updated-new trans or rebuild current

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67barracuda

67barracuda

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Ok, I have a 904 non lockup and not sure if I should rebuild or buy new. It looks like for 1300-1500 I can get a new manual/auto shift from many different places. I like the option of having it a manual /auto shift, but can get a clean opinion on which company to go with. If I have someone rebuild mine, who's kit should I get and what should I have them do. It will be a street strip car, motor has 512hp on dyno.
I have a 727 with a cheetah reverse manual valve body #17156 that say not for street use because no low engine brake. Not sure what that means, thinking of sell to get $ for new trans.
 
67barracuda said:
Ok, I have a 904 non lockup and not sure if I should rebuild or buy new. It looks like for 1300-1500 I can get a new manual/auto shift from many different places. I like the option of having it a manual /auto shift, but can get a clean opinion on which company to go with. If I have someone rebuild mine, who's kit should I get and what should I have them do. It will be a street strip car, motor has 512hp on dyno.
I have a 727 with a cheetah reverse manual valve body #17156 that say not for street use because no low engine brake. Not sure what that means, thinking of sell to get $ for new trans.
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For a shift kit, I just installed a TransGo TF-2 in a non lockup 904 tranny for a fellow A-BODY member. Many members of this site use this kit. You will like it!!!!
 
I have a fully built 904 with a high stall converter. 1000 miles on it I can sell to you for 1400 plus shipping! Has all the CRT Racing goodies and the converter was built by Dynamic!
 
This trans was built to handle anything thrown at it. Manual reverse vb, high stall, kevlar band, performance clutches and steelies, billet servo
 
67barracuda said:
TCI has the same kit as the TransGo TF-2, which is better?
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They both do the same thing. The TCI kit has a few extra parts that the TF-2 doesn't have. With the TCI kit you get 1-2 Shift valve replacement and a accumulator rod blocker. Tf-2 kit you have to grind down the 1-2 shift valve and there is no accumulator rod blocker. I will say the instructions for the TCI kit is better explained then the TF-2 kit. You will need a 904 pan gasket as both kits only include a 727 pan gasket. Just a heads up you will have to remove the tail section to get the L/R piston removed to install the replacement spring. There is a pin for the adjuster you have to remove (using a VB bolt that screws into the bolt). I have helped a few guys install the TCI kit, but I have installed 5 TF-2 kits (4-727, 1-904) myself and I have never had a problem installing the TF-2 kit. There might be more cost for the TCI Kit because of the extra parts in the kit. Good Luck
 
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d1970 said:
They both do the same thing. The TCI kit has a few extra parts that the TF-2 doesn't have. With the TCI kit you get 1-2 Shift valve replacement and a accumulator rod blocker. Tf-2 kit you have to grind down the 1-2 shift valve and there is no accumulator rod blocker. I will say the instructions for the TCI kit is better explained then the TF-2 kit. You will need a 904 pan gasket as both kits only include a 727 pan gasket. Just a heads up you will have to remove the tail section to get the L/R piston removed to install the replacement spring. There is a pin for the adjuster you have to remove (using a VB bolt that screws into the bolt). I have helped a few guys install the TCI kit, but I have installed 5 TF-2 kits (4-727, 1-904) myself and I have never had a problem installing the TF-2 kit. There might be more cost for the TCI Kit because of the extra parts in the kit. Good Luck
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There's no need to pull the tailshaft housing to remove the rear servo lever. You just have to loosen up the lever enough to remove the short strut. Then the lever rotates out of the way enough to remove the snap ring and remove the piston. Then just push the strut back up with a screwdriver when you're done replacing the servo spring.

Or if you want to remove the pivot and lever, you can cut the casting nub off that holds the pivot pin in and remove it (replace the o-ring while it's out). Then, once you push it back in, make a small tab that will hold it in out of 1/8" plate and bolt it to the nearest tailshaft bolt.

I'd do it the first way though. Also, some folks don't like the idea behind the accumulator blocker. The Transgo folks are the authority when it comes to shift kits and they recommend not doing it. According to them, it puts a lot more stress on the bellville springs and other components. Your choice...
 
mopowers said:
There's no need to pull the tailshaft housing to remove the rear servo lever. You just have to loosen up the lever enough to remove the short strut. Then the lever rotates out of the way enough to remove the snap ring and remove the piston. Then just push the strut back up with a screwdriver when you're done replacing the servo spring.

Or if you want to remove the pivot and lever, you can cut the casting nub off that holds the pivot pin in and remove it (replace the o-ring while it's out). Then, once you push it back in, make a small tab that will hold it in out of 1/8" plate and bolt it to the nearest tailshaft bolt.

I'd do it the first way though. Also, some folks don't like the idea behind the accumulator blocker. The Transgo folks are the authority when it comes to shift kits and they recommend not doing it. According to them, it puts a lot more stress on the bellville springs and other components. Your choice...
Click to expand...

A 904 transmission doesn't have the strut pieces, they are only on a 727 tranny.
IMG_1993.JPG

the tail shaft has to be removed, to replace the L/R piston spring
 
mopowers said:
There's no need to pull the tailshaft housing to remove the rear servo lever. You just have to loosen up the lever enough to remove the short strut. Then the lever rotates out of the way enough to remove the snap ring and remove the piston. Then just push the strut back up with a screwdriver when you're done replacing the servo spring.

Or if you want to remove the pivot and lever, you can cut the casting nub off that holds the pivot pin in and remove it (replace the o-ring while it's out). Then, once you push it back in, make a small tab that will hold it in out of 1/8" plate and bolt it to the nearest tailshaft bolt.

I'd do it the first way though. Also, some folks don't like the idea behind the accumulator blocker. The Transgo folks are the authority when it comes to shift kits and they recommend not doing it. According to them, it puts a lot more stress on the bellville springs and other components. Your choice...
Click to expand...

That only works on a 727. A 904 doesn't have the strut to remove and the lever will not pivot far enough around to get the servo out. Have to unbolt the tail housing like D1970 said
 
First off, the 904 is perhaps the simplest of automatic transmissions to build. Get a good book like the ATSG service group book and go for it.

Second thing. This "manual/auto" talk is horse hockey. It's a gimmickey selling point for shift kit manufactures to make you think you are getting something special, when you are not.

If the valve body is not a full manual valve body, it is automatic. Period. It will shift when the throttle pressure tells it to. End of discussion. You can manual shift it all you want, but if the throttle pressure linkage is greater than the shifter going into the next gear, it will NOT shift until it reaches the RPM the throttle pressure tells it to. That's just how it works.

Yes, a shift kit will make it shift "differently" but you can "manually" shift a stock automatic all day long. But if you put your foot on the floor, that transmission will not shift until the throttle pressure lets it. End of story. So the "manual auto" thing is only a selling point and nothing more.

The only way to make one shift RIGHT NOW with the shifter is to go full manual.

All that said, I would rip it apart and do it myself, whichever way you decide to go.
 
As RRR said, the "manual" feature on most shift kits will prevent an upshift or force a downshift, but not allow for a forced upshift. Basically they defeat the transmissions ability to prevent engine over-rev.

A 512 hp engine is probably pushing the limits of a 904, even one built with quality parts. If you have a healthy 727 you'd be better off using it. You can always put the TF-2 kit in your 904 valve body and put it in the 727. Trans shops discourage full-manual VB use on the street because they know most customers will get sick of it really quick. Also, much like not doing burnouts in low gear, it may be possible to damage the sprag if you're not careful.
 
My problem is this; I have a fully manual cheetah VB in a 727, but no convertor and a 904 with shift kit, new convertor but bad pump so it go to come out this weekend. If I go with the 727 I'll have to get driveshaft shortened. So I'm leaning towards repairing the 904 unless the convertor is junk.
So you think manual VB is bad on street, and there no such thing as a manual/auto kit?
 
I guess the shaft normally look like that, but why wasn't moving in gear? The pumps two drive teeth are not sheared off, which is what I was expecting to see. Not sure now.
 
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