Gear Ratio ? - Diesel Truck Forum - TheDieselGarage.com
Thread Details Posted by jlbt, this thread has received 22 replies and been viewed 3823 times.

Reply
 
LinkBack Thread Tools Display Modes
post #1 of 23 (permalink) Old 02-12-2011, 02:41 AM Thread Starter
Junior Member
 
Join Date: Oct 2010
Location: Upstate NY
Posts: 16
Points: 18,768
Thanks: 5
Thanked 1 Time in 1 Post
Images: 1
Garage
Gear Ratio ?

Anyone have any idea what the RPM change would be in changing out a set of 3.55 to 3.90 i was told around 200 rpm I have a 18913a trany on 24.5 tall rubber thanks
jlbt is offline  
Sponsored Links
Advertisement
 
post #2 of 23 (permalink) Old 02-12-2011, 03:25 AM
Senior Member
 
Join Date: Dec 2008
Location: tulsa ok
Posts: 1,138
Points: 48,481
Thanks: 28
Thanked 234 Times in 200 Posts
Quote:
Originally Posted by jlbt View Post
Anyone have any idea what the RPM change would be in changing out a set of 3.55 to 3.90 i was told around 200 rpm I have a 18913a trany on 24.5 tall rubber thanks
http://www.4lo.com/calc/gearratio.htm
http://www.4lo.com/calc/gearratio.htm
theakerstwo is offline  
The Following User Says Thank You to theakerstwo For this addition to TDG:
pichu2 (02-12-2011)
post #3 of 23 (permalink) Old 02-12-2011, 02:36 PM
Member
 
Flyingpig's Avatar
 
Join Date: Jan 2011
Location: Belle Plaine, Iowa
Posts: 168
Points: 24,214
Thanks: 6
Thanked 30 Times in 22 Posts
I curious WHY you would want to change it. My trans is a 14609B with a .73 OD. Ive got 3.58 rears on low 24.5s. I ADDED a splitter to make it a 13 speed which gives me a final OD of .63. Im pulling a grain trailer now at around 80K and in the fall they let us go to 88K. And yes there have been times its gotten up to 92K which is legal as long as you dont get caught. Ive been loading in the fields and running the highways with no trouble at all. If Im good and heavy Im in and out of that top OD more often since Ive only got 400hp to deal with. Since you have tall rubber we should be geared very close to the same.

Im one that likes to use ODs to keep the rpms down on the highway. I believe that is one reason I get half way decent mileage.

Who do you call when the lawmakers ignore the law?
Flyingpig is offline  
post #4 of 23 (permalink) Old 02-12-2011, 04:02 PM
Senior Member
 
379Longhood's Avatar
 
Join Date: Oct 2009
Location: Alberta t0m0r0
Posts: 2,555
Points: 94,569
Thanks: 195
Thanked 714 Times in 533 Posts
Quote:
Originally Posted by jlbt View Post
Anyone have any idea what the RPM change would be in changing out a set of 3.55 to 3.90 i was told around 200 rpm I have a 18913a trany on 24.5 tall rubber thanks
Try this link http://www.roadranger.com/ecm/groups.../ct_062746.swf
lets you plugin tire size, trans ratio, diff ratio etc

Canadian Club member 27
'88 379 exhd 3406C 15 40s 10 pete unimounts
'93 K3500 6.5 4L80 4" exh
'62 gmc shortbox 454 super t10 big brakes
JD 820 black dash
12V92 waitin' for a truck (mega ratrod)
pettibone s20 3306 pc
379Longhood is offline  
The Following User Says Thank You to 379Longhood For this addition to TDG:
pichu2 (02-12-2011)
post #5 of 23 (permalink) Old 02-12-2011, 04:28 PM
Junior Member
 
378Pete's Avatar
 
Join Date: Jun 2010
Location: N.C. Illy-noise
Posts: 114
Points: 38,871
Thanks: 0
Thanked 6 Times in 6 Posts
Wish I could find someone to trade me some 3:55-3:70 gears for my 3:90. Right now it's 1500rpm at 65...wouldn't mind a 1350 at 65.

378Pete is offline  
post #6 of 23 (permalink) Old 02-12-2011, 06:50 PM Thread Starter
Junior Member
Threadstarter
 
Join Date: Oct 2010
Location: Upstate NY
Posts: 16
Points: 18,768
Thanks: 5
Thanked 1 Time in 1 Post
Images: 1
Garage
The front rear just let go a bolt out of the ring gear must have come loose and broke 3 teeth off the pinnion gear. I ended up replacing both rears i switched over to 3.90s. I had to turn the rear rear in for a core. The front was replaced with a new one from eaton but had to order the rear they had reman in stock so thats what i did. my caculations show i should have about a 175 rpm change i haul a bucket in upstate ny so any local work is at 102000 i hope the 3.90 will make it alittle easyer on the truck will see on monday:
jlbt is offline  
post #7 of 23 (permalink) Old 02-13-2011, 02:41 AM
Junior Member
 
Join Date: Jul 2010
Location: in a 13 letter [email protected]#% spreader
Posts: 168
Points: 37,903
Thanks: 22
Thanked 41 Times in 36 Posts
Garage
Quote:
Originally Posted by 378Pete View Post
Wish I could find someone to trade me some 3:55-3:70 gears for my 3:90. Right now it's 1500rpm at 65...wouldn't mind a 1350 at 65.
, only I turn another hundred higher and have a cat.
antiquepuller is offline  
post #8 of 23 (permalink) Old 02-13-2011, 04:21 AM
The other guy
 
Join Date: Jan 2007
Location: Brenham, Texas
Posts: 3,936
Points: 108,520
Thanks: 36
Thanked 1,350 Times in 846 Posts
Quote:
Originally Posted by 378Pete View Post
Wish I could find someone to trade me some 3:55-3:70 gears for my 3:90. Right now it's 1500rpm at 65...wouldn't mind a 1350 at 65.
3.55's
ynot is offline  
post #9 of 23 (permalink) Old 02-13-2011, 04:30 AM
Junior Member
 
378Pete's Avatar
 
Join Date: Jun 2010
Location: N.C. Illy-noise
Posts: 114
Points: 38,871
Thanks: 0
Thanked 6 Times in 6 Posts
Quote:
Originally Posted by ynot View Post
3.55's
After I did the roadranger calculator thingamabob that's what I came up with.....22.5, 16918b, yada yada.

What I've got now works fine for construction season, but this time of the year it's more highway time and leg stretchin...

But I spose it's 'spensive and switching them is most likely far out of my area of expertise.

378Pete is offline  
post #10 of 23 (permalink) Old 02-13-2011, 04:34 AM
The other guy
 
Join Date: Jan 2007
Location: Brenham, Texas
Posts: 3,936
Points: 108,520
Thanks: 36
Thanked 1,350 Times in 846 Posts
Quote:
Originally Posted by 378Pete View Post
After I did the roadranger calculator thingamabob that's what I came up with.....22.5, 16918b, yada yada.

What I've got now works fine for construction season, but this time of the year it's more highway time and leg stretchin...

But I spose it's 'spensive and switching them is most likely far out of my area of expertise.
Switchin em is easy and takes almost no tools. I know guys that change their gears back and forth once a year with new fluid for whatever hauling. Bout 4 hours for both and good time to check ujoints.
ynot is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Diesel Truck Forum - TheDieselGarage.com forums, you must first register.
Please enter your desired user 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:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Thread Thread Starter Forum Replies Last Post
What gear ratio on a DRW 4x4?? Sandman12 2011+ 6.7L Power Stroke Diesel 9 05-23-2010 11:20 AM
Gear Ratio WoodBoy 2008-2010 6.4L Power Stroke 12 03-19-2010 08:26 PM
gear ratio ID help vcassens General Gas Vehicle 3 01-04-2010 05:47 PM
Gear Ratio $DIESEL 1994-2003 7.3L Power Stroke 4 12-07-2007 05:09 PM
Gear ratio Chunk 2003-2007 6.0L Power Stroke 12 09-29-2005 03:36 AM

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

 
For the best viewing experience please update your browser to Google Chrome