TF 727 Growls in low - Solved!

Mike5 · Jul 19, 2021

So the transmission runs well, shifts well, fairly quiet when driving normally from stop to freeway speeds. When accelerating hard in low, there is a loud, pronounced growl from the trans and this stops when i ease off the throttle, it shifts to second and does not growl if i hit it hard again. I changed the filter, fluid, adjusted both bands, shift linkage and throttle linkage as per the shop manual. Any thoughts on what is causing the noise before i contemplate pulling the trans for a tear down? It’s in a yellow 1973 Charger with a 318. Thanks for all the help!

493 Mike · Jul 19, 2021

Did you find anything strange in the pan when it was off?
Mike

Mike5 · Jul 19, 2021

493 Mike said:
Did you find anything strange in the pan when it was off?
Mike

Hi, the pan had some super fine dark particles, the fluid was not burnt and the filter looked pretty good. I know that when i got the car a year ago, the throttle linkage was such that it never would have engaged. For how long it was like that, i have no idea. And the bands were more loose than they should have been.

blue69runner · Jul 19, 2021

Sound's like a rebuild in the near future.

R413 · Jul 20, 2021

Are you sure It’s not the exhaust pipes hitting the floor or a crossmember. This can cause a loud rattling or buzzing sound.

It happens more in low gear because there is more gear ratio involved and it torques the engine harder on the mounts.

StrokerSpanky · Jul 20, 2021

There are are 2 sets of planetary gears in your 727. Both sets are used in 1st. Only the front set is used in 2nd. Sounds like there's a problem with the rear planetary gears, rear ring gear and the rear half of the common sun gear. The rest gear set is ALSO used in reverse without the front gear set. If you get the same noise when accelerating in reverse it's for sure the rear gear set. Let me how it goes.

Mike5 · Jul 20, 2021

R413 said:
Are you sure It’s not the exhaust pipes hitting the floor or a crossmember. This can cause a loud rattling or buzzing sound.

It happens more in low gear because there is more gear ratio involved and it torques the engine harder on the mounts.

Good idea. I’ll check the exhaust for clearance today

Mike5 · Jul 20, 2021

StrokerSpanky said:
There are are 2 sets of planetary gears in your 727. Both sets are used in 1st. Only the front set is used in 2nd. Sounds like there's a problem with the rear planetary gears, rear ring gear and the rear half of the common sun gear. The rest gear set is ALSO used in reverse without the front gear set. If you get the same noise when accelerating in reverse it's for sure the rear gear set. Let me how it goes.

Good to know. I’ll test that ‘cause I’m always up for a test drive…….

dvw · Jul 21, 2021

I've only ever seen 2 planetary needle's fail in close to 40 years of building Torque Flites. Both times there was significant amount of magnetic particles in the pan.
Doug

Nevada dan · Jul 21, 2021

At least its one of the simplest transmissions , you don't need any special tools, went through my first one when I was 15

Mike5 · Jul 24, 2021

Solved!! After searching the car for something that was hitting on hard acceleration, I stumbled across bright metal on the tips of the radiator fan. The motor would twist just enough that the fan would hit the shroud. Opened up the fan shroud another 1/2 inch and problem solved. I swear the sound was coming out of the trans. Moral is: check the simple stuff first. Thanks for the help

64fury74charger · Jul 24, 2021

Mike5 said:
Solved!! After searching the car for something that was hitting on hard acceleration, I stumbled across bright metal on the tips of the radiator fan. The motor would twist just enough that the fan would hit the shroud. Opened up the fan shroud another 1/2 inch and problem solved. I swear the sound was coming out of the trans. Moral is: check the simple stuff first. Thanks for the help

Wow, that’s great news about your trans. Do you have a strap on the motor to help limit travel?.

1 Wild R/T · Jul 24, 2021

Check the drivers side motor mount....
Pop the hood, watch through the gap between the hood & the cowl... Start the car, foot hard on the brake, in gear, give it some throttle.. If the engine lifts significantly (It probably will) you need a new mount...

Dibbons · Jul 24, 2021

I thought I heard somewhere to test the motor mount putting the selector in reverse? Maybe not.

69L48Z27 · Jul 24, 2021

You can hold the brake in forward then reverse. That will test each engine mount at a time. Usually the drivers side mount is the one you worry about, and that would be in forward.

1 Wild R/T · Jul 24, 2021

Usually the driver side mount is broken & the passenger side mount is collapsed...

beanhead · Jul 25, 2021

Mike5 said:
Solved!! After searching the car for something that was hitting on hard acceleration, I stumbled across bright metal on the tips of the radiator fan. The motor would twist just enough that the fan would hit the shroud. Opened up the fan shroud another 1/2 inch and problem solved. I swear the sound was coming out of the trans. Moral is: check the simple stuff first. Thanks for the help

Absolutely! Thanks for the follow up.

TF 727 Growls in low - Solved!

Mike5

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493 Mike

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Mike5

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blue69runner

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R413

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StrokerSpanky

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Mike5

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Mike5

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dvw

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Nevada dan

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Mike5

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64fury74charger

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1 Wild R/T

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Dibbons

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69L48Z27

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beanhead

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