TH400 Rebuild Series - Inspection (A successful rebuild starts here)

Increasing the odds of a successful rebuild begins with a good inspection.
See what it takes to inspect the GM TH400 automatic transmission. Learn about the basics, along with some things that are easily overlooked. Accidentally overlooking worn out, and/or damaged, parts can lead to a premature transmission failure.
See what it takes to inspect the TH400:
1). Pump.
2). Input Drum.
3). Direct Drum.
4). Planetary gear set.
5). Case.
This video is led by Andy. He's an ASE Master Certified Automotive Technician, that specializes in automatic transmissions. He's been wrenching on automatic transmissions for over 40 years.
About Andy:
Coming Soon!
Help This Channel Grow:
Coming Soon!
*****TH400 Build Series*******
TH400 Teardown: • TH400 Rebuild Series -...
TH400 Inspection: You're currently watching it.
TH400 Building Clutch Drums: • TH400 Build Series - B...
TH400 Building Clutch Drums (Continued): • TH400 Build Series - B...
TH400 Bushings: • TH400 Build Series - B...
TH400 Prepping Case for Assembly: • TH400 Build Series - P...
TH400 Planetary Gear Set - Assembly & Installation: • TH400 Build Series - P...
TH400 Intermediate Clutch, Band, Direct & Forward Drums: • TH400 Build Series - I...
TH400 Pump + Front End-Play: • TH400 Build Series - P...
TH400 Valve-Body + Servos: • TH400 Build Series - V...
TH400 Filter + Pan + Modulator + Governor + Speedo: • TH400 Build Series - F...
TH400 Different Cases (Chevy vs BPO): Coming Soon!
RESOURCES:
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3) TH400 Repair Manuals: 📕
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230-Piece Tool Set: amzn.to/2L0AtWv
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3-Ton Arbor Press (12 inch working height): amzn.to/2Reqmyx
Lip Seal Installer: amzn.to/2Gz4KI5
Lip Seal Installer (Huge Time/Headache Saver): amzn.to/2MxUC8O
Pump Alignment Band: amzn.to/2J13lNF
Universal Clutch Spring Compressor (Use in trans & drums): amzn.to/2YHQGn6
Adjustable Clutch Spring Compressor (Use with shop press): amzn.to/2W2DAQs
Universal Bushing Driver Kit (Larger Sizes): amzn.to/2M1aQHn
Universal Bushing Driver Kit (Smaller Sizes): amzn.to/2Et1ON3
Snap Ring Pliers (Clutch Spring Compressor Snap Ring): amzn.to/2GwwixP
Snap Ring Plier Set (Pump Circlip Snap Rings): amzn.to/2IUxpdu
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Feeler Blades (Offset): amzn.to/3Y3ehy1
Pick Set: amzn.to/3F9ezL7
Pocket Screwdriver: amzn.to/3FfsCiC
5) TH400 Parts: 🔩
Overhaul Kit (Includes Bushing Kit, Bearing Kit, Bands, etc): amzn.to/2MhK4e7
Valve-Body Kit: amzn.to/2HwNAwE amzn.to/3iKqF67
Accumulator (Aluminum): amzn.to/3FhYxzt
Band (Front) (Intermediate): amzn.to/2EpgZGU
Band (Rear) (Low/Reverse): amzn.to/2QjqpbN
Intermediate Sprag: ebay.us/PA63ZL
Intermediate Roller: ebay.us/lK2SXd
Low Roller: amzn.to/3W17C5P
Pump Gears: ebay.us/uLDtbP
Bushings:
Kit: amzn.to/2QpxY0V
Upgraded Case Bushing: amzn.to/3Bjhy2L
Bearing Kit: amzn.to/30APEev
Washer Kit: amzn.to/2QgjPmx
Oversized Washer: ebay.us/H5BzBd
Governor Gear Kit: amzn.to/2WjQ7lU
Modulator (Red Stripe): amzn.to/2ErS99H
6) Shop Supplies: ✏️
Transmission Assembly Gel: amzn.to/2WrN7nT
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Brake Parts Cleaner: amzn.to/2HxQ1Pz
DISCLOSURE: 🕵
Links provided are affiliated links with the associated websites. While there is no extra cost to the purchaser, a small portion of the sale goes to support this KZbin channel.

[@johndifabrizio4344]

I am going to rebuild my th400 from watching this video! Alot of information that a DIYer can do in their garage! Thank you for the walk through of the trans.

[@SouthpawAutoworks]

Right on! Wishing you the best on your build.

[@tameramin8993]

Amazing 👏

[@SouthpawAutoworks]

Glad you enjoyed it! Thank you for dropping us a line.

[@azkards]

Good stuff gentlemen

[@SouthpawAutoworks]

Thanks for paying us a visit, Mike!

[@kenchaffin4946]

Another outstanding video can't wait for the next one 👏

[@SouthpawAutoworks]

More to come! Thanks for dropping us a line!

[@REPOOCNITSUJ]

Another awesome video!! I think you have the best videos anywhere on KZbin. I can clearly see every piece and I love the step by step. The build video can't come fast enough!!

[@SouthpawAutoworks]

Wow, thank you! Glad you're enjoying the series. Thanks for dropping us a line! BTW Your support is appreciated. More BTS (behind-the-scenes) footage on the way.

[@carwerks101]

I rebuilt my first Turbo400 during covid, it has since stopped moving, glad you guys released your video series

[@SouthpawAutoworks]

Congrats on your 1st TH400 build. Bummer about the setback.....sh*ft happens. I hope this video series serves you well.

[@johnkuscsik9928]

A rebuild video would be good. You guys are very knowledgeable. The straightforward style is good. Keep them coming

[@SouthpawAutoworks]

The positive feedback is appreciated. This build series is already complete. Here's all of the episodes. ******TH400 Build Series******** TH400 Teardown: kzbin.info/www/bejne/i6WppGVqm5yEh68 TH400 Inspection: kzbin.info/www/bejne/fmezcqKDnLJrp5I. TH400 Building Clutch Drums: kzbin.info/www/bejne/nWWQZ4mYiMt3g5o TH400 Building Clutch Drums (Continued): kzbin.info/www/bejne/aWG6ZJWqbt9pj9E TH400 Bushings: kzbin.info/www/bejne/oWbMqIWkqJepbac TH400 Prepping Case for Assembly: kzbin.info/www/bejne/jqvdoZ2ZdrGdnsU TH400 Planetary Gear Set - Assembly & Installation: kzbin.info/www/bejne/hYmWgmaOqsuEhtk TH400 Intermediate Clutch, Band, Direct & Forward Drums: kzbin.info/www/bejne/naitanSuq5iSb7M TH400 Pump + Front End-Play: kzbin.info/www/bejne/qpe0mnuGj9F8h6s TH400 Valve-Body + Servos: kzbin.info/www/bejne/rH-6Y5ehidNql80 TH400 Filter + Pan + Modulator + Governor + Speedo: kzbin.info/www/bejne/qpDTopqopcprmJI

[@JL-nb9ye]

Thank you thank you… for releasing competent expert explained how to videos !

[@SouthpawAutoworks]

Glad you enjoyed it.

[@nickkiofetzis5667]

another very impressive tutoring video by Robert and andy there video's are the best i have seen.thanks again guys for the wealth of knowledge.

[@SouthpawAutoworks]

Right on! Thanks, Nick.

[@larrysnellings7992]

I just took apart my HD TH400 this evening. I am needing the rebuild video! I've got the manual; but it is nice to learn from one experienced in rebuilding it. Thank you for the clear instructions in this and the previous teardown video.

[@SouthpawAutoworks]

Right on! You're welcome. Actively working on the other TH400 videos. Stay tuned.

[@JomsF]

Superb vid Rob, lots of moving parts with the trans, all the best bro!

[@SouthpawAutoworks]

Thanks, man! I appreciate you stopping by.

[@JomsF]

@@SouthpawAutoworks you are welcome bro

[@ntdracing]

You guys are amazing. Thanks for sharing your knowledge . Our race team is setting up our own TH400 rebuild process. Will be using and promoting your videos on our channel. Question…best way to shed heat from a TH400? Does a larger torque converter resist heat better? Thanks.

[@SouthpawAutoworks]

Right on! I took a look at your channel, and your website. Looks like a LOT of fun! Would love to attend an event... My thoughts regarding heat management: 1). Using a deeper than OEM oil pan (more fluid capacity, for better heat management). 2). Running external oil coolers (with clean airflow...if that's possible)(maybe something that has electric fans equipped). 3). Lower stall speed converter. (larger in size)(consult with a torque converter manufacturer). Converter Size: If you don't already know (and you're probably way ahead of me), converter size/design is typically matched with engine/cam, gear ratios, tire size, vehicle weight, intended outcome of vehicle, etc. One of the varying specs of converter design is what's called stall speed. A contributor of torque converter heat is the stall speed. Higher stall speeds (typically associated with performance) equal more heat. Higher stall converters are generally small, when compared to OEM applications. I think the best course of action is to reach out to a torque converter manufacturer. Find one that you're interested in working with. Let em know what you're trying to accomplish, and they will be able to point you in the right direction. Some of them will custom-build a converter, for your exact needs. Your positive feedback is very appreciated. Thank you for the support! -Robert

[@ntdracing]

Thanks for the reply. We are running a huge CBR cooler with big elec fan. Just put on a deeper aluminum pan with cooling fins. My error is the torque converter. Will look to change that out before the Baja 1000. It should survive the Mint 400 and Vegas to Reno as is. Huge thanks for the help. Your biggest fan! NTD Racing.

[@ourkid2000]

I have a fancy switch pitch converter in my THM. I guess you wouldn't replace that one? Just leave it?

[@jraydelatorre]

This was the first transmission model that I learn how to overhaul Wayback in the 1980s. probably around 82 or 84 and she was paired up to a nice big powerful Pontiac 400ci or 455ci engine I pulled that engine and transmission from a Pontiac Lemans sport coupe 1970 model with intentions of building a GTO. i love the video. Do you think that during the overhaul procedure your friend can demonstrate to us how to properly flat file the valve body mating surface and the pump as well plus any special file sizing requirements. length, grit, and so forth

[@SouthpawAutoworks]

Right on! That's really cool! Great question! We can definitely do a video on that.

[@calebprovencio482]

Caleb here from NTD racing - thanks for the video, great job with the step by step. I'm going to be rebuilding these for the race team and I'm trying to get an idea which parts NEED to be replaced each time. Looks like the overhaul kit you posted has more stuff than some of the kits I was looking at from JEGS and Summit, but maybe still a few parts missing than what you said in the video should be replaced. Those would be the pump gears, boost valve and sleeve and the pressure regulator spring? Those parts in addition to the rebuild kit you posted would cover the parts that must or should be replaced?

[@SouthpawAutoworks]

Hey Caleb, In my down time, I enjoy following the NTD Racing YT channel. Looks like a lot of fun. ***Initial build (street build)*** Overhaul Kit (Includes Bushing Kit, Bearing Kit, Bands, etc): amzn.to/2MhK4e7 Valve-Body Kit: amzn.to/2HwNAwE Accumulator (Aluminum): amzn.to/3FhYxzt Band (Front) (Intermediate): amzn.to/2EpgZGU Band (Rear) (Low/Reverse): amzn.to/2QjqpbN Intermediate Sprag: ebay.us/PA63ZL Intermediate Roller: ebay.us/lK2SXd Note: You're trans will either be a sprag-type or a roller-type. In other words, you don't need one of each. It's one or the other, depending on what your TH400 is already equipped with. Low Roller: amzn.to/3W17C5P Pump Gears: ebay.us/uLDtbP Bushings: Kit: amzn.to/2QpxY0V Upgraded Case Bushing: amzn.to/3Bjhy2L Bearing Kit: amzn.to/30APEev Washer Kit: amzn.to/2QgjPmx Oversized Washer: ebay.us/H5BzBd Governor Gear Kit: amzn.to/2WjQ7lU Modulator (Red Stripe): amzn.to/2ErS99H 4L80E Center Support Bolt: amzn.to/3Dq5FJ4 ***Extras you might want to have handy*** Gaskets are a one-time use (pump gasket, valve-body gaskets [also known as separator plate gaskets], governor cover gasket, etc). You might want to order extras, to have on hand...thought I'd throw that out there. Note: There are different VB gaskets, for different years. Something to be aware of. Also not a bad idea to have extra metal clad seals (pump, shifter linkage, etc). And also extra bushings (at a bare minimum, extra pump bushings). If you don't already know, if the from pump seal is leaking, it's a good practice to replace the pump bushing at the same time). ***If you're looking to freshen up the unit, between races, or at some other interval*** Performing a visual inspection of all parts will help determine what needs to be replaced. At a minimum, you'll need: 1). All new gaskets (they're a one-time use). 2). Pump seal (the "O-ring" that lives on O.D. of pump), as it will get disturbed. 3). Pump bolt washers (or O-rings...whatever applies). 4). Might consider replacing the front pump seal (metal clad) and the pump bushing, too...just for added insurance. 5). Etc. Caleb, Thanks for stopping by. I hope this info is helpful. I look forward to seeing the next adventure at NTD Racing YT channel.

[@user-rb6gf7hg8d]

Causes of too much input shaft endplay correction damages to transmission of too much input shat endplay

[@bloodfallinCOD]

I just installed my th400 that I rebuilt. I used a reman torque converter from autozone. I followed a manual step by step while rebuilding. Now in gear I feel shuddering while accelerating and it won't shift. Could it be the TC or did I mess something up on the rebuild. The shuddering is in Drive and reverse both

[@SouthpawAutoworks]

Do you have an automatic transmission pressure gauge (Over 300 psi)? If so, what's the line pressure with the engine idling, and trans shifted into Park? What's the line pressure with your foot on brake, engine idling, and trans shifted into Reverse? What's the line pressure with your foot on brake, engine idling, and trans shifted into Drive? This has me thinking converter, pump, vacuum modulator, etc. These things are used regardless of shifter position.

[@rogersibilsky3786]

At 19:34 in the video...a small threaded hole can be seen in the case just below the linkage arm. The hole is spot/flat faced and looks to be a 1/4-20 thread. I was told that this hole is found only on the early TH400 cases. What is this hole used for??

[@SouthpawAutoworks]

Good eye! That hole leads right up against the Center Support. The bolt (set screw) is jammed up against the Center Support. To the best of my knowledge, the idea was to prevent the Center Support from rocking back and forth (Which, if allowed to rock back and forth, could result in a clunk sound). More on this, in a future video.

[@rogersibilsky3786]

@@SouthpawAutoworks Awesome! I've asked a lot of people about this "mystery hole" and nobody really knows anything about it. I really enjoy watching your TH 400 videos.

[@jasonjennings5833]

Do you guys dual feed your directs?

[@SouthpawAutoworks]

Great question. Not typically, but it's definitely something we could cover, in a future video.