Finally think I solved my vibration issue

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Put a 1/4 spacer between the trans mount. Didn't change. Except for headers now hit the steering linkage turning right. Hahahaha. Again no vibes in park reving. Most noticeable above 4000 rpm (starts after 3000). Goes away in neutral when the throttle is released. Comes back in neutral at speed above 4000 rpm.
 
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727 is out.
 
Sent a video to a fellow coworker that knows transmissions. Must be sleeping. Must be normal because the 727 does the same thing (although I checked the 727 with the tailshaft off)

The 904 that's going in seems to have a lot of play.

[ame="https://m.youtube.com/watch?v=qiLGVRqzOr4"]https://m.youtube.com/watch?v=qiLGVRqzOr4[/ame]
 
I'm going to be putting the 904 in today. What are all the things needed just to make sure I got everything.

Again using torque converter and driveshaft from slant 69 dart. Balance flex plate. Figure I will leave the valvebody alone (although I read they're interchangable). I swapped the shift linkage for the ratchet shifter. Also the kickdown lever is shorter for the 904. I will have to swap rear yokes but the 742 doesn't have a crush sleeve so that should be painless.

Swapped fitting for the trans cooler lines. They look pretty close to where the 727's position.
 
Re the endplay at the input shaft.
Thats BAD. Do not install it like that. There may be one of several things wrong inside. Some more serious than others. All will lead to destruction. Perhaps its already too late.Spec on a 69 trans reads .030 to .089. Yours looks to be on the big end perhaps well over.
When the end play gets to be this large its usually an indicator that the unit has a lot of miles. Often its just the stack of thrust washers that are in there (6 or 7, maybe more) . If end play gets to be too big the parts can move around too much inside, leading to mis alignments of the various hard parts, and oilcircuit failures or hard parts breakage.There is no way I would install that thing, unless I was stranded in a foreign country, and my life depended on it.lol.Seriously though, it needs attention.
 
As to your vibration; I know youre working hard at it. And youre pretty sure its in the trans. And it may well be a contributor.But Id like to relate something that I think might apply.
Years ago, I was chasing an annoying vibration too.In my research, I came across an article that said something like this;Every spinning component in that driveline has a natural frequency at which it wants to vibrate. Some like to add up to others. Some cancel others. The article went on to say that each member in the drivetrain could be well balanced, yet when together, could vibrate. It went on to say that there were 3 major contributors; powertrain,wheels, and body.
Since your combo vibrates when stopped, you can pretty much rule out body.
Since it vibrates with the wheels off, thats out.
Since youve tried it with out axles,third member, etc,youve pretty much ruled everything out, except the trans, and the combination of engine/trans. Good work BTW.
So, at this point, I would suggest bolting on a proper balance flywheel and bell house, to eliminate the engine once and for almost all. I suggest this for three reasons. #1)the 727 is down and the 904 is kaput, and 2) if the engine isnt the source, then,the tranny has to be, and 3) its extremely rare that the automatic would be the source, although I can easily imagine internal situations that could be contributing.
If you cant find a correct balance flywheel, I myself can imagine a way of bolting on a neutral balance flywheel, and that flexplate behind it. Get creative, I am sure you can figure out a way.
Anyway, this late in the day, youve probably already bolted that 904 on, and are nearly ready to post results.
 
Thanks for all the replies. Against my better judgment I went ahead and put the 904 in. Last step put the driveshaft in. It's too long. It's Easter so I kept the swearing down. Started it up anyway. No crazy noises. Although I did almost start the car on fire. do to the trans cooler line that was taken off to reroute the shifter cable and never put back on. Who would have thought the slant 904 combo would have a different length shaft than a small block 904. Keeping positive but only have a week to figure it out or put everything back the way it was and live with it. Girlfriend has secret birthday plans that involve the dart. Happy Easter.
 
The 904s should be the same lengths. But driveshafts are very specific as to wheelbases, rear ends and even years.
How much too long?
You can get 1/4 to 3/8 inch at the rear spring/front hanger bolts. Or you can slot out the holes in the spring perches, and probably get a half inch there. So thats a total of at least 3/4 inch.Is that enough? I know youre anxious to get this sorted out, so I thought Id at least mention it.Youve probably considered it already tho.......
 
Here you go, hopefully this helps determine the length you need.

driveshafts.jpg
 
found a pdf in the forabodiesonly search engine.
got it cut last night (couple friends came over to help out)
was too late to test it out. we'll see tonight.

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[ame="https://m.youtube.com/watch?v=-30tqxh_n_I"]https://m.youtube.com/watch?v=-30tqxh_n_I[/ame]
 
I had a bad vibration after installing a Tremec 5 speed. I tried a couple things that didn't work. I ended up on the phone with Denny from Denny's drive shafts. He told me to set the drive shaft angles at 3 degrees down at the trans and 3 degrees down at the rear. This was against most of the advice I had heard. I did what he said and it pretty much cleared up the vibration. At 80 MPH it is not as smooth as a modern car but at least now I can use the rear view mirrors.
 
Decided to put the leaf springs back in there factory locations and do some road testing. Maybe I can rig up my go pro under the car to see something wrong.

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It does not vibrate at all in park.
Oh boy. did I miss this?Sorry.

What about neutral?In neutral the line pressure rises, and with it the convertor charge pressure too.This engages the turbine and things inside there will start to move pretty good, at or near to crank speed.
In park, the line pressure is very nearly dumped, and with it the convertor charge pressure.The turbine slows down and everything comes to a halt inside.If you rev it up in park, the turbine may want to spin up some and that would carry the guts along with it.
But all this is moot, because your tranny swap more or less proved that.

cuda69 sparked a memory.
To avoid d/s related vibration, on a balanced shaft , the front and rear angles need to be IIRC within 1 degree of each other, but oppositly; one up. one down, under running conditions.
 
As I lay rubber down hwy 67 I pray this transmission holds together. I think of every bolt that should be tight. As I grab 2nd the car takes flight. The driveshaft that we shortened comes to mind, but I grab 3rd and get my spring time high. Let off the throttle no rpms left. Get the car seats Hun it's time for a family ride.
 
skep419 said:
As I lay rubber down hwy 67 I pray this transmission holds together. I think of every bolt that should be tight. As I grab 2nd the car takes flight. The driveshaft that we shortened comes to mind, but I grab 3rd and get my spring time high. Let off the throttle no rpms left. Get the car seats Hun it's time for a family ride.
Click to expand...

what? you found the vibration?
 
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