Impossible vibration (1 Viewer)

[ElCid04]

For the life of me I cannot fix my driveline vibrations... No matter what I've replaced, it's there. I've searched, a lot. I'll skip the normal stuff and get to it.

1994 TLC 230k

OME mediums f&r, with yellow castor bushings, OME steering dampener
30mm spacers up front
ARB bumper, no winch yet

In the last month, here's what I've done:

Front knuckle/axle rebuild, Terrain Tamer kit with Timken wheel and trunion bearings, OEM studs, both types
TR and draglink ends, OEM
ALL F&R suspension bushings, everything, OEM
Sway bar links and bushings F&R, OEM
All new U-Joints, MOOG
Cleaned and greased both shafts
Drained and filled both diffs and t case
Transmission mount, OEM
Pass side engine mount (havent got to driver side yet) OEM
Rotated tires (285 BFG AT)
Set toe-in to 1/8" by tapemeasure method
I think thats it, but it feels like I'm forgetting something...

I also checked the DS spline slop/play and they move enough to feel, but almost imperceptible to my eyes. Maybe 0.5mm play tops...

I also greased shafts and released grease pressure by removing the zerk for a second.

I'm freakin stumped at this point. And its driving me nuts... Obviously

Do 1994s have a transfer case dampener? Mine does not, hasnt since I bought it last summer. Maybe that would fix it?

I'm getting the standard decel and coasting grrrrr, and also heavy vibes between about 55 - 75 mph.

It sits 1/4" lower in front. Have I maxed the oem driveshafts angles?
Should I buy a digital angle finder for DS flange checks? Would it tell me anything?

Please dont let me throw more money at it...

Thanks
Matt

 

[Jeeper]

Wow. That is an impressive list of work/parts. Simple stuff first here:

Have you pulled front shaft, locked center diff, and driven it?

With 2.5" lift plus 30mm spacer, you're in the realm of needing more caster beyond the ome bushings. Eithet way, this may lead to a new front driveshaft w double cardan joint.

 

[Ridgerunner78]

Eithet way, this may lead to a new front driveshaft w double cardan joint.

This was my solution. I have a '97 w/ OME mediums F&R, 30mm spacers on the front, Slee adjustable caster bushings, heavy custom bumper w/ winch. I'm sitting at about 3" lift in the front and have the same types of vibes. I rebuilt my front shaft with Matsuba joints and had it balanced after and still have the vibes and grrrrrr on decel. I'm going the route of a Taco DC shaft shortened to fit. Picking it up tomorrow and hoping for the best.

As Jeeper said, pull the front shaft, lock the center diff and drive it. Mine was smooth as glass when I did that.

 

[ElCid04]

Ok I will try that. When i drove it with it off to replace the u-joints, the vibes were still there. But that was before the new bushings, so maybe it'll change. I've driven without the rear shaft in recently, but little change if any.

Believe me I hated myself for buying all the OEM stuff, but I am damn sure happy I did now. It rides and tracks like a dream, except for the grrr vibes...

Would the weight of a winch bring the front down enough to take the stress off the DS angle?

 

[Tenzig Norgay]

Drive flanges, they wear like all parts and if not maintained will cause grrr

 

[Squash]

I also greased shafts and released grease pressure by removing the zerk for a second.

Grease coming out means the system is under pressure.
My question to you is did grease come back out? If yes is the answer then you need to clean out the splines.
Or if you are lazy like me remove the zerk and spray some degreaser in, drive around reinstall zerk grease and go!

Your splines need to travel in and out of slip yoke, old grease prevents this and loads up diffs causing the grrr.
Try having someone jump up on your bumper while you are below and watch the rear DS splines for travel.

FYI I grease my DS's twice a month and yes they take grease.

My old JDM HDJ81 came with a 6" lift, OEM DS's and suffered your problem till the above remedy.

 

[95ToyCruiser]

I've also got a crazy vibe, not all the time, it's intermittent..

My hypothesis is that it's the body mounts...I've done all the usual stuff, but can't get it to go away, seems to be the same speed you mentioned and almost a harmonic vibration, like the tires almost match the frequency of the truck and the whole thing shakes...

Have you tried new shocks? Helped mine a little, but I still say it's the body mounts being so old and hard and allowing vibrations to reach the cab and almost "build up", if that makes any sense

 

[ElCid04]

Ok I took the front DS off 2 nights ago and have driven it about 100 miles since. The "heavy" vibration is gone, as is most of the grrr on decel and cruise control, but not all.

So now I am getting much lower frequency vibes between 60-65, so its a smaller window with less vibes, but they are still there. I'm also getting a very faint grrr on decel and cruise control, but not nearly as bad as before.

When I had the front DS off last month to replace the u-joints, the change was not as drastic and lead me to believe the front DS was fine. Since then I have replaced all the front OEM bushings, and it seems that has corrected the suspension slop, but also put the stress all back on the front DS.
So a note for future readers - sloppy bushings and suspension can mask a vibrating DS that is outside it's proper angles. At least in my experience.

As for the slight vibes and grrr I am still getting between 60-65, could that be something other than the rear DS? When I had the rear DS out last week, I didn't notice a change in vibes and grr at all, but that may have been because the front was so bad....

How do I check the t.case and pinion flanges to see if there is something wrong with those?



Squash - I had already taken my shafts apart to clean and regrease when I replaced the u-joints. When I bolted them back up, that's when I unscrewed the zerk fittings to release the pressure. A little grease came out, maybe the size of a pencil eraser, but no more than that. I wiped it off and screwed them back in. I can see on the splines that the shafts are moving as they need to.

Could the splines on the rear DS be causing the slight grr and vibes I still feel with the front DS off? I felt minimal spline play by hand, but not even enough to see with your eye.



95ToyCruiser - I think you make perfect sense, and I've considered the same. I get the normal popping and stuff you expect from bad body mounts, but only when I hit speed bumps or pull in to my driveway. They are next on my list to replace, but I haven't been able to find any threads that say new ones have any affect on ride quality or vibes...

The OME shocks I have on came with the lift kit, and I know they are super stiff shocks like everyone else says, so I may replace them for a softer ride.

I've only had the lift on for about 20k miles at this point, so they should still be new enough to not cause problems, right?

 

[ElCid04]

Another question, if I buy a DC front shaft, do I need to adjust the pinion angle somehow? Don't the DC shafts require a different pinion alignment than the factory shafts?

 

[Squash]

Grease should not flow back.
I really would clean the yoke out any way you can, a locked yoke and spline transfer pressure to other components causing undue wear.
Try my lazy man system to start, you can always take it apart later.
My old HDJ81 came with a 6" lift and stock DS set up ran quite smoothly after the above fix and pinion seal replacement.

 

[baldilocks]

Another question, if I buy a DC front shaft, do I need to adjust the pinion angle somehow? Don't the DC shafts require a different pinion alignment than the factory shafts?

Your front pinion angle is probably already correct for a DC shaft, which is why you now have the vibration you have. It's my experience that when proper castor correction is applied, you will be in the realm of zero operating angle at the pinion U-joint which is what's required to run a DC joint at the transfer case.

 

[Alleycats]

Two stupid simple things:

1) perhaps you have a wheel out of round
2) didn't see it in your list but are your front wheel bearings tight enough to not cause vibration?

 

[lcwizard]

Try phasing your front drive shaft 90 degrees. From the factory it is 90 degrees out of phase. Before you spend too much time, pull it apart and rotate it 90 degrees

 

[ElCid04]

I will take the front DS apart again and get it spotless to see if it helps before I buy a DC shaft. When I did the u-joints recently I made sure the front was out of phase when installed.

As for the wheel bearings, they feel perfect. I did the knuckle rebuild and spent extra time on preload as it was my first time. With the shaft off they feel fine.

 

[ElCid04]

Oh and I'm pretty sure the wheels are true. I put 17" bronze Method 8's on it after I got it. Tire rotation didnt change anything for vibes either.

 

[jonheld]

If the issue is only apparent during coasting or the sweet spot between acceleration and deceleration, that is usually an indication of slop in the slip yolks. When there is no rotational load on the drive shafts they will tend to "flop around" at the slip yolk until load is applied in either direction.

 

[canman]

Like Squash, I find when I get vibes, it's time to COMPLETELY clean out all the grease from the spines. It's difficult and time consuming, but this works for me. I have the OME heavies up front with a Slee 1" spacer and Toyo 315MTs with no vibration. Perhaps, as you said, old worn out bushings etc can mask the problem, but it seems to be driveshaft related. What type/ grade of oil did you use in the diffs?

 

[baldilocks]

I'm chasing a no load/deceleration only growl myself since going up to the Slee 4". DC shaft up front has that part of the equation solved.
Last week I had my rear shaft rebuilt including new spline joint. The shop said my Koyo U-joints were fine and of course balanced. My angles were verified to be within .5 degrees and the growl remains unchanged.
Experience is erging me to stop chasing this vibe and go to a DC shaft before I either go crazy or damage is done to other bearings and gears in the drive train.

 

[ElCid04]

Update time.

This week I installed the Tatton DC front shaft I ordered recently. It helped a lot, but now I have a different vibration that starts at 65mph... I can't believe its the brand new shaft, so what do I do now?

I think I've done everything possible. I will take the Tatton DC shaft off to see if it goes totally away. But even if its the new shaft, is it something I have to deal with?

Either I'm at some mythical angle where neither the oem shaft nor the DC shaft work, or I'm missing something.

Could this be a wheel bearing preload problem?
Could my toe setting being out of whack cause this?
Is it possible the transfer case components are bad? How to check/What to check?

I cant be the only person who's ever installed OME springs and 30mm spacers to have this problem...

 

[ElCid04]

Would posting my pinion flange angles tell you anything?