Transmission or rearend? - 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 03-08-2006, 11:14 PM
Registered User
 
Join Date: Mar 2006
Location: Casper,Wy
Posts: 11
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Transmission or rearend?

Hey guys I have a question I just bought an 83 chevy 1/2 ton P.U. with a 3/4 rearend my question is my other truck is a 74 3/4 ton with the same motor not sure about the transmission but the 74 picks up alot quicker than the 83 and I was wondering if it's the transmission that makes it pick up faster or is it in the rearend?

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 03-09-2006, 12:39 AM
curtis73's Avatar
Hates: Liver. Loves: Diesel
 
Last wiki edit: How to find cheap parts
Last journal entry: Found an LQ9 today
Last photo:
Join Date: Dec 2005
Location: Carlisle, PA
Age: 41
Posts: 5,173
Wiki Edits: 16

Thanks: 7
Thanked 9 Times in 6 Posts
It could be one of a thousand factors. First of all, the transmissions have very similar gear ratios regardless of what tranny is in there, so I doubt it would make a huge change in your perception. Tire size, rear axle ratio, and engine power are the big ones, and if you are trying to compare the engine output of a 74 to an 83, its a tough comparison. Smog equipment, cam changes, technology, everything is vastly different between them. Literally night and day. Also, rear end ratios can vary between 2.73:1 all the way up to 4.56:1. That could mean a difference of 67% in the amount of torque that makes it from the engine to the wheels between the economy gears and the performance gears.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 03-09-2006, 07:45 AM
Registered User
 
Join Date: Mar 2006
Location: Casper,Wy
Posts: 11
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
ok I see, the engine in the 74 is an 80-85 block not sure if that makes a difference and the tire size is the same on both trucks.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 03-09-2006, 08:05 AM
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
What transmission is in each one?
You can look in the knowledge base for my transmission information thread for identification purposes.
The rear axle gears are definitely going to be different too. (This will make a HUGE difference).
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 03-11-2006, 02:00 AM
Registered User
 
Join Date: Mar 2006
Location: Casper,Wy
Posts: 11
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
both trannys are th400's but i'm guessing the rearends are different the 74 tranny shifts harder more torque than the other.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 03-11-2006, 02:07 AM
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
I'd say you have different gear ratio's in those axles.

Only way for sure to tell what you have is to remove the covers from both, and chechk the ratio's.

We are waiting to help you out should you decide to take this mission.
This message will not self destruct.
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 03-11-2006, 11:11 AM
Registered User
 
Join Date: Mar 2006
Location: Casper,Wy
Posts: 11
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
ok i'm gonna look at the gears in the rear end. How do i know which ones are there count the teeth? and if they are different how hard would it be to swap gears?
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 03-11-2006, 12:43 PM
curtis73's Avatar
Hates: Liver. Loves: Diesel
 
Last wiki edit: How to find cheap parts
Last journal entry: Found an LQ9 today
Last photo:
Join Date: Dec 2005
Location: Carlisle, PA
Age: 41
Posts: 5,173
Wiki Edits: 16

Thanks: 7
Thanked 9 Times in 6 Posts
You can count the teeth, but 9 times out of 10 there are numbers stamped in the ring gear. Rotate it around until you find them and it will say something like 41/10 which is the number or ring and pinion teeth. Just divide those two (which equals 4.10) to get your ratio. If those numbers aren't stamped, you'll have to count the teeth yourself and then divide.

You can also get close by jacking it up, turning a wheel once and counting how many times the driveshaft spins. If you have a posi it will be easy. If you don't have a posi, only jack up one wheel, then you'll have to double the number of driveshaft spins. Its only a guess though. If you get 4 turns of the driveshaft it could be 3.90, 3.92, 4.10... but it would probably get you close enough without having to drain the rear lube
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
Hotrodders Knowledge Base: Transmission - Rearend Jon Transmission - Rearend 0 11-26-2005 06:23 PM
Transmission Information. M&M CUSTOM Transmission - Rearend 1 08-24-2004 03:15 PM
Transmission and Rearend set up william27103 Transmission - Rearend 4 08-13-2004 02:52 PM
transmission - rearend bryyrb Transmission - Rearend 2 02-23-2003 04:27 PM


All times are GMT -6. The time now is 06:12 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.