T400 Trans Mods... What's out there?

[74bigblock]

Being largely unfamiliar with the workings of Automatic transmissions, I'm wondering if anyone can share their expertise on the T400 trans, and what I can get done to enjoy crisper shifting, downshifting upon flogging of throttle etc...

Thanks

 

[gmjunkie]

Turn the itty bitty screw in Vac. modg.if ajustable!! Pull vac line on modg. and there's a little screw in inlet!! Turn in clock wise 1/8 turn and try! Don't go more than 1 turn !!! and you can ajust elect. switch on gas peddle!! Cheepest Quickest if that don't do what want Shift Kit!! junk!!

 

[AKRAY4PLAY]

as stated, play with what you have then think about mods. a shift kit is nice, but i'd get a stall converter instead. don't go for a run of the mill cheapy either, you're wasting time, money and HP. go with a highend unit like Yank Performance. the effecientcy numbers are higher and your tranny will run cooler. i had a 2400 B&M converter, swapped to a 3800 Yank and my tranny runs 10 degrees cooler. all that and my 60 mph rpms dropped from 2800 to 2600. the car has drammatically improved street manners. Yank is'nt the only name in the game, but i have nothing but good to say about them. costomer service and end product are top notch.

 

[74bigblock]

Turn the itty bitty screw in Vac. modg.if ajustable!! Pull vac line on modg. and there's a little screw in inlet!! Turn in clock wise 1/8 turn and try! Don't go more than 1 turn !!! and you can ajust elect. switch on gas peddle!! Cheepest Quickest if that don't do what want Shift Kit!! junk!!

Junk.. what will tightening this screw in do?? make shifts quicker or harder or both???

Thanks,
D

 

[black_81_vette]

Shoot all kinds of goodies available! If your trans is in good shape wich im sure it is id get a good shift kit for it B&M makes one that has different springs for tha valve body ect,along with a new seperator plate for the valve body.That kit come with all the parts to make good firm shifts all the to a full manual set up in one box! If your thinking about a stall speed change Il give you some advice on what ive seen through years of doing this type of work.#1 selecting stall speed involves alot of variables, the convertor makers useualy give the stall speed within a certain range IE. 2200 to say 2600 or so.The reason is that the engine car weight gearing ect is a factor on how the convertor will react. A good example is a 200hp small block may only get 2200 rpm out of the convertor where as a healthy big block will get the 2600 stall if not more(flash stall) reason being the big block has more tourqe and hp and will rpm much sooner.also cam selection will make a big difference actualy its almost as important as the gear thats in use.Most of the time Joe racer has installed a wild cam on his 8.5 compression small block and now his car is a complete dud off the line. So what does he do? Gets a huge stall speed to help launch the car do to the engines soggy bottom end grunt.Se what happens is this the converter thats in there say a 3500 stall is so loose the car turns megga rpm and hes not going anyplace IE the conver will slip untill the rpm is reached where the converter is locked up.Another factor is the use of proper rear gearing, a 3500 stall useally likes at least a 3.73 or better gear depending on the engine combo.A good rule of thumb is try to match the stall speed to where the cam is about 1/4 to 1/2 way into the useable hp range.Alook at the cam card will spell that out for you.Id say if the cam is in the 290 duration range and your running a 3.73 gear with a big block a 3000 rpm stall should get you going rather quickly off the line.As for what the other poster said about him going to a higher stall and running cooler and turning less rpm my guess he had a bad convertor because the exact opposite is most likley,higher stall speeds generate more heat.Any way I hope I wasent too long winded!!And I hoped I helped you too!!! have a great day! PS always run a larger cooler if go with a higher stall speed heat kills tranys!

 

[Tyler Townsley]

There is also a way to put a ford overdrive on one for better mileage. Also some motorhomes used a 400 with a gear venders overdrive unit so if you have a wrecking yard with motorhomes check them to see if one is there. Make sure you get a chev version not a Buick/Olds version.


Tyler

 

[gmjunkie]

Junk.. what will tightening this screw in do?? make shifts quicker or harder or both???

Thanks,
D

Turning in Rt. will make it hold in gear a little longer and then will shift Ouicker & Harder, turning out Lt. will make it shift sooner and Softer!! (More Cushy) Dave did you get your Passing Gear switch working?? If not get that fixed first and try!! Turning in little screw can make a Heck of a diff!! Don't over do it, just a 1/8-1/4 turn at time!! and no farther than 1 turn!! and make shure you have good Vac on line going to it First!! If you over do it it can Brake diafram in Modgl. Just puting a New Modgl. may do what you want if old one is weak!! $15.- $25. If diafram is bad it will suck Tranny Fluid through vac and Make it Look Like James Bound opened up a Smoke Screen!! junk!! P.S. Don't Change Conv. Stall It will probly make your Gas Mileage go to ****!! (if you have any)

 

[74bigblock]

Turning in Rt. will make it hold in gear a little longer and then will shift Ouicker & Harder, turning out Lt. will make it shift sooner and Softer!! (More Cushy) Dave did you get your Passing Gear switch working?? If not get that fixed first and try!! Turning in little screw can make a Heck of a diff!! Don't over do it, just a 1/8-1/4 turn at time!! and no farther than 1 turn!! and make shure you have good Vac on line going to it First!! If you over do it it can Brake diafram in Modgl. Just puting a New Modgl. may do what you want if old one is weak!! $15.- $25. If diafram is bad it will suck Tranny Fluid through vac and Make it Look Like James Bound opened up a Smoke Screen!! junk!! P.S. Don't Change Conv. Stall It will probly make your Gas Mileage go to ****!! (if you have any)

Junk,

There is nothing wrong with the passing gear switch... except that it has no power going to it! This is why I started the thread about wire harnesses... There is no fuse in my guage fuse box, yet myu guages work. The Kick down switch is fed by this fuse... so now you see my problem. I suppose I could rig it... but I dunno which wire coming off the switch is the positive lead!

No converter... already did the shift kit w/new valve body.

 

[gmjunkie]

Junk,

There is nothing wrong with the passing gear switch... except that it has no power going to it! This is why I started the thread about wire harnesses... There is no fuse in my guage fuse box, yet myu guages work. The Kick down switch is fed by this fuse... so now you see my problem. I suppose I could rig it... but I dunno which wire coming off the switch is the positive lead!

No converter... already did the shift kit w/new valve body.

Ok,Ok I'll get under my Dash and see if I can Fig out what you need to Know!! junk!! P.S. Hope the wire's are the same color from 74 to 78 Probly are!!

 

[74bigblock]

Ok,Ok I'll get under my Dash and see if I can Fig out what you need to Know!! junk!! P.S. Hope the wire's are the same color from 74 to 78 Probly are!!

They are so faded they all look pink/orange fade... like a melted slurpee.

 

[USNA1969]

Great looking car

I'm sorry I can't help with the tranny question. But I had to ask about the side pipes. I'm thinking about getting a set of pipes for my '72 big block and yours look really great. Do they muffle the sound enough to make the car street legal? Hopefully not more than just enough. Also, do you have any heat problems with them right below the doors, and does it make any difference in the heat coming into the car. My car doesn't have a/c and it gets right warm on the feet during the summer.
Good luck with the transmission.

 

[gmjunkie]

They are so faded they all look pink/orange fade... like a melted slurpee.

OOOOO maybe trans solenoid is bad and was blowing fuze's and someone put tOOO big of fuze and Fryed the wire's!!!! If so been nice to know while pan was off!! junk!!

 

[74bigblock]

OOOOO maybe trans solenoid is bad and was blowing fuze's and someone put tOOO big of fuze and Fryed the wire's!!!! If so been nice to know while pan was off!! junk!!

He checked the wiring in the trans... said it was fine. The wiring is a different issue all together... not sure who did what or why.... but it's bad news in there. Nothing is fried... just everything is all wrong.

 

[74bigblock]

I'm sorry I can't help with the tranny question. But I had to ask about the side pipes. I'm thinking about getting a set of pipes for my '72 big block and yours look really great. Do they muffle the sound enough to make the car street legal? Hopefully not more than just enough. Also, do you have any heat problems with them right below the doors, and does it make any difference in the heat coming into the car. My car doesn't have a/c and it gets right warm on the feet during the summer.
Good luck with the transmission.

Thanks.. sent you a PM.