Reply
 
Thread Tools Search this Thread Display Modes
 
Old 11-03-2008, 07:14 PM   #1
New Member
 
1984 27' Airstream 270
long beach , California
Join Date: Jul 2008
Posts: 4
gear ratios

My 1984 Excella 270 with a 14 bolt corp. axle with 4:56 gears. Has anybody switched to 4:11's? Drag racers and rock climbing 4x4s have 4:11 ratios so they are available and I'll bet the 4:56 would make an offroad vehicle climb that much better and my 454 should more than enough power to use the slightly lower gears?
__________________

__________________
ixnaycraig is offline   Reply With Quote
Old 11-03-2008, 07:25 PM   #2
Rivet Master
 
Wingeezer's Avatar
 
2005 30' Classic
Burlington , Ontario
Join Date: Sep 2008
Posts: 2,708
Not sure I'm understanding here!

My 1/2 ton sierra 4x4 has 4.11 diffs. Yours are actually lower than mine - unless I am very confused, which isn't entirely impossible!


Brian.

Brian.
__________________

__________________
Wingeezer is offline   Reply With Quote
Old 11-11-2008, 08:45 AM   #3
Rivet Master
 
GlenCoombe's Avatar
 
1984 28' Funeral Coach
Belleview , Florida
Join Date: Jun 2005
Posts: 1,635
Images: 27
Craig, that's one low rear end... but lots of Moho's had 4.56's.

What do you turn (rpm) at 55 mph?

Check out Jegs or Summitt Racing for Ring and Pinion sets.

Make sure you get someone to do this swap who has experience and the right tools. As I understand it you can tear up a new rear end if it's not installed and meshed just so.
__________________
Glen Coombe AIR #8416
1984 28' Funeral Coach
Former Rolling Showroom & PuttLab (now party bus)
"I'm not an expert. But I did sleep in an Airstream last night."
GlenCoombe is offline   Reply With Quote
Old 11-11-2008, 08:55 AM   #4
Well Preserved

 
1993 21' Sovereign
Colfax , North Carolina
Join Date: Jun 2003
Posts: 20,191
If I understand your question, you want to swap your lower-ratio gears for something a little more highway-friendly. The ring gear and pinion gear need to be installed together as a set, and need to be "set up" or preloaded. Most pinion gears use a crush sleeve and/or shims to accomplish this. It is something you can do, but requires more than basic automotive knowledge.
__________________
Meddle not in the affairs of dragons, for you are crunchy, and taste good with ketchup.
Terry
overlander63 is offline   Reply With Quote
Old 11-11-2008, 09:42 AM   #5
Rivet Master
 
hampstead38's Avatar
 
1967 26' Overlander
Upperco , Maryland
Join Date: Jun 2008
Posts: 1,087
Blog Entries: 22
I don't think it's something you need to worry about with a '84, but when I took a look at new gears for the rear of my Titan, I was told I would need to have the dealer reflash the ECU.
hampstead38 is offline   Reply With Quote
Old 11-11-2008, 11:43 AM   #6
Well Preserved

 
1993 21' Sovereign
Colfax , North Carolina
Join Date: Jun 2003
Posts: 20,191
Quote:
Originally Posted by hampstead38 View Post
I don't think it's something you need to worry about with a '84, but when I took a look at new gears for the rear of my Titan, I was told I would need to have the dealer reflash the ECU.
That's why my '02 Silverado will continue with the OEM 3.73 gearing. I am not sure if the '84 has an electronic speedometer or not, if it does, it will need a different VSS. If it doesn't, it will need a different speedometer drive gear. Both are located in the same place, in the tailshaft of the transmission.
__________________
Meddle not in the affairs of dragons, for you are crunchy, and taste good with ketchup.
Terry
overlander63 is offline   Reply With Quote
Old 11-16-2008, 11:06 PM   #7
Rivet Master
 
blkmagikca's Avatar

 
1987 32' Excella
Nepean , Ontario
Join Date: Mar 2006
Posts: 1,131
Before you mess around with changing the diff, do a bit of calculating - - figure out how much distance 1 rev moves the rig - remember that to do this, you need to know the diameter of the tires. I once had a Chev G20 van that came with a 2.73:1 diff. It was useless for towing, so I bought a set of 4.10:1 gears, but I increased the tire size so that it was effectively the same as a 3.96:1 rear.

BTW, if you do change the diff ratio, you will also have to change whatever is used to calculate your speed and odometer, either a small gear, or, more likely, you will have to change the DRAC (digital ratio adapter controller), a small module that interfaces between the sensor and the speedo.

Personally, I would be inclined to keep what you have. With the Chev van, I actually got better mileage with the 4.10:1 than the 2.73:1, not to mention the power to pull a heavier load. By moving to a numerically lower ratio you will lose load carrying capacity of your rig.
__________________

__________________
VE3JDZ
AIR 12148
1987 Excella 32-foot
1999 Dodge Ram 2500HD Diesel
blkmagikca is offline   Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not 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 Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Gear vendors gloran Land Yacht/Legacy Motorhomes 1 03-31-2008 05:54 PM
Gear Ratio ??? slow-canoe Argosy Motorhomes 2 07-24-2007 11:09 AM
Gear Ratio ? slow-canoe Mechanics Corner - Engines, Transmission & More... 9 04-10-2006 09:29 PM
gear ratios RVNUTTY Tow Vehicles 11 09-04-2004 04:38 PM
Gear vendors vs Us Gear LKappenman Mechanics Corner - Engines, Transmission & More... 0 04-18-2002 09:00 AM


Virginia Campgrounds

Reviews provided by




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 06:41 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.

Airstream is a registered trademark of Airstream Inc. All rights reserved. Airstream trademark used under license to Social Knowledge LLC.