My th400 swap notes

[pdiddy]

I just wanted to start a thread to discuss my th400 swap process and expenses so others could have an idea from first hand..


So let's start with the list of parts and keep in mind I am swapping out a m6..

Transmission w/ valve body and trans break I am using fti
Convertor I am using fti
Flexplate "make sure your convertor has same bolt pattern" I am using tci
Oil cooler w/fan and thermostat and hoses "derale makes a few nice ones"
Drive shaft
Transmission bushing poly or rubber for your application
Transmission cross member "can modify the manual one to work"
9-11 quarts of tranny fluid type f for my application l
Shifter with nuetral safety and reverse light micro switches

Optional
Tranny temp gauge and some sort of mounting solution as your factory one won't work no solution this far anyway


As things come up throughout my swap I might change some of these things so far I have taken out all the old stuff just waiting on the new now. Some key things I have come to so far is one if u plan on using a tranny temp gauge ask your trans builder to tap a hole in the pan for it makes things very easy. Also keep in mind u will need to make your reverse lights and neutral safety work I believe I have a solution for these and even retain my backup sensors after working with a very helpful vendor on here I will follow up once I am certain everything works. Something else to keep in mind as it could be an unexpected expese is a gear change to match your plans with the car I am swapping my 3.91 back to 3.45

I am looking at about 4200 bucks all new parts this will be a setup rated for up to 900 hp. I sold my stock tranny and accessories for 2500 so the cost was not bad at all considering what a big clutch would have cost me this winter had I keep the manual. I have pictures and will post some over the next week or two as progress continues

[LS7 427]

Thanks pdiddy. I'm doing the same swap from a 6l80. I'll add my list of things as well in addition to yours. My list is mostly incidentals that people may need for track purposes.

• (Lingenfelter) LNC-003 Dual RPM Launch Controller
• (Summit) ENS-3-1108G Poly Transmission Mount
• (Summit) MSD-8963 LED Shift Light
• (Summit) SBR-MUSH-0 Biondo Momentary Trans Brake Switch
• (Summit) DEI-165028 Aircraft Toggle Switches for Trans Brake & Linelock
• (Summit) PCO-0956PT Pico Add a Circuit Fuse Holders
• (B&M Racing) 81040 Magnum Grip Pro Stick Shifter
• (B&M Racing) 81060 Magnum Grip Side Plate Momentary Switch for Line Lock
• (B&M Racing) 22166 Aluminum Transmission Dip Stick

DSS has a driveshaft for a Th400 to stock diff listed on their website.

Interesting your going from 3.91 to 3.45. I have 3.45 and was considering going to 3.70. Maybe I'll just leave the 3:45's in for now and see how it goes.

Gforce1320 is doing a swap for a customer later in January and is building a crossmember specific to the TH400 swap. They said they would keep the measurements and be able to build one for customers if needed.

Bryan

[pdiddy]

The dip stick was something I had initially forgot but figured out and be sure it's locking for the track

[pdiddy]

Why the toggle and trans break switch is that so u don't accidentally turn on the trans break ??

[pdiddy]

I would look into a fire wall mount locking dip stick lokar makes them they are pricy but will lock and mount to fire wall which is ideal for the 5th gen from my understanding

[ttshovel]

Originally Posted by pdiddy

I would look into a fire wall mount locking dip stick lokar makes them they are pricy but will lock and mount to fire wall which is ideal for the 5th gen from my understanding

The one I had was a pos, after I pulled the stick for the first time it wouldn't go back into the pan as it was a cheap plastic dipstick that bent. This was a jegs brand, maybe a lokar one would be better

[LS7 427]

Originally Posted by pdiddy

Why the toggle and trans break switch is that so u don't accidentally turn on the trans break ??

Thats correct. I want a 12v on/off toggle switch and momentary button for both Trans Brake and Line Lock. Not so much for me but for my son, he cruises around town once in a while with the car.

Bryan

[LS7 427]

Originally Posted by pdiddy

I would look into a fire wall mount locking dip stick lokar makes them they are pricy but will lock and mount to fire wall which is ideal for the 5th gen from my understanding

This particular dip stick is locking and bolts up to the bell housing. I'll check out the Lokar.

[pdiddy]

It is locking it didn't seem like the description on it was its a hell of a lot better price than the lokar

[pdiddy]

It seems weird that bm offers a locking one for a 6l80 that's 130 then the one u posted for 50 I might give them a call about it and see what it's all about

[Bo White]

My th400 is a stock rebuild with a good drum and 34 sprag to handle my 630rwhp. That will handle the vast majority of the people that will do this conversion. A th400 is a tough tranny in stock form.

[Snidely Whiplash]

Originally Posted by Bo White

My th400 is a stock rebuild with a good drum and 34 sprag to handle my 630rwhp. That will handle the vast majority of the people that will do this conversion. A th400 is a tough tranny in stock form.

I concur the T400 is a brute. Back in the day, the dump trucks the city bought to haul off mud from digging up water main breaks, were powered by big block Chevy motors and T400s. Along with a buddy, we bought a truck at an auction and removed the motor/tranny a sold the truck to a salvage yard. We ended up, for $560, with a base 427 4 bolt main block with steel crank/rods, and a T400 that just needed a rebuild kit for that model tranny. Those trannies hit gear changes HARD!

[pdiddy]

Ordered all my parts today

[LS7 427]

I got my 6L80 out today. Have everything here except the flex plate and converter.