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I stumbled on to this site and hope it provides partnerships assisting each other with information in support of our wonderful SUV's. I drive a 91 GMC Sub with a 6.2 diesel. Gutless and reliable. My wife says its a guy car. It does ride a little rough. 3/4 ton.

My only problem has been a vibration starting about 65 mph. I balanced the driveline, replaced u-joints, balanced tires, checked bearings, adjusted the angle of the driveline coming off the transmission and visually inspected everything I could think of. Anyone else experience this vibration? Any suggestions of what to look for?

Mike Conley
 

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Does your 6.2 have a turbo? If it doesn't there are a few mods you can do that will greatly improve its performance(although it still won't be a Duramax/Cummins/Powerstroke). As for your vibration problem what tires are you running(certain tires produce different traits at different speeds regardless of balance). Check your engine and transmission mounts, Diesels vibrate the vehicle enough with good mounts and with a cracked or broken mount it will amplify itself at different rpm's. A broken tranny mount can cause a balanced driveshaft to vibrate as well.
Check for broken shock mounts also. Let us know what you find. :D
 

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Hey Mike, et all

Thanks for signing up and jump right into any questions or comments that you might have.
 

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Hey Mike, A buddy of mine had a similar problem on a t bucket, he replaced everything he could think of just like it sound like you did. The problem turned out to be one of his tires was "out of round". Once he swapped tire brands to another maker the problem disappeared.
 

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I've had front end problems before that just some new tires seemed to fix.
 

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Discussion Starter #6
Thanks

Dieselburb said:
Does your 6.2 have a turbo? If it doesn't there are a few mods you can do that will greatly improve its performance(although it still won't be a Duramax/Cummins/Powerstroke). As for your vibration problem what tires are you running(certain tires produce different traits at different speeds regardless of balance). Check your engine and transmission mounts, Diesels vibrate the vehicle enough with good mounts and with a cracked or broken mount it will amplify itself at different rpm's. A broken tranny mount can cause a balanced driveshaft to vibrate as well.
Check for broken shock mounts also. Let us know what you find. :D
I will check for broken or cracked transmission and shock mounts. Another thing I did was jack it up, put it in 4WD and run it up to 70 MPH while looking for the vibration or something not running true. I did not see anything out of line.
 

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Anything obviously out of the ordinary, like uneven tire wear? Maybe some feathering?
 

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Diveline Vibration.

Hello all, Im a new b on here, I have built everything from low riders, baggers, suzuki samurais with small blocks, rotarys, etc... I just bought a 1990 gmc sle 1500, 4wd, was gonna use it to pull toys and family, I drove it before I bought it, ran smoothly, when I picked it up 1 hour later, I was 1 mile from the peoples home I bought it from, when a nasty vibration started, I was at 25mph when this began, at 35 it seemed to clear up, 45 , smooth over that the vibration started again, I got it home and checked the u joints, seemed tight no play, I could smell gear oil fairly strong, but did not see any leaks, Its a stock suspension, the rear differential is not at a exterme angle, the tires do have a few spots of uneven tread wear, but not extreme, I would almost think it was a driveshaft balance issue, but it clears up , and runs smoothly, I have checked all I can think of, and everything seems to be solid as far as mounts, Could this be the differential , transmission Transfer case,? Im not sure, I really want to try and clear it up over the weekend, so any pointers would be greatly appreciated. at idle everything is smooth, if i put it in neutral going downhill, it still has the vibration, so it seems it has to be driveline related, but Im just not sure , I am gonna change the tires out this weekend to see if it makes any difference, once again Thanks In Advance
 

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wow now thats a bump. I would try making a thread in one fo the tech sections. you will most likely get a better response there :great:
 

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Ive got a 1990 3/4 ton burb , and I have the same issue with a vibration at around 65mph. The only thing we have been able to come up with is, it's the tires. right now im running 33x12.50 BFG all terrains. A friend just got me some new 35x12.50 MT's . We havent put them on yet do to the lack of money for a suspension lift. Otherwise the truck rides fine if i dont go on the hwy.
 
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