what's wrong with the 7.5 malibu rear? - 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 04-12-2006, 10:25 PM
Augusto's Avatar
From the middle of the world
 
Last wiki edit: How to rebuild an engine Last photo:
Join Date: Mar 2006
Location: Ecuador, South America
Age: 51
Posts: 1,311
Wiki Edits: 6

Thanks: 4
Thanked 2 Times in 2 Posts
what's wrong with the 7.5 malibu rear?

I have read a lot of bad things about the stock rear of my 81 malibu lately (converted to el camino by myself ) the truth is I didn't pay any attention to it until now, it hasn't braked anything yet ( I hope it won't ) it lives behind a 350 with a 144 B&M supercharger and it's hotter cam, 600 cfm holley, headers, etc. do you think I should worry about it? I have a 1977 malibu rear end sitting in my shop, I'm not sure about the size but it's the one with the squared ears at the bottom of the pumpink, is this a better choice? should I replace it? I don't race the car, it's a street tire fryer only.
Augusto.
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 04-13-2006, 01:24 PM
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
It depends on several things. The 7.5 lives fine in F-bodies behind some respectable torque, but they are very traction limited. The tires go up in smoke long before enough torque gets put to the 7.5.

If you put more than about 350 lb-ft to it and you get any shred of traction, there is a very good chance you'll rip the axle in to pieces. Small bearings, small ring gear, and a small casting. It was designed as a lightweight economy axle. It takes some abuse, but not where traction is involved.

If you feel saucy, go for the 8.5 from a Grand National or 442. They're not as hard to find as you might think, and if you get one from a flat-rate junkyard they're no more expensive than a Chevette axle.

The flat-eared axle you have is probably an 8.2. Its a little better than the 7.5, but if you're putting a 144 blower on things I'd go at least 8.5.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 04-13-2006, 02:02 PM
xntrik's Avatar
Save a horse, Ride a Cowboy.
 
Last photo:
Join Date: Jul 2005
Location: Arkansas
Posts: 5,131
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
Run it until you break it. With limited traction, it might run for years.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 04-13-2006, 03:22 PM
Augusto's Avatar
From the middle of the world
 
Last wiki edit: How to rebuild an engine Last photo:
Join Date: Mar 2006
Location: Ecuador, South America
Age: 51
Posts: 1,311
Wiki Edits: 6

Thanks: 4
Thanked 2 Times in 2 Posts
thanks for replying, as I begin to understand the problem with this axle is in racing duty, this might explain why it has survived so far, there is the problem that I live ten thousand miles from the nearests junk yard that has american cars and must do with wathever I run into, are the 9 in ford rearends that are so desirable for cars up there the same that are found in the back of mid seventies F-150 pickups? those are plentiful here, lengthwise I don't care I own a machine shop and I'm acustomed to fabricate almost anything, we have to sometimes when parts are imposible to find. should I adapt a new axle or just use until it breaks?
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 04-13-2006, 05:03 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: 42
Posts: 2,228
Wiki Edits: 9

Thanks: 0
Thanked 1 Time in 1 Post
The 77 should have had an 8.5 in it and nothing else.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 04-13-2006, 05:45 PM
Guy Hiltz's Avatar
Member
 
Last photo:
Join Date: Sep 2005
Location: Nova Scotia Canada
Posts: 1,004
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
re:whats wrong with the 7.5 malibu rear?

I 'm fairly certain that the rear end from the 77 will not be a direct bolt in,the 9 inch from a Ford pickup would be a much better choice.
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 04-13-2006, 09:09 PM
Augusto's Avatar
From the middle of the world
 
Last wiki edit: How to rebuild an engine Last photo:
Join Date: Mar 2006
Location: Ecuador, South America
Age: 51
Posts: 1,311
Wiki Edits: 6

Thanks: 4
Thanked 2 Times in 2 Posts
a) how good/bad is the 8.5 rear end? ( for my street supercharger )

b) installing lower gears like a 4.10 prolong life expectancy of the rear end?
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 04-13-2006, 09:28 PM
xntrik's Avatar
Save a horse, Ride a Cowboy.
 
Last photo:
Join Date: Jul 2005
Location: Arkansas
Posts: 5,131
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
Quote:
Originally Posted by Augusto
thanks for replying, as I begin to understand the problem with this axle is in racing duty, this might explain why it has survived so far, there is the problem that I live ten thousand miles from the nearests junk yard that has american cars and must do with wathever I run into, are the 9 in ford rearends that are so desirable for cars up there the same that are found in the back of mid seventies F-150 pickups? those are plentiful here, lengthwise I don't care I own a machine shop and I'm acustomed to fabricate almost anything, we have to sometimes when parts are imposible to find. should I adapt a new axle or just use until it breaks?

If I were you I would find a Ford 9 and begin narrowing it and getting ready to install..... someday. Then when/if the old one dies, you won't be without your fun car for a weeks.
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 04-14-2006, 07:43 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
The '77 rear end is not a simple bolt-in, but Southside Machine made a set of conversion control arms to make the '73-'77 rear fit the G-body. They're no longer in business, but somebody might have some left-overs or some knock-offs.
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 04-15-2006, 12:07 PM
Augusto's Avatar
From the middle of the world
 
Last wiki edit: How to rebuild an engine Last photo:
Join Date: Mar 2006
Location: Ecuador, South America
Age: 51
Posts: 1,311
Wiki Edits: 6

Thanks: 4
Thanked 2 Times in 2 Posts
thanks guys, you all are very helpful.
Augusto.
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
Stock rear gears on a '73 Chevelle Malibu? Malibu73 Transmission - Rearend 1 07-21-2005 04:32 PM
7.5 rear end performance question 1BADSS-10 Transmission - Rearend 2 12-16-2004 07:45 PM
57 chevy rear disc romine Suspension - Brakes - Steering 2 11-06-2004 05:43 AM
can i put 8.5 into 7.5 rear end houseing bradsregal85 Transmission - Rearend 2 02-25-2003 06:11 PM
Rear end Buffed Engine 3 10-31-2002 05:11 AM


All times are GMT -6. The time now is 02:31 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.