Thread: Clanking Question
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12-13-2010 12:39 PM #1
Clanking Question
OK, I have a TH 400 trans, 406 chevy engine, 73 Nova rear all in a 37 Chevy. When I accelerate or decel from either first to second, or second to first there is a clank (like a double clanking) sound. It sounds like it is coming from the transmission or front u-joint area, but the car is short so is hard really to tell. Obviously I can run beside the car and listen from the outside. I have had the car on stands (actually still is) and I cannot find any thing. U-joints seem tight, I pulles the diff cover and all looked good in there. it only does it going from 1st to 2nd on the upshift or from 2nd to first on the downshift. Does not matter how hard or how easy the accel is.
Any ideas? Is there somethign in the trans that could be the issue, but that would allow the car to drive perfect other than that clank.
Brett
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12-13-2010 12:48 PM #2
How's the transmission mount? The 1-2/2-1 shift is the harshest - could it be bouncing a bit on the mount? Just a thought.Roger
Enjoy the little things in life, and you may look back one day and realize that they were really the BIG things.
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12-13-2010 01:41 PM #3
Mount is fine, bolts are tight. I agree the 1-2 is the hard shift, but not coming back down from 2-1 is it? I for th elife of me cannot figure out wha tit is.
I can't make myself believe there is something broken in the tranny that owuld only clank between 1-2 or 2-1 yet be perfect otherwise.
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12-13-2010 02:03 PM #4
Could it be something other than the transmission. Is this a new build or something that just started. Are the motor mounts tight could it be an exhaust pipe close to something and the torque from 1 to 2 and 2 to 1 has it klunking? Do you still have the ears on the transmission? I will try to find a picture and post. Does it klunk harder if you get on it? Is your cross member tight to the frame? I don't know what it is just trying to come up with something.
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12-13-2010 07:55 PM #5
I'd go with your first thought, U-joints.Ken Thomas
NoT FaDe AwaY and the music didn't die
The simplest road is usually the last one sought
Wild Willie & AA/FA's The greatest show in drag racing
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12-14-2010 02:18 PM #6
You know I guess U-joints are cheap enough to change and see. As far as new build/old build, it is old, well about 7 years. No problems to date. everything else looks good as far as everything else mentioned on here. At least no one so far has said hey tha tis a broken tranny and it will cost a hundred million dollars to repair....LOL
I appreciate the help, I will certainly post what I find when I find it.
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12-14-2010 03:08 PM #7
I hope it is that good of news. Good positive thinking!
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12-14-2010 03:16 PM #8
My money is a pinion bearing going south.www.adoptafriendforlife.org
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12-14-2010 04:37 PM #9
put it up on jack stands in nuetral and turn the drive shaft back and forth quickly by hand and see what you hear
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12-14-2010 05:14 PM #10
Sometimes a cracked flex plate will make a metallic clank when the trans shifts. Usually they make other noises too, but not always.
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12-14-2010 05:53 PM #11
Hoss429, I did that. Did not hear anything. However it is not easy to turn. I have a friend tha tis a pretty good mechanic, he is goign to come over and see what he can hear. Believe me, it is not listening hard to hear something. It is pretty loud, but it is the exact same noise everytime, very consistant. It is two clanks everytime and does not do it on acceleration like a u-joint would normally make. Only does it from 1-2 and 2-1.
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12-14-2010 06:39 PM #12
take the pan off the trans and you will find a pile of chips/metalic sludge below the 1-2 planetary----in a few days you will be leaving a traffic lite and the noise will be worst(louder) but the car will continue---til the next stop, then it won't move at all
For proof----you can do a couple of things--lock the trans in 1st and accel then decel---will be quiet----lock in second----might not move at all but if it does, it will be quiet
But---you are cruuising around looking for a ride on a flatbed---parts to fix it about $80 plus oil and gaskets
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12-14-2010 08:03 PM #13
You might want to check to be sure all of your flex plate bolts are tight and for a crack like R Pope suggested.Bug
"I may be paranoid but that doesn’t mean they are not watching me"
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12-15-2010 01:01 AM #14
I would start with U joints buddy.For vauxhall corsa car mats visit mycarmats.co.uk
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12-15-2010 04:42 AM #15
Roger
Enjoy the little things in life, and you may look back one day and realize that they were really the BIG things.
Welcome to CHR. I think that you need to hook up your vacuum advance. At part throttle when cruising you have less air and fuel in each cylinder, and the air-fuel mixture is not as densely packed...
MSD 8360 distributor vacuum advance