2nd Gen Non-Engine/Transmission Still Shakin’

[wilsonsh]

I'm still chasing this same problem as well! I crawled under and felt around a bit on the rear end the other day and the pinion bearing housing was quite a bit warmer than the rest of the rear end. Have you considered the pinion shaft bearing?

 

[BEnglish]

I'm still chasing this same problem as well! I crawled under and felt around a bit on the rear end the other day and the pinion bearing housing was quite a bit warmer than the rest of the rear end. Have you considered the pinion shaft bearing?

i have thought about it but have not checked it yet. It was lower on the list.

The next thing will be to follow it in another vehicle while my wife drives it down the highway. Hopefully that will narrow it down, I only wish I would have started with that instead of throwing new parts at it.

 

[Joe Mc]

Try this, get it on level ground and place 4 stands under the closest point of suspension on each housing tubes. Hop in fire it up and put in gear, and let the drive line spin on it's own to see if it vibrates without throttle. If it doesn't gradually increase the throttle, it will shift so just go easy, notice when the vibration starts, then increase throttle noting speeds vibration gets worse and/or goes away. If no vibration, let off throttle, pop in neutral allow speed to come as low as it will (may keep spinning may not) then turn key off - still in neutral. After verifing everything has stopped spinning, put in 4-wheel high and repeat. Now, when you get the vibration - whether in 4wd or 2wd, get someone you trust to repeat (bring to speed vibes were noticed) and then you start looking around to see if you can locate it. Look at the tread line on the tires, look for wobble on wheels, drive shaft, lay under the rear and place your hand on each tube of the housing, on the diff cover, move on up to the carrier bearing, then the transfer case, the transmission tail shaft, working your way up touching everything in the driveline not moving (duh except exhaust) even the oil pan.



What I located doing this was a bad crankshaft vibration dampner. I went with the Fluidampr - SCH-MOOOOTH!



However, since you have it up on the stands, try this as well, take off the tires, make sure you tighten on a few lug nuts on each hub so you don't loose anything and spin her up again to see if the vibration is still present, if so then remove the drums and do it again.



I want to make 3 things "very" clear when you are performing this test:

1-If you don't have very good stands "don't even think of doing this".

2-Do "Not" try to maintain the vibration speed by using the cruise control - remember cruise control works in conjunction with load increase decrease - notice when you go uphill it increases speed and decreases down hill? Trust me - my buddy was in my truck holding the speed for me and decided he wanted to see what I was doing - so he set the cruise control as I was laying on the ground underneath the truck all 4 wheels and back drums off "WHAAAAAAAA" I about pooped my shorts#@$%! then the motor slowed to an idle. He says, "WTF happened all I did was put the cruise on?" So trust me don't even try - and make sure you tell your buddy or wifey don't touch the cruise:-laf

3-Don't apply the brakes "at all", remember there's a good deal of mass spinning with those tires and to hit the brake while they're spinning freely could "brake" something you don't want to replace. Emphasis on why I mentioned earlier "let off throttle, pop in neutral, then turn off the key after everything stops spinning or slows as much as it will". Oh, don't put it in Park until you walk all 4 corners to make sure nothing is spinning too . . . Also, if the brakes are applied with the drums off "pop" goes the wheel cylinders:{



This is a good method to locate the "area" of the vibration "if" it is drive train related. If there are no vibrations during this test then your vibrations are related to something in the suspension. It could be a loose component in the front end, or even a bad band in a tire.



Locating a vibration can be more difficult than fixing it. I chased mine for over 4 years before I found it was a combination of: crankshaft dampner, loose sector shaft (DSS Steering Stabilizer fixed that one), bad band in a tire, 3 stock type POS trackbars (DSS 3rd Gen adjustable fixed that one). I'm telling you, it's almost embarrasing how much money I threw trying to cure the "vibration monster", front hub assyemblies, rear axle bearings, drive shaft rebalance, numerous alignments, tires, shocks, drums, and even "Centramatics" (only helped a little bit). :{



But the end result is SCHA-WEETOo.



You really gotta love the truck to not get fed up and dump it for something else when chasing this type of situation, it's a love/hate thing for sure.



Good luck and keep us posted.

 

[wilsonsh]

Engine damper?

I got a question for ya Joe... before you installed a Fluidamper, did you notice the vibration in all gears or at like 40mph and then again at 65+mph. My vibration doesn't seem to be engine related but could be since the load on the engine is about the same per gear at each speed...

meaning: the load on the engine is about the same in 4th at 40mph as it is in 6th at 65mph. I'm guessing from the sound of it, BEnglish is in about the same situation.

 

[TBartlett1]

Could you describe the vibration? Can you feel it in the steering? Is it the front or rear end? What is the frequency? Is it a low frequency such as tire rotation or high frequency such as driveline. Knowing this will help us point you in the right direction. Unbalance in any component will usually come and go as you accelerate. It could possibly be the engine. Does pushing the clutch in or engine speed change it?

 

[wilsonsh]

High frequency in the rear end.

My vibration is high frequency in the rear end... which, from the sound of it, is the same or almost the same as BEnglish's.

I'm basing my evaluation on the vibration being in the rear on: I don't feel the vibration in the steering and I can feel it in the seat and floorboard; I had a gas can with the long filler tube in the bed and I could watch the filler tube bounce at the stated speeds.

High frequency as in it doesn't bounce the truck but it does shake the back of my truck in a very fast, minimal motion.

I've tried driving past the vibration speeds and then pushing the clutch and letting the truck slow and it still vibrates.

I've tried running at these speeds in different gears and it still vibrates. I also checked the timing marks on the damper and flywheel and they are perfect with the damper's overall condition very good.

The best I can describe the vibration at 65+ is tough on a computer but:



whaaaa... . smooth... whaaaa... smooth...



This cycle is about 4 sec length.

I also have had both front and rear driveshafts rebuilt with new u-joints and balanced. I added centramatics to my brand new tires to eliminate the tires and wheels from the equation.



Sorry BEnglish, not trying to hijack your thread!!

 

[TBartlett1]

Sounds like the rear drive shaft has a bad u-joint that may be siezedor loose. Look at the u-joint closely and see if there is any red powder around the caps (rust), the joint may appear tight but it may be siezed. To verfiy disconnect the shaft to check the joint for loosness (wear) or stiffness. While there give the pinion a wiggle it should be tight.

 

[wilsonsh]

Just rebuilt the driveshaft 3 months ago... new u-joints and the works. I have jerked on the pinion shaft pretty hard and it is tight. Judging from this thread, it seems the next logical step is to replace the pinion shaft bearings, though.

 

[BEnglish]

Try this, get it on level ground and place 4 stands under the closest point of suspension on each housing tubes. Hop in fire it up and put in gear, and let the drive line spin on it's own to see if it vibrates without throttle. If it doesn't gradually increase the throttle, it will shift so just go easy, notice when the vibration starts, then increase throttle noting speeds vibration gets worse and/or goes away. If no vibration, let off throttle, pop in neutral allow speed to come as low as it will (may keep spinning may not) then turn key off - still in neutral. After verifing everything has stopped spinning, put in 4-wheel high and repeat. Now, when you get the vibration - whether in 4wd or 2wd, get someone you trust to repeat (bring to speed vibes were noticed) and then you start looking around to see if you can locate it. Look at the tread line on the tires, look for wobble on wheels, drive shaft, lay under the rear and place your hand on each tube of the housing, on the diff cover, move on up to the carrier bearing, then the transfer case, the transmission tail shaft, working your way up touching everything in the driveline not moving (duh except exhaust) even the oil pan.



What I located doing this was a bad crankshaft vibration dampner. I went with the Fluidampr - SCH-MOOOOTH!



However, since you have it up on the stands, try this as well, take off the tires, make sure you tighten on a few lug nuts on each hub so you don't loose anything and spin her up again to see if the vibration is still present, if so then remove the drums and do it again.



I want to make 3 things "very" clear when you are performing this test:

1-If you don't have very good stands "don't even think of doing this".

2-Do "Not" try to maintain the vibration speed by using the cruise control - remember cruise control works in conjunction with load increase decrease - notice when you go uphill it increases speed and decreases down hill? Trust me - my buddy was in my truck holding the speed for me and decided he wanted to see what I was doing - so he set the cruise control as I was laying on the ground underneath the truck all 4 wheels and back drums off "WHAAAAAAAA" I about pooped my shorts#@$%! then the motor slowed to an idle. He says, "WTF happened all I did was put the cruise on?" So trust me don't even try - and make sure you tell your buddy or wifey don't touch the cruise:-laf

3-Don't apply the brakes "at all", remember there's a good deal of mass spinning with those tires and to hit the brake while they're spinning freely could "brake" something you don't want to replace. Emphasis on why I mentioned earlier "let off throttle, pop in neutral, then turn off the key after everything stops spinning or slows as much as it will". Oh, don't put it in Park until you walk all 4 corners to make sure nothing is spinning too . . . Also, if the brakes are applied with the drums off "pop" goes the wheel cylinders:{



This is a good method to locate the "area" of the vibration "if" it is drive train related. If there are no vibrations during this test then your vibrations are related to something in the suspension. It could be a loose component in the front end, or even a bad band in a tire.



Locating a vibration can be more difficult than fixing it. I chased mine for over 4 years before I found it was a combination of: crankshaft dampner, loose sector shaft (DSS Steering Stabilizer fixed that one), bad band in a tire, 3 stock type POS trackbars (DSS 3rd Gen adjustable fixed that one). I'm telling you, it's almost embarrasing how much money I threw trying to cure the "vibration monster", front hub assyemblies, rear axle bearings, drive shaft rebalance, numerous alignments, tires, shocks, drums, and even "Centramatics" (only helped a little bit). :{



But the end result is SCHA-WEETOo.



You really gotta love the truck to not get fed up and dump it for something else when chasing this type of situation, it's a love/hate thing for sure.



Good luck and keep us posted.

Thank you for your detailed response. And all the responses for that matter.

I would be very surprised if it turned out to be in the front as it shakes the truck not the steering wheel. The rear axle would be my first guess and the engine is going to be my second at this point. I too have thrown a lot of parts at it, but don’t have any intention of giving up, but before I buy anything else I am going to do more diagnosing.

I have been at the vibe speed and put it in neutral (auto) and the shake stayed the same speed.

Tomorrow I will be following it down the highway, and if I still can’t pin it down I will use your suggestion. And I do have a bunch of good (12 ton, I need the tall ones for my Jeeps) stands. Thanks for telling the cruse story, both because it was funny and I probably would have tried it.

I will let you all know what I find.

Ben

 

[TBartlett1]

It definitely sounds like you have located the source. When did the vibration start? Did it happen all of a sudden, or did it develope slowly? Kinda fishing here!

You can check the pinion bearings with a mechanics stethoscope by putting the truck on a lift or jackstands and letting it run in gear (with someone in the vehicle) and listening to the differental in the area of the bearings. It should sound smooth. To calibrate yourself listen to other areas of the vehicle such as alternator or fan hub. I had a noisy rear axle in my jeep and I disconnected the driveshaft and rotated the pinion by hand and could feel the rough bearings.

Don't give up we'll find it!

 

[BEnglish]

Well this weekend I had my wife drive it down the highway and I drove next to it and watched. I couldn’t see any of the tires shaking (other than normal 75mph road shake) the only thing I really saw moving was the front end (nose of truck not front drive parts).

When I got home I put it up on stands (positioned under the axles as close to the tire as I could get) and had her run it up to 55mph. I was too intimidated to run it up any higher. I didn’t see any movement. The drive train was solid. The motor mounts are solid. The DS looks balanced.

The only thin I noticed when I was inspecting was that the ball joint on the front track bar is shot (1/4” of movement in the ball). This is a new bar. I replaced it with a Napa piece that turned out to be no good, then I returned that one and got a second one that is now shot after only maybe two or three months. I will do some searching on here for the best replacement, but suggestions are welcome. I also intend to replace the steering gear box to a 3 and ½ turn box and one of the cross brace things too.

 

[Dave M]

There are many choices for a track bar so you must decide. I'd get rid of the joint on the track bar by replacing it with a SS adj 3rd gen track bar and SS 3rd gen track bar conversion kit. Then no more joint to worry about just a bolt thru bushing on both ends.



I also like the 3 turn PSC SG-841M steering gear that allows steering with one finger and the DSS steering stabilizer.



Good Luck,

Dave

 

[BEnglish]

I just finished ordering from PSC a 3 turn steering gear box and their DSS for the sector shaft.

I also got, from KLM the SS track bar conversion kit and the 2003 adjustable track bar.

I hope this fixes my shake!

 

[TBartlett1]

I don't know why I didn't think of this before??? Check the driveshaft for signs of a missing balance weight. That will certainly cause this mysterious problem. The weights are spot welded on so you need to look closely for the remains of a rusty spot weld.

I had a friend with a F250 loose one, he heard a something that sounded like a rock hit the body then the truck started shaking.

 

[BEnglish]

Good idea, but with the way the rear is a two piece and is allowed movement via the rubber in the carrier bearing, and I was under it while the tires were spinning 55 MPH, I think I would have seen the DS moving if it were unbalanced but I didn’t. it looked balanced.

 

[TBartlett1]

In your post you said it happened at 40 then 65+ mph. When you put it on stands you only ran it up to 55mph.

40 and 65 are the critical rpms.

Also the fact that it was on stands would tend to ground or null the vibration out.

Your symptoms are typical of unbalance, Check the shafts very carefully.

 

[Joe Mc]

I got a question for ya Joe... before you installed a Fluidamper, did you notice the vibration in all gears or at like 40mph and then again at 65+mph. My vibration doesn't seem to be engine related but could be since the load on the engine is about the same per gear at each speed...

meaning: the load on the engine is about the same in 4th at 40mph as it is in 6th at 65mph. I'm guessing from the sound of it, BEnglish is in about the same situation.

During my search for the vibration I came about the dampener issue as described in previous post. Since the stock one's rubber looked weak, appeared to have shifted from the crank part of it and the alignment marks could not be found I replaced it. Had one fail on an old hot rod once - not good - so I considered it cheap insurance Vs the cost of an engine job.



My vibration was more like someone was beating on the pass front floorboard with a rubber mallet around 55 - 75 mph under and over that it wasn't "that" noticeable.

 

[Joe Mc]

Also the fact that it was on stands would tend to ground or null the vibration out.
Your symptoms are typical of unbalance, Check the shafts very carefully.

As far as being on stands nulling out the vibrations, if it's a rotating mass issue this method will reveal it.

A funny thing I just remembered, check the rear axle bearing pre-load before you go tearing into the pinion/carrier. 120 - 140 ft lbs as you rotate the axel and then back off 1/8th turn, don't forget to get new wedge thingies as you are not "supposed" to reuse the old ones.

The biggest number one thing I did that helped was the steering stabilizer and dump the track bar (went with 3rd gen adj & adapter bracket).

Lay under the steering box looking at the sector shaft, have wifey in truck motor running and tell her to turn lock to lock as you watch the center of the shaft - if it moves side to side BINGO!

 

[wilsonsh]

Just some info: I went to the shop today and they showed me that my tires are out of round.



They jacked up the rear end and had a guy put it in gear(4th) and let it turn at idle. Using a straight edge between the ground and the tire, under the tire, you could see how the tire was out of round. He found both back tires out of round and suspected more. Now, these are BFG ATs with about 5k on them. Next step for me is to try and get the dealer I bought them from to replace them but that'll be another thread, I'm sure. I'd like to get a second opinion and make sure it isn't the rims that are bent! It is VERY frustrating, expensive, and time consuming to find a shop that will take you seriously!



Just thought I'd share and give you another step you could take at home to diagnose the shake.

 

[CRWilliams]

You guys running the PSC steering gears, I have a question. I am going to order one soon and need to know if you are running the sg-841M or the sg-841MX. The "X" box says that it has very low steering effort. If you are just using the regular variable ratio box, can you turn the wheels while at rest. I have a large winch bumper on the front and 35X12. 50 tires on 17" wheels.