TH400 build

[NickTransmissions]

The 727 and 518 snap rings are listed as the same. I got a kit to start that has 4 in it. .062", .074", .088", and .106".

You should be covered.

Read this: great description and illustrations of the advantages of the heavy duty BOP case.

https://www.ckperformance.com/Tech-Blog/2018/11/TH400-Transmission-Case-Identification-and-Interchange

I have built hundreds of 400s making well over 1000hp using the stock case. Assuming the chassis and engine mounting is correct, the case is way down the list of upgrades.

Chris of CK performance died earlier this week. I talked with him many years ago when I was playing around with the 2004R trans. I learned a lot from him.

Agree - I've built god knows how many TH350s and 400s and never had any issues w/the bells breaking unless there was something seriously wrong with the rest of the vehicle, structurally or otherwise. I will propose Reid cases and bells for racing apps in excess of a 1000 HP.

Very sad to hear of Chris' passing...I spoke to him about three weeks ago re TH400 and 4L80E parts/products including one of his D3 transbrake set ups for a potential customer. Learned a lot from him in our conversations over the years...I've since stopped building 200-4Rs...Parts are getting stupidly hard to come by and the cost/benefit for me simply isn't there relative to all the other units I work on.

 

[Tonimus]

You should be covered.

Agree - I've built god knows how many TH350s and 400s and never had any issues w/the bells breaking unless there was something seriously wrong with the rest of the vehicle, structurally or otherwise. I will propose Reid cases and bells for racing apps in excess of a 1000 HP.

Very sad to hear of Chris' passing...I spoke to him about three weeks ago re TH400 and 4L80E parts/products including one of his D3 transbrake set ups for a potential customer. Learned a lot from him in our conversations over the years...I've since stopped building 200-4Rs...Parts are getting stupidly hard to come by and the cost/benefit for me simply isn't there relative to all the other units I work on.

So is there any evidence of Chevy TH400 cases breaking in any of the reinforced BOP areas when there wasn't something really wrong with the car?

I actually spoke to Chris' daughter Monday. I called for a parts availability question and she told me. I felt absolutely terrible for her and the rest of the family.

 

[NickTransmissions]

So is there any evidence of Chevy TH400 cases breaking in any of the reinforced BOP areas when there wasn't something really wrong with the car?

I actually spoke to Chris' daughter Monday. I called for a parts availability question and she told me. I felt absolutely terrible for her and the rest of the family.

Evidence? From whom? Speaking to my own personal experience, I have never built a TH400 where I did just a bolt-on SFI bell housing. I have only done them with Reid Case, Ext Housing and Bell together. And only three that I have ever built were like that. 99.999999% of the time you don't need any of that if you're keeping it under 1000 HP and, as @Matt69olds has stated, even a bit beyond 1000HP, it's usually not necessary but every build is unique and builders all have to use their best judgement based on the complete picture.

You are certainly free to build your unit however you'd like...I am a big proponent of over-building, especially when in doubt about one or more aspects of the project. So there's nothing technically wrong with what you're doing w/the bell as long as case is properly machined/prepped and bell is fitted correctly. Matt was simply sharing his perspective based on experience (he's built more of these than I or most ever will).

 

[dragstews]

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.... Where's the BEEF ? ....

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[Tonimus]

Evidence? From whom? Speaking to my own personal experience, I have never built a TH400 where I did just a bolt-on SFI bell housing. I have only done them with Reid Case, Ext Housing and Bell together. And only three that I have ever built were like that. 99.999999% of the time you don't need any of that if you're keeping it under 1000 HP and, as @Matt69olds has stated, even a bit beyond 1000HP, it's usually not necessary but every build is unique and builders all have to use their best judgement based on the complete picture.

You are certainly free to build your unit however you'd like...I am a big proponent of over-building, especially when in doubt about one or more aspects of the project. So there's nothing technically wrong with what you're doing w/the bell as long as case is properly machined/prepped and bell is fitted correctly. Matt was simply sharing his perspective based on experience (he's built more of these than I or most ever will).

I'm not discounting either of your professional opinions. I started off by replying to you saying your videos have been very helpful.

This all started from "don't cut up a factory Chevy case", which then turned into BOP cases are stronger. Just trying to figure out how I'm wrong by doing so.

We're doing a SFI bellhousing due to NHRA rules for time. We run at NHRA tracks, so we have to meet those specs. Anything quicker than 9.99 needs a shield or bellhousing. In the '63 there's no more room for a shield. The car should be capable of high 9s when we get the tune and trans dialed.

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[NickTransmissions]

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Not from my point of view. As I said, you have to make the right calls and decisions for your build based on your requirements. I also appreciate you watching my videos; thank you for the support on YT.

 

[Ricko1966]

Read this: great description and illustrations of the advantages of the heavy duty BOP case.

https://www.ckperformance.com/Tech-Blog/2018/11/TH400-Transmission-Case-Identification-and-Interchange

I have built hundreds of 400s making well over 1000hp using the stock case. Assuming the chassis and engine mounting is correct, the case is way down the list of upgrades.

Chris of CK performance died earlier this week. I talked with him many years ago when I was playing around with the 2004R trans. I learned a lot from him.

Very good read, thank you. I already saw the value of modifying the more common housing and leaving the rarer housings alone,for people/situations that need them. Never knew the structural differences.

 

[Keith Seymore]

We're doing a SFI bellhousing due to NHRA rules for time. We run at NHRA tracks, so we have to meet those specs. Anything quicker than 9.99 needs a shield or bellhousing.

Came here to make this point.

K

 

[Tonimus]

Very good read, thank you. I already saw the value of modifying the more common housing and leaving the rarer housings alone,for people/situations that need them. Never knew the structural differences.

I'm really not trying to be difficult, just trying to understand. What people/situations need an unmodified Chevy TH400 case?

 

[xm20k]

I'm really not trying to be difficult, just trying to understand. What people/situations need an unmodified Chevy TH400 case?

You'd be surprised how many stock street cars/trucks eat the lugs out of a case and yet don't break or burn up anything else.

It's why I currently have the guts from 2 sitting here, cases chewed up but internals all like new.

One was a BOP case the other a Chevy.

 

[Ricko1966]

I'm really not trying to be difficult, just trying to understand. What people/situations need an unmodified Chevy TH400 case?

The tow truck driver,the rv owner,the guy with a 1971 Caprice convertible. 90 percent of people that end up needing a Chevrolet th400 case,do not need or want to buy a seperate bell housing. Did you read the strength advantages of the BOP case in Matt's article?

 

[Tonimus]

The tow truck driver,the rv owner,the guy with a 1971 Caprice convertible. 90 percent of people that end up needing a Chevrolet th400 case,do not need or want to buy a seperate bell housing. Did you read the strength advantages of the BOP case in Matt's article?

Agreed. But not needing a case with a separate bellhousing is different than needing one with a factory bellhousing.

 

[xm20k]

Think of it like this cost of rebuild add a case because it's toast 3-400 all you find is ones with the bell removed or the wrong bell, BOP for a chevy or vice versa now add the cost of an aftermarket bell 3-400 so 6-800 on top of the rebuild, labor, etc.

Aftermarket cases are around 2 grand without a bell so closer to 2200-2500 for just the case a rebuilt stock trans is around that. If you go this route your close to the cost of most full-on race transmissions.

Most guys are not going to want to spend that kind of money especially if they have a vehicle they are trying to keep stock

 

[NickTransmissions]

Agreed. But not needing a case with a separate bellhousing is different than needing one with a factory bellhousing.

It's not necessary to keep beating this horse to death. Frankly nothing that is not directly related to your build and requirements matters.

If there is one thing I continuously see in DIY or novice builders, it's unwarranted fixation on something not deserving of that person's energy or attention.

Those that build transmissions for a living, including me, have our own approaches, strategies and methods for each trans we work on and those have been honed/refined over years/units of experience but there is no "one size fits all", just a general consensus at a high level around what works and what doesnt. And even then, there are disagreements.

So, to reiterate: All that counts is that the transmission you are building is fit for your purposes and needs. That's it. Dont get wrapped up in anything that doesn't matter.

Ask for help if you need it; apart from that enjoy the experince and have fun with it. There's nothing like building your own engine and transmission then enjoying the fruits of your labor...

 

[bucket]

Agreed. But not needing a case with a separate bellhousing is different than needing one with a factory bellhousing.

It all depends on what happens down the line. When y'all are done using this trans and go to sell it, some basic Chevy guy like me won't be willing to spend the extra money on the trans just because of the sfi bellhousing, just to take a chance on a used trans and shove it in their street car. I'd just wait longer and spend less when a Chevy th400 is found that can be gambled on. ...But that's just one example.

Honestly though, it doesn't matter to me at all. You a building a trans for your needs, not anyone else's.