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TH400, what will this hold?

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Old Feb 29, 2012 | 06:14 PM
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Default TH400, what will this hold?

For the TH400 experts, any idea how much power the trans will hold? Can pick it up for a decent price. Thanks!

400 T transmission
Manual Rev. valve body
Raybestos “RED” clutches/ band
Deep pan
Roller output bearing
Dual feed direct drum
FRESH BUILD
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Old Feb 29, 2012 | 07:15 PM
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Does it have a 34 element sprag and drum?If so if its built right it should handle 650 hp.
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Old Feb 29, 2012 | 07:49 PM
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Thanks for the info. Just got off the phone with the guy, he said it has a 16 element which came with the RV's and big trucks, or something like that. I guess he has a pretty good rep and builds some of the cars at our local track. I asked him what it would hold and he said there are a couple of big blocks at our track pushing around 800hp with this same trans. Sound like BS or is that possible?

Trans is $600. He said he could build a th350 that can hold 650hp for around $550-600.
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Old Feb 29, 2012 | 10:25 PM
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Originally Posted by Tan327
Thanks for the info. Just got off the phone with the guy, he said it has a 16 element which came with the RV's and big trucks, or something like that. I guess he has a pretty good rep and builds some of the cars at our local track. I asked him what it would hold and he said there are a couple of big blocks at our track pushing around 800hp with this same trans. Sound like BS or is that possible?

Trans is $600. He said he could build a th350 that can hold 650hp for around $550-600.
Sure sounds like bs .The low prices are give aways.The trans wont handle that with a 16 element sprag.No one building a hi perf specced unit is going to use a 16 element sprag.Not giving him a beat down just speaking from experience.
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Old Feb 29, 2012 | 10:32 PM
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Put it this way... that trans has more than $600 in parts.
You can take a stock valve body and modify it to a fully manual valve body but if it's a reverse pattern it's a $200 valve body.
Your clutches, bearings and pan are easily $200.

Even if it is only a 16 element sprag (which is frowned upon by many), I see it as a great thing! That means you have the early style direct drum... for $60-90 you can get a 34 element sprag and it is simple to change.


However, I don't believe him one bit. If he rebuilt it and is selling it for a profit (as a business), he didn't do anything to it. I am a fan of "you get what you pay for".


And if everything he said is true, switch to a 34 element sprag and you can throw 800 crank horse at it without blinking.
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Old Mar 1, 2012 | 11:47 AM
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16 element sprag or roller clutch? Big difference.
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Old Mar 1, 2012 | 03:02 PM
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Originally Posted by slow67
16 element sprag or roller clutch? Big difference.
Well he said sprag... I'd bet it's a roller clutch for this price though cause the older style direct drum is worth $100 used by itself.
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Old Mar 1, 2012 | 04:24 PM
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He told me 16 element sprag, he had to go find his parts sheet and didn't lie about it having a 34 element when I asked, so idk why he would lie about it having the 16. Never know though. He said 16 element and something about a wishbone, I have zero knowledge when it comes to transmissions. I think the price is fairly cheap because he told me he builds a couple of spares just in time for tax season, so these are just sitting there.

I know he has a pretty good rep in the area and people from local forums either know him or know of him, so if I were to get screwed it wouldn't take much to ruin that rep in such a small location.

So the trans + 34 element and I'm good to go? Appreciate the input everyone.
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Old Mar 1, 2012 | 09:39 PM
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If you have no experience with it, I wouldn't change it.
The biggest issue here is GM made 16 element sprags for 3-4 years and then the rest of the TH400's life was spent with a 16 element roller. The roller design isn't bad by any means and it's difficult to explain why they fail. Elements are the equivalent to ball bearings. Basically, a roller assembly has teeth that don't allow it to slip and force it to strip/bend/blow out the elements while a sprag assembly is rounded and if push comes to shove it will just keep doing its job.
The sprag assemblies are desired by anybody with half a brain but in order to switch from roller back to sprag it is pricey (around $400 aftermarket) and even used it will cost close to $200... if you can even find a used sprag style direct drum. Why he didn't change the sprag (if it really is a sprag) to a 32 element for $60-90 is beyond me.


I just can't see how this transmission is full of half-decent parts if the parts list adds up more than the asking price... now add a good TH400 core and that's another $200-300.



A more logical solution is he's old school. I believe a dual feed direct drum is when you just add extra clutch packs. Not very good with my terminology though. I know a stock valve body can be modified to be manual pretty easily so once again he isn't spending any money on it.
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