Driveline vibration out of now where! Help!

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Local mopar swap meets coming up are a good place to look. I just like having one around so I can plug the transmission tails so I when I take them out they don't make a royal mess all over the shop floor. 727 Big Block and 727 Small Block trans take the same yoke so it is multi purpose. 904 yokes do not work on the 727s.

I have bought them on Ebay and get them shipped in. That mopar tranny shop in your area that you are trying to find may borrow you one if you bring it back in one day.

Ask one of the members on here to borrow you one.
 
Can put something like a tin can over it if you can find one with a good fit to the tail housing secure it with a large hose clamp. When all else fails and you just want to make your test quick.

This is probably not a good idea because you need the yoke sleeve in there to support the end of the tail shaft at the rear bushing so it does not wobble around and cause more damage.
 
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George Jets said:
Can put something like a tin can over it if you can find one with a good fit to the tail housing secure it with a large hose clamp. When all else fails and you just want to make your test quick.
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Do all year 727's use the same splined slip yoke? I know this trans is out of a 1969..
 
Yes, the earlier 60s and some motor homes have a different tail all together. Like a flat flange to bolt the drive shaft to, not sure of the years and the applications but you will know when you see it that it won't work for you.
 
Could it be wrong / damaged slip yoke? What happens if the sprag is damaged? So far as U joint timing you can SEE them. Put the shaft on a bench, immobile with rags, blocks, vise. Level one end rotationally. Other ends should also be level. I'm talking about the U joint yoke ends.

Other than that take it somewhere and re-check driveshaft straightness/ balance
 
In neutral, the output-shaft should spin fairly freely in the "normal" direction with almost no noise; just the noise of the slipping sprag; Kind of a squeak/creak that should be obvious..
But in the opposite direction the sprag will lock up and spin the low drum. The squeak will now be gone, and drag will be increased as the clutch plates will be dragging due to the sungear being involved, and the bands may drag as well. This increased drag is quite pronounced.
Edit: this is normal
 
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AJ/FormS said:
It only takes a few minutes to pop the yoke off the driveshaft, and requires no special tools. Grease the splines before you install it and it will stay on there.
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AJ/FormS has the right idea here to make your quick test with the drive shaft disconnected.

Take the yoke off of your existing drive shaft, pretty simple. Grease the removed yoke splines and slip it on to your transmission tail shaft.

Now you can do your test right here, right now without having to buy parts and the many days of delays finding a used spare yoke. 7260 U-Joints are readily available also for putting the yoke back on the drive shaft if you need a new one.

These 727s have 2 bands that can be readjusted too. If you can find someone locally who knows how to adjust these 2 bands. If these band adjustments are way out of whack, it would suggest more serious problems. If they are within specs, all the better.

You could do this band adjustment and see if it makes the internal noises better or worse. Another piece of the puzzle . . .
 
AJ/FormS said:
In neutral, the output-shaft should spin fairly freely in the "normal" direction with almost no noise; just the noise of the slipping sprag; Kind of a squeak/creak that should be obvious..
But in the opposite direction the sprag will lock up and spin the low drum. The squeak will now be gone, and drag will be increased as the clutch plates will be dragging due to the sungear being involved, and the bands may drag as well. This increased drag is quite pronounced.
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That's exactly how it acts, easy to spin one way and a good bit harder to spin the other way.
 
man, its been so long, i dont remember how to get the yolk off the driveshaft and get the u-joint caps off..embarrasing to say, just been a loong time since i built this car, and the driveshaft shop installed the u-joints back then..
 
Just thinking about your issue a little bit If it is a problem in 3rd gear, I would not think it is planetary related. Both front and rear clutch packs are engaged in 3rd and there is no gear reduction or internal movement in the planetary gear sets. I would verify the tail shaft bearing has not failed first. It I an easier repair and can be done in the vehicle. As mentioned I would pull the speed gear and take a look inside with a flashlight. Turn it by hand. If it is knocking as loud as you say it is, the problem should be obvious.
 
Went out and tinkered with it a little after work. I still have it supported on jackstands under the rear frame. I removed the brake drums just to be extra sure it wasnt them. Still the same thing. Next, i put a floor jack under the rear chunk so i could raise and lower the whole axle to change angles..It didnt make it change any. Last, i put a 2x4 between the seat and gas pedal and got it to the rpm it does this the worst and looked up under the car with a light, both at the rear and at the trans..The driveshaft spins just as straight and smooth as can be!..So i sat in the car and played around with it..It starts at 1400 rpm and ends at 1900-2000. It is barely noticeable in 2nd gear at these rpms but very bad in 3rd gear at these same rpm's..After 2000 RPM it smooths right out..I really dont know what to think at this point. Transmissions arent cheap and i really hate to buy one without more evidence that the trans is the problem for sure..I just dont know..
 
mopower440 said:
Went out and tinkered with it a little after work. I still have it supported on jackstands under the rear frame. I removed the brake drums just to be extra sure it wasnt them. Still the same thing. Next, i put a floor jack under the rear chunk so i could raise and lower the whole axle to change angles..It didnt make it change any. Last, i put a 2x4 between the seat and gas pedal and got it to the rpm it does this the worst and looked up under the car with a light, both at the rear and at the trans..The driveshaft spins just as straight and smooth as can be!..So i sat in the car and played around with it..It starts at 1400 rpm and ends at 1900-2000. It is barely noticeable in 2nd gear at these rpms but very bad in 3rd gear at these same rpm's..After 2000 RPM it smooths right out..I really dont know what to think at this point. Transmissions arent cheap and i really hate to buy one without more evidence that the trans is the problem for sure..I just dont know..
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Is it possible that something may have moved and maybe you just have an exhaust pipe or something hitting the body transmitting engine vibration into the vehicle?
 
It is time to drop the pan on the transmission and see what is in the bottom of the pan and if there is a magnet in there how much excess steel is on the magnet.

If there is a real problem with the transmission it is going to show up in the pan.

Also what color is the transmission fluid, Bright Red or Brown ?
 
Side note: if you are going to remove the Speedo Gear to take a look at the Large Tail Shaft Bearing, take and mark the speedo gear aluminum flange (where the speedometer cable screws on) to the tail shaft housing with a dry marker. this way you you can get it back in the correct spot to go with the plastic gear that is inside.
 
George Jets said:
Side note: if you are going to remove the Speedo Gear to take a look at the Large Tail Shaft Bearing, take and mark the speedo gear aluminum flange (where the speedometer cable screws on) to the tail shaft housing with a dry marker. this way you you can get it back in the correct spot to go with the plastic gear that is inside.
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ok, but how will i be able to check that bearing just by looking through the hole without being able to grab hold of it and spin it and feel for roughness?
 
Look through the hole with a bright flash light to see if you can see rust or bearing damage.

Put your finger up in there on the tail shaft and slowly turn the driveshaft with your other hand in the proper forward rotation. If there is a bad bearing there you will feel the roughness in it as it conducts the vibrations to the tail shaft.

Prossess of elimination:

If you can determine that the tail shaft bearing is still good by this method but still feel the clunking on the tail shaft then you know the damage if farther up the line into the transmission. And now it's time to pull the pan and check it out.

Any suspect transmission problems I have on any automatic car or truck, the first thing I do is drop the pan. This tells you the whole health of the transmission.
 
Yeah pull the dipstick out of the automatic transmission and wipe it on to a clean white paper towel. Let us know if the transmission fluid color is Bright Red or Brown ?
 
Just a question, but if it does turn out to be a bad trans, where do you guys buy your 727's? Back when I got this one, there were plenty in the for sale section here and on every mopar forum. I found this one rebuilt and ready to go and able to be picked up at a local show to me..
 
It seems you have this "Huge Fear" of your transmission that you need to get over. If it needs to be fixed you take it out and get it rebuilt, the case is not going to be damaged. The overhaul kits are only 100 dollars online, plus any hard parts but you won't know this until it gets opened up.

Owning these cars you need a network of friends and associates that you stay in contact with so that when something happens you have them watching your back, and they can guide you along as to what needs to be done, and line you up locally to the people they trust to do the specialty work. Then do it.

So now go back and take the pan off and tell us what you find. If you don't I can't help you anymore.

This supposed to be fun, and part of the fun is being around all the good people that know how to keep the cars going. You can provide your experiences and support to them too when they need it.
 
Getting her Done . . .

727sb.jpg


Good Buddy Brian built this 727
$120.00 in parts working great.

In my 76 D100 360/727 build right now . . .
 
George Jets said:
It seems you have this "Huge Fear" of your transmission that you need to get over. If it needs to be fixed you take it out and get it rebuilt, the case is not going to be damaged. The overhaul kits are only 100 dollars online, plus any hard parts but you won't know this until it gets opened up.

Owning these cars you need a network of friends and associates that you stay in contact with so that when something happens you have them watching your back, and they can guide you along as to what needs to be done, and line you up locally to the people they trust to do the specialty work. Then do it.

So now go back and take the pan off and tell us what you find. If you don't I can't help you anymore.

This supposed to be fun, and part of the fun is being around all the good people that know how to keep the cars going. You can provide your experiences and support to them too when they need it.
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Im going to when I get a chance between work and all, just planning ahead because I only know one friend that messed with these and don't think hes doing it anymore..Havent talked to him in a while. He used to be on here.
 
Didnt mess with it tonight, been having some stomach issues so just doing this when i can. I did check the trans fluid on a white towel and its clean! No metal particles that i could see. Still pinkish red. Could the trans mount cause this pulsating vibration or would it be more of a steady vibration? Curious to that question but think i may change it out this weekend as it most likely needs it anyway.
 
Pinkish Red fluid is a great sign.

Trans mounts get hammered out and the rubber in them goes away setting the trans tail metal on metal conduction sound. So yes check that out, good thing to get done. Time takes it toll on those rubber parts.

You could take your floor jack, a couple short 2x4s and small pad of carpet or cardboard and jack the tail of the transmission up off the rear cross member about a half an inch. Then start it up on the jack stands and run it and see if your noises go away. This could have something to do with things moving while you jacked the front of the car up doing the front brakes.

You might get lucky . . .
 
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