Author Topic: Trans Swap  (Read 1256 times)

Offline lunyty

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Trans Swap
« on: August 17, 2020, 06:42:20 PM »
My Turbo 400 is going out in my 86 Silverado ,,and i have a turbo 350 sitting here,what exactly am i going to need for swap,,it's a long bed and i know i'm gonna have driveshaft issues since the 350 is shorter,,,,can i get away with an extended yoke ??i have changed many transmissions but never to a diffeerent type

Online VileZambonie

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Re: Trans Swap
« Reply #1 on: August 17, 2020, 08:59:36 PM »
Downgrading and then spending the difference in modifications is illogical
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74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline lunyty

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Re: Trans Swap
« Reply #2 on: August 17, 2020, 09:05:33 PM »
I already had the trans so what the heck,i noticed there was holes in the frame to move the trans mount i guess i'm mostly wondering about the drive shaft length problem...i thought maybe they made some TH350 long beds ,,so i would be able to get DS,,i dont know

Online VileZambonie

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Re: Trans Swap
« Reply #3 on: August 17, 2020, 09:12:46 PM »
Sell your TH350 to help fund rebuilding your TH400 or get a used one. Driveshaft, yokes, U-joints, trans mount, detent cable, brackets, fluid, filter, gaskets.  Where's the savings or benefit? What's going on with your 400 that you don't want to fix it?
,                           ___ 
                         /  _ _ _\_
              ⌠ŻŻŻŻŻ'   [☼===☼]
              `()_);-;()_)--o--)_)

74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline lunyty

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Re: Trans Swap
« Reply #4 on: August 17, 2020, 11:53:02 PM »
as soon as you let off the gas a little and it quits pulling,,theres nothing there...and after a couple seconds it downshifts  and doesn't want to upshift,,,,,i never ha done do this


Offline MIKE S

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Re: Trans Swap
« Reply #5 on: August 18, 2020, 08:50:57 AM »
3 things to check. First make sure you have a good supply of vacuum at the modulator. Take line off at modulator with engine running and check. Make sure there is no atf leaking from modulator nipple. Remove kick down solenoid wire on left side of transmission and test drive. Last if none of these are the problem check the governor. Remove the 4 bolts on the cover and remove the valve. Check the gear to see if is stripped.

Offline JohnnyPopper

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Re: Trans Swap
« Reply #6 on: August 19, 2020, 01:09:53 AM »
Sounds like something silly like a slipped vac line.

When did you last service it, as in fluid and filter? Nothing makes them last as long as when their clean... 8)
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction