tranny swap TH350 to 4 speed in 1980 gmc - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Transmission - Rearend
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 07-08-2010, 01:14 AM
Registered User
 
Join Date: Nov 2009
Location: wyoming
Posts: 70
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
tranny swap TH350 to 4 speed in 1980 gmc

hey guys i need to know what i need and how hard it is to take a 1980 GMC half ton 4x4 with a 350/350 combo and swap it out with a standard chevy 4 speed manual transmission please let me know thanks

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 07-08-2010, 05:59 AM
Registered User
 
Last photo:
Join Date: Apr 2010
Location: Hawaii
Posts: 373
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Other than the usual Clutch pedals/linkages, bellhousing/clutch/flywheel...which 4-speed are you looking at? The typical SM465 (granny-first gear), or a car-type 4-speed (Saginaw/Muncie/ST-10)? If you're going with a granny-first, probably best to find a donor-truck/blazer/suburban to get ALL the parts from.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 07-08-2010, 04:19 PM
Registered User
 
Join Date: Nov 2009
Location: wyoming
Posts: 70
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
tranny swap th350 to 4 speed 1980 gmc

im going with the sm456 with granny first i wanna do this cuz my truck was a 1980 chevy scottsdale that i build a 400sbc in high school (im only 19) and it was a 4 speed and i loved them. but thanks to a stupid 15 year old kid and running a stop sign sideswiped me and totalled out my truck and i lost everything so my new one is an automatic and id rather drive a 4 speed again so if i can do this with the help of you guys let me know id appreciate it alot
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 07-08-2010, 08:57 PM
Registered User
 
Join Date: Mar 2010
Location: pennsylvania
Posts: 12
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
The four speed trucks have a special little bracket located on the drivers side top of the frame under the cab fire wall that the balljoint of the pivot rod bolts too... You need to configure that bracket if your gonna run a mechanical clutch... You can run a hydraulic clutch but I've always had them blow at bad times... Mechanical linkage only wears out two main parts... Knees and shoulders... There is a hydraulic and mechanical linkage bell housing too... And ya have to make sue you have the right spline 465 to fit transfer case... I swapped my 86 short bed... I found a fine spline output shafted 465 for my 208 transfer... I wish I woulda went 465 205 transfer but I like my transfer case shifter better... Aside from the flywheel clutch pressure plate and basic stuff that is the problems I ran into... If I remember anything else I'll let you know...
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 07-09-2010, 01:57 AM
Registered User
 
Join Date: Nov 2009
Location: wyoming
Posts: 70
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
tranny swap th350 to 4 speed on 1980 gmc

thanks guy does the ball joint bolt to the frame or do i gotta weld it on and how would i find out which trnasfer case i have?
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 07-09-2010, 05:23 PM
Registered User
 
Join Date: Mar 2010
Location: pennsylvania
Posts: 12
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
there's like a piece of pipe with to ears welded on it... One ear on each end of the pipe... And the ears point in opposite directions... That's the best I can describe it... Anyhow there's a ball that bolts to the block or bellhousing ( I forget) and the other ball bolts to the bracket I mentioned above... then one ear on the tube has a rod that comes from the pedal and on the other tab a rod goes to the clutch fork... that's the best I can describe it... As for transfer case that would depend upon shift pattern, is the case aluminum or cast, and is it slip yoke tail shaft...
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 07-09-2010, 05:28 PM
Registered User
 
Join Date: Mar 2010
Location: pennsylvania
Posts: 12
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Oh yea duh?! I'm dumb... Look for a little circle badge on the transfer case about the size of a silver dollar... It'll say somewhere on it something like MODEL and then like NP208 or NP205 so on and so fouth... Do that first...
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 07-09-2010, 05:41 PM
Registered User
 
Join Date: Aug 2006
Location: Alexandria, VA
Posts: 1,754
Wiki Edits: 0

Thanks: 4
Thanked 65 Times in 63 Posts
You need to find a donor truck with a working 4 speed, transfer case, and driveshafts, or you will spend a lot of time putting the right pieces together.

The output of the TH350, TH400, and 4 speed have different spline counts, and the count is not even consistent across all years for each trans. This means the transfer case to transmission adapters are different for various trucks. Also, since each transfer/trans combo is a little different in length, that changes the driveshaft length for both front and rear.

You should have an NP208 transfer case, unless someone has swapped it out.

Bruce
Reply With Quote Quick reply to this message

Recent Transmission - Rearend posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Engine and tranny Swap in 78 Monte... BRSleeper2 Hotrodding Basics 6 07-08-2008 12:49 PM
Transmission swap: TH250 to TH350 Torque converter issues. 35oldstruck Transmission - Rearend 5 05-21-2008 03:43 PM
Tranny swap/ rearend swap? aggar Transmission - Rearend 2 03-16-2008 03:07 PM
old th350 swap for new th350 72donk Transmission - Rearend 2 08-31-2005 09:49 AM
th350 - th400 tranny swap gilby246 Transmission - Rearend 2 03-23-2005 05:08 PM


All times are GMT -6. The time now is 12:47 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.