3.55 vs 3.73 9-inch - 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 03-27-2002, 10:26 PM
mustang66maniac's Avatar
Ford Freak
 
Last photo:
Join Date: Feb 2002
Location: Rockville, MD
Age: 30
Posts: 676
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Post 3.55 vs 3.73 9-inch

I have a 66 mustang with a 5.0 and a c4 that i plan on changing in favor of an AOD. I cant decide if i want 3.55s or 3.73s in the rear. It is a daily driver and my only car so im looking for respectable gas mileage, i also take it to the races on weekends sometimes so im looking for acceleration. What do you think would be the best gear ratio for an automatic overdrive daily driver/weekeng warior????

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 03-28-2002, 07:58 AM
dmorris1200's Avatar
doesn't play well with others
 
Last photo:
Join Date: Feb 2002
Location: Maine
Age: 49
Posts: 1,834
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Post

If you go with the 3.55 set-up that's just about what you would find in Crown Vic. police car. I would think you should have no problems going a little higher if you're scrapping the C4. Funny you brought up rear changes. I'm waiting right now for my tax return to do mine. I'm stiil running a C4 trans into a 3.00 8-inch rear. I'm either rebuilding the 8-inch with a set of 3.80 gears or try and find a 9-inch which came in the MachI's and use that. The 9-inch would be the preferred way to go but depending on the finances I might just throw gears in the 8-inch. I've been beating this poor car for 11 years. I've had to rebuild the engine and trans so far but that 8-inch rear, even with it's poor reputation, has held together so far. I'm not exactly running nitrous here, but with a good running 302 and enough hole shots to take out the trans and brake the rear shock mounts over time that 8-inch rear just keeps hangin' on. Like to here how yours ends up, might be another month or so for me.
__________________
BUILT FORD TOUGH
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 03-28-2002, 01:24 PM
lakeroadster's Avatar
Hot Rods are Built, not Bought
 

Last journal entry: Lakeroadster's '31 Model A Tudor
Last photo:
Join Date: Dec 2001
Location: High Plains - Rocky Mountains
Age: 53
Posts: 643
Wiki Edits: 0

Thanks: 26
Thanked 88 Times in 80 Posts
Post

4lo.com has a gear calculator that helps you to choose gear ratios. Check it out, its pretty slick.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 03-28-2002, 05:29 PM
Member
 
Join Date: Mar 2002
Location: Melrose FL
Posts: 291
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Post

I'd opt for the 3.70 cogs, but then I am an off road guy

Seriously though, 3.70 times OD gives you like 2.70:1 which is going to give you lower RPM than a 3.00 gear (I know, duh). You don't want to go too low on the cruise RPM though, or you will actually lose fuel efficiency. That's what's great about an OD tranny, you get the best of both worlds
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 03-29-2002, 11:41 AM
mustang66maniac's Avatar
Ford Freak
 
Last photo:
Join Date: Feb 2002
Location: Rockville, MD
Age: 30
Posts: 676
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Post

this ones to dmorris.
Yeah on my mustang it has an 8 inch right now with 3:00 gears also, but I've been like the luckiest person on earth and found a 9-inch from either a shelby or a k-code 65 mustang. So itll just drop right in with no mods. Talk about lucky huh? You never see those. As for me, ive run on the 1/4 mile 7 times with my 8inch now and its never been rebuilt to my knowledge. Its holdin up real well if you ask me. My 302 has a little over 300 horses but i think that the 3:1 gear ratio is holdin me back. My best time so far is 14.7@95. Im hopin the 9 with the 3.73s will improve on that.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 03-29-2002, 02:59 PM
dmorris1200's Avatar
doesn't play well with others
 
Last photo:
Join Date: Feb 2002
Location: Maine
Age: 49
Posts: 1,834
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Post

Hi again mustang66, good to see I'm not the only one beating up an 8-inch rear. I'm hoping I may get lucky also. I just haven't had the time yet to start searching the local yards and still waiting for my tax return. Like I said late model Crown Vic. police cars run approximately a 3.55 rear with an overdrive trans. The overdive advantage is yes you do lower your final drive ratio in overdrive but you still get a rippin' first gear take-off. Again I would go a little higher (3.70-3.80) but you're not gonna want to go too high if you are driving this car every day. If you hadn't noticed police cruisers aren't exactly hurtin' off the line and do well at highway speeds and that's at about 3.55, go a little higher and I think you would have a great daily driven street pounder. Then all you have to do is drive that Ford on over to Jersey.
__________________
BUILT FORD TOUGH
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 04-02-2002, 12:41 PM
Member
 
Join Date: Mar 2002
Location: Southern USA
Posts: 61
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Post

To be able to predict performance of a vehicle and make an educated estimate for this combination you will need a bit more information.

When building a car for both street driveability as well as bracket racing it is extremly important that the combination is right.

In short:

What size tires are on the rear? (245/60/15)

What type of tires will you use? (Radial, drag radial, slick some of the time)

For a detailed performance report, email me a request and I'll run the data for you and email you the performance report.

Contact information
pchotrod@hotmail.com

<a href="http://www.pchotrod.com" target="_blank">www.pchotrod.com</a>
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



All times are GMT -6. The time now is 11:59 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.