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Re: Bulletproof 727?
#129776
05/14/09 08:44 AM
05/14/09 08:44 AM
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Joined: Apr 2007
Posts: 871
WA 98043
thecarfarmer
super stock
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super stock
Joined: Apr 2007
Posts: 871
WA 98043
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QFT: Quote:
...snip...
A lot of it has to do with making sure the clearances are set correctly, everything is meticulously clean and you start with a core that has good hard parts to begin with.
...another snip...
We pretty much all accept this holds true for engines; why not for transmissions?
If the TH400 was inherently superior, why would guys have adapted the 727 behind BBC engines back 'in the day' for use in funny cars, etc.?
The 727 has one well-documented issue: the overrunning clutch is prone to failure if the load is removed under power (i.e. driveshaft or axle failure). This mandates disassembly and inspection if this occurs.
IMHO, it's largely assembly techniques and operator responsibility. And, yes, a little bit of luck.
-Bill
Seduce the attractive, and charm the rest.
******
489 C.I.D., roller cam, aftermarket heads, tunnel ram, stock '54 Dodge rear axle assembly: which of these doesn't belong?
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Re: Bulletproof 727?
[Re: thecarfarmer]
#129777
05/14/09 10:06 AM
05/14/09 10:06 AM
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Anonymous
Unregistered
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Anonymous
Unregistered
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Quote:
The 727 has one well-documented issue: the overrunning clutch is prone to failure if the load is removed under power (i.e. driveshaft or axle failure). This mandates disassembly and inspection if this occurs.
Quite a few members here (myself included) have recommended that the trans. be inspected after racers have posted driveshaft and axle failures. More people need to spread the word that this is a requirement with a torqueflite and not an option after driveline failure!
The only reason I brought up the cleanliness part is I've had to go through and re-do transmissions that were done by big name shops. Honestly a monkey could've done a better job rebuilding one from what I saw! It was obvious the transmission had been burnt up before being rebuilt and they didn't even bother to completely disassemble and clean the valvebody!  Guy went to all the trouble to ship it to Kansas from Arizona thinking it was a good piece.... 
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Re: Bulletproof 727?
[Re: 6o4o]
#129781
05/25/09 08:55 AM
05/25/09 08:55 AM
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Joined: Jul 2008
Posts: 30,447
Florida STAYcation
dOoC
The village idiot's idiot
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The village idiot's idiot
Joined: Jul 2008
Posts: 30,447
Florida STAYcation
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Quote:
don't know about you guys, but I see broken rear servo spring retainers about on a monthly basis! Just got a 727 on my desk with broken retainer, broken reverse band arm, rear servo and also rear band and drum burned up
... TF-2 kit installed with pressure plate at 0 position (as recommended for street use).
So to me installing a billet rear servo or at least a reinforced spring retainer is a MUST with a street TF-2 kit.
How much line-pressure are you running ?
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Re: Bulletproof 727?
[Re: 6o4o]
#129783
05/26/09 08:10 AM
05/26/09 08:10 AM
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Joined: Jul 2008
Posts: 30,447
Florida STAYcation
dOoC
The village idiot's idiot
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The village idiot's idiot
Joined: Jul 2008
Posts: 30,447
Florida STAYcation
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I am not familiar with that TF-2 kit at all..... but if this is like some other kits or valve-bodies ... NO WONDER you are breaking rear servos. With a std VB .. you get as much as 2.5 times the line-pressure in reverse to the rear servo...as you do in forward gears. So .. if you are running some of these high line-pressures that some say they are running(165 psi!) ... that rear servo is seeing over 400 psi !! All I can say is ..
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Re: Bulletproof 727?
[Re: 6packattk]
#129785
05/26/09 09:59 AM
05/26/09 09:59 AM
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Joined: Jan 2003
Posts: 75,043
U.S.S.A.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,043
U.S.S.A.
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Quote:
Would make me not go backwards much like ever,there has to be a way to depressurize that or why would you ever use a tf-2 kit at all.I was thinking of adding a shift kit but may just go turbo action valve body like I always have.Surely there has to be a fix for that.Don`t want to steal post but this got my attention.....
The fix is to get the billet retainer since all aftermarket valve bodies and kits RAISE LINE PRESSURE , reverse can be as high as 3 times line pressure. A low band apply VB with a heavier spring for reverse/low servo can also pop out the retainer .
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Re: Bulletproof 727?
[Re: dOoC]
#129786
05/26/09 10:31 AM
05/26/09 10:31 AM
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Joined: Jan 2003
Posts: 16,928
NC
440Jim
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,928
NC
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Quote:
So .. if you are running some of these high line-pressures that some say they are running(165 psi!) ... that rear servo is seeing over 400 psi !!
I don't think a factory regulator can be adjusted to go to anywhere near 165 psi. It would require a spring change at minimum.
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Re: Bulletproof 727?
[Re: 6packattk]
#129789
05/26/09 12:58 PM
05/26/09 12:58 PM
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Joined: Jul 2003
Posts: 577
Grand Rapids, MI
11secondC
mopar
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mopar
Joined: Jul 2003
Posts: 577
Grand Rapids, MI
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Just had this very thing happen to mine end of last summer. Rev/lov servo retainer let go, shattered the rev/low servo, killed the band and the drum was in 2 pieces. Trans had been together for 7+ years, with nothing more than red clutches and keolene steels with a TF-2 kit. Just last year I had swapped in a TA forward pattern low band apply mvb. Made it about 4 months after that. As of saturday, it got a bolt in sprag, 4.2 lever, reinforced strut, billet rear servo, and new clutches/steels etc. I'll be happy if it goes another 7 years for me... 
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My car is not making huge horsepower,and my trans is a stock 727 using a Turbo Action Tranz Box kit,Cheetah valve body and their 3800 converter.
I bought a heavy duty retainer on second build cause I bent the heck out of original pulling it.Well I learned something today about tranny`s, thanks guys