727 Vibration GONE

[Pastortom1]

Well, the verdict seems to be IN on the 727 vibrations that were driving me NUTS on this particular build.

It's a swapped out 360/727 combo which was shaking the car apart, and destroying tailshaft bushings.

We had a new driveshaft built and balanced first.........installed it, but the vibration persisted.....very little change.

Next, we had a local shop check and change the tailshaft bushing and bearing...it sounded like marbles rattling around in there it was so bad....they chose to leave the bearing (WHY, I will never know....they didn't "feel" it needed changing).... After this, it felt better, but still had the chronic vibration. After just 100 miles or less, it started to rattle AGAIN. All they did was eat my money.

Next, I took it to CRT Racing Transmissions in Z-Hills.........He looked at the driveline angle going INTO the tail, and said he wanted to raise the tail by 1/2"..........OK.........if he says so. Next, he said the yoke shaft had not been properly cleaned and emery'd before the last installation...there were high spots, although very tiny, that were affecting the bushing........OK...if he says so. Next, he stated that he didn't like the bearing either (obviously, a man after my own heart)....so while he was there, he changed it and cleaned up the tailshaft. A new bushing also, and a re-install. Next, he stated that the black rubber rear mount was too soft for my application, and served to allow too much movement at the tail........He installed a more stiff nylon mount bushing, jacking up the tail by his 1/2" that he wanted, and took it for a test drive.

He called me this morning and I went to pick up the car. He told me that at about 50 MPH he felt a slight harmonic, but he felt it could simply be a driveshaft balance adjustment........he said I could have it checked at his favorite shop to see, but that it wasn't a big deal.

I paid him a total of $175.00 ( !!!!!!!! ) for the parts and work, and took the car out for a run through it's paces. I now get a very loed chirp into second gear at about 3/4 throttle, and another nice little one into 3rd. There are NO vibrations AT ALL that I can discern, although I CAN hear the slightest little harmonic over 50......but it's what I would call a "normal" sound for a high revving cruiser. (it could even be a very slight harmonic coming from the motor...but nothing I'm worried about).

Apparently this guy knows his beans. This cup of Joe I'm GLAD to pay $175. for.........It's like a new transmission........all worries gone........enjoyment and smooooooooth ride is BACK baby!!

I'd like to take my hat off to CRT and the gang. Great job diagnosing and finally FIXING the problem.

Again, they smoothed out the yoke and polished it......They changed the tail bearing and bushing........they raised the drive angle at the tail by 1/2" upward (to slightly increase it), and installed a stiffer nylon rear mount bushing. Problem solved. Happy Camper. End of story. :rolling::santa::HappyNewYear::yes::tongueflap::rolling:

 

[ACME A12]

I love a happy ending...
:grin:
Ray

 

[69 Runner]

Kinda brings a tear to your eye like in Bambi:sad:

Good to hear you found someone who knew what they were doing and got it all fixed for ya.....and at a reasonable price too:sSig_goodjob:

 

[Meep-Meep]

Here's a good one. Years ago I picked up a 69 RR with a Dana 60, a 727 and a hot 440, and when I took the drive train out I noticed the drive shaft had "68 Firebird" written on it. Anyway, I swapped the Dana and drive shaft into my 68 RR and for the first time I had major vibrations. Like you, I took the drive shaft to have it balanced, and when I told them this is out of a MoPar not a Firebird, they gave me a nice education on drive shafts and yoke phasing. Camaros and Firebirds have the weld yokes 15 deg out of phase on the shaft because the drive shaft leaves the tail shaft up and over to one side on those cars. MoPars just go down without side to side deviation, but having the yokes phased at zero and balanced was only part of the problem. I also had to shim the tail shaft about a 1/2".

It seems strange that the length of the Firebird shaft happens to be the same as the B body combo mentioned above (I know the U joint is the same as the MoPar large yoke), but it was in there and it was running low 12's at the track. The previous owner must have had no feeling in the seat of the pants!!

 

[Pastortom1]

Yup...........A set-up like that will definitely make for a nice "Vibrating Lounger".

:grin::grin::grin::grin:

 

[Pistol Pete]

Tom, CRT being Cope ?

 

[Pastortom1]

CRT Performance Transmissions Inc. is the full legal business name......in Zephyrhills, Florida.

They're leaving tonight for a big weekend long drag event down here.......He said he expects to get about 10 hours sleep in 3 days if he's lucky....they rebuild trannies there at the track as quick as the entrants blow 'em.....said he turns around an average race powerglide in about 45 minutes. They run a mean Pro-Mod Falcon too..........outrageous car.

I'm convinced.......these are the guys I'll use from now on. :yes:

 

[69 Runner]

I'd be scared shitless to run a trans it took someone 45 minutes to build. Then again, maybe a glide is that simple. No parts? No time to rebuild:edgy:

 

[Pastortom1]

Yeah I hear ya'..............This guy better know his stuff..........been doin' it for quite a spell though..........

All I know is that I is a happy camper once agin'. :bighug::campfire: (I'm so happy, I tink I'll go hunt me a wabbit........)

 

[69 Runner]

:rolling:

 

[Patrick]

Good vibrations "NOT"

Still you should have no vibration at any speed. What you need to do now is replace the engine mounts. When the rubber in a spool mount goes soft you get metal to metal contact. The transmission mount is what fixed your car. It's hard to believe all of those other people paid any attention to the mount.
:black_eye::tongueflap:

 

[69 Runner]

found it...

http://www.youtube.com/watch?v=EJAXJWm8G4A&feature=related