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-   -   1977 impala th400 swap (https://www.impalaforums.com/impala-1st-5th-gen-discussion/1810074-1977-impala-th400-swap.html)

Stockcar10 03-01-2018 09:01 AM

1977 impala th400 swap
 
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

Stockcar10 03-09-2018 09:05 AM

anyone at all?

hatzie 03-09-2018 09:59 AM

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

Stockcar10 03-09-2018 11:35 AM

Quote:

Originally Posted by hatzie (Post 3580490)
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

hatzie 03-09-2018 01:10 PM

If your TH400 is the same length as the old TH350 you shouldn't have to change the shaft.

If the TH400 is a different length you'll have to install it and measure.
How to Measure for the Correct-Length Driveshaft - Hot Rod Network

Stockcar10 03-19-2018 10:27 AM

Quote:

Originally Posted by hatzie (Post 3580770)
If your TH400 is the same length as the old TH350 you shouldn't have to change the shaft.

If the TH400 is a different length you'll have to install it and measure.
How to Measure for the Correct-Length Driveshaft - Hot Rod Network

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

Dwayne J 03-19-2018 12:58 PM

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.

hatzie 03-19-2018 01:03 PM

Quote:

Originally Posted by Stockcar10 (Post 3586778)
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.

Stockcar10 03-19-2018 05:39 PM

Quote:

Originally Posted by hatzie (Post 3586882)
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

Stockcar10 03-19-2018 05:42 PM

Quote:

Originally Posted by Dwayne J (Post 3586874)
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

Dwayne J 03-19-2018 07:21 PM

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.

Stockcar10 03-19-2018 07:30 PM

Quote:

Originally Posted by Dwayne J (Post 3587202)
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!

Stockcar10 03-19-2018 07:33 PM

[IMG]https://i.imgur.com/6fC8hqX.jpg?1[/IMG]
[IMG]https://i.imgur.com/i5sgp5Z.jpg?1[/IMG]
[IMG]https://i.imgur.com/OVW9Rxz.jpg?1[/IMG]

intake has changed since then, going to change it again

Stockcar10 03-19-2018 07:34 PM

Quote:

Originally Posted by Dwayne J (Post 3587202)
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]https://i.imgur.com/adFtC3u.jpg?1[/IMG]

Stockcar10 03-20-2018 07:10 AM

trans guy called yesterday, going to go pick it up this afternoon in colorado


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