th350 TC in a th400

cburgin

Well-Known Member
Joined
Mar 20, 2005
Location
statesville/boone NC
What has to be dont to run a th350 Torque converter with a th400 trans? I ask because I had planned on running my th400/203/205 behind my 4.0L. Advance makes an adapter to do so but for whatever reason, the guy I talked to wasn't sure if the 350 tc needed would work with the 400. The stock th400 will not work with the adapter. Any idea's?

Also, I would consider selling what I have a going another route if it ends up being easier...I just dont think I will find anything as bullet proof and the 32 spline 203/205 with triple shifters
 
Can't be done... sell it to me!!!

TC's for TH350 and TH400 are the same. I think the diesel TH400's had an extra flex plate bolt but that is the only exception I know of.
 
Im confused. The guys at AA said I would need to run a th350 tc since they th400 would not work with their adapter so if they are the same why wouldnt either one work??

You might be in luck. I am debating on selling this setup and running a tf999/atlas or staks at this point.

I would need at least $2200 for my stuff thought if I did sell it. I have it all. th400 and TC pulled from a driving truck with the factory 203 behind it. a completely rebuilt (shafferbuilt) 205 with 32 spline all the way through, hot tanked and looks brand new. A NIB Gen 2 ORD aluminum adapter with shaft, and their complete triple shifter kit NIB as well. Everything you need in one stop!!
 
I think what he means is the 350TC's are 3 lug,meaning they have 3 mounting points that the converter bolts go thru.The 400 TC will have 6.The nose on a TH400 diesel converter is bigger in diameter and will only fit a diesel crank.
 
1-tonmudder said:
I think what he means is the 350TC's are 3 lug,meaning they have 3 mounting points that the converter bolts go thru.The 400 TC will have 6.The nose on a TH400 diesel converter is bigger in diameter and will only fit a diesel crank.
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I guess so. He said they adapter will work with the th400 but I will have to get a th350 torque converter...So is this going to be a problem for me?
 
IIRC a stock conv is around $75/$100 and they will interchange.All GM V series engines (with the exception of the 2.8) share the same trans bolt pattern.Somewhere in the late 90's they changed some.Buy the AA flexplate/adapter and a Th350 conv and use your 400.
 
th350 tq in th400

putting a th350 tq is an older secret. cause of the lower first gear in a th350 than a th400 the difference in lockup speed of the th350 converter will actually make the th400 feel kinda racey. not much but if your not lookin to spend money on a new converter, it is a cheap upgrade. and really you just slide the th350 converter on. if your using a diesel th400 u can swap it over to gas very easily. ive done this to my th400/np208. that i got out of a cucv.
 
Im pretty sure its from a gas motor, how can you tell?...I just talked to the guy from AA again and he was saying their adapter only works with the th350 because the bolt holes on the th350/700r4 are closer in diameter than the th400 but other than that the adapter works. Also the setup only seems to be about 7" longer than the stock ax15/231 with the slip yoke...I am stretching the rear 10"!
 
Im not sure I follow the AA guys logic.

The Bellhousing bolts are identical of course because they need to bolt to the same engine.
The TC to flexplate holes/studs are the same except the diesels....if you look in a tranny rebuild parts book
 
The TC's are interchangable. There are two different bolt patterns for the 3 bolts that bolt to the flexplate, one is a little larger diameter than the other. That is not a 350 vs 400 deal, as I have seen both patterns on numerous differnet TC's. Alot of (but not all) flexplates have both patterns.
 
SkyHiK5 said:
Im not sure I follow the AA guys logic.

The Bellhousing bolts are identical of course because they need to bolt to the same engine.
The TC to flexplate holes/studs are the same except the diesels....if you look in a tranny rebuild parts book
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Yeah im not really sure either...I guess I can just order the adapter and then get the TC I need...I hope its that easy...What should I be looking for TC wise...I know nothing about them...Also, all th400 are non locking correct? What about th350s and how do I need to approach this and the stall numbers?
 
I don't think the TH400 or TH350 were ever lock-ups. I think that was a 700R4 and up thing.

TC choice depends on how you want to drive it. If you're crawling, a stock converter would probably be just fine. Or you could pony up a little more and get a TCI high torque towing converter.
If you wanna launch it, get a higher stall. Problem is they tend to generate lots of heat at slower speeds.

That 203/205 sounds like the shiz.
I hear you're looking for a tow rig. I'll trade you straight up for an '81 Chevy dually, reg cab, 4x4, 454, 4 spd. It has your obligatory rust under the door sills and a couple holes in the driver side rocker, but other than that it is solid and actually looks pretty presentable. I'll get you more info and pics if you're interested.
 
Some of the Th350's around 80 had lock-up converters.Mine did and when I had it built he did away with the lock-up.Unless your running a big cam all you need is a stock stall converter 1500-1800 RPM IIRC.
 
the engine is stock...so I assume the stock TC for a 350 is a parts store part? any particular brand?

Casey, if I do end up getting rid of it, I will need the money to replace it with an atlas or staks
 
I've got a stock TH350 converter, don't know anything on the condition, got it in trade on a parts lot...came with the transmission. Was told everything was good, drove fine before pulled. You pay for it's ride and you can have it.
 
That would be a great kit to go with. Just make sure you measure all your tolerances that would be given in a service manual. Otherwise you'll have premature clutch failure, slow/no shifts, etc. As far as the full compression braking reverse manual, those are usually only used in offroad racing. They're very nice! Sure you really need something with that kind of price tag? They are exactly like the feel of driving a manual, obviously without the clutch pedal. When driving slow and you let off the gas, they'll slow you pretty hard.
 
cburgin said:
Casey, if I do end up getting rid of it, I will need the money to replace it with an atlas or staks
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I hear ya, but if I spend that kinda coin, I'm going with a planetary. Trade me, take that $5000 grand you were gonna spend on a high dollar tow rig and buy ya a three range Stak plus a night out on the town for you and the little lady.:huggy:

When I rebuild my TH400, I am definitely going with a reverse manual valve body. BIG advantages to that...
- manual control of gear selection (for compression braking as you mentioned)
plus
- full pressure on the clutch packs
- the capability to drop straight between 1st and reverse (and back)
 
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