TH 400 Speedo Gears - 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 04-01-2005, 11:43 PM
rs67ss's Avatar
Registered User
 
Last photo:
Join Date: Oct 2003
Location: Yorktown, VA
Age: 45
Posts: 12
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
TH 400 Speedo Gears

Well, here is one that I hope someone knows. Have a TH 400, 1967 vintage, that I just got from a friend running it in a 68 Camaro with 396. Car was set up for strip, trans is full manual, reverse pattern, billet shafts, all internals upgraded with the heat treated sprags, etc. At a c note, I wasn't going to hesitate. I'm looking at putting it in my 67 RS/SS with a 454 ( 450HP) ( rear end yet to be decided on )that will see both street and strip, but 75 percent will be the street. Now comes the problem. The speedo housing and gear, which on this short tail model is in the end of the trans case and not the tail housing, has a myriad of available gears...Being as this was used on the strip, a plug had been used in the inch and 3/4 hole where the speedo drive gear and housing was inserted. I can get the new housing and o rings from the local GMPP shop, but am mystified as to what gear to get. There are two housings, one for gears with 20-32 teeth and another for the 33 and up. These speedo drive gears are color coded ( green has 4 different shades for 4 different numbers of teeth ). I am assuming that these teeth are somewhat related to rear end gearing but I have no clue where to start. Has anyone torn down their TH 400 lately and if so, what color gear do you have? And I am assuming that these will vary with year of trans, gear ratio, etc. So if you could include those as well.....Just looking for a starting point so I can at lease know which casing to get as a start...... Thanks....Dan

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 04-02-2005, 06:06 AM
Deuce's Avatar
Hotrodders.com Moderator
 
Last wiki edit: Choosing a trailer
Last journal entry: Jan 13 2013
Last photo:
Join Date: Aug 2002
Location: Deuceland USA
Age: 66
Posts: 5,657
Wiki Edits: 6

Thanks: 0
Thanked 9 Times in 9 Posts


DO NOTHING........

Until you get the rear end. Then tire size and gear ratio will tell you which ones to get........

http://www.tciauto.com/tech_info/speedo_gears.htm

here is a site with all the information you need.once you have the rear end ratio and tire size.

__________________


"I won't be wronged . I won't be insulted, and I won't be laid a hand on. "






Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 04-02-2005, 09:12 PM
Member
 
Last photo:
Join Date: May 2003
Location: Shreveport LA
Age: 64
Posts: 5,103
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
www.novaresource.org/speedo.htm is another good speedo site.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 04-02-2005, 11:19 PM
M&M CUSTOM's Avatar
Hotrodders.com Moderator
 
Last wiki edit: Transmission identification
Last journal entry: 1988 Suburban, the project continues.
Last photo:
Join Date: Mar 2003
Location: Northwest Pennsylvania.
Age: 43
Posts: 2,231
Wiki Edits: 9

Thanks: 0
Thanked 1 Time in 1 Post
You won't be able to accurately determine what speedometer hears you need until you get the rear gear ratio you want, AND the tire size you plan on using.

Both of these are the deciding factors in determining what speedometer gears you need to use to get the gear reduction necessary to give the speedometer itsself the correct input ratio.

I have heard an awful lot about a speedometer input of 1000 rotations per mile, but on the other hand I have heard of a few other per mile rotation count speedometers. I have also heard (but never checked for accuracy) that there is an input value (rotations per mile) on the back of some (not sure here either) if not all speedometers.

I have quite a few speedometers I salvaged from many parts vehicles I have dismantled in the past, and have to work in the shop later on today (I am on here at 1:19am) so I will try to check.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 04-03-2005, 10:30 PM
Gametech's Avatar
New Member
 
Last photo:
Join Date: Dec 2003
Location: Springfield, MO
Age: 44
Posts: 27
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Here's yet another nice link that explains most of the same information as the ones mentioned above, as well as the "part number" for each different gear. Hope this bit of info helps in some way.
Speedo Gear Selection
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 04-03-2005, 11:58 PM
packratwrecker's Avatar
Too many hobbies!
 
Last photo:
Join Date: Dec 2003
Location: Kansas
Age: 41
Posts: 240
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
if you are just itching to do something RIGHT NOW, buy one right in the middle.
Then, get one of the inline adapters, so you can tailor the adjustment later. If you have cruise control, get one that will fit inline just ahead of the cruise unit, so you don't have to crawl under the car, to change it. Another plus to that is being able to easily change the speedo reading, if you decide to change tire size, or axle ratio.
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
Speedo calibration novatech Transmission - Rearend 2 02-12-2004 07:46 PM
speedo drive gears for muncie 345coupe Transmission - Rearend 3 09-21-2003 07:11 PM
Speedo not working..4spd Trav Transmission - Rearend 5 07-31-2003 01:21 AM
Speedo DoubleVision Transmission - Rearend 2 01-25-2003 08:16 AM
turbo 400 failure to shift, or hold gears 85s-10prostock Transmission - Rearend 3 11-26-2002 01:37 PM


All times are GMT -6. The time now is 12:56 AM.


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.