some, added a diff drop, and took the diff out for 4.88 gears and lockers. Thoughts on what else this can be? The driveshaft was re-indexed a few times to check that, but no vibration before that.

I'm an open book.. I am about to return to stock and see if i get it to go away (except the gears, of course), but its a lot of work and i want/need it lifted.

Thank you!

 

[98100series]

Beautiful LX!

From the photos it appears you built it pretty level? 100s typically like to maintain the OE rake even when lifted, my experience is they drive/handle much better.
Before chasing down anything further I would reduce torsion preload/realign and drive. This should not cause a vibration concern but figured I’d throw it out there for ride quality.

Also look at those tires on a balancer to see if they are hoping around. I noticed there are no pound on wheel weights on the outside (typically enthusiasts request against that) but there is no better balance than dynamic (furthest outside and furthest inside of wheel barrel). Static, which is what yours may be can cause high speed issues. If weights outside is an absolute no for you I would consider having the tires rebalanced and if it’s asking for anything more than 1.5oz I would have them 180 the tire to find an optimal balance location on the wheel. Do not weed out a small separation in the tire tread either, this work would find that as well.

Another thing that maybe worth looking into, if you removed the cross member damper weight after removing the running boards (that big ugly metalish rubber mount bolted to the chassis on passenger side) that maybe causing a slight chassis vibration that’s being confused for suspension? Typically is dampens vibrations at idle but I have seen it affect freeway speeds when there is not much load on motor.

Good luck

 

[whatsvanos]

Beautiful LX!

From the photos it appears you built it pretty level? 100s typically like to maintain the OE rake even when lifted, my experience is they drive/handle much better.
Before chasing down anything further I would reduce torsion preload/realign and drive. This should not cause a vibration concern but figured I’d throw it out there for ride quality.

Also look at those tires on a balancer to see if they are hoping around. I noticed there are no pound on wheel weights on the outside (typically enthusiasts request against that) but there is no better balance than dynamic (furthest outside and furthest inside of wheel barrel). Static, which is what yours may be can cause high speed issues. If weights outside is an absolute no for you I would consider having the tires rebalanced and if it’s asking for anything more than 1.5oz I would have them 180 the tire to find an optimal balance location on the wheel. Do not weed out a small separation in the tire tread either, this work would find that as well.

Another thing that maybe worth looking into, if you removed the cross member damper weight after removing the running boards (that big ugly metalish rubber mount bolted to the chassis on passenger side) that maybe causing a slight chassis vibration that’s being confused for suspension? Typically is dampens vibrations at idle but I have seen it affect freeway speeds when there is not much load on motor.

Good luck

can't thank you enough for the response...

I'm glad to see you mention the tires as that was also a huge vibration as well. About 2 weeks ago I had them road force balanced and wow what a difference. Dead smooth now off throttle at any speed. (I just learned about "road force" balancing).

I should also mention that the truck is smooth after 75 under any load. Wide open throttle after 75 - dead smooth. Vibration under load from 65-75 is still present though. I lowered the truck once a little to see if the vibration persisted and it did.

I will continue to drive it as it doesn't bother me THAT much. Maybe its the diff...maybe CV's. One CV is a bit older than the other although still toyota oe.

 

[98100series]

can't thank you enough for the response...

I'm glad to see you mention the tires as that was also a huge vibration as well. About 2 weeks ago I had them road force balanced and wow what a difference. Dead smooth now off throttle at any speed. (I just learned about "road force" balancing).

I should also mention that the truck is smooth after 75 under any load. Wide open throttle after 75 - dead smooth. Vibration under load from 65-75 is still present though. I lowered the truck once a little to see if the vibration persisted and it did.

I will continue to drive it as it doesn't bother me THAT much. Maybe its the diff...maybe CV's. One CV is a bit older than the other although still toyota oe.

I have stock shafts on an 01 with 170k and they are perfect, if they are new I don’t think it’s an issue, if they are “oe reman” it could be.

Rack bushings? Maybe rack? I would not consider urethane bushings if you have stability control.

I’ve worked a ton of 100 series after others have “built” them to work out similar characteristics, can be daunting.

Good luck