Front DC drive shaft vibration: (1 Viewer)

[ShottsUZJ100]

OK guys. So far I believe this is what we'll try:

1. Before driving to Phx for lockers and gears we'll space the front up by 15-20mm. I'll have to see what I have at home. I have some trim packs. This should better the pinion angle for the DC shaft.

2. If the vibration is still there, I'll check for vibes with the rear removed.

3. I'll check wheel bearings and all other wear items.

4. We'll analiyze data though hopefully it will be gone.

THANKS ALL!

 

[concretejungle]

But it's smooth as silk with only the rear shaft? Rear shaft would be good then? No?

Trust me shotts, i have lots of experience in this. Take the rear shaft out and see if it drives smooth with only the front shaft in.

I was chasing down vibs just like you are. Would remove the front shaft and it was smooth as silk with only the rear in. Put the front shaft in and vibs would come back. Turned out to be the rear shaft (80%) and a little front shaft (20%), but i would have sworn it was just the front shaft.

 

[ShottsUZJ100]

Trust me shotts, i have lots of experience in this. Take the rear shaft out and see if it drives smooth with only the front shaft in.

I was chasing down vibs just like you are. Would remove the front shaft and it was smooth as silk with only the rear in. Put the front shaft in and vibs would come back. Turned out to be the rear shaft (80%) and a little front shaft (20%), but i would have sworn it was just the front shaft.

Yes sir. I will. It's on that list. I am going to add the 1-inch first because it takes minutes and will impeove the angle. No time to play with shafts before the Phx trip. I will the second I return though.

 

[clarkrw3]

. Before driving to Phx for lockers and gears we'll space the front up by 15-20mm. I'll have to see what I have at home. I have some trim packs. This should better the pinion angle for the DC shaft.

Who does your gears in Phx?? I need to get mine done as well.

 

[ShottsUZJ100]

Who does your gears in Phx?? I need to get mine done as well.

4 Wheel Parts and Supply. They've done MANY of my friends Jeeps. I was freaked but they did my 100. They did a SWEET job. No issues, no breaks, and I lucked out and found the same lead mechanic to do the Lexus. I'm not worried at all. Ahhhh, 4.88 gears. I'm excited! Gotta go to the bathroom now.

 

[sleeoffroad]

Are you at least installing new inner axle seals and packing the bearings at the same time? Also some longfields so you can run the Rubi with this truck

 

[ShottsUZJ100]

Are you at least installing new inner axle seals and packing the bearings at the same time? Also some longfields so you can run the Rubi with this truck

YOU ARE TROUBLE! I knew I should have stuck to 3-inches and bought the kit from Wal-Mart!

 

[clarkrw3]

I lucked out and found the same lead mechanic to do the Lexus.

Names...I need names!!! I will check them out.

 

[ShottsUZJ100]

Names...I need names!!! I will check them out.

Brent at the 7th and I-17 location. Call Kevin. Tell him I sent ya. 602-218-4760

 

[clarkrw3]

Thanks Shotts!!

 

[-Spike-]

If you're worried about the vibration on your trip to get the gears done, why not pull the front DS for the trip?

-Spike

 

[ShottsUZJ100]

If you're worried about the vibration on your trip to get the gears done, why not pull the front DS for the trip?

-Spike

Krrrrapppp! Cuz I'm not smart enough to think of that. Good idea Spike. Too late though. We're heading out.

 

[ShottsUZJ100]

OK...my last info update before we go looking and trying things.

I drove the 2 hours to Phx today. Here's the deal:

Fairly smooth all the time until about 45MPH...then constant vibes set in.

The faster I go the more constant vibe I get.

When I'm cruising at 55-80 the vibration is steady AND I get a repeating very low freqency HMMM HMMM HMMM HMMM that you can hear (rumbling...pulsing) and feel (in the floor, the center armrest, and a tad in the steering wheel).

The vibration is WORSE when accellerating (uphill) and less when decellerating (downhill).

HAVE YOUR IDEAS CHANGED? THANKS!

 

[Darwood]

Have you tried driving with the rear driveshaft removed yet?

 

[sleeoffroad]

Did you add the packers?

 

[landtank]

My idea is still the same but I'm clearly odd man out. IMO because this is a full time 4WD setup both shafts influence each other. I beleive everyone with this problem has a DC shaft up front that is not set to the proper pinion angle but has gotten rid of the vib problem by finely tuning the rear shaft. Most would say that it was a rear shaft issue all along I however beleive it to be the front pinion angle as the root of the cause.

Best of luck.

BTW this is what a properly aligned pinion should look like for a DC shaft.

 

[ShottsUZJ100]

WOW, YOU GUYS ARE ON THIS! THANKS MUCH!

We haven't been able to try anything because the thing went Phx for gears and lockers. They said they would try it with the rear shaft out and report back to me. I don't intend to have them troubleshoot this, though they will have the shafts out and in anyhow.

When it comes home I will add 20mm to the front. My angle does NOT look like Rick's AND it happens to be at that BAD number "23" Rick threw out on a previous thread.

If vibes are still there we'll go on a total search for issues. If not arise, the DC rear shaft gets ordered.

Meanwhile....is the repetitive HMMM HMMM HMMM low-pitched rumble a common sound with this problem?

 

[Darwood]

My idea is still the same but I'm clearly odd man out. IMO because this is a full time 4WD setup both shafts influence each other. I beleive everyone with this problem has a DC shaft up front that is not set to the proper pinion angle but has gotten rid of the vib problem by finely tuning the rear shaft. Most would say that it was a rear shaft issue all along I however beleive it to be the front pinion angle as the root of the cause.

In my case adjusting the rear pinion angle on the rear driveshaft only moved the vibrations around related to speed. The DC rear driveshaft solved my problems. The fact that the playing with the rear driveshaft changed the vibrations leads one to believe that that is where the problem is.

The thing is when all is said and done, if adjusting the rear drive shafts 'fixes' a front driveshaft vibration problem then it doesn't really matter what was vibrating. It fixes the problem.

 

[Darwood]

If vibes are still there we'll go on a total search for issues. If not arise, the DC rear shaft gets ordered.

If the vibes are absent without the rear shaft, then I would first play with the rear pinion angle to see if you can effect the vibration, or even eliminate it. In my case I couldn't eliminate it, but others have been successful.

 

[landtank]

I just see things a little more black and white. If the front shaft is setup wrong and generating a vibration then adjusting the rear pinion to alleviate the problem IMO isn't fixing it but compensating for it.

If I though the rear pinion angle was at fault I'd take the readings of the flanges and then determine if it needed adjustment and then adjust it to spec and nothing more.

Like I said, it's black and white for me and installing adjustable arms and futzing with angles in hopes for a good result really isn't my style.