1994 Blazer transmission vibrating

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  #1  
Old 08-19-08, 01:28 PM
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1994 Blazer transmission vibrating

Alright, I have a 94 S10 Blazer with a 4.3L motor and 5speed tranny. It's louder and vibrates more than normal transmissions. I am sure it is the tranny. The faster I go, the more the sound and vibration are noticeable. It's louder and vibrates more than any other tranny I've had. Could it be low on fluid or what other problems could this be?
 
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Old 08-19-08, 07:38 PM
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U-joints come to mind. Bad tire. Exhaust system.
 
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Old 08-19-08, 07:52 PM
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The U-Joints appear fine. The drive shaft doesnt move when you try to move it with your hand. The exhaust has been needing to be fixed for a while. This problem recently arose though. It only does it while you hold in the accelerator. Doesn't seem to matter how much or how little you hold it in while driving, it still happens. But one you take your foot off, it stops.
 
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Old 08-20-08, 06:17 AM
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Alright, could the vibrating be coming from the rear end because I know the rear is low on oil but would that cause the tranny to make noises?
 
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Old 08-20-08, 07:00 AM
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I don't profess to know. My knowledge of transmissions and their clutches and the gears and how they are all locked in place and their bearings, is limited.

But I know this much that the driveshaft, depending on if under load or letting off the gas, will cause the driveshaft to go forward and backward. You probably can see shiny marks indicating this travel, if you take a close look. That sound could be caused by gear play in the trans or the rear end, as indicated by how much of that forward/reverse travel you get. A certain amount of that travel is normal and also needed during the flex of when the rearend geometry changes with it's relative position to the transmission. But excess fore/aft travel on the level, with hard throttle, then letting off the gas, may indicate severe bearing wear that is allowing the relationship of mating gears to change how they engage.

The driveshaft itself could easily transfer the sound through it's hollow tube so that you wouldn't know where the sound is originating.

Inspect closely for oil being slung out at say where the rear yoke goes into the pumpkin. And also at the rear of the transmission seal. If your rear end is low on oil, that particular bearing could be going out and allowing the rear pinion to move forward and backward too much. That happened in one of my pickups years ago.

Also, you can't always go by if a driveshaft does not wiggle in your hand. I have seen the u-joints get so bad that the needlebearings inside start climbing ontop of each and jam up and lock the u-joint as if the shaft has no play, when in reality, it was beyond bad.

Get underneath and take a real good look at the geometry of it and also if you see long clean marks on the shaft where the front splines go into the transmission. When you look though, the driveshaft may be forward and not show this. Also try pulling in and out on where the rear yoke goes into the pumpkin.


You might also learn something visually if you could get say the front of your vehicle up against a big tree and pulsate on the gas pedal or have someone do that, while you see what the driveshaft and transmission (even it's mount) and rear end at the yoke try to do. Don't overdo this though as this is really hard on the transmission. Just get it so you do pulsating nudges, on and off the throttle some.


And remember that sound through hollow metal can really telegraph, like the old kids 'telephone' made with tin cans connected by a length of string.
 
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Old 08-20-08, 10:34 AM
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You didnt mention it......2 or 4 wheel drive?

4x4's are common for tearing up the front joints....does your vibration change with 4wd engaged.......

Also look at the trans/ transfer case mount. If the unit isnt securely mounted down, any "Imperfection" in geometry and rotation is 100 times worse.
 
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Old 08-20-08, 03:13 PM
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Well, I'm almost certain that the problem is the rear end. There sometimes is a humming coming from the rear end when you got the throttle pressed in lightly and it gets extremely hot. It's a 4wd by the way.
 
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Old 08-20-08, 03:48 PM
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Well jeez Joey..
If you know the rear is low on oil...WTH are you waiting for??

$7-8 bucks for lube...just do it!
 
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Old 08-20-08, 05:43 PM
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The plus was rounded out and couldnt get it out. Anyways, we jacked up the ass end of the blazer, took off the cover of the differential and there seems to be a few spots of wear but overall good. The driveshaft however has a good size dent in it and throws the drive shaft off while it rotates so that is definitely needing replaced. That would probably be a big cause of my problems. So we put the cover back on and made a lil hole in the cover to add oil and plugged it back (going to replace the rear end soon). Went and test drove it. Doing the same thing. So going to try to find a drive shaft for it soon and throw that one with the new-used rear end.
 
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Old 08-21-08, 12:12 PM
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Does anyone know if there is any other drive shaft I can use? It's a 4 door so I dont know if one out of a 2 door would work?
 
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Old 08-21-08, 02:31 PM
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Call up the junk yard. That's where you'd get one from anyway, right?
 
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Old 08-21-08, 03:36 PM
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Would the rear off of another s10 blazer with a 2.8 4wd with 4.11 ratio work on my 4.3L or would it be better to just replace the guts in mine? Also the worst would be true would that 5 speed work in place of my 5 speed?
 
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Old 08-21-08, 03:44 PM
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If I remember correctly --2.8 and 4.3 are totally different animals, and 2 different transmissions were used. Likely your driveshaft will need to be a 4.3 "Manual trans...the auto will be too short, and the other motor combos will bolt up differently.
 
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Old 08-21-08, 04:05 PM
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Originally Posted by Joeykh View Post
The driveshaft however has a good size dent in it and throws the drive shaft off while it rotates so that is definitely needing replaced.
Depending on your latest desires, you might also have a shop do what it takes to rebalance your driveshaft.
 
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Old 08-21-08, 05:31 PM
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The rear just needs bearings replaced I hope. When we had the cover off yesterday, we found a small piece of metal that seemed like a part of a bearing. When I'm going down the road, it sounds to me like a pop can is in there bouncing around.
 
  #16  
Old 08-25-08, 09:08 AM
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Alright, got a brand new driveshaft, the vibrating and clanging persist. I figured out what is making the clanging though, not sure what its called but its a circular piece that goes over the yoke on the rear end that is loose. How do I fix that back up? Not sure yet if I need to replace the bearings or not. Would that be a cause of the intense vibrating or that piece that is loose going everywhere be a source?
 
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