Journey with Confidence RV GPS App RV Trip Planner RV LIFE Campground Reviews RV Maintenance Take a Speed Test Free 7 Day Trial ×
 


Reply
 
Thread Tools Display Modes
 
Old 08-17-2020, 10:18 AM   #11
Senior Member
 
deserteagle56's Avatar
 
Join Date: Jan 2012
Location: Middle of Nevada
Posts: 299
If you do decide to regear, go at least to 4.30 gears. That engine does better with higher rpm, especially with the weight you are hauling, and your whole drivetrain will thank you.

__________________
Worshipper of Wild Country
2007 Quigley V-10 on 33s with 4.56 gears (Toyhauler)
deserteagle56 is offline   Reply With Quote
Old 08-18-2020, 08:41 AM   #12
REF
Senior Member
 
REF's Avatar
 
Join Date: Jan 2009
Location: Boulder, CO.
Posts: 2,552
Send a message via MSN to REF
Re-gearing from 3.73 to 4.10?

Quote:
Originally Posted by tedujam View Post
Thanks for all the feedback. I'm now looking at BFG Mud Terrain 255/75R17s or Nitto Terra Grappler 285/70R17s. Neither of them are bigger than 32.7 inches, so it sounds like I should just stick with my 3.73 gearing.

And why the size differences between the two tires?
There’s no way to give you gearing advice without knowing what size tires you’ll ultimately end up with, so I’d finalize that before doing anything else.
Most SMB 4X4 conversions run 285’s, and depends what engine when it comes to gearing, some of us have gone bigger to 315’s, but it might take some other modifications to get there, including gearing. My 7.3 started on 285’s from SMB with 4:10, I’m now running 315’s with 4:56, but I’m also towing.
So it really all depends, but if you’ve got a ujor 4X4, they usually are setup with a pretty good lift, I think you’d want some tires to fill in the wells at least a little bit, 285’s at the minimum.
Got a pic of your rig to share?
__________________
'03 Ford E350 7.3L Diesel
(de)SMB'd Custom RB-50
Quigley 4X4 w/Deavers & Agile Offroad's R.I.P. package
CCV High Profile Pop Top
REF is offline   Reply With Quote
Old 08-19-2020, 01:24 PM   #13
Senior Member
 
tedujam's Avatar
 
Join Date: Jul 2020
Location: Austin
Posts: 167
Quote:
Originally Posted by REF View Post
And why the size differences between the two tires?
There’s no way to give you gearing advice without knowing what size tires you’ll ultimately end up with, so I’d finalize that before doing anything else.
Most SMB 4X4 conversions run 285’s, and depends what engine when it comes to gearing, some of us have gone bigger to 315’s, but it might take some other modifications to get there, including gearing. My 7.3 started on 285’s from SMB with 4:10, I’m now running 315’s with 4:56, but I’m also towing.
So it really all depends, but if you’ve got a ujor 4X4, they usually are setup with a pretty good lift, I think you’d want some tires to fill in the wells at least a little bit, 285’s at the minimum.
Got a pic of your rig to share?
The tire size difference is only about 1/2 inch. I didn't pick those sizes specifically, those are just the best 2 used/nearly new tire deals near me right now. I'd normally go with whatever new tire deal Costco is running, but right now it's $150 off Bridgestones I'm not interested in. The 35's on there right now are too big.
Attached Thumbnails
van 8-19.jpg  
tedujam is offline   Reply With Quote
Old 08-19-2020, 01:56 PM   #14
REF
Senior Member
 
REF's Avatar
 
Join Date: Jan 2009
Location: Boulder, CO.
Posts: 2,552
Send a message via MSN to REF
Then I’d probably look to step down to 285’s, anything smaller will look off in proportion and too small in my opinion, see how feels before doing any gearing change. Going from 35’s(315) to 285 is significant enough to notice a difference in gearing and engine performance.
__________________
'03 Ford E350 7.3L Diesel
(de)SMB'd Custom RB-50
Quigley 4X4 w/Deavers & Agile Offroad's R.I.P. package
CCV High Profile Pop Top
REF is offline   Reply With Quote
Old 08-19-2020, 02:09 PM   #15
Senior Member
 
tedujam's Avatar
 
Join Date: Jul 2020
Location: Austin
Posts: 167
Quote:
Originally Posted by REF View Post
Then I’d probably look to step down to 285’s, anything smaller will look off in proportion and too small in my opinion, see how feels before doing any gearing change. Going from 35’s(315) to 285 is significant enough to notice a difference in gearing and engine performance.
Anything will be an improvement over the 245/16s the original owner had on it!
Attached Thumbnails
e350 front tire.jpg   20200728_142438.jpg  
tedujam is offline   Reply With Quote
Old 08-20-2020, 01:16 PM   #16
Junior Member
 
Join Date: Sep 2019
Posts: 17
While doing a re-gear you may run into other things that might need replacing. Be prepared for those kind of surprises. Look into swapping from stock limited slip to an Eaton Detroit TruTrak. When we did the rear end two years ago, the costs were equal.
wilma is offline   Reply With Quote
Old 08-25-2020, 04:22 PM   #17
Junior Member
 
Join Date: Dec 2017
Posts: 26
Do you have experience with your 4r75e not lasting? im running factory 20" 2015 take offs , with the 5.4
motovan85 is offline   Reply With Quote
Old 08-28-2020, 07:37 AM   #18
Junior Member
 
Join Date: Feb 2020
Posts: 21
The formula is new tire size divided by factory old tire size times current gear ratio. That keeps it stock and the transmission in the same shifting rpms. But every one seems like to run at a higher rpm for more power and less mpg. Ford declined that drive train for fuel economy. At least mine 1999 e-350 5.4 with 4r100. My formula is 35/30.5x3.55=4.07
Itchy feet is offline   Reply With Quote
Old 07-31-2021, 11:44 AM   #19
Senior Member
 
boywonder's Avatar
 
Join Date: Jul 2013
Location: So Cal
Posts: 4,046
I'm considering re-gearing from 3.73's to 4.10's........


I have a kingpin Dana 60 on the front and the stock full floater on the rear (2008 Passenger RB).


Will this require a different carrier F or R?
__________________
2008 E350 RB passenger 4WD SMB penthouse
2013 KTM 350 EXC
2008 KTM 250 XCF-W
2003 Honda Element
boywonder is offline   Reply With Quote
Old 07-31-2021, 12:26 PM   #20
Senior Member
 
Join Date: Sep 2013
Location: Newberg, OR
Posts: 1,385
Quote:
Originally Posted by boywonder View Post
I'm considering re-gearing from 3.73's to 4.10's........


I have a kingpin Dana 60 on the front and the stock full floater on the rear (2008 Passenger RB).


Will this require a different carrier F or R?
The carrier split is 4:56 I'm pretty sure.
mgmetalworks is offline   Reply With Quote
Reply

Thread Tools
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

» Featured Campgrounds

Reviews provided by

Powered by vBadvanced CMPS v3.2.3
Disclaimer:

This website is not affiliated with or endorsed by Sportsmobile SIP or any of its affiliates. This is an independent, unofficial site.


All times are GMT -6. The time now is 08:04 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2024, vBulletin Solutions, Inc.