Yet another 80 Series Vibration Thread. Replaced almost everything but the truck. (5 Viewers)

[tmxmotorsports]

All of the bearings in the front hubs and knuckles are new. Reused all of the rear bearings.

Rear hub bearings reused ? What about on the rear differential ?

 

[12bit]

Rear hub bearings reused ? What about on the rear differential ?

I haven't done any work on the diffs yet.

 

[tmxmotorsports]

I haven't done any work on the diffs yet.

Oh

 

[Kabanstva]

Did you ever figure out what the issue was?

 

[Njck22]

Is it more of a sound than a feeling? Exhaust heat shield under passenger floor board is my guess if its a sound.

Also 100% check motor mounts and trans mounts. Maybe even a harmonic balancer?

 

[CharlieS]

I also suspect motor mounts and transmission mount.

 

[BILT4ME]

Past the point of losing my mind over this. I've got a 1994 triple locked 80 with around 220,000 miles. I've been chasing a vibration that you can feel in the whole truck for a very long time. The type where when you hit a small crack in the pavement, it's like it echoes throughout the whole truck (not a sound, but the feeling). Like a shudder or clattering feeling. Like something is loose. Basically, the truck drives like crap. You can feel it at any speed.

Here is what I have done so far:

• Front axle rebuilt (twice). New TREs (555), spindles (OEM), birfs (HDK), inner axles (OEM), bearings (Koyo), seals, etc. Bearings preload set. Steering knuckle studs torqued.
• Rear axle rebuilt.
• New OEM shocks. Dobinson stock height coils. All new OEM suspension bushings (radius arms, control arms, panhard). Triple checked torque.
• New OEM sway bar bushings, OEM end links.
• Pulled front & rear drive shafts. Replaced with new OEM.
• Tried 3 different sets of wheels/tires.
• Alignment done.

I've gone back and retorqued things multiple times. I am basically out of ideas and starting to wonder if it's not suspension related at all, but something like a misfire or motor mount. One other thing worth mentioning is that there is a whine coming from the center or front of the vehicle only under load. Seems to be diff whine.

Thinking about rolling it off a cliff. Any ideas?

1) What tire pressure are you running?
2) Bearings in front axle "preload set" to what?
3) Did the front trunnion bearings get changed out?
4) What is your toe-in and how was it measured?
5) What are your camber / caster numbers?
6) Are the rubber/plastic cups still under the springs after the new springs installed (IDK if you did them or a PO)?
7) Have you checked your nuts? (On the bottom of the L/R steering knuckles)
8) Have you lubed your shaft? (On the driveshafts - I see you have new OEM)
9) Are your DS in proper phase? Front 90° out of phase, rear in phase
10) What tires and wheels are you running?

Please post a few pics of the truck as overall and undercarriage so we can see other stuff. Someone may spot something out of line.

 

[12bit]

1) What tire pressure are you running?
2) Bearings in front axle "preload set" to what?
3) Did the front trunnion bearings get changed out?
4) What is your toe-in and how was it measured?
5) What are your camber / caster numbers?
6) Are the rubber/plastic cups still under the springs after the new springs installed (IDK if you did them or a PO)?
7) Have you checked your nuts? (On the bottom of the L/R steering knuckles)
8) Have you lubed your shaft? (On the driveshafts - I see you have new OEM)
9) Are your DS in proper phase? Front 90° out of phase, rear in phase
10) What tires and wheels are you running?

Please post a few pics of the truck as overall and undercarriage so we can see other stuff. Someone may spot something out of line.

1) What tire pressure are you running?
30 PSI currently.

2) Bearings in front axle "preload set" to what?
set to around 12 lbs on a fish scale (torquing the inner nut to 45lbf the last time around)

3) Did the front trunnion bearings get changed out?
Changed bearings and races with new Koyo.

4) What is your toe-in and how was it measured?
will post a pic of my readout. The rear left 'toe' reading seemed a little odd to me.

5) What are your camber / caster numbers?
will post a pic of my readout

6) Are the rubber/plastic cups still under the springs after the new springs installed (IDK if you did them or a PO)?
I swapped the coils. There is a rubber insulator on the top of the rear coil, but no plastic cups under any coils.

7) Have you checked your nuts? (On the bottom of the L/R steering knuckles)
Torqued to 71 lbf

8) Have you lubed your shaft? (On the driveshafts - I see you have new OEM)
Yes.

9) Are your DS in proper phase? Front 90° out of phase, rear in phase
Yes. Front is out of phase, rear in phase.

10) What tires and wheels are you running?
Right now, 305s BFG K2s (E rated) on factory alloy wheels. I have also ran 285 K2s (E rated) & 265 Michelin Defenders (SL rated). In each case at around 30 PSI.

Will take some pics of the undercarriage.

 

[12bit]

Is it more of a sound than a feeling? Exhaust heat shield under passenger floor board is my guess if its a sound.

Also 100% check motor mounts and trans mounts. Maybe even a harmonic balancer?

No sound. Just a shaky feeling in the whole vehicle when hitting any slight imperfection in the road.

 

[NeverFinis]

No sound. Just a shaky feeling in the whole vehicle when hitting any slight imperfection in the road.

Does the vehicle wander or dart when hitting these slight imperfections?

Can you provide more details on this statement?

Basically, the truck drives like crap

 

[Devils Paw 80]

I was under the impression that caster values should be greater than that. Suppose you've ruled out a wheel issue with tire rotations?

 

[NeverFinis]

I was under the impression that caster values should be greater than that. Suppose you've ruled out a wheel issue with tire rotations?

Good catch. I didn't see the pic of his alignment initially.

Yes, caster should be higher than that at 3°. Caster is odd because he is using "stock height" springs. Something is going on there..

The alignment shop did correct the toe-out situation..

 

[12bit]

Does the vehicle wander or dart when hitting these slight imperfections?

Can you provide more details on this statement?

It doesn't wander too bad, but I can still feel a need for some caster correction. I have a set of Eim Keith brackets that I plan to install.

At one point I had an OME 2" lift and Iron Man drop brackets installed. Caster felt OK then, but I removed it all and went with a stock height (dobinson c59-210v, c59-221v) setup while chasing these vibration gremlins.

As for "drives like crap", it just feels like something is loose. Not much bump steer or poor handling, but a rattling feeling. Feels like all the bushings are shot when they are all brand new OEM.

 

[12bit]

I was under the impression that caster values should be greater than that. Suppose you've ruled out a wheel issue with tire rotations?

I would suspect a bent rim or bad tires, but I have tried a few different sets of wheels & tires and it doesn't reduce the vibrations.

 

[EricT4R]

New exhaust all the way to the tailpipe, so I don't think it's an exhaust whistle/whine.

Transfer case is all stock.

Any chance there is a loose hanger or something improperly routed with the exhaust rework?

 

[CharlieS]

My transmission mount was in two separate pieces and that became very apparent when I I tried to jack up the transmission/transfer. The rubber wasn't even bonded to one aide of the steel mount. This is easy to check, and easy enough to replace.

 

[Ragnaroek]

Do you still have the drop brackets? I'd put them back in with the current springs, just to see what what happens.