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727 TF hi gear drum retainer bushing #3003213
01/08/22 03:18 PM
01/08/22 03:18 PM
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BRIDGEWATER
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Tr jimi Offline OP
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Tr jimi  Offline OP
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BRIDGEWATER

Hello All,
I need a competent AT trans tech to look over my shoulder so I don't wind'up with the same problem after a second rebuild.

When this trans was powering my car it developed a vibration after shifting into 3rd not every time but one times out of 10 but steadily got worse .

I had suspected that the front drum was wobbling because it never happened in 2nd when the band was applied , sure enough suspicion confirmed the back of the drum where the metal sealing rings ride dug into the metal and ruined the drum the pattern is obvious that it was not running true.

New rebuilt pump assem. replacement drum,installed new bushing and they fit together very loose . .010" clearance /// pump stator hub measures 2.492.0" bushing in drum is 2.502.5" CarL Monroe states in his book .005" thou is correct . Is this expectable now that the stator support hub is been polished too many times , is there an over sized bushing available ? can I set the end play on the drum maybe so it doesnt walk back & forth . I'll shut up and listen now and Thanks for your answers much appreciated. Jim
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Re: 727 TF hi gear drum retainer bushing [Re: Tr jimi] #3003258
01/08/22 06:56 PM
01/08/22 06:56 PM
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Posts: 9,252
MI, usa
dvw Offline
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dvw  Offline
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Wide or narrow bushing? What is the endplay? Are the reaction shaft support ring grooves square? Or are they tapered ? Steel or aluminum drum?? Cast or Teflon sealing rings? What is the line pressure? What did the high frictions look like? Never had a drum cause a vibration.
Doug

Re: 727 TF hi gear drum retainer bushing [Re: dvw] #3003359
01/09/22 06:37 AM
01/09/22 06:37 AM
Joined: Nov 2020
Posts: 348
Isle of Sheeps
Gtxxjon Offline
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Gtxxjon  Offline
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Good subject indeed!

I have recently had a front drum bearing failure on a pre 1971 727. fan

With this in mind I will be using the 71-up drum and reaction shafts from now on!
Lots of Folks us the earlier narrow bearing drum without problems...

I think its down to the individual trans and end float etc?
Some 727's seem to have way too much end float so i like to 'cut it back' to around 30 thousanths now...

Good luck with you front drum issues, they can be troublesome indeed...

I personally would not go anywhere near a dragstrip 'without' a Cope steel drum now...(1971-up only)... drive

5848326-Reaction_supports.jpg
Last edited by Gtxxjon; 01/09/22 06:39 AM.

Carpe diem, quam minimum credula postero, thanx Horace!

There’s no point trying to fix stuff that ain’t broke,,, 'but if ain’t broke',,, you is not trying hard enough...
Re: 727 TF hi gear drum retainer bushing [Re: Tr jimi] #3003399
01/09/22 10:30 AM
01/09/22 10:30 AM
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Tr jimi Offline OP
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Guys , Thanks for the help ,

The trans case is 72 but running 78 internals so its the latter wide bushings /// Drum is stock cast metal . My Javelin only runs high 13.90

the clutch frictions and steels look perfect and will be re-used no strange wear patters , it never gotta a chance to slip in 3rd so there nice its a 4 friction drum
the support grooves are square and last time i was utilizing metal hooked type rings
This time i will use nylon slash cut ring so I don't damage the drum where they ride like last time plus I understand the hold pressure better.

I"m sorry but I dont know the line pressure...I have a transgo TF1 kit VB with the double yellow PR. springs ,also I tryed a totally stock VB and the high gear vibration problem was still present so dont think its Valve Body related.

End play was set verticle on out put shaft at .035"
Maybe my reconditioned front pump is is not in spec at 2.492.0 Thanks Jim

Last edited by Tr jimi; 01/09/22 10:35 AM.
Re: 727 TF hi gear drum retainer bushing [Re: Gtxxjon] #3003405
01/09/22 10:45 AM
01/09/22 10:45 AM
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Posts: 22
BRIDGEWATER
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Tr jimi Offline OP
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John ,
I think your 100% correct on the 70 and down thin bushing I have always seen alot of wear and scoring on even the wide style pump stator surface , thats why I suspect they polish the stator and leave it out of spec. even if you use a new bushing , Maybe its time one of the specialist need to produce an oversize bushing.

Also I heard Richard from Performance Trans down in Texas (who is exceptional ) says he junks the thin bushing set-up even for stock rebuilds.

Re: 727 TF hi gear drum retainer bushing [Re: Tr jimi] #3003454
01/09/22 12:54 PM
01/09/22 12:54 PM
Joined: Mar 2006
Posts: 9,252
MI, usa
dvw Offline
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The steel ring doesn't normally wear the drum. It wears the stator support grooves. There isn't enough movement of the drum to cause a vibration. Let's see pictures of the drum and rings. Is there any side wear on the ring? If there is, the stator support groove is worn. Put a new ring in it and hold it up to the light.
Doug

20200303_173755.jpg
Last edited by dvw; 01/09/22 12:56 PM.






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