Vibration hum @ 2k-2.3k RMP

[SCREWd2V]

1990 Ext cab STX 4x4 auto

real quick, love this truck, but its got some issues! i want to get this beast back up to par! almost a year ago i got in a wreck, and since then i've been picking up the pieces.

I have refered to the tech library and also searched the forums for the problems i am having.

right now i have this high pitch "hummm" vibration at 2000 RPM - 2300 RPM every gear (auto) and it is only noticeable under load (motor also shutters at idle but rpms dont drop or bounce, its more like its got a slight case of tourettes)

I'm going to explain all details so that nothing gets left out
after the wreck the driveshaft was destroyed (carrier baring) and i needed a new one.( the truck could barly drive down the road so i don't know if the vibration is related to the driveshaft or not) found the one piece swap on here under tech library and replaced, all u joints were good, fit like a glove, but when i would get up in the 2k-2.3k rpm i would get this vibration... and i wouldn't think it would be driveshaft related cause its only related to rpms and not speed.
also the motor takes a while to turn over and sometimes i can smell raw fuel
i have replaced the motor mounts and the harmonic ballancer and transmission mount, has new plugs and wires, and cleaned the MAF sensor and the the IAC valve.

today i tried the turn the driveshaft 180' but no luck. also when i did purchase it i did not have it balanced

FWIW the body bushings are shot in the front and i ordered a body lift kit and new bushings today

Help me TRS!!!!!

Preston

 

[Brownie Mobile]

1990 Ext cab STX 4x4 auto

real quick, love this truck, but its got some issues! i want to get this beast back up to par! almost a year ago i got in a wreck, and since then i've been picking up the pieces.

I have refered to the tech library and also searched the forums for the problems i am having.

right now i have this high pitch "hummm" vibration at 2000 RPM - 2300 RPM every gear (auto) and it is only noticeable under load (motor also shutters at idle but rpms dont drop or bounce, its more like its got a slight case of tourettes)

I'm going to explain all details so that nothing gets left out
after the wreck the driveshaft was destroyed (carrier baring) and i needed a new one.( the truck could barly drive down the road so i don't know if the vibration is related to the driveshaft or not) found the one piece swap on here under tech library and replaced, all u joints were good, fit like a glove, but when i would get up in the 2k-2.3k rpm i would get this vibration... and i wouldn't think it would be driveshaft related cause its only related to rpms and not speed.
also the motor takes a while to turn over and sometimes i can smell raw fuel
i have replaced the motor mounts and the harmonic ballancer and transmission mount, has new plugs and wires, and cleaned the MAF sensor and the the IAC valve.

today i tried the turn the driveshaft 180' but no luck. also when i did purchase it i did not have it balanced

FWIW the body bushings are shot in the front and i ordered a body lift kit and new bushings today

Help me TRS!!!!!

Preston

Just curious do you have the kind where it bolts into the tranny or the spline system or what ever they call it? ive heard with the spline system if its even off a little bit youll get this, also Improper u joint replacement could do it, Even though you put in new ones try moving it a round and be rough ( consider that this has to put up with 100s of pounds of force every day) If you put it in without loosening the u joint so they move properly you can wear them out prematurely. I wish i could feel your problem ive had like every different possible drive shaft vibration problem happen with me or my friends trucks. Also did you try and drive after the crash? if so that could be your problem right there my friend had a similar problem where his tranny-engine bolts were way loose and it ran for a while sagging and when he went to retighten them pieces in the tranny were supposedly bent one way and when he ran it after being straightened it definitely vibrated especially around mid rpm range. IDK thats my 2 cents though

 

[SCREWd2V]

Just curious do you have the kind where it bolts into the tranny or the spline system or what ever they call it? ive heard with the spline system if its even off a little bit youll get this, also Improper u joint replacement could do it, Even though you put in new ones try moving it a round and be rough ( consider that this has to put up with 100s of pounds of force every day) If you put it in without loosening the u joint so they move properly you can wear them out prematurely. I wish i could feel your problem ive had like every different possible drive shaft vibration problem happen with me or my friends trucks. Also did you try and drive after the crash? if so that could be your problem right there my friend had a similar problem where his tranny-engine bolts were way loose and it ran for a while sagging and when he went to retighten them pieces in the tranny were supposedly bent one way and when he ran it after being straightened it definitely vibrated especially around mid rpm range. IDK thats my 2 cents though

thanks brownie, on the trans i have no idea what did your friend have? i did drive it for a bit after the crash only a couple of miles but the onlything that was destroyed was the carrier baring, i hope my tranny isnt fncked! do you think my problem could be driveshaft related with rpm issues? thanks for the info, at this point i have no clue where to go except to take the driveshaft out and take it to get it balanced and take the truck into the shop and see what they can do.
how long did your friend drive the truck for? i mean i only drove it just to get it home and to the repair shop for the front end. fml

 

[Brownie Mobile]

thanks brownie, on the trans i have no idea what did your friend have? i did drive it for a bit after the crash only a couple of miles but the onlything that was destroyed was the carrier baring, i hope my tranny isnt fncked! do you think my problem could be driveshaft related with rpm issues? thanks for the info, at this point i have no clue where to go except to take the driveshaft out and take it to get it balanced and take the truck into the shop and see what they can do.
how long did your friend drive the truck for? i mean i only drove it just to get it home and to the repair shop for the front end. fml

He was driving a '80 toyota pick up at the time. He drove it about 10 miles or so got me home then went back to his house and parked it there till he tightened it back up, and of course still gets a tranny vibration to this day not too bad though. But before you get scared just take the drive shaft to the shop see if its all good. And yes i do think it could be driveshaft related because i had loose u joints and was getting the vibration but only at certain speeds. But it is a bit different for you, do you get the vibration sitting in neutral? just reving it up to 2k if you dont get it then then its not your tranny i imagine. Its unlikely to be a bad tranny anyways. I think its the driveshaft get it checked out and report back . Also check the way the tranny is mounted since the wreck maybe its pointed slightly right or left and wanting to be so precise with the drive train a few degrees could do something like that.
Edit: the drive shaft thing; look at your tranny where the driveshaft hooks into it. Does it slide in and look like nothing is holding it or is it bolted to the drive shaft right at the tranny? if the 1st you have the spline drive shaft if bolted then you have the bolted kind

 

[SCREWd2V]

when I. Put it in neutral and Rev it to 2k it doesn't vibrate standing still or rolling. It seems to be when there's a lot of load it is the worse, like if I'm pulling on to the freeway at an incline. When I'm just cruising its not as severe but still there. Fncking annoying! Feels like a massive restaurant buzzer when on a wait is under my cab and every time I get to 2k my table is ready! Argggg! Will take a look tomorrow and report back. Thanks again Brownie!

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[SCREWd2V]

update.

okay! did some more observation today, and heres what i found.

-in neutral, standing still or rolling, i can feel vibration from the motor in the front at 2k-2.2k but not resonating through the cab
-while driving in gear (auto) when theres load on the motor around 2k is when the vibration resonates through out the cab.
-in first gear on the tree, the vibration occurs around 1.8k rmp and ends around 2.1
-in 2nd on the tree, as well in any other gear the vibration occurs at 2k and ends at 2.2k

i did not get a chance to crawl under the truck today to look at which tranny i got.

i'm thinking it's not driveshaft related now, because when the motor is engaged i think the vibration is traveling through to the tranny to the driveshaft which then buzzes the whole cab.

 

[Brownie Mobile]

update.

okay! did some more observation today, and heres what i found.

-in neutral, standing still or rolling, i can feel vibration from the motor in the front at 2k-2.2k but not resonating through the cab
-while driving in gear (auto) when theres load on the motor around 2k is when the vibration resonates through out the cab.
-in first gear on the tree, the vibration occurs around 1.8k rmp and ends around 2.1
-in 2nd on the tree, as well in any other gear the vibration occurs at 2k and ends at 2.2k

i did not get a chance to crawl under the truck today to look at which tranny i got.

i'm thinking it's not driveshaft related now, because when the motor is engaged i think the vibration is traveling through to the tranny to the driveshaft which then buzzes the whole cab.

Motor mounts tranny mounts? idk. when you say resonate do you mean resonate or resonate? lol do you mean the sound just shakes/vibrates the whole cab or literally the frequency of the motor is resonating and causing a hum. I wouldnt know what to tell you either way truthfully without some more info videos? sound recordings? idk the reason i ask is cause i had some friends vehichles where if you hit the sweet spot in the rpm range it would LITERALLY resonate meaning something sciency and complicated lol.

 

[SCREWd2V]

I will make a video tomorrow and post it up, going skydiving today!

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