Replaced T-400 and have the same problem - 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 09-24-2013, 07:52 AM
Registered User
 
Join Date: Sep 2013
Posts: 7
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Replaced T-400 and have the same problem

Hi,

I'm new to this forum and saw some good info and am hoping for some help. Sorry this is so long. I have a 57 Chevy with a 350, mild cam (i don't know specifics since I didn't install it), turbo 400 and 355 rear end. The car has always shifted hard into second gear (thumps) when I drive it slow. First shift is fine then every one after is bad. If i give it some gas it's fine. I checked vacuum which is 15 and even replace the modulator with an adjustable one and no difference.

I decided to replace the transmission and installed it and a 2200 - 2400 stall converter. After $1500 and 10 hours installing it by myself, it does the same thing! I'm besides myself. I've asked some local shops and I get everything from I don't know to that transmission is too big for a small block. We don't have a lot of shops in my area that deal with cars like this. I don't know what to do. Any help will be appreciated.

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 09-24-2013, 09:08 AM
Speedshift_Sam's Avatar
Mekanicus Automotive Group
 
Last photo:
Join Date: Oct 2006
Location: Longmont, Co
Posts: 161
Wiki Edits: 0

Thanks: 1
Thanked 10 Times in 10 Posts
Hmm, puzzling.

By no means is that 400 too big for your sbc. We have two motorhomes with 400 small blocks and 400 trans' behind them. I also had a pickup with a TH-475. All of them shift a little hard into second if you are "*****-Footing" around. They are heavy duty transmissions, and built to take some very severe thrashing. Since they are a Vacuum controlled kickdown, have you checked your lines? One could be kinked or slightly plugged.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 09-24-2013, 01:37 PM
Registered User
 
Join Date: Sep 2013
Posts: 7
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Yeah I did check the line. I just got a hold of the tech at the company I bought the transmission from. He is sending me a spring to put in behind the modulator? I'm really a novice at transmissions so am not sure what this will do but am going to try it.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 09-24-2013, 02:27 PM
Faith - Respect - Trust
 
Last photo:
Join Date: Sep 2012
Location: Ontario
Age: 58
Posts: 3,508
Wiki Edits: 0

Thanks: 192
Thanked 638 Times in 572 Posts
You mentioned you had a 3:55 rear end...Where did the diff come from and who installed it? Also, how long have you had the car, if it's been a while, are you going through U joints quickly?

Just reading your posts, if the rear end is a donor from another vehicle, you may want to check the pinion angle...it could very well be that your transmissions are fine, but, with an improper pinion angle, it is possible to get a hard shift feeling if not under load.

Something to check

Ray
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 09-25-2013, 05:26 AM
Registered User
 
Join Date: Sep 2013
Posts: 7
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by 69 widetrack View Post
You mentioned you had a 3:55 rear end...Where did the diff come from and who installed it? Also, how long have you had the car, if it's been a while, are you going through U joints quickly?

Just reading your posts, if the rear end is a donor from another vehicle, you may want to check the pinion angle...it could very well be that your transmissions are fine, but, with an improper pinion angle, it is possible to get a hard shift feeling if not under load.

Something to check

Ray
The rear end is a stock housing from the 57 so I'm told. It was in there when I got the car. I've had the car for 5 years. No u joint replacement but you make a good point. Can you tell me how to check this?
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 09-25-2013, 08:03 AM
RWENUTS's Avatar
Registered User
 
Last photo:
Join Date: Nov 2011
Location: Nanaimo, BC, Canada
Age: 63
Posts: 2,017
Wiki Edits: 0

Thanks: 60
Thanked 215 Times in 203 Posts
Is your tranny side mounted or rear mounted? Is the motor front mounted or side mounted?
Stock was motor front mounted, tranny side mounted.
Your motor/tranny might be moving a bunch causing the clunk.
Here's a link with a chart and a video on pinion angles if you need it.
Pinion angle? - The 1947 - Present Chevrolet & GMC Truck Message Board Network
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 09-25-2013, 08:35 AM
Registered User
 
Join Date: Sep 2013
Posts: 7
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Great post reference! Thanks
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 09-25-2013, 08:52 AM
RWENUTS's Avatar
Registered User
 
Last photo:
Join Date: Nov 2011
Location: Nanaimo, BC, Canada
Age: 63
Posts: 2,017
Wiki Edits: 0

Thanks: 60
Thanked 215 Times in 203 Posts
BUt the question remains, how's your motor/tranny mounted?
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 09-25-2013, 08:56 AM
Registered User
 
Join Date: Sep 2013
Posts: 7
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Sorry, I'm trying to do this at work. The motor is side mounted and the transmission is rear mounted.
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 09-25-2013, 09:16 AM
RWENUTS's Avatar
Registered User
 
Last photo:
Join Date: Nov 2011
Location: Nanaimo, BC, Canada
Age: 63
Posts: 2,017
Wiki Edits: 0

Thanks: 60
Thanked 215 Times in 203 Posts
Good!
Could be pinion angle then. Here's a link to a good angle finder for checking angles.
Swanson Tool Magnetic Angle Finder - AF006M - Swanson Tool Store
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 09-26-2013, 01:27 PM
Registered User
 
Last photo:
Join Date: Nov 2006
Location: Woodstock
Posts: 913
Wiki Edits: 0

Thanks: 2
Thanked 76 Times in 69 Posts
Quote:
Originally Posted by Speedshift_Sam View Post
By no means is that 400 too big for your sbc. We have two motorhomes with 400 small blocks and 400 trans' behind them. I also had a pickup with a TH-475. All of them shift a little hard into second if you are "*****-Footing" around. They are heavy duty transmissions, and built to take some very severe thrashing. Since they are a Vacuum controlled kickdown, have you checked your lines? One could be kinked or slightly plugged.
I thought the 400's had electric kickdowns?

peace
Hog
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 09-26-2013, 03:39 PM
Faith - Respect - Trust
 
Last photo:
Join Date: Sep 2012
Location: Ontario
Age: 58
Posts: 3,508
Wiki Edits: 0

Thanks: 192
Thanked 638 Times in 572 Posts
First of all I'm not saying it is pinion angle...just that it could be. The angle checker that "RWENUTS suggested would work fine and it is a place to start.

The pinion angle is something that you may want to check...I usually set mine between 4 and 5 degrees but, everybody has a different opinion of the pinion so I tried to do a bit of research and some of the best information I found was right here on this site.

Pinion Angles and Driveline Setup for the Street

Some good information on pinion angle and how to check it and set it up...also on a few other threads...what can happen with a bad pinion angle.

Check out the thread and your car...I sincerely hope this helps.

Ray
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 09-26-2013, 07:03 PM
Registered User
 
Join Date: Sep 2013
Posts: 7
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I purchased a magnetic angle tool. I'm really a backyard mechanic so bear with me. Do I set this at each end of the driveshaft and see what it reads? My car is lowered so I can't get under it without jacking it. Do I need to put something under the wheels so it is level? Sorry if these are dumb questions.
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 09-26-2013, 07:21 PM
RWENUTS's Avatar
Registered User
 
Last photo:
Join Date: Nov 2011
Location: Nanaimo, BC, Canada
Age: 63
Posts: 2,017
Wiki Edits: 0

Thanks: 60
Thanked 215 Times in 203 Posts
Put the base of the angle finder on the flat part of the yoke where you see the cup of the u-joint. Put the flat part of the yoke down. Put the rearend of the car up on some blocks under the tires so the suspension is loaded. After it's on the blocks bounce it so it's settled before measuring. Block the front tires so it won't roll away.
In this link posts 11 and 19 show where to put the angle finder.
How much is too much stock driveshaft angle - Jeep Wrangler Forum
Reply With Quote Quick reply to this message
  #15 (permalink)  
Old 09-26-2013, 08:48 PM
Faith - Respect - Trust
 
Last photo:
Join Date: Sep 2012
Location: Ontario
Age: 58
Posts: 3,508
Wiki Edits: 0

Thanks: 192
Thanked 638 Times in 572 Posts
What I have done in the past is check the angle of the tail shaft of the transmission. The angle that the transmission is sitting at will give you an idea of what the pinion angle should be offset at. Sometimes, I've seen factory diff's installed at 0, or 1 & 2 degrees. If your 350 and TH400 where installed perfectly level, you won't have enough angle and will not have enough load on the drive shaft...I try and install engines at 4 or 5 degrees and offset the diff accordingly...again, others may disagree and I would welcome other opinions...but this is what I've done, had success, I've seen drive trains installed with virtually no angle and problems arise.

Hope this helps

Ray
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:
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
T-400 problem TJ555 Transmission - Rearend 11 10-18-2012 05:13 PM
T-400 problem again cletusvandamme Transmission - Rearend 4 05-15-2010 03:07 PM
T-400 problem cletusvandamme Transmission - Rearend 3 11-08-2009 01:32 PM
400 TH Problem? reflog Transmission - Rearend 6 07-16-2008 07:39 AM
Replaced Brushes & replaced battery terminals 78novaman Electrical 1 10-01-2006 07:39 PM


All times are GMT -6. The time now is 12:00 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.