Calling all Turbo 400 guys!

[shawn57nomad]

Hey guys in the process of a rebuild and had a few questions on building up the trans. Ordered the kit today from Northern for about $140 and am looking at upgrading the sprag and direct drum assembly with a 4L80E piece. Also I will be installing the TransGo 400-1&2 kit along with the rest. Looking for insight on this rebuild, as this is my first transmission rebuild. Anything is appreciated. Oh, I will have a manual and access to AllData Pro for upgrades as well.

[silverstreak]

Take your time, don't rush, and double check everything.

I rebuilt a C4 and forgot a seal on one of the clutch drums. I took it for a test drive and had no reverse. Had to pull the trans and pull it apart again. Wasn't much fun the second time. I've also built a couple of turbo 350's.

Tips;
Use a dab of vaseline to hold the check balls in place.
Use two very large worm type hose clamps to hold both halves of the pump in alignment when bolting it back together.
Lubricate all seals with atf prior to assembling units.
When you dis assemble the valve body, lay the parts out on the table in the order in which they came out for proper reassembly.
Pour about a quart of atf in the converter before installing it. Listen for the clicks to make sure it seats all the way. Use some wire or fabricate some device to hold it in place while the trans is lifted into position.


Tools;
Two small slide hammers to remove pump.
Feeler guages to check clutch pack clearance.
Dial indicator to check end play.
Torque wrench to assemble valve body.
Trans jack with safety chains.
Air nozzle with rubber tip to check piston seals.
Snap ring plyers.
May have to rent or fabricate something to compress the pistons so the snap rings can be removed.

[shawn57nomad]

thanks for the tips. you wouldn't happen to know about the intermediate sprag and the likeness of the 4L80E counterpart and intechange would ya? thanks again.

[Bob 68327]

Go Buy a 32 sprag . I can't remember the year of hot rod magazine it was in but the trans build in mine was origionally printed in Hot rod with a few improvements . Oh wait you never asked me did ya . If you got questions I still live up the street and know a very good tranny guy's phone number when you need help. Bob

[Lugnut64052]

I would recommend you hunt up a copy of Ron Sessions' excellent book "How to Work With and Modify the Turbo Hydra-Matic 400 Transmission." Study it for a while before plunging in.

Agreed on the Vaseline. Go up to the drug store and get an economy sized tub. It's the all-purpose assembly lube for automatics. Lubes seals, sticks check balls in place and sticks gaskets in place.

Ditto on the feeler gauges. If you have a donor transmission or two you can mix and match steels to get the clutch stack clearances you want, but you'll have to check them with feeler gauges. Also, a feeler gauge makes a decent piston seal installer.

Installing pistons by the feeler gauge method is maddening at first, so be patient. You may tear one or two before you get the hang of it.

The high element intermediate sprag interchanges between the 4L80E and the 400. Certain direct drums do too, but call around first to make sure you know what you're doing. I do know that if you use a 4L80E drum, you'll have to use a waved steel on the bottom of the clutch stack, or your bottom steel may fall out of the grooves and jam the clutch piston (don't ask me how I know that). You'll end up with instant burnt direct clutch stack.

Also, if you're swapping direct drums pay close attention to the check balls. Some trannys came with a check ball in the drum and not in the piston, and some came visa-versa. Just be sure one or the other has a check ball.

[shawn57nomad]

Thanks again Bob for stopping by and it only took about 50 min to get the trans out and to Van's shop for disassembly later this weekend. I will let you know for sure if I get in a bind...Let's hope not. Bumped into Mark at NAPA and he said give him a shout if I needed help too. This is great! Just wanna get all my ducks in a row.

[shawn57nomad]

Lugnut thank you to you as well. I am glad to see that I am getting first hand responses, that really helps out. Could you explain clutch spacing a little more. I assume...that the closer together they are the firmer the shift? Correct me if I am wrong. Thanks alot for the reply!

[Lugnut64052]

Clutch stack clearance is the space between the stack and the backing plate. If it's too sloppy, the clutch may be late applying, causing slip between the gears. You'll get a smooth, cushy feeling shift like in an old lady car. On said cars, it was engineered in on purpose.

On a performance transmission you want crisp, tight shifts. The trans should last longer that way too, since you have less slip as the clutches apply/release. Tightening up the stack clearance will make the clutch apply quicker. Don't overdo it though; if you get them too tight they may not release promptly. One clutch dragging while another is applying is bad juju.

Clutch stack clearance should be .040 -.080. I'd shoot for the lower end of the spec. Steels come in a couple of thicknesses-- .0775 and .0915. By mixing thicknesses you can get the stack clearance you're after. I've even placed two steels back-to-back in the center of the stack to get it to come out right.

Did a little more looking on direct drum swaps. Performance Transmission sells a direct drum/high element sprag combo kit that goes into both 4L80E and 400. I'm not 100% sure any and all drums swap in all cases, however.

[shawn57nomad]

Cool sounds good I will give it a shot..if all else fails try again I guess. thanks again!