727 converter

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doopdoop67

doopdoop67

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Hi guys so I just bought a 727 drove about an hour thinking it would have a converter in it. It has a cheetah manual valve body in it. I picked it up for $250. It has no torque converter. What do you guys recommend for a replacement? Can I find stock one anywhere? I have a 318 in it right now.
 
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doopdoop67 said:
Hi guys so I just bought a 727 drove about an hour thinking it would have a converter in it. It has a cheetah manual valve body in it. I picked it up for $250. It has no torque converter. What do you guys recommend for a replacement? Can I find stock one anywhere? I have a 318 in it right now.
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Are you running a cam?
 
If you're going to run a reverse manual valve body in that transmission I recommend that you check and make sure it has a bolt in sprag or one-way clutch whatever you want to call it.
 
The 3/4 ton dodge club cabs with 4:10 gears have high stall converters that would be good for your application. Don't use a converter that is as big as the inside of the ring gear. You want one that is set back from the ring gear at least half an inch or so in diameter.
 
gtsdude said:
As long as the sprag is set in the case and isn't stripped out, no need for bolt in sprag imo.
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With a manual valve body this applies even more so.

All of the combined kinetic energy of the transmission (as transferred from the engine) is absorbed by the sprag. So if/when it comes loose, the sprag can literally spin out of the transmission case with catastrophic effect. To counter the sprag working itself loose, many resort to drilling and tapping the factory sprag, bolting it down in place. Other manufacturers provide what are aptly called a “bolt-in sprag” that are already drilled and tapped, as well as packed with new springs and rollers.
 
It depends on the manual valve body having low band apply or not. With low band apply it greatly reduces the chance of a sprag failure. Also the rollers and springs are what usually fail first, by rolling over, then it can take out the outer part of the sprag. Unless you put a super sprag in that has more rollers and can’t roll-over like a normal sprag.
 
Low band apply does not really matter with a manual valve body when it comes to the greater shock of the shift against the sprag that is produced.
The stock unit is a ring of Steel pressed into an aluminum case and then locked by a set screw. They fail in everyday use so why take the chance of it failing using a manual valve body.
 
I think we are talking 2 failures, your talking about the outer half spinning in the case, I’m talking about the rollers and springs laying over. Both sprags use the same rotating parts, the only difference is how they are attached to the trans. The bolt in might keep the outer part in place but the moving parts are the same and will fail equally.
 
Also the low band apply is helping keep the low reverse drum from moving, along with the sprag that only moves in one direction. Without low band apply you are relying on just the sprag to hold the low/reverse drum. Keep in mind it’s only 1st gear the sprag is used, it freewheels in 2nd and 3rd. How can the 727 sprage fail in a transmission ?

1. Any time the sprage is shocked, you break a U-joint, axle, or ring&pinon, it can cause sprages to fail
2. Driver error. In the heat of competition/excitement a driver could accidently nuetral-drop the transmission. I know what your thinking, I've never done that. But it could happen.
3. If the carb or ignition causes a back-fire and the car noses down and picks back up, or if you get in and out of the throttle while in first gear, you can damage the sprage.
4. If the car hooks, then the tires spin, then hooks again, the sprage can fail. And I know none of us have EVER had traction probs. (yeah, right)
5. Doing burn outs, starting in first gear is the biggest no-no of all. Burn outs should be done starting in 2nd gear and shifting into 3rd gear.
All 5 conditions are while in first gear.
 
It's not just 1st gear. At the top end in 3rd when a u joint lets go you can rip it apart.
 
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