Experts Only - Desperate Plea for Help - FJ40 Driveline Vibration. LONG Post. (1 Viewer)

[nazdackster]

Serious issue here, I've done a lot of work getting ready for an off-road trip (approaching 100 hours on various things), have a driveline vibration, need to go on the U.P. Overland expedition next week, and need your help.

Facts of the case:

• 2/1980 FJ40, all stock except 2.5" lift
• Vehicle exhibits driveline vibration starting at 35 MPH, peaking at 51 MPH, and goes away again by 67-70 MPH (by GPS). This was not present before any changes. A small vibration was present last year (enough to shake the image in the rear view mirror at 62 MPH)
• Power sensitive - Only felt under acceleration or deceleration, when clutch or neutral is selected, noise goes away
• Rear U-Joints felt fine. Replaced anyway and had driveshaft balanced. Somewhat off balance, 2 washers welded on, one at yoke, one at diff end. Vibration still present
• Changed transmission and transfer with used (supposedly low mileage) units before vibration present.
• Old transfer had a high speed gear with too much wobble on output shaft (excessive oil clearance discovered last year on same exercise for different reason)
• Old transmission was non-USA low geared 1st, great for crawling, but I don't need it, thought I'd change as a pair.
• "New" Tranny and transfer both had layer of sludge / dirt in bottom, probably settling out anything in there from years of non-use. They both appeared to be in otherwise great shape, with none of the looseness or slop of the previous transfer. Some metal in the sludge I filtered, but I suppose in the gram range for both.
• Axial clearance readings on transfer idler shaft excellent, no slop detected on high or low speed gears, no detectable idler bearing radial movement (even after removing side cover after installation and trying to find any slop that might be in there, applying any force I could)
• All gaskets and seals changed on both units, no bearings changed (operation seemed fine)
• Transfer output after install had slight (guessing 0.010") radial movement, added shim to eliminate. Small difference could easily have been due to new gasket thickness difference. 0.015" shim at output bearing restored a little pre-load, guessing 2 lb at brake drum diameter. This seems to be controlled by the gasket thickness at the T/C / output / speedo sleeve interface, and shim thickness. Transfer output after installation feels buttery smooth, and I'm driving transmission too when I do this.
• Had to drain fluid to do shim above. Clean, no metal on a paper filter I used after 100 miles, re-used.
• Transmission seemed to shift normally and move easily, maybe looser than previous (easy and free rotation & shifting)
• Diff output nut was loose, but staked. Un-staked, tightened 1/6 turn (to 175 ft-lb) and re-staked. Pre-load felt good at that adjustment, no axial or radial play, and 3/16" radial pinion to ring gear play at the flange OD. Bearings and axle rotation feel good with no erratic bearing feel (smooth rotation)
• No excessive bearing slop noted on input or output shafts of transmission before or after attachment to transfer
• All driveline drain plugs on vehicle (4) showed the normal silver powdery stuff, a few 0.5mm x paper thin chips here and there, all places (normal for this vehicle). I do this often, and haven't noted any changes in the diffs (tranny and transfer are unknowns)
• Rear diff had thick (140W) fluid in before, now has 80W
• Removing rear driveshaft and running on front drive (unloading rear drive train) makes vibration go away completely (diff unloaded, transfer rear output unloaded)

This would seem to indicate:

• Rear diff
  • but was fine last year on last major run
  • Diff should make noise at any speed if bad, not have resonant speed peaks, right?
  • There is a little whine on decel if I listen close enough, but I think that might be normal, it's really hard to hear
  • Replacing fluid tomorrow with 140W to try to reduce shock load, if any.
• Driveshaft
  • but just had new U-Joints (Matsuba from Kurt at Cruiser Outfitters) installed, and was balanced
  • If it was off balance, should not go away when put in load-neutral situation. This should also eliminate tire balance (a different frequency too)
  • Shaft is in-phase.
• Drive angles
  • Transfer output and pinion not parallel, but not unusual for a vehicle like this, per the driveline guys who have seen it (doesn't have to be perfect on lifted Jeeps / FJ40's, etc)
• Transfer output
  • but power going to front is driven by same shaft as power going to rear (once the coupling sleeve is moved over to engage the 2 shafts). I don't see why having a rear driveshaft attached or not would make a vibration unrelated to driveshaft or diff. Same bearings, right?
• Transfer idler bearing or shaft
  • but I don't see any play anywhere and can't seem to budge anything in there in a way that would make a vibration.
• Transmission
  • but I can't feel any vibration on the shifter. Shaft alignment seems to be controlled by pilot bearing (new) & front trans bearing, rear trans bearing and transfer input bearing. All seemed fine when I put together.

My options:

• I need advice on what to check next, what the best probability is, and what I can fix if I get parts overnighted
• I have access to presses and things at work (take vacation and use the equipment)
• One guy said swap the front and rear diffs. Rear sounds easy, front, not so much (is it hard to get the axles out?)
• I can't rebuild any diffs in time, I don't know how and want it done by an expert. Too critical.
• I could rebuild the transfer in time & reinstall by Thursday if I got parts by Tuesday morning (I think).
• I can't do a transmission rebuild in time. But I have an H41 that seemed to work fine last year. I could mate that to a rebuilt transfer in time to eliminate new transmission as a cause.
• Take my CJ7 on the trip. Pristine, restored, flawless. Ouch. But I might have to.

I've talked to JTO, Kurt, SOR, Indiana driveline, Surge driveline, Book Racing, some have driven it, and given this combo of details, frankly, they're all stumped. Contradictory facts for one reason or another. But they agree I've checked the right things so far.

I'm looking for suggestions, experience, whatever at this point. I really want to take this vehicle on this trip. I started this process more than 6 weeks ago and it hasn't worked out quite right yet. Thanks so much!

Mike S.

 

[FJforty]

Not sure if I'm an expert, have to let my peers do that.
I didn't see anything about tires.
Do you have a different set of tires to try?
Swap tires front to rear and test?
Have the tires been balanced, did a weight fall off?

 

[1911]

Simple question, just making sure - is the offending drive shaft properly in phase on both ends? Being out of phase will give you an rpm-specific vibration.

 

[Fast Eddy]

Definitely not an expert. Don't listen to anything I say.

I assume you know what in-phase means. Post up a picture maybe.

You can put a few big hose clamps on the drive shaft loose enough so you can just turn them with two fingers and the heavy part will spin to the unbalanced side. I heard about this 2nd hand via Skillet and D'Animal; seems to work.

Edit: I just read that running in FWD eliminates the vibration. That eliminates tires as the source.

I don't see how anything in the tranny, xfer case or rear would exhibit this behavior. I would expect grinding or vibration all the time.

I'm putting my money on the shaft somehow. Post up a picture.

 

[Poser]

[*]Drive angles

• Transfer output and pinion not parallel, but not unusual for a vehicle like this, per the driveline guys who have seen it (doesn't have to be perfect on lifted Jeeps / FJ40's, etc)

This is far more important that you have been lead to believe.

If you do not own an angle finder, purchase one and post up what your rear output on the transfer case is sitting at and what the rear differential companion flange is sitting at.

 

[BlueCruiser84]

Edit* Poser beat me to it, but definitely check that.

If your pinion and Tcase output aren't parallel it would technically give you driveline vibrations. That being said, my forty's rear driveshaft angles were waaaaayyy off AND I had bad u-joints, but ithe vibrations weren't anything I couldn't live with. Obviously, you wouldn't want that setup for an expedition..... I'm just saying it's driveable.

It would be easy enough to shim the rear axle so the two flanges are parallel and see if that helps.

Brian

 

[60fj25]

Also check your rear lug nuts to make sure they are not loose and check that the wheel holes are not elongated. If they are you will get vibration on aceleration and deceleration. Front wheel drive only will not place any stress on the rear wheels.

 

[nazdackster]

Definitely not an expert. Don't listen to anything I say.

I assume you know what in-phase means. Post up a picture maybe.

You can put a few big hose clamps on the drive shaft loose enough so you can just turn them with two fingers and the heavy part will spin to the unbalanced side. I heard about this 2nd hand via Skillet and D'Animal; seems to work.

Edit: I just read that running in FWD eliminates the vibration. That eliminates tires as the source.

I don't see how anything in the tranny, xfer case or rear would exhibit this behavior. I would expect grinding or vibration all the time.

I'm putting my money on the shaft somehow. Post up a picture.

I figured "Expert Only" would be controversial, but it looks like I drew some in... Thanks for your opinion. I do feel like I'm negotiating a double-black in ski (or off-road) terms. It's definitely in-phase, with the zerks in the right position for original balance, and zerk drilled holes in compression for forward motion (both yokes parallel) There is a little radial slop in the slip joint, but nothing I'd consider bad. The shaft is still straight if I press really hard on it at the slip joint

I think shaft too. I called a competing place and told them where I got it balanced, and they said, basically, I know those guys, if they did it, it's right, which I'll take with a few grains of salt based on general life experience. Feels the same before and after. With accel or decel off (like in neutral) all vibration goes away, which tells me something is resonating in the system, but if it was driveshaft balance, it would probably get worse in a neutral torque situation since there would be nothing else to tend to stress it and hold it in position. Kind of at a loss.

Poser: "This is far more important that you have been lead to believe.

If you do not own an angle finder, purchase one and post up what your rear output on the transfer case is sitting at and what the rear differential companion flange is sitting at."

My wife has an I-phone, if I take it while she's not looking, I might be able to give exact angles, they have an incredible angle finder on them, an app you can download, and damn accurate.

Using my own eyeballs, the engine/transfer is about -6° viewed from the driver's side, and the pinion would be more like -15°, meaning the pinion is pointed above the transfer output. I'll post some pics tomorrow. This would mean the pinion would need to be made more parallel with the ground, which would increase the driveshaft length too, and increase the risk of it separating, I would think. This didn't change since the other things changed. It's always had a little rumble spinning up through 3rd gear, which is still there as normal. But this vibe is different.

60fj25:
"Also check your rear lug nuts to make sure they are not loose and check that the wheel holes are not elongated. If they are you will get vibration on aceleration and deceleration. Front wheel drive only will not place any stress on the rear wheels"

Lugs are good, have never seen elongation.

One option I'm thinking of is remove the driveshaft, drive the 500 miles to the U.P., put it back on for the 4WD stuff, then take it off again for the ride home. 3 of 4 guys I spoke to said I shouldn't do that because driving by the front will cause excessive wear. OK for low speed, not OK for high speed. Must be a heat dissipation thing, but I would think it could take it. Opinion?

 

[bikersmurf]

"Diff output nut was loose, but staked. Un-staked, tightened 1/6 turn (to 175 ft-lb) and re-staked. Pre-load felt good at that adjustment, no axial or radial play, and 3/16" radial pinion to ring gear play at the flange OD. Bearings and axle rotation feel good with no erratic bearing feel (smooth rotation)"

Pinion bearings should be replaced. They are worn.

Slip yoke?

 

[waiting for time]

Here is an example of what vibration caused by a wrong angle on the axel side does. The PO was almost at the top when he came down sideways flipping it more than one time. This rig was only used for wheeling, he never drove it on the roads so it didn't bother him until.............

 

[inkpot]

Howdy! Yea, me neither as an expert, but I have been running lifts/custom driveshafts in a bunch of rigs over 35 years. Hardest diagnosis I've had was brand new ujoints that were Name brand, but not OEM, that had lateral play in the yoke due to the clips not being in a position to keep the cross tight in the yoke. Ended up using clips from a Sammi or something that was way fatter than the ones that came with the ujoints. Ran like a dream after that. Success with DS angle will vary from rig to rig. Like Poser said, get some pix and numbers. You could try about 400 pounds of ballast in the back ind of the rig to see if that will change the DS angle enough to make the vibs better or worse. John

 

[nazdackster]

Here is an example of what vibration caused by a wrong angle on the axel side does. The PO was almost at the top when he came down sideways flipping it more than one time. This rig was only used for wheeling, he never drove it on the roads so it didn't bother him until.............

Welp, THERE's your problem! I almost wish something would just break so I know what to fix! Angles are the same before and after.

The more I think about this, the more I think, for this trip only, until I have to really get under this vehicle and drop everything again, for the THIRD time in 3 years... An unbelievably long and drawn out tale I will not drag you through...

Why don't I just remove the rear shaft and drive it to the U.P.? WHAT is the big deal about stressing the front axle or shaft?

It doesn't make any sense to me why this should be any different from any other 4x4.

1. I will be driving in a straight line, for the most part
2. This means the birfs are going to be applying constant force to a fixed point driving the wheels forward. There should be no heat generated more than that by simply having the axle engaged by the Warn hubs.
3. I often leave my drive axles engaged and can forget for a very long time. The wheels are driving the shafts anyway. What's the big deal about the shafts driving the wheels? It would seem that an engineer, somewhere along the way, presumed that eventually the shaft would have to drive the wheels.
4. This was the standard before Warn locks.
5. I see no risk at all, the more I think about it. Can anyone enlighten me? It's not an ideal situation, but I can't see how it is an excessive wear situation either.

 

[nazdackster]

Howdy! Yea, me neither as an expert, but I have been running lifts/custom driveshafts in a bunch of rigs over 35 years. Hardest diagnosis I've had was brand new ujoints that were Name brand, but not OEM, that had lateral play in the yoke due to the clips not being in a position to keep the cross tight in the yoke. Ended up using clips from a Sammi or something that was way fatter than the ones that came with the ujoints. Ran like a dream after that. Success with DS angle will vary from rig to rig. Like Poser said, get some pix and numbers. You could try about 400 pounds of ballast in the back ind of the rig to see if that will change the DS angle enough to make the vibs better or worse. John

Yep, thanks John. Nice Pig! I was thinking the same thing. Whatever I do, I will have this thing loaded down pretty heavily for the trip, which should improve the drive angles. Previous U-joints felt fine to me, and the driveline shop, but since I had already bought the Matsuba joints from Kurt, I told them to put them in anyway to try to eliminate unknowns. They said they looked like fine joints, as good as OEM. I have a little more ballast than called for in the driver's seat!

 

[amaurer]

[*]Drive angles

• Transfer output and pinion not parallel, but not unusual for a vehicle like this, per the driveline guys who have seen it (doesn't have to be perfect on lifted Jeeps / FJ40's, etc)

This is your problem. I suspect you know it, but you're having trouble figuring out why its torturing you suddenly. The "change" might not even be mechanical, maybe a body mount bushing has gone bad and now you're feeling the vibes like never before. Regardless, the angles are your problem.

Adding grist to the mill - if your 2.5" lift is OME then I have exactly the same vibe in 3rd gear and it must just be part of the lift.

1. I will be driving in a straight line, for the most part
2. This means the birfs are going to be applying constant force to a fixed point driving the wheels forward. There should be no heat generated more than that by simply having the axle engaged by the Warn hubs.
3. I often leave my drive axles engaged and can forget for a very long time. The wheels are driving the shafts anyway. What's the big deal about the shafts driving the wheels? It would seem that an engineer, somewhere along the way, presumed that eventually the shaft would have to drive the wheels.
4. This was the standard before Warn locks.
5. I see no risk at all, the more I think about it. Can anyone enlighten me? It's not an ideal situation, but I can't see how it is an excessive wear situation either.

You're handwaving a bit, just accept the common wisdom that driving on the front axle can be done, and won't destroy it instantly (or even shortly), but it is still best done sparingly. Some guesses as to why:

• The front third member drives on the "wrong" side of the ring gear.
• There definitely is a difference between a coasting front axle (with lightly loaded birf balls and low shear forces on the grease therein) and a front axle being driven (with high loads on the grease and sliding members).
• The knuckles oiling system (grease pack) is not designed for long term use under power. It may hold up (as its not all that different than the wheel bearing grease arrangement) but it certainly wasn't was Mr. Toyota had in mind.
• I would imagine that driving long term in front wheel drive will wear the 4wd shift collar and the splines on the front output from vibration and direction changes, much like the gear on the transmission output shaft wears those splines away (probably a many-thousand-mile-phenomenon, however).

 

[cjgoode]

My first 40 came with no rear drive shaft, took 3 weeks to get one in from Toyota, we drove it in 4 wheel drive (front wheels only) after replacing the rear end with no problems at all, and we were kids and drove it hard. In reverse we could get back wheels off the ground if we punched it.

Take out the rear drive shaft and drive around, if the vibration is gone, then no questions about it is in the rear drive line, if still there then engine mounts, body mounts, tires etc. Could also be in the rear end axles, maybe a brake drum way off balance, with all the work you did it is not going to be an obvious common problem.

I am no expert, but I have found when you have beat your head on the wall and had experts look at it a non expert might be your best bet, you have done about everything possible. Now you might need a non expert, that one guy who is clueless except for the one vibration problem he had on his rig and got fixed.

 

[waiting for time]

I am no expert, but I have found when you have beat your head on the wall and had experts look at it a non expert might be your best bet, you have done about everything possible. Now you might need a non expert, that one guy who is clueless except for the one vibration problem he had on his rig and got fixed.

I agree but the problem is you don't know which non-expert has the right answer for this problem.

 

[Aussie 25]

Is the vibration tail sharft speed or wheel speed?. I chased one in a 75series in 4wd and it turned out to be the sharft angles in the frount. I changed diff centers, rebuilt transfur case,tried three frount drive sharfts, still their. One day an old feller said you have a 2" lift yes. He said the fix is a cardernal joint. [ that is one with 3 unis 2 close together] I modfied a frount sharft out of a hilux, i think usa call them a mini truck. 4years later and 40000k of hard sand driving and no vibration. I think some comp trucks run them on the rear.

 

[bsevans]

When I put an OME 2.5" lift in I also started getting a vibration at highway speeds, especially when I either accelerated or decelerated. This vibration was completely eliminated when I had the rear drive shaft sectioned and a CV joint added. The angle to the axle is within acceptable limits.

 

[nazdackster]

I LIKE IT!

When I put an OME 2.5" lift in I also started getting a vibration at highway speeds, especially when I either accelerated or decelerated. This vibration was completely eliminated when I had the rear drive shaft sectioned and a CV joint added. The angle to the axle is within acceptable limits.

This makes sense to me! I see you flipped the driveshaft to put the slip joint at the back. Any idea what PN your cardan joint is? I would need to get that part on order ASAP so a driveline shop could do this, like Tuesday. Or Monday if they already had the part. Or maybe you could tell me who did this and I could call them? I think this is worth a shot and is doable in time.

I also had a loose rear engine mount last year. Enough that I could turn the nut by hand. I tightened both somewhat and added a larger washer so I had a place to put the cotter pin through. The rubber is more compressed than before by maybe 1/8". Could this also be a contributor?

Maybe the tranny and transfer are "so good" now, that they are more sensitive to vibration than before...?

I'm going to have to make a good guess and take a shot at this point. I like this one.

Either that or I drop the tranny and transfer out and try to rebuild the transfer in time, and maybe put the H41 in since it's known good. Your idea is way easier and makes a lot of sense...

It would seem amaurer and Poser agree it could be angles.
Aussie 25: It's shaft speed. Is there a direct bolt-in replacement, or a longer Toyota shaft I can cut down and fit the rear? I think I'm going to have trouble asking a driveline shop to wing it. If I could take a longer CV shaft that would otherwise fit and cut it, I think that might work. Starting to search...

Any others agree with this approach? What's the fast solution?

 

[CRZR45]

Have you lubed the slip joint on the drive shaft? This is a common problem on FZJ80's front shafts once lifted. That it my guess because I have had vibrations in the past on my 40 and my 80 like you describe and that fixed it by lubing the slip shaft. Grab the drive shaft where the slip joint is and push up and pull down on the shaft and see if there is any play in there. My 2c