727 Vibration is BACK....Bushing Shot

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pastortom1

pastortom1

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My gremlin is back...........Joy, Rapture.............

I have a 727 (A-Body) that's a real peach...... Chronic harmonic vibrations, that get worse over time (a SHORT time)........

I just had a new bushing installed on the tailshaft....old one was beat to death and rattling like marbles...they said the bearing was like new, and the shaft was fine.....After about 70 miles, it started AGAIN!!! Now it's really bad, vibrating the floor and anything else that rattles.....over 45 is a killer.......My output shaft MUST be twisted or out of balance.........it destroys the u-joints too.........HELLLLLLLLLP !!

I'm tired.........I want it fixed..........No more mechanics........I'd like a complete tailshaft housing ready to bolt in, rebuilt if possible (that would be nice) but not absolutely necessary if it's known to be problem free. I'd ALSO like to find one of those heavy bolt on weights for that tail housing....really heavy cast, bolts up to factory holes on the end of the housing.

DOES ANYBODY HAVE ONE????? IS ANYBODY OUT THERE???????????

(and oh, Merry Christmas..............Sorry I yelled).
 
Are you sure of the following:

The front yoke/slipjoint is proper outer diameter and good spline inside?
The output shaft is straight?
The tailshaft housing is not warped or cracked?
The driveshaft is not bent?
The u joint is properly installed and is not missing ay bearings?
The bearing (not the bushing) at the front end of the tailshaft housing is good and properly seated?


Just stuff to look at.
 
At what speed does the vibration start?


This is the weight that he is looking for guys. The 904 and 727 ones are not the same but a big block 727 one will work on a smallblock 727.

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If your driveshaft has twisted slightly or has been shortened by someone that got it out of phase you will have this problem.
 
man,It's got to have something causing that to happen,I'll talk to my tranny guy and see what is up and if he has some of those weight "thingies"
 
Then look and see if the output shaft is centered. If not it is most likely bent and needs replaced. Doesn't happen that often but it does happen. And yes this would destroy the output bushing and rear seal in time.
 
pastortom1 said:
I'm tired.........I want it fixed..........No more mechanics........I'd like a complete tailshaft housing ready to bolt in, rebuilt if possible (that would be nice) but not absolutely necessary if it's known to be problem free. I'd ALSO like to find one of those heavy bolt on weights for that tail housing....really heavy cast, bolts up to factory holes on the end of the housing.

DOES ANYBODY HAVE ONE????? IS ANYBODY OUT THERE???????????

(and oh, Merry Christmas..............Sorry I yelled).
Click to expand...

2 things , not being a jerk ..

First is the tail housing assembly is the housing and the bushing ... NOTHING ELSE .

Second the weight is not going to fix the problem , your car never had one to begin with .

What is causing this is either the driveshaft or the mainshft in the trans is bent , or BOTH , the drive shaft being screwed up bent the mainshaft ...
 
JohnRR said:
Second the weight is not going to fix the problem , your car never had one to begin with.
Click to expand...

Not true if he has swapped the tranny. My 73 Scamp had this problem after I swapped from a 904 to a 727. the pinion was set right, the driveshaft was new and ballanced and I had a vibration over 35mph that would screw up the rear seal in the tranny. I threw one on and it solved the problem.

However I am starting to think that it is the driveshaft due to the amount of damage that it is causeing.
 
The driveshaft is brand new from front to back........this was the first thing we changed, and though it was smoother driving (the old u-joints were shot), it did NOT change the harmonic.....same with both shafts.

The pinion angle is dead on.........the driveshaft length is near perfect (no jamming the output shaft under torque....room to move, but not too much...just right).

The bearing on the tailshaft was pronounced "like new" by the trans shop, and they didn't change it.....just the bushing, which looked like it went through WW2.

I told them the shaft was most likely "torqued" or bent a little to be causing such damage, BUT they said no.......I wasn't there to witness the shaft being tested for round, so I'm in the dark essentially.

With a new bushing, the harmonic was still there.

I'm gonna double check everything later today from the balancer right back to the pinion.......gonna get her in the air ans see what I can see...maybe these guys have missed something, like a neutral torque converter or something...a missing or snapped bolt, etc...........

I'll find it sooner or later, but hope it's a bit sooner.

Thanks for the input guys........................:toothy10:
 
That's what I think, like some other guys here.......

Bubba C gave me a call last night, and he had the same general idea........I wish I had been there to test the shaft on a good flat bench to see what's up.
 
pastortom1 said:
That's what I think, like some other guys here.......

Bubba C gave me a call last night, and he had the same general idea........I wish I had been there to test the shaft on a good flat bench to see what's up.
Click to expand...

You would think that there has to be away to "see" if the tranny output shaft was bent now that everythings back together.
I'd get in on a lift and remove the drive shaft, tranny nose cap and oil seal. Reinstall the driveshaft and turn the driveshaft using the rear wheels. You would think that if the tranny output shaft is bent then you should see the yoke sleeve wobbling within the tranny bushing as you rotate everything.

Terry
 
I'd think you could sure check it that way with a dial indicator. I'm sure there's a spec somewhere. Wouldn't think it would be more than a few thousandths allowed.
 
demon seed said:
You would think that there has to be away to "see" if the tranny output shaft was bent now that everythings back together.
I'd get in on a lift and remove the drive shaft, tranny nose cap and oil seal. Reinstall the driveshaft and turn the driveshaft using the rear wheels. You would think that if the tranny output shaft is bent then you should see the yoke sleeve wobbling within the tranny bushing as you rotate everything.

Terry
Click to expand...

Terry the clearance between the yoke and the bushing is only a few thousands , I don't think anyone can see that withthe naked eye .

As far as checking the output/mainshaft of the trans , the trans is going to have to come out and be pulled apart to accurately check it in a set of V blocks .

pastortom , how does the yoke look ? if it's chewing up the bushings then at some point the yoke is going to get damaged .

You say you have tried a different driveshaft than the new one and the problem is still there ?
 
360scamp said:
Not true if he has swapped the tranny. My 73 Scamp had this problem after I swapped from a 904 to a 727. the pinion was set right, the driveshaft was new and ballanced and I had a vibration over 35mph that would screw up the rear seal in the tranny. I threw one on and it solved the problem.

However I am starting to think that it is the driveshaft due to the amount of damage that it is causeing.
Click to expand...

I guess throwing one on , assuming his tailshaft has the holes in it for one to be attached , would be worth a shot .
 
Well, I'd like to try that counterweight, BUT they're apparently like hens teeth.........Can't be found.

I'm gonna pull the new driveshaft today and see what's up......I think I'll take a pic of the yoke and see what you guys think........:read2:
 
What can you guys tell me about this transmission? I'm considering a complate change instead of throwing more money at my problem.....I'm not sure that a rebuild is even available for this price anymore.........

It's the TCI Sizzler 727 for small blocks, with the long tailshaft housing (18-3.4" I think)...............

Price to my door is under $750., ready to bolt up and juice. Opinions?

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demon seed said:
It sounds like you're convinced that the tranny is the culprit. Before commiting to TCI I'd have a talk with these guys first. I've heard a lot of bad things about TCI and some good things about CRT.
https://www.coperacingtrans.com/product_info.php?cPath=21&products_id=30

Terry
Click to expand...

what he said , the TCI trans isn't much more than a stockish rebuild at that price , you should be able to find a smallblock 727 locally and have it rebuilt for that price , then you don't have to deal with long distance warranties . but if you don't mind long distance warranty then by all means call COPE .
 
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