THM 400 rebuild - 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 05-25-2008, 07:19 PM
Sneefers's Avatar
I we Todd did.
 
Join Date: May 2008
Location: Murrayville, GA
Age: 47
Posts: 9
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
THM 400 rebuild

I have recently rebuilt the engine and transmission in my 86 GMC K2500 4WD. The engine rebuild went great so far. .30 over on the block, new cam, lifters, timing set, pistons - all at stock specs. Balanced the crank, had the q'jet remanufactures, runs really sweet. Now if I can get it to move; the transmission, 3L80, was working before the rebuild, yes my wife has told me if it ain't broke..... but that has never stopped me before. I purchased a kit and the ATSG manual. I have followed very diligently and everything seemed to go together well. After starting up the engine and setting the idle and timing I have found that I have no movement in any gear. Nada, nothing. Just sits there. I am hoping to hear some so possible places to start looking. I lowered the transmission and removed the pump to check the boost valve assembly, as well as double check the pump to case gasket position. I have replaced the new modulator with the old one as well. I have not purchased a pressure gauge yet, hoping to borrow one this coming week so I don't know if I am getting pressure. I have double checked the fluid level, no leaks, no sounds. I have the correct end-play and the inner shaft will spin by hand. Getting ready to pull it out (again) any suggestions?
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 05-25-2008, 08:52 PM
68NovaSS's Avatar
Hotrodders.com Moderator
 
Last wiki edit: Working with chromed bolts
Last journal entry: New to me T-Bucket
Last photo:
Join Date: Sep 2002
Location: Tri-Cities, Washington
Age: 67
Posts: 5,151
Wiki Edits: 9

Thanks: 86
Thanked 122 Times in 114 Posts
I won't ask if the converter is bolted to...nah

Did you make any changes to the valve body? Have all the check balls in the correct location? Separator plate and the correct gasket in place? Linkage tight, when apart did the rooster comb go in correctly? Just some 'simple fix' thoughts, were you able to air test it?

I rebuilt my T-400 as well, but not a true guru, we have some here though.....
__________________
Boost adds dignity to what would otherwise be a vulgar brawl...

Midnight Sun Street Rod Association
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 05-26-2008, 07:06 AM
Sneefers's Avatar
I we Todd did.
 
Join Date: May 2008
Location: Murrayville, GA
Age: 47
Posts: 9
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I know the converter was/is bolted because I installed my flexplate backwards and had to drop the tranny (again) to correct. No changes to the valve body, however, I did have an extra gasket. (2) gaskets exactly alike and a third that was different to go around the detent solenoid. I left out one of the two since the book only shows one on top of the steel and one below. Maybe my gaskets are missaligned? I did not remove any of the valves in the valve body.

Not sure how to air test. As far as I know, and that ain't far, I checked and triple checked the check ball locations. The roster comb seamed fine, as I never disassembled those parts only the spring roller was removed, and I can "feel" the bumps as I work the shift lever.

A couple of things that I expected to be in the kit were not; such as new seals in the rear servo/accumulator assembly, the front servo, the three "ring" seals the go around the neck of the center support and the same type of seals around the neck of the pump cover assembly, these are delicate little things, beveled on both ends, and they fit loosely, not something that I would suspect to hold a great deal of pressure.

Sounds like I will be pulling it back out and going thru again, evidently I need the practice.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 05-26-2008, 11:58 PM
SSedan64's Avatar
Registered User
 
Last photo:
Join Date: Dec 2007
Location: Macon, GA.
Age: 50
Posts: 6,016
Wiki Edits: 0

Thanks: 0
Thanked 46 Times in 46 Posts
VB gaskets

1 thing to check. The Valvebody gaskets are usually marked VB & Trans. VB marked gasket goes between Valvebody & Plate, Trans goes between Plate & trans case.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 06-18-2008, 07:08 AM
Sneefers's Avatar
I we Todd did.
 
Join Date: May 2008
Location: Murrayville, GA
Age: 47
Posts: 9
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
UPDATE:

The truck is now running. It seems that one should read and follow ALL of the sentences in the manual. Especially, the one that states "make sure the manual detent pin is engaged to the manual valve". One pet peave is the fact the the trouble shooting tips refer to this as the "rooster comb"; be nice if they called everything the same thing througout the book and all the pictures. Anyway, thanks for all the advice. See you on the road.
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
Ok, here's the debate of the century: 383 or 400 chevy!! Cast your vote and reason killerformula Engine 303 03-28-2013 08:08 PM
400 sbc Devin 427 Engine 19 06-08-2010 07:17 PM
400 - sbc gilby246 Engine 4 10-19-2006 10:44 PM
400 trans rebuild? DeathByGreaser Transmission - Rearend 3 11-27-2002 01:54 PM
400 327 crank limey Engine 8 09-24-2002 07:53 AM


All times are GMT -6. The time now is 01:25 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.