Tf727 servo questions

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bcuda1$3$

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Talked to two 727 servo manufacturers about my rebuild. 318 2 barrel /727 weekend driver. Anyway they were saying I need low rev billet servo because I did the tf-tc “shift correction kit” with heavy duty springs. I’m assuming because that servo can’t handle higher pressure.

Anyway I’m assuming the retainer is the problem right? Do I just get a thicker stronger retainer or a full billet piston/ spring/ retainer kit? Is that TSR any good? Price is good.

Also is the DIY accumulator block off rod. What will that give me? Worth doing? Am I asking for too hard of shifts or fun

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The blocker rod simply firms up the shift because the fluid does not need to slowly "accumulate" enough to overcome the spring between the piston and valve body. The first thing I do when rebuilding a VB is to trash the spring and put in a blocker rod. Been doing that for 40+ years. For simple daily driving you're not going to need to get different servos, IMHO. I just install a Fairbanks shift kit that has all the components & blocker rod you'll need to have a nice shifting unit.
 
Ricks70Duster340 said:
The blocker rod simply firms up the shift because the fluid does not need to slowly "accumulate" enough to overcome the spring between the piston and valve body. The first thing I do when rebuilding a VB is to trash the spring and put in a blocker rod. Been doing that for 40+ years. For simple daily driving you're not going to need to get different servos, IMHO. I just install a Fairbanks shift kit that has all the components & blocker rod you'll need to have a nice shifting unit.
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So if I wanted to make a blocker rod for the accumulator, I’m reading anywhere from 2.75-2.9inches long and simply put said rod in place of spring and make sure the valve body sets flat when installing.
 
bcuda1$3$ said:
So if I wanted to make a blocker rod for the accumulator, I’m reading anywhere from 2.75-2.9inches long and simply put said rod in place of spring and make sure the valve body sets flat when installing.
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Or just buy one..
 
The SK TFSC it is a minor kit to improve shifts. It is not a performance kit, and before I took the word from someone who is trying to sell me something, I'd contact Transgos' tech department and see what they think. I had one in my Challenger, and the builder did not change any servos. Perfect kit for my car and driving habits. I know damaged/cracked servos can cause issues but I don't see with the minor kit you're installing they will need changing. There are a couple of smart ex builders, on this board, Rusty Rat Rod is one, ask what they think.
 
transman said:
The SK TFSC it is a minor kit to improve shifts. It is not a performance kit, and before I took the word from someone who is trying to sell me something, I'd contact Transgos' tech department and see what they think. I had one in my Challenger, and the builder did not change any servos. Perfect kit for my car and driving habits. I know damaged/cracked servos can cause issues but I don't see with the minor kit you're installing they will need changing. There are a couple of smart ex builders, on this board, Rusty Rat Rod is one, ask what they think.
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Yep ask someone selling something and yep you need it! They said I would blow out the low /rev servo retainer. And needed to upgrade it and nothing else. Idk it’s just a 100-115$, but this thing keeps 100$ing me haha.
 
bcuda1$3$ said:
Yep ask someone selling something and yep you need it! They said I would blow out the low /rev servo retainer. And needed to upgrade it and nothing else. Idk it’s just a 100-115$, but this thing keeps 100$ing me haha.
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Where I've seen the rear servo cover "blow" was when people would set the valve body line pressure to the moon. Just follow the instructions and you'll be good. Several kits have levels of heavy duty, street, and race. Build your VB with an honest determination of how you will use your car. The street settings are not obnoxious, but firm things up nicely. Have fun!
 
I would think veeeeeery carefully about replacing a spring with a rod. A rod is cheaper, so why didn't Mopar use it? Because the spring cushions the shift & cushions the shock load on trans parts. The Transgo shift kit came with a stronger L/R servo spring, no rod.
 
Bewy said:
I would think veeeeeery carefully about replacing a spring with a rod. A rod is cheaper, so why didn't Mopar use it? Because the spring cushions the shift & cushions the shock load on trans parts. The Transgo shift kit came with a stronger L/R servo spring, no rod.
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The rod goes under the accumulator piston, not the L/R servo. The L/R servo is modified by some shift kits to add a shim to essentially make the servo solid for a faster apply/release of the rear band.
 
Ricks70Duster340 said:
The rod goes under the accumulator piston, not the L/R servo. The L/R servo is modified by some shift kits to add a shim to essentially make the servo solid for a faster apply/release of the rear band.
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Yes I understand that. Separate the low reverse servo question and the accumulator question.

Is full kit needed with this shift improver?
Is a blocking rod, a good mod while I’m in there?
Ricks70Duster340 said:
The rod goes under the accumulator piston, not the L/R servo. The L/R servo is modified by some shift kits to add a shim to essentially make the servo solid for a faster apply/release of the rear band
Click to expand...
 
bcuda1$3$ said:
Yes I understand that. Separate the low reverse servo question and the accumulator question.

Is full kit needed with this shift improver?
Is a blocking rod, a good mod while I’m in there?
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What is needed is what you expect from the trans. The improver kit will help, but it will not provide the nice firm shifts that a kit like Fairbanks will. I always use the blocker rod.
 
bcuda1$3$ said:
Yes I understand that. Separate the low reverse servo question and the accumulator question.

Is full kit needed with this shift improver?
Is a blocking rod, a good mod while I’m in there?
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The SKTFSC is A SHIFT KIT. What do you mean by "if full kit needed with this shift improver? I don't understand the question. If you want firmer, more aggressive shifts then use the Transgo TF-2 shift kit, instead if the SK TFSC kit. 25 cents worth of advise, unless you're a transmission builder and fully understand the hydraulics of the transmission, or have a builder assist you, just follow the instructions in the kits. I've seen my share of valve bodies where the instructions supplied where not followed, but bad advise from someone who wasn't a builder was, resulting in a valve body that headed for the scrap heap. JMHO I'm sure that Trail Beast and Rusty have seen this happen.
 
transman said:
The SKTFSC is A SHIFT KIT. What do you mean by "if full kit needed with this shift improver? I don't understand the question. If you want firmer, more aggressive shifts then use the Transgo TF-2 shift kit, instead if the SK TFSC kit. 25 cents worth of advise, unless you're a transmission builder and fully understand the hydraulics of the transmission, or have a builder assist you, just follow the instructions in the kits. I've seen my share of valve bodies where the instructions supplied where not followed, but bad advise from someone who wasn't a builder was, resulting in a valve body that headed for the scrap heap. JMHO I'm sure that Trail Beast and Rusty have seen this happen.
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transman said:
The SKTFSC is A SHIFT KIT. What do you mean by "if full kit needed with this shift improver? I don't understand the question. If you want firmer, more aggressive shifts then use the Transgo TF-2 shift kit, instead if the SK TFSC kit. 25 cents worth of advise, unless you're a transmission builder and fully understand the hydraulics of the transmission, or have a builder assist you, just follow the instructions in the kits. I've seen my share of valve bodies where the instructions supplied where not followed, but bad advise from someone who wasn't a builder was, resulting in a valve body that headed for the scrap heap. JMHO I'm sure that Trail Beast and Rusty have seen this happen.
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Is a full billet low/rev servo piston kit. Or just a better piston retainer. And since that kit pic above in comments) isn’t as performance as the other you mentioned, would I benefit from the rod? Thanks
 
I was told once you increase line pressure, a billet low/rev servo is cheap insurance. Stock ones can crack and the stock retainers can bend and pop out of the case with higher line pressures. Is it true? I do not know, but I heed that advice on 727s that I install reverse manual valve bodies on.
 
I think anyone sayin you need a billet servo on a 318 2 barrel has got to be a farkkin idiot.
 
Yes, the pressed steel L/R spring retainer will 'leave the premises' with the stronger spring. The retaining clip [ circlip ] is not really strong enough for the extra spring force, plus the pressed steel flexes/bends & lets go. Had it happen a few times. I made a beefed up spring retainer & that worked ok....
 
FWIW: I just bought and am in the process of installing an A&A manual valve body and billet reverse servo kit. Per their instructions they say to remove the accumulator spring. No big deal for me as mine didn’t have the accumulator spring to begin with. But the instructions make no mention of using a blocker rod. I called A&A and asked them if the rod was needed? Their answer was “No”.

So as for me, I’ll be putting mine back together without the spring and without a blocker rod. Guess we’ll just have to wait and see.
 
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