WTB Big Block 727

[RyanB89]

Hey all,

Looking for a 727 Big Block tranny for my 69 Coronet R/T. Located in Southern New England.

I think I’ve narrowed down my harmonic vibration to the tranny but want to throw another tranny in to confirm 100%

Has anyone worked with Don’s Transmission in Rhode Island? They’ve quoted me $950 for a rebuilt unit with stock TQ.

Thanks in advance!

 

[dvw]

I've never seen a 727 cause a vibration unless the output shaft is bent. Never seen one bent that didn't disentrgrate the tail housing. Been building them fo close to 50 years.
Doug

 

[QuickBpBp]

I've never seen a 727 cause a vibration unless the output shaft is bent. Never seen one bent that didn't disentrgrate the tail housing. Been building them fo close to 50 years.
Doug

Yep they cracked right across where the mount is...

 

[RyanB89]

Really? I'm been chasing this vibration for a few months now and I'm completely stumped. If you have any ideas on things it could be, I'm all ears! Really just want this fixed before the good weather rolls around.

Here is the thread I have going on the issue: Vibration on Highway at 60+

Thank you!!

 

[Fran B]

Tailshaft bushing possibly. If you grab front yoke and it moves .010, had .013 on mine rattled at 65 mph.Puller and installation tool.

 

[RyanB89]

Tailshaft bushing possibly. If you grab front yoke and it moves .010, had .013 on mine rattled at 65 mph.Puller and installation tool. View attachment 1985820

Replaced the bushing already and no improvement. However, it does feel like there is some play when moving the slip yoke.

- Do they make any bushings that might be a little thicker than stock?
- Perhaps a new slip yoke, but it still vibrates when the driveshaft is removed, so I'm not thinking it's that.

 

[Fran B]

The driveshaft was short on my car and didn't rattle until I had 15,000 miles on it.

 

[PROSTOCKTOM]

Does it have the correct neutral balanced damper, flexplate and convertor?

Later big blocks used external balanced dampers, flexplates, and convertors. This is a lot of times the issue. Also check the rubber in the damper. This also causes a lot of issues.

Have you checked the u-joints, and inspected the driveshaft for any abnormal signs, or had the (propshaft for those that have it wrong) balanced?

Lastly, I had a set of custom-made steel rims on a car one time and they had to be balanced on the car because either the axle flange, and, or the drum

wasn't correctly round.

You can chase a lot of issues before you get it found.

Tom

 

[Pepe70]

Gents what is the average price 727 transmission used and working that came from car?

 

[Dave6T4]

I had a bad vibration with my 1967 R/T. I traced it down to a bad water pump. Grab your fan blade, and see if it has any play. Don't do this with engine running! LOL. The pump did not leak, but the fan shaft had some play in it.

 

[Dave6T4]

If you are buying a transmission, try to find a '71- newer non-lockup. It will have wider front drum bushing and Part-Throttle Kick Down. A lock-up 727 will have an input shaft with a drilled hole down the centre of it to supply hydraulic pressure to clutch in torque convertor. Also, the splines do not go to the end of the shaft.

 

[robert horman]

If you are buying a transmission, try to find a '71- newer non-lockup. It will have wider front drum bushing and Part-Throttle Kick Down. A lock-up 727 will have an input shaft with a drilled hole down the centre of it to supply hydraulic pressure to clutch in torque convertor. Also, the splines do not go to the end of the shaft.

My 1968 727B hemi developed a vibration between 55 mph and 65 mph. I replace the drive shaft u joints and had the drive shaft balanced. still had vibration. replace the tail shaft bushing on the trans and vibration was gone. trans had 77000 miles on it. Ryan did you have driveshaft balanced? Bob Horman

 

[1966satellite]

I have a bb 727 that I'd sell. It shifts fine but leaks from I think the front seal. I think it is early 70's but I'd have to check to make sure. It's located in central Illinois.

 

[Moparguy59]

If it vibrates with no driveshaft
Probably
Wrong damper
Bad damper
Wrong balance on T converter
Maybe has six pack rods and shouldn’t



I suspect u joint seized up or rear bushing otherwise