1991 Chevrolet K2500 4X4 transmission problems - 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 02-23-2008, 06:15 PM
Registered User
 
Join Date: Feb 2008
Location: Pennsylvania
Posts: 5
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
1991 Chevrolet K2500 4X4 transmission problems

Hi!
I have a 1991 Chevrolet K2500 4X4 with a 4L80E transmission and a 454 engine.
The question I have is : I had the transmission rebuilt and had them install a non-lock up torque convertor.The transmission works great but we ran into a problem.When engine is cold transmission shifts 1 to 2- 2 To 3 - 3 to OD. With in 5 mins. you can be going down the road at 65 MPH and transmission shifts back to Drive from Overdrive. You can move the shifter,speedup or slow down and it will not go back in to O/D. Myself and the gentleman that rebuilt the transmission are trying to find out why! Any Ideas! Thanks!
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 02-23-2008, 07:29 PM
327NUT's Avatar
Registered User
 
Last photo:
Join Date: Dec 2004
Location: So. Utah
Age: 67
Posts: 3,180
Wiki Edits: 0

Thanks: 0
Thanked 58 Times in 52 Posts
Just curious....why a non-lockup converter?
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 02-23-2008, 07:59 PM
Crosley's Avatar
Hotrodders.com Moderator
 
Last wiki edit: T-350 rebuild tech
Last journal entry: Bar under the dash
Last photo:
Join Date: Nov 2002
Location: ... USA
Posts: 7,986
Wiki Edits: 1659

Thanks: 258
Thanked 86 Times in 83 Posts
easiest thing to try is replace the shift solenoids... The solenoid could hold the pressure enough for lower gear , not hold for OD.

Could also be a worn out distributor bushings among other items. Bad speed-O input

A quality scanner with shift control program can up shift the trans into OD.... at a low speed 25-30 mph. Then you mash the loud pedal to the flooor. IF the trans drops back to 3rd gear, the solenoid is not holding pressure.

Hopefully the trans was modified for the non lock up converter
__________________
Some people are like Slinkies... Not really good for anything, but they still bring a smile to your face when you push them down a flight of stairs.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 02-23-2008, 08:05 PM
Registered User
 
Last wiki edit: How to title a hot rod Last photo:
Join Date: Feb 2007
Location: West Virginia
Age: 24
Posts: 3,389
Wiki Edits: 8

Thanks: 14
Thanked 1 Time in 1 Post
Quote:
Originally Posted by 327NUT
Just curious....why a non-lockup converter?
X2 they provide better economy
Shane
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 02-24-2008, 04:39 AM
curtis73's Avatar
Hates: Liver. Loves: Diesel
 
Last wiki edit: How to find cheap parts
Last journal entry: 1999-2001: Getting it on the road
Last photo:
Join Date: Dec 2005
Location: Pittsburgh, PA
Age: 40
Posts: 5,128
Wiki Edits: 16

Thanks: 0
Thanked 1 Time in 1 Post
Quote:
Originally Posted by Chevrolet4x4s
X2 they provide better economy
Shane
Uh... say what? Its the other way around. Lockup converters positively lock the engine and tranny together. Non-lockups continually waste energy as heat in a converter that is only connected fluidly.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 02-24-2008, 02:34 PM
Registered User
 
Join Date: Feb 2008
Location: Pennsylvania
Posts: 5
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Seeeking Advice on Torque Convertors!

Can someone explain to me the difference between Lock-Up and Non-Lock-Up Torque Convertors. Also the advantages and disadvantages of both.
I pull a travel trailer in the summer time that weighs 9700 Empty Dry Weight! In the winter time I have a snow plow on the truck. That was one of the reasons I went with a non lock-up convertor.
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 02-24-2008, 05:47 PM
Registered User
 
Join Date: Feb 2008
Location: Pennsylvania
Posts: 5
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
1991 Chevrolet K2500 4X4 4L80E trans. with 454 CID

Can someone explain the difference to me on a lock-up convertor and a non-lock-up convertor? I had the person that rebuilt my transmission install a non-lock-up convertor because I pull a 31 Foot travel trailer that is 9700Lbs. dry weight,and have a snow plow attached to the truck in the winter. I figured that it would increase the performance of the low end of the truck because when pulling that travel trailer I needed all the help I could get. Did I make a mstake or not! Looking for positive or negtive feedback! Thanks!
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 02-24-2008, 07:52 PM
Crosley's Avatar
Hotrodders.com Moderator
 
Last wiki edit: T-350 rebuild tech
Last journal entry: Bar under the dash
Last photo:
Join Date: Nov 2002
Location: ... USA
Posts: 7,986
Wiki Edits: 1659

Thanks: 258
Thanked 86 Times in 83 Posts
you asked the same question twice.... I merged the threads so members can follow the question on the same vehicle.






lock up & non lock up converters are just that....

a lock up converter has a clutch that is applied inside the converter. This clutch removes all slippage from normal operation of the converter. it is 1-1 with the engine while locked up.

The vehicle computer controls this lock up.

While unlocked ... the lockup converter operates the same as a non lockup converter

IF your trans was not modified for the non lock up converter , damage can result. Over heating is one.

I am surprised you do not get trouble codes if there is a non lock up converter in the truck.


__________________
Some people are like Slinkies... Not really good for anything, but they still bring a smile to your face when you push them down a flight of stairs.
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 02-24-2008, 07:57 PM
Jmark's Avatar
Hotrodders.com Moderator
 
Last photo:
Join Date: Sep 2003
Location: phoenix
Age: 60
Posts: 4,787
Wiki Edits: 0

Thanks: 0
Thanked 3 Times in 3 Posts
It appears you have added some extra info to your post since I read it earlier, but i'll add this.

Gleaning from the previous posts, the lockup converter "locks" the engine to the trans, eliminating slippage between the two, resulting in a little better fuel economy.

A non-lockup converter has a certain amount of slippage built in, so it won't stall the engine at idle, but it still slips some at "speed" so there is some waste in economy.

The builder "may" have used a non-lockup converter because they can fail when in the lockup mode AND pulling huge loads, like your trailer. He may have been trying to save you a converter failure down the road but may have missed something or caused another problem since you now have shifting problems.

Mark
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 02-24-2008, 08:02 PM
327NUT's Avatar
Registered User
 
Last photo:
Join Date: Dec 2004
Location: So. Utah
Age: 67
Posts: 3,180
Wiki Edits: 0

Thanks: 0
Thanked 58 Times in 52 Posts
I'm with Curtis.....or he's with me.... and Shane needs to do some homework.
Craig, A lockup converter does exactly that, it locks up in O/D just like you were running a stick shift trans which = no slippage which = no excessive heat which = longer trans life and BETTER fuel economy.

A non lock up slips in O/D which = heat build up.........I think you get the idea. AND if you're pulling that much weight you are really putting a LOT of unnecessary wear and tear on your new trans by not running a lock up conv.
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 02-24-2008, 08:12 PM
Registered User
 
Last wiki edit: How to title a hot rod Last photo:
Join Date: Feb 2007
Location: West Virginia
Age: 24
Posts: 3,389
Wiki Edits: 8

Thanks: 14
Thanked 1 Time in 1 Post
Quote:
Originally Posted by curtis73
Uh... say what? Its the other way around. Lockup converters positively lock the engine and tranny together. Non-lockups continually waste energy as heat in a converter that is only connected fluidly.
X2 ..was also wondering why they weren running a lock up converter, I was stating that the lockups provide better economy but forgot the comma so it was a little confusing
Sorry about that

Shane
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 02-24-2008, 09:57 PM
Jmark's Avatar
Hotrodders.com Moderator
 
Last photo:
Join Date: Sep 2003
Location: phoenix
Age: 60
Posts: 4,787
Wiki Edits: 0

Thanks: 0
Thanked 3 Times in 3 Posts
Really hoping the trans experts will add some tomorrow. I'll toss this in, in the meantime.

Lockup converters are usually not up to the task of maintaining lockup under BIG torque loads. Thanks to a tour of a converter shop I had not long ago, I saw firsthand the one single friction plate that is inside most LU converters. That is why almost every vehicle manufacturer says to NOT tow in OD or in LU. There are finally some HD multi disk converters coming on the market for the towing crowd.

Mark
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 02-25-2008, 12:06 AM
327NUT's Avatar
Registered User
 
Last photo:
Join Date: Dec 2004
Location: So. Utah
Age: 67
Posts: 3,180
Wiki Edits: 0

Thanks: 0
Thanked 58 Times in 52 Posts
To Shane.........sorry, didn't get the "X2"....my apologies, Dave
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 02-25-2008, 03:14 AM
Registered User
 
Join Date: Feb 2008
Location: Pennsylvania
Posts: 5
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
In your honest opinion: Do you think I made the right move! Be Honest! I don't want to ruin this transmission!
Reply With Quote Quick reply to this message
  #15 (permalink)  
Old 02-25-2008, 07:04 AM
Jmark's Avatar
Hotrodders.com Moderator
 
Last photo:
Join Date: Sep 2003
Location: phoenix
Age: 60
Posts: 4,787
Wiki Edits: 0

Thanks: 0
Thanked 3 Times in 3 Posts
Quote:
Originally Posted by Craig Eppley
In your honest opinion: Do you think I made the right move! Be Honest! I don't want to ruin this transmission!
We will need to wait out some more answers from the experts. As Crosley has stated, to run with LU disabled, the trans needs to be set up accordingly. Hopefully he or the other trans builders will join in with some good replies.

Mark
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
3 Speed Automatic Transmission Problems - 93 Pontiac Sunbird JOEMAMA Transmission - Rearend 4 04-17-2003 06:35 AM
700R4 Transmission shifting problems Judd Wymer- VA Transmission - Rearend 1 01-10-2003 03:17 AM
Transmission problems kemo Transmission - Rearend 2 11-21-2002 01:48 PM
move over motor now I got transmission problems cuda66 Transmission - Rearend 3 11-11-2002 04:19 PM
Transmission swap.....now experiencing problems Oldsdiesel Transmission - Rearend 2 10-10-2001 06:31 PM


All times are GMT -6. The time now is 12:03 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.