Vibration When Accelerating

darkstar_one

Registered User
hey,

as u people know i just installed my rebuilt transmission... i have a problem though.... when i step on the accelerator i get this nasty vibration and i dont know what it is... anybody have any idea... please let me A S A P im trying to get my SC back up and running
 
Just guessing that it DIDN"T do it before the rebuild, and a competent repair shop or mechanic rebuilt it. I am no trans expert and am just guessing here, but I would check for something hooked up wrong like the transmission mounts? U-joints gone bad? Motor to bell housing bolts tight? Is it stick or Auto? Torque converter or flywheel not bolted on right/tight? If you had someone do it, then take it back to who did it and have them check out.

Maybe a tranny expert will chime in here for ya...

PS. I get the same thing from my exhaust system rubbing or too close to something under there when I really reef on it.
 
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well im thinking its probably some sensors ??? like the TPS or the IAC or something?? please somebody let me know

also its a AOD tranny...
 
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couple of things

1] motor mounts
2] drive shaft

1] if you still have stock motor mounts ...they can be ripped apart if you don't support the back of the motor ...when replacing the tranny...note if bottom of oil pan is still above cross member...and oil filter is not rubbing on cross member

2] did you index the drive shaft ? ... when you took it apart at the diff..if not rotate it 180* note this vibration only if your driving ....dave
 
Could be wrong but IAC can be checked if you unlug while car is running, car should die. Also IAC sometimes makes dying goose sound upon shut off. TPS I THINK only controls fuel mixture for ECM, I THINK. I can't see how either will cause this problem. I have replaced both of these. One due to mechanic stupidity. OK it was me, I broke the TPS trying to get it off. I hate screws!

We need more info to try and help:
Did a shop or you rebuild tranny?
Did it do this BEFORE rebuild?
What was replaced or disconnected?
Did you brace motor when pulling trany? (Good idea Mercsc)
 
ok check it out...

me and my dad took out the transmission... my dad is a certified mechanic for CHEVRON.

We took out the transmission to get rebuilt by his long time friend who owns a TRANSMISSION shop. The transmission was rebuilt completely with SHIFT KIT and was delivered back to us.

me and him popped it back in. My dad has years of experience.

my dad said that when he accelerates... the it makes a vibration. He thought it was the Throttle Body that it needed calibration but he checked it out and turns out ok. He also checked the IAC and that sensor is long gone. So now he is gonna check the mounts and everything.

The transmission did not do this before rebuilt.
Nothing was replaced except the transmission.



Whats this about the DRIVESHAFT and a 180 degree turn??
 
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When you remove the driveshaft you should put index marks on the rearend flange and install it exactaly as you took it out. Those parts are balanced together. You could have them installed 180 deg out of phase with each other. Make sure ALL of the engine and tranny mounts are good, there very easy to tear up removing the tranny and they could be the source of your problems.
 
Whats this about the DRIVESHAFT and a 180 degree turn??

Yeah Dave,
I'd be interested in this too. Indexing? Is this a balance issue in the drive shaft?

He also checked the IAC and that sensor is long gone.

So the IAC is bad or missing? I had problems with fuel/air mixture when mine went bad, but no vibration problem. Those engine mounts can be hard to see.
 
Well after rereading his post it sure sounds like some mounts are bad. Since it appears to only do it when accelerating, if it did it at a certain speed range regardless to rather he was accelerating or coasting I would then suspect the drive shaft. Thing about the motor mounts is visually they can look good. Mine did, but as I was removing the engine I learned the drivers side was ripped completely in two. Sure did look good that is until I started lifting the engine.

Bob yes the indexing is a balance issue. Anytime you remove rotating parts like that you should always replace them in the same orientation they were removed.
 
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loosen up your exhaust and tranny mount and croosmember..(dont take anything apart just loosen it) so u can neutralize everything make sure nothing is pulling the tranny to one side or another. then grab the end of your tranny and just shake it up a little make sure it moves freely---- then tighten mount, crossmember after tranyy is tight in place then tighten your exaust.
 
yeah i fixed it. my bad IAC caused my AUTO TRANNY to burn out. It would idle at 1800 RPMS and it burned up the clutchpacks. So when i would step on it. It would vibrate. Like a slip style vibration. But if would put it on 1 it wouldnt. I had it rebuilt and its now better. Now that i fixed the IAC also.
 
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