OK...so is this the correct assessment?

[allen_ajones]

OKay, I'll remember that.

Also, It did some testing today on the road. It feels like the vibration is definitely at highway speeds.
I did not notice anything around 50.

Although, I need to keep a record...70+ MPH seems like the magic number at which the vibration really is noticeable. I threw it into neutral at this speed and noticed some improvement but it was too hard to tell since I would slow down to under 70mph. When I go to work next or drive later today, I will get it up past 70. Out here in CA we have 65mph speed limits. SO people haul A$$.

Next test, check ujoints parked and in neutral, right?

 

[nyk438]

That somewhat like my 91's problem. I hit 50+ and I'm getting too much vibration, then 60-70 is when it's the worst. You don't know anyone with another 80 that you could just swap driveshafts to see if thats the problem?

 

[IdahoDoug]

How about more clariity on the tires? You say the others are "new". New means I bought them and they're a month or less old. If your "new" is 3 tires have a lot of tread on them, and one does not, then we're still at square one. What brand/size are all 4 tires and what's the story with them? I think I know where this is going and it's not good. How long have you owned the truck?

DougM

 

[firetruck41]

How about more clariity on the tires? You say the others are "new". New means I bought them and they're a month or less old. If your "new" is 3 tires have a lot of tread on them, and one does not, then we're still at square one. What brand/size are all 4 tires and what's the story with them? I think I know where this is going and it's not good. How long have you owned the truck?

DougM

Are you thinking burned up/locked up center diff?

Doug brings up a good point about the tires, some have recommended that all tires should be replaced at the same time, but at the least both tires on each axle should be as close to identical regarding outer tire diameter. So if the newer tires have been on for a while, it *might* be a good idea to replace both on the rear axle with new ones.

 

[IdahoDoug]

Actually, more critical that F/R diameters match than side to side as the steel differential gears in the axle can spin at different rates all day. The high range viscous in the center diff is what needs to be protected. The F/R shafts will actually spin at the average rotation of their respective tires.

DougM

 

[Kalawang]

I was able to determine I had a driveshaft problem by simply putting it on a gas station lift and having a friend run the engine in drive at high revs. If the driveshaft shakes, it needs replacement or repair. At $ 400, I think replacement is the better option. You can also look at your wheels at the same time and see if they shimmy. Check the side walls for ply separation while they're up. If it's onl;y a shimmy, balance them. If it's a bulb at the sidewall, replace the tire. You might also want to look closely at your wheels as they really do sometimes get bent out of shape.


Kalawang

 

[allen_ajones]

The three tires are michelans and they are probably less than 3 months old. I am going to replace the 4 and get all balanced and rotated (if needed). However, I am really starting to think its the damn roads out here CA. The highways are not smooth but the shaking is from side to side and not up and down. So, I really am flustered. I don't know what it is. I don't know anyone with an 80 to swap DS with.

Also, I took it up to 80 and through it into neutral and nothing changed. SO, that is not the DS, right?

 

[IdahoDoug]

The driveshaft is still rotating at the same speed when you put it in N, but it's not getting torque applied to it by the engine power at that point. If no change it points to a tire issue. The reason I asked about the tires is that it does not take much wear and they're a different circumference. Even now you're going to have 3 "old" tires and 1 new tire so there will be a circumference difference. With a car that's full time 4wd, this is an issue and not ideal. If the tires are more than 3 months old (sounds like you're guessing) then they may have 3500 miles on them for example. That's 10% of their life and therefore compared to the new one there will be a 10% difference in their revolution speed. Now the ABS is trying to compare speeds, the viscous coupling is fighting the different rotating speeds, etc.

So, that's why I asked and no I don't know if you switching from 3 new tires and 1 old to 3 old tires and one new will change your issue as you're taking a tire rotational difference with you.

DougM

 

[allen_ajones]

If that is true and what is actaully causing my then I am very DEPRESSED INDIVIDUAL.

Tires that size are not inexpensive especially michelans. It is very, very hard from me to believe that 3 months caused this

Either way, I can't chuck those tires. I can't.

Thanks for your insight I appreciate it. now I am going to go jump off the building roof.

 

[photogod]

Thinking the odd tire is the kulprit and the side to side movement is from the sipeing in the concrete. Change your tires and have a ballance and check your allignment as this has happened to me in the past. Really bad on my motorcycle. The tires were not lined up properly and the thing danced from side to side. Also check for excessive run out in the tread this will cause vibration no matter how well they are ballanced and alligned.

 

[allen_ajones]

and the side to side movement is from the sipeing in the concrete. Also check for excessive run out in the tread this will cause vibration no matter how well they are ballanced and alligned.

What do you mean by "sipeing in the concrete" and "excessive run out in the tread this will cause vibration"?

 

[landtank]

You could have just thrown a weight, bent a rim, whatever. Just move both front tires to the rear and take it for a drive. If the front now vibrates than it's one of those tires.

 

[allen_ajones]

You could have just thrown a weight, bent a rim, whatever. Just move both front tires to the rear and take it for a drive. If the front now vibrates than it's one of those tires.

Got it! I plan on getting the forth tire tomorrow. However, I simply can't replace the three new ones, though. They are brand new. I mean they look great. Maybe 3 months old but hardly any miles on them as I was driving another car to work mostly.

 

[firetruck41]

Get your tire at a shop that has a Hunter GSP9700 and have them balance all 4 tires on it, I have had difficult to find vibrations in 2 vehicles that have been solved with the GSP9700, even brand new tires balanced on a regular computerized balancer did not work, I went the next week to a different shop and had them balanced with the GSP9700 and problem was solved. It is critical that you have them balanced on a road force balancer machine like that, IMHO. That way you can at least rule out bad tires.

 

[allen_ajones]

Duly Noted. FT you have made a point about this over and over. I really appreciate you driving that point home. It is only because you have mentioned it several times that I remembered. But this last time made the difference. I will make sure that I get the tire and the balancing down at a shop that has the Hunter GSP9700. I will let you guys know soon. And you will have me singing your praises if it fixes this problem. Until then...thanks because you guys make this forum invaluable to folks like myself.

 

[Riley]

Did Ben mention that he owns stock in Hunter Engineering?

Q2 has been looking a little slow for Hunter and I think he's trying to the numbers up by recommending them.



JK....

 

[firetruck41]

Did Ben mention that he owns stock in Hunter Engineering?

Q2 has been looking a little slow for Hunter and I think he's trying to the numbers up by recommending them.



JK....

It just fixed the problem on a BMW I owned, after I replaced the entire front suspension (really), and several "computerized" balances trying, to find the problem. I worry that people see me recommend a Hunter GSP9700 and think, "I already had it computer balanced!", but it is not the same!! So I repeat myself in the hopes people will see the difference.

 

[IdahoDoug]

Ben,

I had my tires done at a Les Schwab in Hayden Idaho where they used a Hunter with "road force" to get them perfect. Is this the same thing?

DougM

 

[firetruck41]

Likely, I know some of the Les Schwabs around here have it. I don't know all the models Hunter has, I know they have computerized balancers, but the GSP9700 is different and is a dynamic balancer that (from what I remember) can check wheel roundness & runout, tire roundness, balance with road force, lateral balance, etc. So if it was a Hunter road force/dynamic balancer it is probably the same. There's a bunch of cool info at www.gsp9700.com with animations etc of how it works, apparently now it can solve "pulling" that is not caused by alignment...

 

[photogod]

What do you mean by "sipeing in the concrete" and "excessive run out in the tread this will cause vibration"?

If I'm not mistaken your roads have groves cut into them to help channel water. This is called sipeing (sp) and will cause an out of allign drive train to jump from side to side as the tires don't lighn up with ths groves in an out of allign situation. Excessive run out is when the tread was laid on to the carcus of the tire improperly. The tread layers have a bit of serpentine movement in relation to the carcus. If you look straight on to your tire and spin the tire you will see a wobble or back and forth movement in the tread from side to side. This will cause a vibration or shimmy at highway speed. I reciently had a set of Bridgestone Desert Dulers replaced because of excessive runout. They will try to ballance the tire and rotate it 180 on the rim to try and hide the fact that there is to much run out so stay close if you have someone else test for that. If it is the problem the tires should be replaced. Nothing can be done to correct the situation.