Vibration after Th400 install. - JeepForum.com

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post #1 of 25 Old 08-24-2014, 06:58 PM Thread Starter
skizriz
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Vibration after Th400 install.

Been having vibration issues after a recent rebuild of my TH400. I've had it off and apart with no issues before, but after a recent rebuild, new flex plate, and new torque converter, I am having vibration issues.
I unbolted everything today, and slid the trans back about 1/2", and rebolted everything up to make sure nothing was crooked.
Everything seems fine. The torque converter has about 1/16 gap between the mounting pads and flex plate. Spins freely when unbolted. The T/C bolts start right in with very little effort to line the holes up.
The vibration isn't driveline, it does it with it in park, at about 1,500 to 2,500 rpm.

What might I be missing here??

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post #2 of 25 Old 08-24-2014, 07:27 PM Thread Starter
skizriz
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Wonder if it could be the crank bushing missing? I never even noticed whether there is one in there or not. The converter seems to slide in very easy, almost too easy. And I can push up on the converter slightly to start the bolts in.
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post #3 of 25 Old 08-24-2014, 07:44 PM
RenoF250
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Quote:
Originally Posted by skizriz View Post
Wonder if it could be the crank bushing missing? I never even noticed whether there is one in there or not. The converter seems to slide in very easy, almost too easy. And I can push up on the converter slightly to start the bolts in.
So you are saying the TC can move relative to the crank when loose? That is not good, it is quite heavy and if not centered would certainly vibrate.
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post #4 of 25 Old 08-24-2014, 07:53 PM Thread Starter
skizriz
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Originally Posted by RenoF250 View Post
So you are saying the TC can move relative to the crank when loose? That is not good, it is quite heavy and if not centered would certainly vibrate.
I did notice that I pushed up on it a hair to get the first t/c bolt started. Got me wondering if the bushing came off with my old t/c (turned it in for core), or it never had one, and I was lucky before and it didn't vibrate without it.

I never even knew about the bushing until I started looking into the problem. Got me wondering now.
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post #5 of 25 Old 08-24-2014, 09:12 PM
RenoF250
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Quote:
Originally Posted by skizriz View Post
I did notice that I pushed up on it a hair to get the first t/c bolt started. Got me wondering if the bushing came off with my old t/c (turned it in for core), or it never had one, and I was lucky before and it didn't vibrate without it.

I never even knew about the bushing until I started looking into the problem. Got me wondering now.
Have you run it with the cover off to see if the TC is centered?
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post #6 of 25 Old 08-24-2014, 09:13 PM
RenoF250
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You could take the plugs out and turn it over with the starter and use a micrometer to get it centered.
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post #7 of 25 Old 08-25-2014, 02:24 AM
dg6772
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AMC TH400 has a torque converter bushing? The standard GM does not. Just fits into the end of the crank. I would assume the same......

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post #8 of 25 Old 08-25-2014, 02:39 AM Thread Starter
skizriz
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Originally Posted by RenoF250 View Post

Have you run it with the cover off to see if the TC is centered?
That i did. Could see it wobbling some. I have no idea what is a normal amount to compare to. Ill do it again after work today, and post some video of it.

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post #9 of 25 Old 08-25-2014, 04:55 AM Thread Starter
skizriz
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Originally Posted by dg6772 View Post
AMC TH400 has a torque converter bushing? The standard GM does not. Just fits into the end of the crank. I would assume the same......

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From what i understand the AMC cranks will fit the 727 and used a bushing for the th400.

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post #10 of 25 Old 08-25-2014, 05:04 AM
grasmo
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there shouldn't be a 'bushing'. it would serve no purpose seeing how the tc/flexplate/cs all bolt together.....I have heard that re-clocking the tc in relation to the flex plate removes vibration sometimes.
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post #11 of 25 Old 08-25-2014, 06:07 AM
dg6772
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Originally Posted by skizriz View Post

From what i understand the AMC cranks will fit the 727 and used a bushing for the th400.

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Damnit. ....learned something again.....thanks! Lol

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post #12 of 25 Old 08-25-2014, 06:08 AM
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Originally Posted by grasmo View Post
there shouldn't be a 'bushing'. it would serve no purpose seeing how the tc/flexplate/cs all bolt together.....I have heard that re-clocking the tc in relation to the flex plate removes vibration sometimes.
Good idea....I've heard of that before...

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post #13 of 25 Old 08-25-2014, 07:05 AM Thread Starter
skizriz
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Quote:
Originally Posted by grasmo View Post
there shouldn't be a 'bushing'. it would serve no purpose seeing how the tc/flexplate/cs all bolt together.....I have heard that re-clocking the tc in relation to the flex plate removes vibration sometimes.
I set out to do that yesterday, but couldnt get the trans back far enough to get a rotation out of the t/c. Those darn nubs on the flex plate keep it from rotating fully like a normal t/c would do when unbolted.

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post #14 of 25 Old 08-25-2014, 09:49 AM
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Quote:
Originally Posted by grasmo View Post
there shouldn't be a 'bushing'. it would serve no purpose seeing how the tc/flexplate/cs all bolt together.....I have heard that re-clocking the tc in relation to the flex plate removes vibration sometimes.
Yet AMC did install a thin bushing into the back of the crank when used with the TH400. Even with bolts holding things together there can be enough leverage at RPM to have runout at the front of the convertor.

Bolt holes are far from precise when it comes to rotating assemblies as well.

Novak sells replacement bushings.
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post #15 of 25 Old 08-25-2014, 09:51 AM
jblue1555
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If the sleeve isn't in the crank you have to pull the trans and put one in it. 727 fits without.
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