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Discussion Starter #1
anyone know how much you have to take out of the drive shaft on a 1977 impala aero coupe when swapping out a th350 for a th400?
car already has a 8.5 10 bolt in it.

also anyone have a p/n for the slip you for the transmission

any help would be appreciated
 

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Discussion Starter #2
anyone at all?
 

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Any driveshaft shop should be able to get you the TH400 Yoke.
Google is your friend...
 

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Discussion Starter #4
Any driveshaft shop should be able to get you the TH400 Yoke.
Google is your friend...
Yeah i can get a yoke, but im just curious if shortening of the shaft is even needed. Rather just getting a th400 short snout yoke. theres about 11/16" difference in a th350 short shaft to a th400 short shaft
 

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Discussion Starter #6

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if street or street/strip a TH350 should handle anything but a knarly bigblock and if swapping for a street car I would only consider a overdrive transmission.

TH400 is overly heavy and may actually slow down a street/strip car.

The LS swap could have moved the tranny location some too so I would measure not rely on a published number unless that number is published with your full swap kit for that engine in that car with that transmission.
 

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yeah the yoke is different diameter and the trans is longer.
just dont know how much i need to change just yet
Yeah the yokes are different.

Longer trans means shorter driveshaft. Easier than needing a longer shaft.:D

Once you have the measurement(s) needed...
And assuming you don't have any other issues.
You can get a driveline shop to shorten and balance your old shaft. I'd have them install your new TH400 slip yoke and put in brandy new U-joints before they balance it.
 

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Discussion Starter #9
Yeah the yokes are different.

Longer trans means shorter driveshaft. Easier than needing a longer shaft.:D

Once you have the measurement(s) needed...
And assuming you don't have any other issues.
You can get a driveline shop to shorten and balance your old shaft. I'd have them install your new TH400 slip yoke and put in brandy new U-joints before they balance it.
yeah thats the plan, possibly have them build a HD shaft
 

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Discussion Starter #10
if street or street/strip a TH350 should handle anything but a knarly bigblock and if swapping for a street car I would only consider a overdrive transmission.

TH400 is overly heavy and may actually slow down a street/strip car.

The LS swap could have moved the tranny location some too so I would measure not rely on a published number unless that number is published with your full swap kit for that engine in that car with that transmission.
looking to push 7-800 to the tire, but my th350 failed becuase i was scammed an didn't get a built trans. is what it is and im moving onto a better setup. and the swap plates put it in the same location but yes your correct the drive shaft will have to be moved to make up for the longer trans
 

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At 700wheel then yeah a TH400 becomes a reasonable idea and you don't need the lower first gear something like a 4L60 would get you.
A properly built TH350 should handle the soft power delivery of a turbo though but finding someone to reliably build one locally is likely getting hard since that tranny has been out of OEM production probably 35years.

What mount kit did you use?

YEARS ago I dismantled my 96 Caprice with the intent of a turbo LQ4 swap, then "life" happened and it has sat since.
 

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Discussion Starter #12
At 700wheel then yeah a TH400 becomes a reasonable idea and you don't need the lower first gear something like a 4L60 would get you.
A properly built TH350 should handle the soft power delivery of a turbo though but finding someone to reliably build one locally is likely getting hard since that tranny has been out of OEM production probably 35years.

What mount kit did you use?

YEARS ago I dismantled my 96 Caprice with the intent of a turbo LQ4 swap, then "life" happened and it has sat since.
yeah that what i was figuring. yeah i didnt really want the 4l60e just from the build price point.. about 6-800 more than the th400. Around here not many people like messing with the th350 for these kinds of builds.

an mount kit, im guessing you mean turbo mount kit? I custom fabbed the entire turbo kit, minus the manifolds
no time like the present to start!
 

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Discussion Starter #13
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intake has changed since then, going to change it again
 

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Discussion Starter #14
At 700wheel then yeah a TH400 becomes a reasonable idea and you don't need the lower first gear something like a 4L60 would get you.
A properly built TH350 should handle the soft power delivery of a turbo though but finding someone to reliably build one locally is likely getting hard since that tranny has been out of OEM production probably 35years.

What mount kit did you use?

YEARS ago I dismantled my 96 Caprice with the intent of a turbo LQ4 swap, then "life" happened and it has sat since.
[/IMG]
 

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Discussion Starter #15
trans guy called yesterday, going to go pick it up this afternoon in colorado
 

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The 2007+ truck intake is actually very good and cheap. Called the Trailblazer SS intake in this article.
20 LS1 Intake Manifolds: Tested! - Hot Rod Network

Mocked up the stock 2004 intake in my Caprice and while it was going to need some cowl hammering it looked like it could work with the custom built mounts I got from a GM powertrain engineer.
 

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Discussion Starter #17
The 2007+ truck intake is actually very good and cheap. Called the Trailblazer SS intake in this article.
20 LS1 Intake Manifolds: Tested! - Hot Rod Network

Mocked up the stock 2004 intake in my Caprice and while it was going to need some cowl hammering it looked like it could work with the custom built mounts I got from a GM powertrain engineer.
thats actually the intake im ordering this week. and putting the holley mid ram up for sale

i want to be able to reuse my 92mm throttle body
 

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Discussion Starter #18
Mocked up the stock 2004 intake in my Caprice and while it was going to need some cowl hammering it looked like it could work with the custom built mounts I got from a GM powertrain engineer.
what did they have to do to make the mounts work?
 

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KDS Performance the guy who I tested prototype mounts for ended up opening this shop.
The 94-96 cars have an odd low mount AC compressor that makes the passenger side motor mount a but unique.

Right now I have little ambition to work on the Caprice, kids, bigger yard/house, career, getting fat and middle aged are all working against it. Car isn't worth anything so no motivation to sell it either, maybe work on it when the kids are a little older, local track starts some bracket racing at 13yo with parent in car and without at 16yo.
For now the family hotrod is electric, with 440tq from 0-43mph and 416hp from there to 73mph and will run 12.4 in the quarter stock, without all the noise and drama of a high stall and loud exhaust etc.

What are you doing for an axle? the low spline count stocker even if an 8.5" 10-bolt is going to be stressed, the later 30spline axle should handle it unless you are putting a brake in the TH400
 

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Discussion Starter #20
KDS Performance the guy who I tested prototype mounts for ended up opening this shop.
The 94-96 cars have an odd low mount AC compressor that makes the passenger side motor mount a but unique.

Right now I have little ambition to work on the Caprice, kids, bigger yard/house, career, getting fat and middle aged are all working against it. Car isn't worth anything so no motivation to sell it either, maybe work on it when the kids are a little older, local track starts some bracket racing at 13yo with parent in car and without at 16yo.
For now the family hotrod is electric, with 440tq from 0-43mph and 416hp from there to 73mph and will run 12.4 in the quarter stock, without all the noise and drama of a high stall and loud exhaust etc.

What are you doing for an axle? the low spline count stocker even if an 8.5" 10-bolt is going to be stressed, the later 30spline axle should handle it unless you are putting a brake in the TH400
ill have to check them out.
and i hear you i have another 77 impala coupe sitting in my yard with a cage in it. trying to get a title for it and want to do a back half kit on it.. but this one is gonna be the toy for now. my little girl should start racing 1/4 midgets this year so well see how far we get on her street car (this one).
im gonna run the 28 spline till it breaks. having moser make me some bop replacements so i can the factory c clip eliminators and then its off the the junk yard to get some s 10 blazer brake brackets calipers and rotors!

putting the trans in tonight after work hopefully
 
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