TH400 Questions
Thread Starter
Staging Lane
Joined: Oct 2004
Posts: 90
Likes: 0
TH400 Questions I have a million questions about my TH400. First of all the car is a 69 Camaro i purchased a year and a half ago with a 454 and turbo 400. The trans blew immediately. I got an AAMCO rebuild for 1000 which is a lot but it has a lifetime warranty. Anytime there is any problem at all i just pop in and they fix it free! 
So far it has only had leaks. It works great and smokes the tires into second even shifting at 4500.
My question is about manual valve bodies. I hear about full forwards and reverse only and all sorts of terms and I really dont understand what it means. From what I understand it allows you to shift your own gears. How do i know if I have a manual valve body? I dont think i do. I do use my Quarter stick to shift when i want, and I down shift with it because I have no kickdown solenoid. When i leave it in drive (3rd) it starts in first and shifts at 4500rpm to 2nd and 3800 rpm going to third, thus i do the shifting.
I hear this can wear out the trans if it has no manual valve body. True? I have a lifetime warranty anyway so whatever let it break. I also hear that manual valve body setups dont rob as much power as normal setups. What should i know about this stuff? And what is the most efficient setup in case it blows or i feel like upgrading? Let me know what the different valve body setups are.
Thanks and sorry for the long post. I did searches but could not find the info i need.
So far it has only had leaks. It works great and smokes the tires into second even shifting at 4500.My question is about manual valve bodies. I hear about full forwards and reverse only and all sorts of terms and I really dont understand what it means. From what I understand it allows you to shift your own gears. How do i know if I have a manual valve body? I dont think i do. I do use my Quarter stick to shift when i want, and I down shift with it because I have no kickdown solenoid. When i leave it in drive (3rd) it starts in first and shifts at 4500rpm to 2nd and 3800 rpm going to third, thus i do the shifting.
I hear this can wear out the trans if it has no manual valve body. True? I have a lifetime warranty anyway so whatever let it break. I also hear that manual valve body setups dont rob as much power as normal setups. What should i know about this stuff? And what is the most efficient setup in case it blows or i feel like upgrading? Let me know what the different valve body setups are.
Thanks and sorry for the long post. I did searches but could not find the info i need.
manual valvebody, you HAVE to shift it into each gear or it wont shift. As far as kickdown solenoid...my understanding is you need that to be working to get full line pressure at WOT....I'd check into that
TECH Regular
Joined: Feb 2004
Posts: 439
Likes: 1
From: burbank ca
passing gear just for laughs run 12volts to the male plug on the passenger side of your th400. do this through a switch. the reason for that is that your trans does not know you are at full throttle unless you tell it, and that is 12volts to the kick down system.
Thread Starter
Staging Lane
Joined: Oct 2004
Posts: 90
Likes: 0
So your say if I run voltage to my trans i'll get full line pressure and it'll have even firmer shifts? I guess i'll start getting those parts together and install it when i send the motor for a rebuild soon. The trans has an awesome 1-2 shift I cant imagine what it'll do when thats improved.
Lets say i am running voltage to the transmission with the solenoid. Which will have a firmer shift?
The trans shifting automatically?
Or ME putting around with my little quarter stick?
And let me know if its a rumor that a full manual valve body steals less power than a regular setup.
Whats involved in making my trans a full manual valvebody setup, i always shift the trans myself anyway.
Anything else you think i should know tell me. I dont know much about how auto work. The extent of trans work ive done is rebuilding the 2 speed on my brothers revo nitro rc truck.
Lets say i am running voltage to the transmission with the solenoid. Which will have a firmer shift?
The trans shifting automatically?
Or ME putting around with my little quarter stick?
And let me know if its a rumor that a full manual valve body steals less power than a regular setup.
Whats involved in making my trans a full manual valvebody setup, i always shift the trans myself anyway.
Anything else you think i should know tell me. I dont know much about how auto work. The extent of trans work ive done is rebuilding the 2 speed on my brothers revo nitro rc truck.
TECH Regular
Joined: Feb 2004
Posts: 439
Likes: 1
From: burbank ca
designed you must remember that the factory made differant transmissions for each application. if you have a trans that was made for your 454 you will probably be in good shape. the reason for the firm shift 1-2 is the pressure is about 150-160lbs. which was for decelleration. the factory intended the trans to be left in drive and not manually shifted. that is why the kick down must be on when you are at full throttle, it will raise the line pressure and the shift points. it works best when it is set up to work automaticlly. l hope that helps.
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Thread Starter
Staging Lane
Joined: Oct 2004
Posts: 90
Likes: 0
Thanks a lot John this really helped. I am going to get the solenoid working properly and see what happens. My only question now is how do i make the trans shift at the RPMs i want? Right now i dont rev it past 5000 because its a 73 truck 454 and it's cam doesnt want to go any higher. But after my rebuild i'm going to want the trans shifting at about 6k depending on how i get the engine setup. Time to buy an SC too.
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