Limited slip
Senior User
Joined: Dec 2003
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Originally Posted by t_j82
Yesterday I went to leave my driveway and the right rear wheel ended up on a patch of ice, I put it in drive and gassed it and went no where. I goosed it again and still no movement. I pointed my mirror down at the left tire and wrapped it up to about 17k and it never moved and neither did the truck. So I had to go into 4wd because ONE tire was on ice. Didn't know I bought a one legger. Window sticker shows L/S installed.
Called the dealer and spoke with the svc writer and was told to bring it in. Got it back today, was told everything works fine. I was handed a sheet from ford that said to lightly apply the parking brake while accelerating to make the L/S work... WHAT?! So does this mean that I have to drive with my brakes on while in slippery conditions for the L/S to work?
This is the first I have ever heard of this.... Anyone have words of wisdom, or at least logic?
Called the dealer and spoke with the svc writer and was told to bring it in. Got it back today, was told everything works fine. I was handed a sheet from ford that said to lightly apply the parking brake while accelerating to make the L/S work... WHAT?! So does this mean that I have to drive with my brakes on while in slippery conditions for the L/S to work?
This is the first I have ever heard of this.... Anyone have words of wisdom, or at least logic?
This techneque is used when you do not have LS or posi. It causes the other wheel to bite. Take it to another dealer. I don't like mine either I call it the limited slipsalot.
Posting Guru
Joined: May 2004
Posts: 1,366
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From: Northern Utah
Originally Posted by t_j82
I have been carrying 400lbs of sand in my truck since December so I think the weight thing is moot.
Junior User
Joined: Nov 2003
Posts: 83
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From: East Central Ohio
Had a 2000 F250SC SB 7.3 6 speed never noticed any help from LS.This truck slipped on wet grass. Lost that one to a flood and now have 2005 F250SC SB 6.0 6 speed and the LS works most of the time. I agree they need to go back to the drawing or not charge for this option.
Posting Guru
Joined: Jan 2004
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From: Tennessee
PSD60LFX4 had a discussion about this not long ago. I believe that Detroit Locker has a diff coming out soon that will be LS and you can manually engage it to full lock by the push of a button. My truck has LS too fuctions the same way. ****es me off when I try to do a burnout and it only spins one wheel 80% of the time.......
Senior User
Joined: Apr 2004
Posts: 319
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From: Oshawa/Ontario/Canada
As I understand the recomendation (and the description on howstuffworks), it would seem that this type of limited slip requires a little traction to make it work. Howstuffworks calls this type of differential a 'TorSen' ... and it seems reasonable that a small amount of friction is require to make it engage.
The description says that the operation is to apply some multiple of torque (say 5 times, for argument) to the non-spinning wheel. However, if the spinning wheel has 0 torque, 5 x 0 is 0. Applying the brake increases the torque applied and thus the other wheel moves.
Don't mistake this for a regular open differential where the parking brake is also of limited aid. In that case, if your brakes are properly adjusted, nothing happens. An open differential applies the same torque to each wheel --- so when you apply the break, the same torque is being absorbed from both wheels and the result is that you don't move.
The description says that the operation is to apply some multiple of torque (say 5 times, for argument) to the non-spinning wheel. However, if the spinning wheel has 0 torque, 5 x 0 is 0. Applying the brake increases the torque applied and thus the other wheel moves.
Don't mistake this for a regular open differential where the parking brake is also of limited aid. In that case, if your brakes are properly adjusted, nothing happens. An open differential applies the same torque to each wheel --- so when you apply the break, the same torque is being absorbed from both wheels and the result is that you don't move.
Elder User
Joined: Jan 2004
Posts: 900
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From: Arizona
HERE IS THE ANSWER............
Dont ask me why, but, according to Ford tech, you must apply light pressure to the brake peddle or set E-brake on lightly. It works, try it. Miss those Detroit Lockers?
Dont ask me why, but, according to Ford tech, you must apply light pressure to the brake peddle or set E-brake on lightly. It works, try it. Miss those Detroit Lockers?
Junior User
Joined: Mar 2004
Posts: 59
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From: Manassas, VA
I know that everytime I've powerbraked my truck, I've layed down dual rubber. Usually if I just stomp it, I can feel one wheel just barely wanting to slip.
So I would agree, brakes do help the rear out somewhat.
P.S.
Why do some people hate to put their trucks in 4X4?
So I would agree, brakes do help the rear out somewhat.
P.S.
Why do some people hate to put their trucks in 4X4?
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More Turbo
Joined: Feb 2004
Posts: 722
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From: New Orleans to San Diego
Originally Posted by ZBeeble
Don't mistake this for a regular open differential where the parking brake is also of limited aid. In that case, if your brakes are properly adjusted, nothing happens. An open differential applies the same torque to each wheel --- so when you apply the break, the same torque is being absorbed from both wheels and the result is that you don't move.
I have a non-LS or "open" differential.
I understand your above statement but do you know what my inner rear wheel does when i make a U-turn?
I can't figure out if a limited slip or non-slip is better for turning.
Thread Starter
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Elder User
Joined: May 2003
Posts: 833
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From: NW Montana
Originally Posted by labenske
P.S.
Why do some people hate to put their trucks in 4X4?
Why do some people hate to put their trucks in 4X4?
Senior User
Joined: Apr 2004
Posts: 319
Likes: 1
From: Oshawa/Ontario/Canada
Originally Posted by LOOnatic
I have a non-LS or "open" differential.
I understand your above statement but do you know what my inner rear wheel does when i make a U-turn?
I can't figure out if a limited slip or non-slip is better for turning.
I understand your above statement but do you know what my inner rear wheel does when i make a U-turn?
I can't figure out if a limited slip or non-slip is better for turning.
So when you turn a corner, your inside wheel is (say) turning once for every 3 times the outside wheel turns (these trucks don't turn too sharply) so the whole mechanism isn't kicking in (much).
Freshman User
Joined: Jan 2005
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ZBeeble,
The description of the Torsen is accurate but I don't think Ford is using a TorSen differential. In the world of L/S differentials TorSen is relatively new. Ford is using a standard clutch pack design. That's why the dealer can offer to "tighten it up some." I'd be thrilled if they started installing TorSen or Eaton differentials.
BTW, the torque spec for my hotrods 12 bolt posi is 100 lb-ft to overcome the clutch pack manually.
The description of the Torsen is accurate but I don't think Ford is using a TorSen differential. In the world of L/S differentials TorSen is relatively new. Ford is using a standard clutch pack design. That's why the dealer can offer to "tighten it up some." I'd be thrilled if they started installing TorSen or Eaton differentials.
BTW, the torque spec for my hotrods 12 bolt posi is 100 lb-ft to overcome the clutch pack manually.
Senior User
Joined: Dec 2003
Posts: 121
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From: Cincinnati, OH
After carefully inspecting the two 15 foot black stripes that used to be BFG tread… my L/S kicks in immediately- no brakes, just a slight roll and then the SCMT tune makes short work of my tread. The marks start at the same place- at least as far as I can tell. I did, however, gets stuck in a very precarious driveway last year, in 4 high, and 4 low. Was trying to pull a Subaru out. How embarrassing. One rear, and one front tire were slipping. I didn’t think to hold the brakes- must have been the alcohol.
I have seriously considered getting an aftermarket locker. I haven’t done a ton of research yet, but was considering front and rear ARB air lockers. The rock crawlers swear by them, but if my truck goes rock crawling, it won’t be on purpose. I just want to get out of the driveway! I would be interested to hear if anyone has experience with one brand/type or the other. I would like a REAL limited slip/locking diff. They are a bit pricey, though.
I have seriously considered getting an aftermarket locker. I haven’t done a ton of research yet, but was considering front and rear ARB air lockers. The rock crawlers swear by them, but if my truck goes rock crawling, it won’t be on purpose. I just want to get out of the driveway! I would be interested to hear if anyone has experience with one brand/type or the other. I would like a REAL limited slip/locking diff. They are a bit pricey, though.
Postmaster
Joined: Aug 2003
Posts: 4,483
Likes: 2
From: Central Texas
Revving it up will certainly make it slip. Go real slow and it shouldn't slip. If you look at Ford's documentation, they say to go real slow.
"As when you are driving over sand, apply the accelerator slowly and avoid spinning your wheels."
From the Truck and SUV manual
"As when you are driving over sand, apply the accelerator slowly and avoid spinning your wheels."
From the Truck and SUV manual
New User
Joined: Feb 2005
Posts: 17
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From: New Windsor, NY
What ford really needs is the option of a locking rear differential... cough nissan titan cough chevy silverado. 
There are so many situations where an extra wheel of traction could have gotten me farther or out a of somewhere more easily!
There are so many situations where an extra wheel of traction could have gotten me farther or out a of somewhere more easily!