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Why does everyone argue?
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hey eveyone... I just had this happen to me tonight after getting gas, and it also happened about 3 months ago as well. This THUD is comming from the back, and VERY Occasionally happens under HEAVY acceleration. the weird thing is, it never happens while changing gears, it happens later in the acceleration, after the slack in the driveline has already been taken up. anyone else have a similar problem? I also have a howling noise comming from my tires due to a VERY bad alignment when i bought the car (was corrected, bad alignment on right side was the result of a pothole which also killed a rim) I doubt this has anything to do with it, but any info would be appreciated. Thanks! (P.S.-no other noticable changes occur in the car when this THUD occurs)
 

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Yup happens to me veeeery seldom. Just out of the blue... Not hard acceleration always either.. I remember reading somewhere it was a design flaw int he left rear strut assembly. And that to this date no one's figured out exaclty what it is... Or maybe I'm smoking crack... Either way, when it happened to me the first time I thought something hit me. I was in first gear just pulling away from a green light and THUD! Really loud...
I dunno
 

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Wild & Wacky Meerkat
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Hey guys.


Carrier Bearings most likely.

Get under the car, and check for excessive play in the driveshaft, near the front and rear carrier bearings.

an inch of play is normal from what I gather, but it cannot be 'loose' play. ie, the rubber around the bearing should not allow the bearing to move very easily, it should get progessively tougher, the further away from center you push.

If that's not it, then it's something drivetrain related. The driveshaft only thuds against the bottom of the car, when there is a serious load imbalance, and too much torque is being applied to the driveshaft (ie, more torque is being directed to the rear than in the front)

those are my guesses.

:D

good luck.

Elton
(still chasing his own drivetrain demons..... thinks an exorcism is due....)
 

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Wrenchmonkey #839
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4 years,no problems yet

I've had this problem for 4 years and 50,000 miles not problems yet. It is so expensive to fix the stock drivesahft that it is cheaper to get a carbon fiber drivesahft instead.

I am a little nervous about a 1-piece carbon fiber drive shaft, one of these days I'll do the drive line angle and vibrations calculations to make sure it will not cause long term problems. Its just enough work that I'll wait until my drivesahft is completely shot.
 

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A few things...
It's not carrier bearings. I have less than 1/4 inch play in each direction. This is a suspension THUD and it's a LOT louder than and driveshaft movement would be.
I suspected mybe the spring was rotating on the rear shock and the thud was the end of the spring comming back around against something, but I haven't looked into it any more than that.

ASLO, I was told by another member (powelsound I believe) that mitsu now sells new carrier bearing assemblies. Much cheaper than replacing the whole shaft.
 

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Wild & Wacky Meerkat
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yup. Last I heard, they're about 60 bucks each. The both use the same bearings.

But that's a best price deal, from maybe our heavy discounts at Conicelli, or such.

hmmm....

also, did you by any chance check your emergency scissor jack? I've heard of a few people that have it loose in the rear well, and it THUDS against the wall every now and again on a hard acceleration.

Just a thought. I'm still brainstorming what it might be.
(thanks too many problems in mine, I know this darn drivetrain INTIMATELY.... Not bad for someone who's owned a VR4 for only 2 months, eh?)

Elton
 

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Same thing

VR4_Owner,

You say it's under HARD acceleration. Does it sound similar to wheel hop in that it goes "thud, thud, thud, thud, thud" from about 5k to 7k in first under WOT?

Mind you, that's 5 thuds in about 1-2 seconds. Mine's coming from the rear too. I think that driveline idea Elmo said about the torque split might be it for me.

Let me know if your thuds come in multiples.

Travis.
 

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Nope just one, and it's HARD...
Kinda sounds like a dog or something running full speed into the rear quarter pannel.
 

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Wild & Wacky Meerkat
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hahahah


Toyota Celica Commercial.


Looks Fast.


:D

E
 

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Travis, I have that same problem (well, whe it was working :)). I found out my rear engine mount is shot. I'll find out in a few weeks if that solved the problem. I also changed my carrier bearings and that didn't solve the thump on the bottom of my car either. I do get the multiple thumps at high rpms only in 1st though.
 
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see my post

Hey guys,
You are talking about the same problem I figured out the other day. the Post is called "Finally Figured it Out". I'll bring it to the top in a minute.
My problem turns out to be the rear section of the propeller shaft, the one that is formed by 2 diameters of pipe, is slipping at that joint. Anyone familiar with what's inside that pipe?
check out the thread anyway.
cheers, Dan
 

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Why does everyone argue?
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Discussion Starter #12
DANNYBOY-i think you may be onto something!!! I just remembered, the first time it happened, which was on my way home from work, I had a slight incident earlier in the day. when I got to work in the morning, I accidentally put the parking brake on and let off the clutch in 1st...i didnt stall it, but came close. at the same time, i heard a similar sound, but i just figured it was the parking brakes slipping... it may have been the section that you are refering to. Now that I think about it, the noise very well could be the sound of metal "popping" against metal.
 
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