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Old 12-23-2025, 10:20 AM   #1
rideblue00
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TH400 Removal(I need some tips and tricks)

So, my trans is leaking like a sieve and needs some TLC. I need some tips and tricks to remove it from the truck. Its against a 350V8. How do I access the upper bolts against the firewall? I assume when I pull the rear crossmenber and tip the whole thing down a bit I will have a little more room to get to the bolts. I dont have a lift or a trans jack. I will be blocking up the frame with some 6x6's to get some room to do this. I think I can borrow a trans jack, if not, I will build an accessory to grab the trans for my regular jack. Im not a newbie to these trucks or fabbing stuff, but just want to see what others have done to make things easier. Thanks guys
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Old 12-23-2025, 11:30 AM   #2
Grounded63
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Re: TH400 Removal(I need some tips and tricks)

The easiest is a 36" extension, a wobble socket, and a 1/2" impact gun.

Otherwise a box end wrench, 1/8 turn at a time, from the top.

Is it leaking from the front seal ?
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Old 12-23-2025, 12:27 PM   #3
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Re: TH400 Removal(I need some tips and tricks)

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Originally Posted by Grounded63 View Post
The easiest is a 36" extension, a wobble socket, and a 1/2" impact gun.

Otherwise a box end wrench, 1/8 turn at a time, from the top.

Is it leaking from the front seal ?
This is the way. These bolts are a pain! I also have found it somewhat helpful to lift the trans tail housing up or pull it down to give you a little more access as the motor pivots a little on the engine mounts. To avoid this hell I usually pull and install the engine and trans as one connected unit. Good luck!
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Old 12-23-2025, 12:42 PM   #4
rideblue00
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Re: TH400 Removal(I need some tips and tricks)

It's leaking from multiple points.
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Old 12-23-2025, 02:18 PM   #5
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Re: TH400 Removal(I need some tips and tricks)

A ratcheting swivel wrench is another approach .
Especially if your have the frontend off.

Link below for a Wrench.
Link: https://www.amazon.com/DURATECH-Flex...83c03d07c&th=1
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Old 12-23-2025, 06:55 PM   #6
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Re: TH400 Removal(I need some tips and tricks)

From the truck in the picture? Myself I'd consider pulling the motor and trans together from above.
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Old 12-23-2025, 07:17 PM   #7
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Re: TH400 Removal(I need some tips and tricks)

if you can and/ or able to , lay on top of the engine and the two bolts on top of the transmission . and get the rest from the ground , thats if your leaving the engine in the rig ( dont forget to support the engine someway at where you dont stress out the engine mounts )
.
and for the transmission removal , you can pull them out together
if not , you can raise the rig as high it can go with jack stands
than you can use the floor jack ( handle going under whatever door you ll be working under , so you can control the lowering trans ) with a piece of plywood on top of it
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Old 12-24-2025, 10:03 AM   #8
rideblue00
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Re: TH400 Removal(I need some tips and tricks)

bigmoe, I literally just got this engine and front end together and up and running. I dont really want to haul it all back out. Im still considering what to do as far as changing to a 700r4 or rebuild the 400. In retrospect, the better way was to figure this out before putting it in haha
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Old 12-25-2025, 11:24 AM   #9
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Re: TH400 Removal(I need some tips and tricks)

It's not as bad as it sounds. Just lower the rear of the trans, use a couple long extensions and you can get all the bolts. Remove the torque converter bolts 1st. I've pulled them with just a jack many times a trans jack makes it easier but it's not necessary
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Old 12-25-2025, 12:22 PM   #10
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Re: TH400 Removal(I need some tips and tricks)

Getting it back in will be much more difficult than removing. One thing that can help is to buy two long bolts and cut the heads off and put them in the back of the motor at 11:00and 1:00 to slide the trans into position.
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Old 12-25-2025, 12:54 PM   #11
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Re: TH400 Removal(I need some tips and tricks)

Quote:
Originally Posted by bigmoe View Post
Getting it back in will be much more difficult than removing. One thing that can help is to buy two long bolts and cut the heads off and put them in the back of the motor at 11:00and 1:00 to slide the trans into position.
This right here is one of the best tips. I made some for my manual transmission to bellhousing. Makes it so easy to remove and install by myself. I’ve kept them around and ended up using more than once
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Old 12-25-2025, 03:57 PM   #12
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Re: TH400 Removal(I need some tips and tricks)

I cut a slot in mine so a screwdriver can be used to help remove.
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Old 12-25-2025, 04:59 PM   #13
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Re: TH400 Removal(I need some tips and tricks)

Thanks bigmoe. I will take your idea one step farther and weld an Allen head of the appropriate size to mine as I have a socket set of ball Allen's.
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