92 w/ a shaking/shutter problem

[GOODE11]

Hey guys, I have a problem I hope some of you can help me w/.



Its a 1992 extended cab 4X4 w/ the automatic. I have had a shutter in it from about 10-20mph for the past month or so. I replaced the central support bearing, thinking it was the cause, although it was in bad shape it didn't do anything to the shaking symptom.

Last night as I was leaving a toll booth on the interstate and it did the same shutter from 10-20mph then at about 28mph the whole truck started shaking very bad. So I slowed down to about 25mph(slight vibration) for a mile or so and it went away.



Now everytime we slow the truck down and try speeding back up it starts the shaking/vibrating thing until you slow down and run it as I stated above.



I need to get this fixed ASAP. The truck is going up for sale and its a little tough to get anyone to look at it in this condition.



I would really appreciate anyones advise/suggestions.









__________________

Thanks



GOODE11

 

[formula]

Check the universal joints on rear driveshaft. They may well be shot. If you've got the front hubs locked, unlock them and see if the shudder goes away. If so, then probably a front driveshaft universal joint is shot. Did you happen to run anything over? If the driveshaft gets dented it can cause it to go out of balance and eat universal joints, bearings and seals. I've had similar symptoms from fried universal joints on many occasions. Maybe a fuel problem... ... . Check for water in fuel and change fuel filter.



Sean

 

[sgriffing]

Shim

There was something about a shim (1/2" ?) between the crossmemeber and the carrier bearing on extended cabs.

Do you have a shim in this location?

 

[GOODE11]

This is why I love the 1st Gen. forum. Very quick, inxformative responses.



I'll do the shim thing and see if it works. We checked the u-joints when we had the shaft off for the central bearing install.



Thanks again guys.

 

[GOODE11]

I checked for a shim and it does have one installed. We shimmed it down another 1/4" and it made the symptoms twice as bad. U-joints are good.

Do you guys think that I may need to pull the 1/2" spacer? This is my brother's truck so I'm relaying info here. But he said, if he remembers correctly it started all of this shutter/vibration when he installed the add-a leaf from skyjacker in the front spring pack. This is why I wonder if we should pull the spacer that is in there.



What do ya think?

 

[BushWakr - RIP]

If it was worse when you added the extra 1/4" try pulling the 1/2" and using just he 1/4". Maybe that's all you need.

Also, do you see an sign that a balance weight has gone missing off the driveshaft?



Bob.

 

[sgriffing]

Back it up!!

"It all started when he added the sky-jacker add a leaf to the front".

What shape is the front drive shaft in?

If you raised the front, thereby changing the front geometry, the front shaft could likely be the problem.



It's just a thought.

 

[GOODE11]

Maybe I am not explaining the shaking of the truck good enough. You can be going under 5mph and the whole truck shakes, the 4X4 shifter and the steering wheel even shakes back and forth. It's not just a slight vibration. It did this when I put the 1/4 shim on the carrier barring and when I took all of the shims out. I drove it this morning and it had the shutter from 10-25mph but it did not have the heavy shakking like it did last night or like it does right now.



I was linking that maybe something might be heating up and getting some play in it?



I appritiate the responses but after working with propeller shafts

I don't think that is where it is coming from.

 

[Philip]

What you are talking about sounds like a case of what the 2nd gen guy's call the death wobble.



1st I would check to see if the mounting plate the steering box mounts to is cracked or broken.



2nd I would jack the front end up and spin the tires one at a time looking for a bent rim/loose bearings. Also as each tire clears the ground watch to see if it drops down a little like a loose bearing or ball joints.



3rd I would put the truck on jack stands and run it in gear. See if you have the vibration with the wheels unloaded. If you do not have the vibration. Then it is axle related.



IF your front axle componets check good. Check the rear axle to see if it is bent. A bent axle causes uneven drive forces. A first gen will shake from this reason alone. I have seen it on my own truck.

 

[MikeO]

You mentioned that you replaced the center support bearing? IIRC, you need to separate the front and rear shafts for that. Did you put them back in the same orientation? They are balanced together as a unit, not as two individual compontents. If you put it back in 180 degrees off, that would explain the shuddering.



Mike O.

 

[Jluther]

Goode 11... I'd still think u joints??? My 89 2WD did a very similar thing, a vibration that came on at a certain speed. It also got progressively worse over time and became so bad that I stopped and had the truck towed in, thinking that the shaft was going to come off and take innocent bystanders with it.



The U-joints seemed fine when shaken and twisted by hand but we found that the middle U-joint bearings were literally dust. A key might be whether the U joints are unevenly warm to the touch when you stop while its doing the vibration. On my truck the bad one was hotter than the others.



I have an old Volvo wagon doing a similar thing right now, no vibration on acceleration, plenty of vibration at deceleration between 20 and 10 mph. I expect to find a bad u joint under there when it gets warm enough to look.



good luck

 

[GOODE11]

Its fixed

Thanks to all who responded. We isolated it to the driveline so we pulled the driveshaft off one of our other 1st gens and it worked like a charm! Upon further inspection, it looks like a weight on the shaft was bent/pulled away from the shaft. We will ship it to a gear/driveline shop the middle of this week



Thanks again to everyone--

 

[BushWakr - RIP]

B