Drive train vibration

B

Btodd294

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I have a 96 Mark VIII.
I get a shudder or vibration from either trans or drive to rearend . Can't figure whats causing it , It seems like it is a steady vibration almost timed a few seconds apart usually just before shifting into 4th on a hill while easy on accellration if i put my foot into it , doesnt vibrate, or if I let off the gas just before reaching time to shift to high usually don't get the shudder or vibration. It does this no matter if the overdrive is off or on. Thank you
 
That is the TC shudder. When was the last transmission service done?

The best fix is to DRAIN the transmission and torque converter. And refill with MERCON V. You should also change the transmission filter. This needs to be done EVERY 30k miles for the transmission to stay happy.
 
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maxmk8 said:
That is the TC shudder. When was the last transmission service done?

The best fix is to DRAIN the transmission and torque converter. And refill with MERCON V. You should also change the transmission filter. This needs to be done EVERY 30k miles to the transmission to stay happy.
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I'll second that.
 
It also could be the drive shaft which is a common problem with our cars. The variance could be also caused by worn U joints (load on-load off) as well as the straightness problem.
 
The symptoms are indicative to the TC shudder, commonly mistaken for a bad drive shaft/u-joints. Time for a transmission service given it hasn't been WAY over due, my stall converter had a slight shudder at the time of install when it would go into lock-up in 3rd/4th(depending if OD was on/off) but after driving for 2 days with the new Mercon 5 it went away.

Matt....you're on to something if he had it intermittantly as described, but WITHOUT the light throttle and shifting points. A wheel out of balance will give you that vibration at higher speeds, kinda like an on/off vibration, fading away and coming back.

The vibration you're experiencing is the torque converter clutch "skipping" when its going into full lock-up, almost like slipping a clutch in a manual with a badly warped flywheel, or people commonly relate the noise/vibration to "rubble strips". I like to relate it to running over "q-tips" or "bunny rabbits". HAha, J/k. I don't have room to run over anything for that matter.
 
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what about these sounds or vibrations when sitting still specifically in Drive, it goes away in neutral
 
What's the last time you replaced/checked plugs? Could it be the engine doing the vibrating? Gap now to wide? OK with WOT....
 
I'm not ready to be flamed but I haven't since I bought it, lol. Theres too much to pay for all at once

it feels like its in the back and under the car though.
 
Open the hood and look at the engine to see if its perfectly still while idling, and how much it moves when you rev it up.
 
mikecp421 said:
what about these sounds or vibrations when sitting still specifically in Drive, it goes away in neutral
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In the back under the car? Sounds to me like the engine may have a bad drivers side motor mount and the exhaust is "moving" from the mount being weak. This is causing the exhaust to hit a portion of the undercarraige causing the noise.

Do this....pop your hood. Set the parking brake. Have someone look at the engine while you put the car in drive and tap the gas to put a load on the engine. If your mount is bad, you'll see the drivers side of the engine "lifting" up.

Mine was bad and when I'd romp on it and let off real quick, I'd get a "clunk" up front.

You should also check this in reverse, the will change the load to the passenger side mount, and if the engine lifts on that side, that one is bad too.

You can also have someone listen underneath and in the back when you hold it in drive to see where that noise is coming from.

DON'T RUN YOUR FRIENDS OVER.........use common sense, haha. :)
 
it vibrates though, like as if I had a base tube on my stereo and it hit a real low note. It stays for a few seconds then goes away.
 
Waittttt a second, what happened to the original poster, BTODD494? How many people do we have here with the same vibration?

Mikecp, are you working on this car that BTODD posted about?
 
yea I suppose its harmonic, and as for the OP I dont know. I just brought up a point
 
If its harmonic than you are in for some searching. First thing I'd check is all your mounts like we suggested above. After that, get it on the lift and see if you can here what it is, it might just be a heatshield being loose and vibrating.

Todd.....shoot, he probably gave up early or found his info somewhere else. That is about the most common thing that fails on these POS cars........opps, did I say that, hah.
 
The engine in my 98 twists about an inch under hard accelleration as observed on a Dyno. This is with new solid Rubber Motor mounts. Yes, I reinstalled the 13mm motormount to K-Member bolt.
 
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