Driveline Grrrrrrr (round 3)

OK folks, I know you have all been patiently awaiting the results of the chase for the vibration, so here goes.

It all started many moons ago with a lift. I chose the medium lift because I didn’t have a bull bar/winch and wasn’t sure when I would get one, I also don’t carry a lot of loads, don’t have a rear heavy duty bumper and wasn’t sure when I would get one of those either. The medium lift sounded perfect for me. I assume I got the medium springs as Christo has asked me to check the box to be sure, unfortunately I shipped my stock springs in the OME boxes to Lowtiderider for his 60 suspension project, so I was unable to confirm that I did get the medium lift. I did not get an alignment before the lift. After the install of the lift I waited a month so the springs could settle out and took it to Toyota to get an alignment check. With the OME CC bushings in place my castor measured 0 to 1.2 degrees. With the addition of 33 inch Truxus MTR tires she liked to wander the road like a dirty hooker. Note at this time I don’t recall a grrrrrr at all, just a wandering truck. So with a little searching on the mud board I decided to install the castor plates that slee sells. They are a very high quality product. I installed the plates and then two days later drove to the beach (5 hour drive) it tracked much better. I still noticed I had a little stink bug look so for the fun of it I put the Mr. Gasket 1 inch spacers in front. Now the truck sat perfectly level and looked good. Over the following few weeks I started taking Real Estate classes across town and had a highway drive of about 30 miles round trip. I started noticing a vibration coming from what felt like the front end. When I got home I crawled under the truck and noticed the tie rod was sitting on the control arms. Seemed that the vibration got worse and worse, and I could make it come and go with a feathering of the gas pedal. I tested things out by removing the front drive shaft, locking the center diff. and driving around with no vibration. So I figured I had it wooped, it was the front shaft. I put new Ujoints in and put the shaft back in. Vibration was still there. Next I grinded the arms to get the tie rod off the control arms. Took it for a drive with the front shaft in and still had vibrations. Next attempt at a fix was a know-it-all at a driveshaft shop that said my driveshaft was too long and was bottoming out. I still to this day have no idea why I was naive enough to listen to him and pay him to shorten my front shaft. That obviously didn’t fix the vibration either.

Scratching my head and posting on the mud board brought about the discussion of pinion angles and double cardan drive shafts. It appeared that I was a perfect candidate for a double cardan shaft. I really wanted to purchase the shaft from slee since he had given advice on the phone and posted in the threads about this issue, but the price was just too high for my wallet so I had one built here in town for a lot cheaper, sorry Christo. Now things begin to get interesting. I drove around for two weeks with the front shaft out with no grrrrr to speak of. NOW, two days before I picked up my front double cardan drive shaft I drove a good ways on the highway, I noticed a slight grrrrr. What the heck is that I thought. No way! Was I feeling some of the grrr from the rear shaft now? I was really getting frustrated and confused. I picked up my front DC shaft and installed it. Grrr was still there! Man was I pissed off.

Yesterday I drove around with the rear shaft out and the center diff lock locked. Smooth as silk. So there is no issues with the double cardan shaft, all in all I guess that was a good move. I’m guessing that my next move is this: new ujoints in the rear shaft and adjustable upper links to move my pinion down a little. That’s the last thing I can think of to fix this. If that doesn’t work I will sell the truck and buy a jeep.. . . . . . .just kidding. I will sell my lift and get a 6 inch lift!

I don’t know if this helps anyone, but perhaps others tracking down driveline vibrations may learn something from my story. I hope that others can pinpoint the vibration quicker and not throw as much time and money at it as I have.

One thing positive I look at in this entire situation is my education. I have really learned a ton from this experience and feel that I can use this knowledge in the future when tracking down driveline issues or designing 3 and 4 link suspensions.



EDIT: Thought i should try to bring this thread full circle. . . . anyways, grrrrr is gone. Cure ended up being a combination of rear ujoints and, some how, the driveshaft had been installed 1/2 in-phase and 1/2 out-of-phase. Hope that makes sense and helps. As of today (12/7/05) i have not removed the new DC front shaft and replaced with OEM shaft yet to see if there was in fact vibration coming from the front.

Leason learned from this is if you are having driveline issues, and you feel like it's coming from the front, don't count the rear driveshaft out. That could in fact be the problem. When testing for driveline grrrrr, be sure to remove BOTH front and rear shafts, one by one and inspect them closely in order to track down the vibration.

all this trouble with just a medium + (less than) 1" Mr. gasket?
dang!

how will going to 6" make this all go away?

e9999 said:

all this trouble with just a medium + (less than) 1" Mr. gasket?
dang!

how will going to 6" make this all go away?

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Just get everything for the kit and don't try to cut corners, you'll be fine. Christo addresses the driveline issues with all the adjustable links for the 6 inch lift. With the stock set-up you can't really "tune" anything. You just get what you get.

Did you do another alignment after the plates? Changing the axle's position will effect toe.

Concrete,

Add some weight to the rear and see how she does, if it helps, i say time for a rear bumper!

Landtank,

I understand the issues of checking alignment and whatnot, before and after lifting but i dont think any of this would play a part with a rear driveshaft vibration, would it?

concretejungle said:

Just get everything for the kit and don't try to cut corners, you'll be fine. Christo addresses the driveline issues with all the adjustable links for the 6 inch lift. With the stock set-up you can't really "tune" anything. You just get what you get.

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Just as you can't predict you truck's caster needs, neither can Christo. The same eliments that effect the needs of your truck for caster at 3" of lift are there at 6" of lift. I'd actually beleive they are more apparent at the taller lifts because of the arc the arms are travelling, slight variences in height will create more or less need for caster corerection then at lower heights. While custom arms will work on some trucks I can't see how they will work on all trucks. The one benefit though is that CC bushings can be used with them if needed.

Cruiserhead05 said:

Concrete,

Add some weight to the rear and see how she does, if it helps, i say time for a rear bumper!

Landtank,

I understand the issues of checking alignment and whatnot, before and after lifting but i dont think any of this would play a part with a rear driveshaft vibration, would it?

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Don't think so. But running around on the rear shaft only probably pushed it over the edge along with it's new rotating angles. I'd suspect he still has an issue in the front.

Rick, i don't know what else to look for in the front. I will get an alignment done. But i've checked wheel bearings, rechecked the torque on the 54 mm lock nuts, drive shaft balanced, ujoints, double cardan shaft, tie rod not touching arms now, pinion bearings for play. What am i missing?

Cruiserhead, i just had 200 lbs of quickcrete in the back today. No change.

landtank said:

Just as you can't predict you truck's caster needs, neither can Christo. The same eliments that effect the needs of your truck for caster at 3" of lift are there at 6" of lift. I'd actually beleive they are more apparent at the taller lifts because of the arc the arms are travelling, slight variences in height will create more or less need for caster corerection then at lower heights. While custom arms will work on some trucks I can't see how they will work on all trucks. The one benefit though is that CC bushings can be used with them if needed.

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But his six inch kit comes with adjustable suspension links. I imagine you could even use the OME CC bushings in the arms and/or the plates as well with the arms for some tuning. What i was refering to was the fact that the OME medium lift is just springs, shocks and CC bushings. Nothing there but the bushings are really "tunable"

Just be sure the tie rod clamps are in the correct positiion at 60* or you might get bogus results from them hitting the leading arms. The tech needs to know this as well incase he sweeps it after a toe adjustment.

I only know how to troubleshoot one way. That is to check and then verify, starting at the most obvious and through the process of elimination, hopefully come to a conclusion. It would seem that you've done all the obvious stuff and it should have been taken care of by now. While not on a LC, I've been where you are right now many a time on the various equipment that I've serviced. Sometimes you need to take a deep breath and back it up a few steps to make sure you didn't miss something or something hasn't changed along the way.

> With the OME CC bushings in place my castor measured 0 to 1.2 degrees. With the addition of 33 inch Truxus MTR tires she liked to wander the road like a dirty hooker.

Did you ever drive the lift with stock tires. It could have been the tires causing the wandering and never the lift. If you change more than one thing at a time and start getting problems, it is always a good idea to start eliminating the things you have done.


> Note at this time I don’t recall a grrrrrr at all, just a wandering truck. So with a little searching on the mud board I decided to install the castor plates that slee sells.

I assume that you went back to stock bushings. Also, have you had a caster sweep done on the setup with caster plates? Did you have the grrr sound immediately after installing the plates?

>I still noticed I had a little stink bug look so for the fun of it I put the Mr. Gasket 1 inch spacers in front. Now the truck sat perfectly level and looked good. Over the following few weeks I started taking Real Estate classes across town and had a highway drive of about 30 miles round trip. I started noticing a vibration coming from what felt like the front end. When I got home I crawled under the truck and noticed the tie rod was sitting on the control arms. Seemed that the vibration got worse and worse, and I could make it come and go with a feathering of the gas pedal. I tested things out by removing the front drive shaft, locking the center diff. and driving around with no vibration. So I figured I had it wooped, it was the front shaft. I put new Ujoints in and put the shaft back in. Vibration was still there. Next I grinded the arms to get the tie rod off the control arms. Took it for a drive with the front shaft in and still had vibrations. Next attempt at a fix was a know-it-all at a driveshaft shop that said my driveshaft was too long and was bottoming out. I still to this day have no idea why I was naive enough to listen to him and pay him to shorten my front shaft. That obviously didn’t fix the vibration either.

My guess is that you were experiencing rear driveshaft noises and thought it was the front. A lot of people do so. Next time you are under the truck, check the location of the rear output flange on the transfercase in reference to the seats. It is just about under the front seats. A noise from there can easily be interpreted as a front shaft.

>Scratching my head and posting on the mud board brought about the discussion of pinion angles and double cardan drive shafts. It appeared that I was a perfect candidate for a double cardan shaft. I really wanted to purchase the shaft from slee since he had given advice on the phone and posted in the threads about this issue, but the price was just too high for my wallet so I had one built here in town for a lot cheaper, sorry Christo.

No sweat,


> Now things begin to get interesting. I drove around for two weeks with the front shaft out with no grrrrr to speak of. NOW, two days before I picked up my front double cardan drive shaft I drove a good ways on the highway, I noticed a slight grrrrr. What the heck is that I thought. No way! Was I feeling some of the grrr from the rear shaft now?

>Yesterday I drove around with the rear shaft out and the center diff lock locked. Smooth as silk. So there is no issues with the double cardan shaft, all in all I guess that was a good move. I’m guessing that my next move is this: new ujoints in the rear shaft and adjustable upper links to move my pinion down a little.

I am thinking you were fighting worn u-joints all allong with some low caster numbers to start of with. The rear could have been ok at first, and under certain conditions you did not feel it, but pulling the front shaft made the rear do all the work and now it is just showing symptoms.

In the beginning did you ever pull the front then the rear and drove it just with the 1 shaft to diagnose?

These things can be frustrating. Also diagnosing trucks on email and phone calls can be to. Sometimes people will hear noises and experience wandering and you get in the truck and the noises are so small that it is hardly worth bothering about, or the driveability is fine but in their communications it comes over as a huge problem. Not saying it is the case with this, but have experienced it before.

Also, Rick is right re: caster, no two trucks end up exactly the same after a lift and the caster will change. However we can get it pretty close just from experience and having dealt with a lot of trucks and lifts. I wish there was a way to do a easy adjustable caster that can be dialed in, but there is not. Not that it can not be done, but for a mail order setup where you have no idea of the skill level at the other end, it is difficult to do.

Bottom line, when starting to determine driveline vibrations, the only sure way is to pull the shafts one by one. Then diagnose the location of the noise/vibration. After that, start fixing the small things like U joints and be 100% sure the fix is done right. People can install new Ujoints and mess them up in the installation as well.

If you go back to the beginning, it is apparent that your truck drove ok with no noises with the basic medium lift, except the wandering that could or could not have been caster or tires. Or low caster accentuated by bad tires. Swampers are not known as the best road tire there is.

The noises was probably bad u-joints starting to go out made worse by asking them to operate at a different angle.

landtank said:

I only know how to troubleshoot one way. That is to check and then verify, starting at the most obvious and through the process of elimination, hopefully come to a conclusion.

Click to expand...

I just typed a long email saying just that

t would seem that you've done all the obvious stuff and it should have been taken care of by now.

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Almost, he never changed the U joints in the rear shaft. If the fronts are worn and neglected, the rears are probably too/

I was convinced my problem was in the front. Had similar experainces and rebuilt the front. Borrowed a Double Carden and it did not fix the problem. Christo told me the same thing he is telling you and I had the rear rebuilt (U Joints) and balanced and the problem is gone

Christo, Romer,

For what its worth concrete and i seem to be battling th exact same problems. Although he has not done his rear driveshaft u-joints yet, i have and it solved nothing. Im well aware no truck is the same but our trucks seem to be doing the exact same thing. also, this may have already been stated but we both determined our rear shafts to be fine b/c we pulled the front one and everything road just fine. Lastly, im running bfg at's so that should eliminate the swampers from causing any strange noises, as for the wandering, known here.

I also pulled my front shaft and the problem went away. Don't understand why, but when I put the rebuilt front shaft on and even swapped in the Double Cardon, the problem came back. I was scratching my head and took it to Slee and Christo put on the electronic ears and determined it was the rear shaft. I was convinced it was reated to the front shaft and started going through other things until I gave up and went to Slee's.

Did you have your drive shaft balanced?

Both shafts had questionable U Joints (Rear was worse) and needed to be balanced. I should note when Christo took off my rear shaft the play in the U Joint indicated it was bad (It was warm then). The next day after it sat all night the "dead Spot" seemed to go away and the drive shaft shop said it was fine. I had them replace the U Joints anyways (with OEM Joints) and the problem was fixed.

I then re-installed the 1" spacers and still no problem several months later. Don't know that the rear shaft is your problem, but taking care of it would at least eliminate the possibility.

romer,

That all makes sense but again, my rear ujoints have been done. No, regretfully my rear shaft was not balanced and thats something i may do next. My front DC shaft should be here in a few days and i will know how everything feels for sure.

I'm also thinking that this could be some sort of harmonic issue with both shafts attached at the same time. By putting weight on either end you do change the U-Joint angle but you also add a dampner of sorts to the truck as well.


My thinking is that you need to make sure your caster is correct and closely examine the front diff/shaft relationship. With my truck having the caster properly setup and the height I have it's close to straight, which is ideal for a DC shaft.

On the rear it's a stock shaft and no adjusting arms and there is no Grrr from my truck. Original panhard rods as well. If I need to do more to my truck because of the lift someone will have to point out why, because I don't see it.

Thanks again for posting Christo, and everyone else.

I'll try to answer a few questioins. Yes, i thought it was the front shaft since when i would remove it and drive with only the rear shaft, the noise went away.

Yes, there was no Grrrrrrr with the OME CC bushings only in place. I did drive it with 275 size road tires and it did wander. That's when i went and had an alignment check which told me my castor wasn't nearly enough, so i decided to go to the plates.

As far as i remember, with the initial install of the plates i didn't hear any grrrrr noise. It seemed to start very small and get worse and worse.

I will try to take the truck and have an alignment done now with the plates in to see what my current castor set-up is.

Christo, in speaking of feeling the vibration, i do realize the rear output flange on the tcase is almost directly under the seats. But, it seemed to me that the vibration was coming more from the front pedal area in the floorboard.

Yes, i did go back to stock bushings with the plates.

I did have new ujoints put in the front shaft and had it balanced, still did not fix the problem. It was exactly the same.

I also 100% agree about the tires being part of the wandering. THese are not road tires, i know, but they do ride pretty good for swampers. Also, it wandered with the street tires on pretty bad.


Also, one other question. Does anyone think there is something in the tcase it'self that may be causing the grrrrr? It's just funny how removing one of the shafts cures it, and then putting the two shafts back in brings it back. Right now i have been driving around for two days with only the front DC shaft in and there is no grrrrr. I can't even get it to make a slight grrrrrr on the highway, feathering the gas at 70 mph.

concretejungle said:

It's just funny how removing one of the shafts cures it, and then putting the two shafts back in brings it back.

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This is what is making me think it's a harmonic issue. The 2 shafts are interfearing with each other. Alone, neither is out enough to create a problem, but together the two add up to having a problem.

When looking at the side of the front diff and comparing the angle of the front shaft to it, is it like this /\, \/ or this -- ?

Rick,

The flanges on the front diff in relation to the flange face on the rear diff ressemble a \/. That is why i went with a DC front shaft because the pinion face was pointing strait at the tcase. I appologize if i'm not totally understanding what you are asking.

In the rear i'm thinking i have the pinion face pointing to much towards the tcase, which i'm thinking is not what a regular driveshaft likes. The face of the flange should be more | instead of / right?

Another question, do DC shafts need to be in phase or out of phase? Also, does it matter how the front shaft is situated related to the back shaft? In other words do they have to be installed in phase or out of phase of each other? I'm getting ready to thumb through the FSM............