M1009 vibration

[2deuce]

I have this noticeable vibration that seems to be strongest while accelerating between 35 and 45. I've looked at the damper and it is rock solid true running at idle. I had a u joint wear out and replaced that and had the driveline balanced at the same time. The vibration is a engine speed resonance. It is not slow like a bad tire. Is the damper fooling me or something else? The vibration is less noticeable while coasting, but it still there but not as hard. I've watched the engine when I've given it some throttle with the brakes on and it stays put so I think the motor mounts are fine.

Thanks

 

[cucvrus]

Check the rear u joint. It need to have the C clips installed on the caps that good in the differential yoke. If they are not installed the U joint can move back and forth. It may not move now when you have it tight in the clamps/straps but it may not be truly centered in the yoke. Check it out. Does it have the C clips on the caps. Let us know. I have seen this a dozen or more times on M1009's.

 

[2deuce]

When the sun comes up I'll check, but I don't remember seeing any when I installed it. In fact I don't ever remember seeing c clips on the rear caps on any of the M1009's I have flat towed over the years. It makes the same vibration as it did before I had the rear driveline rebuilt. The old driveline made a clicking sound that could be heard with the engine off and coasting. I could see the u joint sliding back and forth in the bearing caps. If the caps were too wide maybe I only needed clips. I still have quite a few M1009's, I'll check them all.

Thanks

 

[2deuce]

I looked at 4 of them in my driveway none of them had a clip in the u joint. The one my son uses runs smooth, but there is slop that a clip would correct. I can make it move a tiny amount by pulling on it. I'm going to give napa a call.

Thanks

 

[cucvrus]

They should have C-Clips. I will look for a picture.There you go. That is how the U joint stays centered in the rear yoke. I hope that helps you.

 

[2deuce]

I went to napa and bought 2, but the vibrating truck has them(my mistake), the smooth running truck that has slop back there doesn't. I'm going to install them in the truck where they are missing. So it must be something else making this truck vibrate. I can't find anything in the drivetrain that is loose. Could the gov loc in the rear cause this? or should I look again at the damper while someone revs the engine? One thing of note is I don't feel any vibration while the engine is revved in park. It is very noticeable like I said earlier between 35 and 45mph.

Thanks

 

[cucvrus]

Check for a bent wheel.

 

[Rvitko]

It could be as simple as tires that have a flat spot from being parked so long or they are out of balance.

i would change the harmonic balancer, mine physically looked fine, but the pulley oscillated when you watched it while running. The biggest improvement I have made was a new balancer it smoothed out the engine so it sounds like a new engine.

You out might also check the front end, my ball joints were shot so the wheels wobbled, I caught this due to my new drag links having the boots rubbed through. I changed the whole axle for a milsurp one as it was cheaper than rebuilding what I had if I factored that I got brand new brakes and locking hubs, but it was not a fun job, 2 men and a day to drop the old one and install the new one but I changed the leaf spring bushings and cleaned and rebuilt the leaf packs while I was at it.

 

[2deuce]

I had enough time yesterday to jack up the truck. No bent wheels. I watched the balancer while it was running and it has no wobble whatsoever. There is no vibration noticeable unless you are moving, and traveling at a steady speed, or coasting makes the vibration hardly noticeable. Accelerating is another matter, the glove box is rattling, the steering wheel is shaking, and windows get noisy. It is a fast vibration like the speed of the engine not the speed of the tires. At speeds above 60 it becomes unnoticeable again. I have thought about removing the driveshaft, but without a load on the engine, I'm doubting I could tell any difference and with the shaft out of the tc, it could get messy. This is a nice AF M1009 with about 80k, zero rust. The vibration didn't just show up one day, it has always been there, but it does seem to be getting slightly worse over the 10k miles I've driven it.

Thanks

 

[NovacaineFix]

I have the same issue with my M1009, it could be your leaf springs. Check the surface of your tires on the axle that you believe is causing the shaking/vibration.
Normal tear wear should be flat even surface on the tire. If you have some feather edging, it most likely is your leaf springs. Feather edging looks like the pic below if you're not familiar. Basically, it will feel like every other tread block is high then low.



New or good shocks can mask the issues with springs.
On certain roads, I can feel the tires dribbling on the pavement like a basketball.
Sometimes the stabilizer will be bad, but that usually causes the dreaded "death wobble", so I would put my money on the leaf springs.

 

[cucvrus]

OK how about u-joints being worn or ferrelled? Motor mounts transmission mounts. Bent drive shaft or a dent in the drive shaft. Is this with the front lock outs locked or free. It is drive line related. I am thinking not a suspension issue at this point. Check power train front to back. Exhaust and all.

 

[2deuce]

It is not the driveline. I had the driveline totally rebuilt thinking it was the cause, but the vibration has not improved. I have run the hubs locked and unlocked without any difference. I have checked the motor mounts, but I will have to take a look at the trans mount. I'm going to put a different set of tires on it to eliminate that possibility, but I don't feel much vibration unless I'm accelerating, so I don't expect that would be a cause. I would like to thank you all for your ideas.

 

[NovacaineFix]

My money is still on the leaf springs.

You stated that the driveline was totally rebuilt, I "assume" the leafs are factory.

If you have a GoPro with a vehicle suction cup mount and fell okay about it, mount the GoPro to the fender so that you can see the wheel in motion as you're driving. Do this for each wheel and review the footage.
If you don't have a GoPro with the needed mount, have a friend drive nest to you as the vibration happens, see what the wheels are doing.
Like I say, just going by what you have checked already, leaf springs.

Not trying to be Mr. Professor or anything like that. The leaf springs don't just provide the weight carrying capacity for the vehicle (1/2 ton, 3/4 ton 1 ton and so on), they also provide downward spring thrust for the suspension so that the wheel stays firmly planted on the road surface allowing the suspension to do it's job. Once the spring wear or lose their tension, the suspension has to do double duty causing it to wear out sooner. Without that spring tension, the wheel will dribble on the road surface like a basketball.
I will not matter on the speed that you are going, but more on the actual road surface, but it seems smoother at higher speeds.

Good Luck man, let us know the prognosis.

 

[2deuce]

I suppose it could be anything causing it, but the vibration is fast. I can see the glove box flutter at 40mph. It is not a bouncing type of oscillation. The road I live on was paved last month and the surface is smooth, very smooth, but the vibration is unchanged. I changed out my 2 front tires today(actually my son did it for me)and I'll give it a test on my way to work tomorrow.
I pulled my truck up a steep incline today where the truck was in low gear and the engine was pulling hard and the speed was about 2mph. There was no vibration felt with the rpm's high and the truck going slow, just like I don't feel anything wrong when in park and then reving up.

 

[cucvrus]

It is not the driveline. I had the driveline totally rebuilt thinking it was the cause, but the vibration has not improved.
You had the pinion bearing replaced and the ring and pinion back lash all properly checked and adjusted? And the outer axle bearings? I mean you are on a mad witch hunt to find this vibration. I had a few vibrations on my Mule and when I disassembled it and replaced a ton of parts just to do some heavy maintenance I found things worn that I never imagined or knew were worn. I replaced everything I could. No more adverse vibrations or issues. I call it a conundrum. I never knew which one fixed it but in the end it is fixed. If you throw enough time, parts and money at something you can fix just about anything. I don't like to put it that way but many times it ends up that way. I start with a small repair and it turns into a major overhaul. The list goes on and on. Spring bushings worn out or leaf springs worn out. ??????You get where I am going. It is 30+ years old and every GI in the Army has worked on it and did whatever they thought needed done even it it did not need done. Like I said in the past. I am glad i am not depending on these vehicles as my Daily driver. That would not do. likeee that many parts I can hardly

 

[2deuce]

Replacing the front tires had no effect. I had these same rear tires on my sons truck where they ran fine. When the truck shifts from 2nd to third the vibration is hard to notice, because it is getting at the upper end of the vibe range. What seems to be is that while the vibes are lessening there is no dramatic change during the 2 to 3 shift. I wish I could run the truck without the rear driveline to test vibes without the power to it. The problem seems to be pointing at the rear end. I do daily drive this truck but I only drive 4 miles to work so it barely warms up. I don't want to rebuild the rear, I'd rather change it for a stronger design if it comes to that. For now I guess I'll watch the hood flutter along with the glove box, until it gets worse or I figure this out. I don't think I can tell anything from jacking it up and running it through the gears because it only comes on strong with a load. I'll keep inspecting and when I do find the answer I'll come back and report it.

Thanks

 

[royalflush55]

The m1009 has a real short rear driveshaft to start with. If this ride has always had this vibration the rear end yoke angle may not be matching the rear of the transfer case yoke angle. A transfer case mount or the rear springs could be causing a problem with this. Sometimes the correct shim wedges between the springs and the spring perches will correct these mismatched angles. With the really short driveshaft and mismatched angles there will be a whirring sound vibration in a certain rpm range but not above or below this range. U-joints will also have a short life span under this condition.

 

[NovacaineFix]

I know I probably sound like a broken record and I'm sure you're tired of hearing it. I also know that replacing the leaf springs is not a quick and simple task like changing tires, but may I suggest installing a helper spring?
It is fairly easy to do and reasonably inexpensive.

Now if it is the leaf springs, the vibration should be toned down if not completely gone after installing the helper spring. But the helper spring would only be a short term fix if it seems to be of some help as that means the leafs are worn and have little or no spring tension left in them. All the helper spring would be doing is supplementing the worn out spring, but it may be enough to help eliminate the vibration you are feeling.

On mine, the vibration tends to be more noticeable on smoother roads as the tires seems to "dribble" on the slightest bump or ripple. The rougher roads I don't notice the vibrations as the road is rough but I do see the frame bumper has made contact with the leafs, so that confirms to me, on mine, that the leafs are deflecting too much for the roads I am riding on.

If it winds up not being your leafs, I'll drive up there and help you figure this thing up, been meaning to take a trip up to Oregon one of these days.

 

[2deuce]

no change in the vibration after I put a hmmwv wheel and tire in the back along with other spare parts. Not a lot of weight and maybe I'll try more but it seems unlikely it is the springs. The road I live on is new and smooth as glass, but it vibrates in 2nd gear at 35mph and is especially noticeable accelerating. It was not as noticeable until they fixed my road. Novacainefix, your talking about the rear leafs? How many miles were on your truck when you changed yours?
This truck has had an easy 85k miles, you can tell by crawling underneath. Driveline misalignment could be it, but how does that happen? The first thing I did was see if anything was loose. I'll check again.
On a side note we drove the truck about 8+ hours last monday. 3+ hours down, 5 hours back. The return trip was held to 50mph with much freeway driving. We were following and could not pass as we were the rear escort. I know this is subjective but we only used a half tank the entire trip, approx 300mi. The economy is crazy good if you can stand going that slow.

 

[jpg]

I had a strange vibration that went away when I tightened loose belts. It would come in at some speeds, and fade away when I sped up or slowed down.

I didn't know it was the belts. I just tightened them because they were loose, and the vibration disappeared.