Reply
 
Thread Tools Display Modes
 
Old 09-12-2009, 07:45 PM   #11
Site Team
 
daveb's Avatar
 
Join Date: May 2007
Location: Turlock Ca
Posts: 9,410
Garage
Re: Differential questions from a new guy

FWIW Sportsmobile suggested to install a selectable locker in the front as the primary locker. I understand what others say and I agree. Wheel spin can cause problems but I have yet to plop down the bucks for a rear locker. From experience I have been stuck in some situations where the front slips and walks off the trail sideways while the rear limited slip never gave way. My thought is that because these vans are so heavy the rear had no problems but the front did. Maybe I'm wrong but as soon as I engaged the front locker I moved up the trail with no problems at all. That being said turning is a big issue. There have been times that I've had to turn the front locker on and off several times during turns to get where I wanted to be. The limited slip has worked so well that a rear locker is low on my list at this time.
__________________

__________________
2006 Ford 6.0PSD EB-50/E-PH SMB 4X4 Rock Crawler Trailer

Sportsmobile 4X4 Adventures..........On and off road adventures
daveb is offline   Reply With Quote
Old 09-12-2009, 09:20 PM   #12
Senior Member
 
Railvan's Avatar
 
Join Date: Jun 2007
Posts: 150
Re: Differential questions from a new guy

"Stumpalump summed it up nicely. I agree!"

X2!

Front and rear air lockers here.

Brian Rutherford
__________________

__________________
http://www.pbase.com/railvan
2006 Ford RB, 6.0 diesel, SMB 4x4, RB50
Railvan is offline   Reply With Quote
Old 09-12-2009, 11:02 PM   #13
Site Team
 
daveb's Avatar
 
Join Date: May 2007
Location: Turlock Ca
Posts: 9,410
Garage
Re: Differential questions from a new guy

Quote:
Originally Posted by railbat
"Stumpalump summed it up nicely. I agree!"

X2!

Front and rear air lockers here.

Brian Rutherford
Yep, there is always that one climb you got to try . I usually run in 4x4 on steep loose grades even though I could make it in 2WD low. It makes sense to spread of the stress. I use the front locker only when it's needed. What I have to decide is what locker to purchase for the rear. As in the other post that is current, there are many opinions on which to choose. So far I have not been plauged with the leaking seal/lines problems that ARB owners have had. My biggest fear is getting into a place that almost requires at least one locker in operation, then having it fail. Sometimes it's rougher coming out than going in. This is where the extra traction might be a life saver. I don't do heavy rock climbing like some of you might because I have an EB, but my van is heavy and a rear locker would help. I feel if I have to use a front and rear locker to get into an area, I shouldn't be there in the first place. Not with a 11K EB van. I still would like the extra insurance.
Dave.
__________________
2006 Ford 6.0PSD EB-50/E-PH SMB 4X4 Rock Crawler Trailer

Sportsmobile 4X4 Adventures..........On and off road adventures
daveb is offline   Reply With Quote
Old 10-13-2009, 02:28 AM   #14
Senior Member
 
Join Date: Jun 2009
Location: Bay Area, california
Posts: 159
Re: Differential questions from a new guy

I have a comment - limited slip diff (LSD) is good when you are in 2 WD mode. If you need to be in 4WD mode, then the trannsfer case locks the differentials front and rear and they are in 4WD hi or lo, whatever you're in. The LSD isn't an issue climbing rocks or off-roading because you are in 4WD and the system works like any 4WD.

By adding front ARB, you give yourself more ability because you can lock the front axles so each tire gets 1/2 the power going to the front (1/4 of total power each). The rear is still acting like a regular 4WD without a locking diff - traction is split between the 2 rear tires altho the one that is spinning gets more of the torque. Tha's a different discussiuon, tho.

If you can afford an ARB in the back then do it because you get max 4WD capability, but LSD in 2 wheel drive mode is good because in normal street driving you get that extra traction LSD provides when one of the rear tires starts slipping for some reason.

So .... what's wrong with my thinking - technically or application- wise? Do I have it right?
__________________
2010 E350 RB 50 Ash Gold V10 gas engine w/mud flaps and rock sliders!
2011 VW GTI
2009 Tacoma 4x4 TRD
warholic is offline   Reply With Quote
Old 10-13-2009, 11:48 AM   #15
Senior Member
 
geoffff's Avatar
 
Join Date: Apr 2007
Location: Seattle, WA
Posts: 858
Re: Differential questions from a new guy

Quote:
Originally Posted by warholic
then the trannsfer case locks the differentials front and rear
Front [to] rear... yes, that all makes sense to me.

The question I have now is -- does there exist a rear diff with both ARB locker and limited slip?

(I'm running front locker and rear limited slip. I do enjoy that limited slip for 2WD driving, especially when making a hard right turn and jumping out into traffic under heavy acceleration.)

-- Geoff
__________________
2004 Ford, SMB 4x4, RB-50
http://octopup.org/sportsmobile
geoffff is offline   Reply With Quote
Old 10-13-2009, 01:59 PM   #16
Senior Member
 
jage's Avatar
 
Join Date: Apr 2007
Location: Franktown, CO
Posts: 7,560
Re: Differential questions from a new guy

Quote:
Originally Posted by warholic
The LSD isn't an issue climbing rocks or off-roading because you are in 4WD and the system works like any 4WD.
This is the only part that seems off to me- in 4WD you've got the axles locked to each other, but without limited slip you're locking 2 open-diff axles (essentially 4WD means 2WD one on each axle).

Slight improvement gained by having a LSD in the rear, because now you've got 1 open and one LSD axle working for you... 2.25WD?) such as small difference can make a difference to getting stuck or not, depending on driver skill.

A locker then adds a whole WD to the equation so with a rear locker engaged and 4WD engaged it's actually 3WD. That's not to say that having the transfer case in 2wd and having the locker engaged (2WD) is equavilent to having the transfer case engaged and open diff axles (2WD) although I've met a number of people who believe a locker is nearly equavalent to 4wheel drive with open diffs. The gist is having pull in the front is more important than doubling the push in the rear (conditions dependant of course).

So ideally if you double your front (ARB locker) and have Limited Slip in the rear you're at 3.25WD on my little scale when everything is engaged and you keep the LSD for 2wd right turns in the rear. That sounds like a pretty good setup.
__________________
and then
everything changed
jage is offline   Reply With Quote
Old 10-13-2009, 05:58 PM   #17
Senior Member
 
Join Date: Apr 2008
Location: Carmel Valley, CA
Posts: 634
Send a message via AIM to Skywagon
Re: Differential questions from a new guy

That's all true, but keep in mind that with limited slip, one rear wheel is not always slipping. So, if both rear tires have relatively equal traction, they're BOTH actually propelling you.
And, while locking both wheels on the same axle together will obviously give you the best traction, there are times when having no differential effect is a liability such as when turning on rocks where too much traction can make it difficult to maneuver. For these rigs, I like LS rear/ locking front. If I had a CJ-5 rock crawler, I'd want lockers on both ends.
Bill
__________________
2008 RB 50 Pueblo gold, Diesel, 4X4, Aluminess
NO2B
Skywagon is offline   Reply With Quote
Old 10-13-2009, 08:11 PM   #18
Senior Member
 
geoffff's Avatar
 
Join Date: Apr 2007
Location: Seattle, WA
Posts: 858
Re: Differential questions from a new guy

Quote:
Originally Posted by Skywagon
That's all true, but keep in mind that with limited slip, one rear wheel is not always slipping. So, if both rear tires have relatively equal traction, they're BOTH actually propelling you.
And even when a wheel is slipping, with a LSD you're putting more power out to the wheel that still has traction than you do with an open diff. With an open diff, they both get the torque of the slipping wheel (perhaps almost zero), but with a limited slip, the good wheel gets that plus the torque required to slip the LSD's friction clutch plates.

-- Geoff
__________________

__________________
2004 Ford, SMB 4x4, RB-50
http://octopup.org/sportsmobile
geoffff 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

» Sportsmobile Registry

Road Roamer

Road Roamer

Van22

Van22
Add your Sportsmobile
Powered by vBadvanced CMPS v3.2.3

All times are GMT -6. The time now is 04:31 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.