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th400 rebuild questions...

jekbrown

jekbrown

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ok, we all know the th400 is the beefiest old school chevy trans you can get. Question is, are there any weak spots that need to be addressed in a rebuild? I plan on going full manual valve body, reverse pattern... and I'd like a nice low rpm stall converter (1800-ish probably). Any opinions on who's valve body I should run? TCI? Carr? How about the converter? This trans is going to be in my offroad-only K5 behind a mild 350. It'll see plenty of offroad abuse. I know in stock form these are hella strong trannys... just wanna see if there is anything "extra" I could add that might be a good idea. TIA,

j
 
I had a Summit brand 1500-1800 stall that was only $80 and it worked fine, never had a problem and it was cheap.

I also ran a Turbo Action Cheetah valve body again with no issues. The shifts were neck snapping fast/hard. On the street I could bark the 38's in 2nd and 3rd. The valve body eliminates the vacuum and TV cable and runs at full line pressure at all times. I would get one that has engine braking. Mine didn't and I wish it did.

I don't know of any weak spots in the TH400
 
yeah, I have done some searching and it seems that most manual valve bodies don't have compression braking... in any gear. Even if it was just in first gear it would be nice!! Supposedly the Art Carr one does have it... but its also $242.22 on their site... hmmm, maybe I can find it cheaper somewhere else. That is prolly MSRP right?

*edit*

did some more research... turns out that the Art Carr VB that does compression braking is actually like $400. Cha-ching! Found a thread on pirate though, that linked to ebay. Looks like a good one here... and its 40% less than the Art Carr...

linky

I pm'd a guy on pirate who says he bought one to see how he likes it. Seller has ZERO negative/neutral feedbacks after 700 auctions... thats a pretty dang good sign. :)

j
 
HERE is the Turbo Action for the TH400 that includes engine breaking for a lot less.... ;)

Part # TAC-24142A Price $165.69
 
are you sure they have compression braking on all 3 gears? Guys on pirate seemed convinced that just the Art Carr / ebayguy / custom-tranny-shop-made ones did. Do you run one of these yourself?

did a search, found this... the part number starts with TBA instead of TAC but is otherwise the same... same manufacturer and it says no brake in 2nd or 3rd...

linky

on the other hand... the manufacturer says it offers "full compression braking"...

linky2

their web site also notes that this is a standard-shift valve body, I'm looking for a reverse manual VB with comp braking...

j
 
I had the non engine breaking one so I can't verify for sure. I know that summit says it has full engine breaking with the part number I listed. You are correct about the shift pattern so it is not what you need. Good luck with the build though!
 
resurrected_jimmy said:
ultimate beef go TH 475..... just had to throw in my smart ass comment of the week
Click to expand...

That isn't totally smart ass, you can replace the planetaries with the straighter cut ones for the TH475, and GM did so, must be some weakness in that portion of the trans.

Of course, that weakness may only be evident pushing 10,000 pounds for thousands of miles behind a 454, but.... :)
 
TH400 questions

I run a TH400/big block combo in my 4x4, and would appreciate someone indulging my ignorance here :bow:

As to compression braking, I shift into first gear and it holds the truck back as much as 2.48:1 gears in 1st and the compression of my engine will allow - which is not slow enough on technical downhills. Ditto for 2nd gear, and I've never been on a road where I would need 3rd to give me compression braking. What additional engine braking is available by modifing the TH400?

Next, the benefit of firm shifts in a 4x4 escapes me. I can see this in a street car, but on my truck I want to roll on the torque of my big block through the drive train as gently as possible so as to not have the additional strain that a firm shift would supply. The last thing I want is to chirp my tires on pavement by firm shifts - I am trying to avoid that kind of shock loading on my axle shafts!

Thanks in advance
 
well, it seems that the ebay guy would still be the best option then. He says his offers compression braking in every gear and is full manual and reverse pattern. $250-ish isn't cheap... but it IS cheaper than a $400 Art Carr or a $pendy custom made one from a local shop...

Anyway, anyone have any thoughts on what brand of torque converter I should go with? I have an 1800 rpm stall one in my Raptor 700R4 and like it, but I'm not dead set on that level of stall. Anyone use something higher and like it?

j
 
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