Limeted slip Diff question

Reply Subscribe

Thread Tools

Search this Thread

Sep 17, 2009 | 03:19 PM

#16

Izzy351

Post Fiend

Joined: Feb 2007

Posts: 14,541

Likes: 2

From: Dallas-Ft. Worth

Quote:

Originally Posted by just another truck

so much to learn

so much to learn

Thank you for that.. time to do the rear end "DOPE" change.. and while I am at it, I will change the fluid to..

Quote:

Originally Posted by Bob Taulbee

I found this on Red Line oil's web page it shows, Joe and Dave to be correct about too much Friction Modifier. I stand corrected, I guess I got some bad info SORRY

Limited Slip Friction Modifier by Red Line

Description: Compatible with petroluem or synthetic gear oils, Red Line's Limited Slip Friction Modifier will significantly reduce the friction break-in of differentials, reducing break-in temps by as much as 50 degrees. Limited slip or positraction units will often chatter without use of this product or a gear oil with a similar modifier, so add only enough to eliminate the chatter and avoid making the plates or clutches too slippery.

No worries, fellers... That's what the site is for!! I think a lot of folks aren't sure what it does, so it's good to have it in a thread for folks to find in a search.

BTW, just in case anyone happens across this, Ford came out with a TSB about the front diff lube. You now use syn 75W-140 in both front and rear diffs. Certainly makes it easier for you 4x4 guys when it's time to change it.

Sep 17, 2009 | 03:37 PM

#17

deereman4020

Postmaster

Joined: May 2008

Posts: 3,099

Likes: 0

From: horicon Wi

Quote:

Originally Posted by rebelchevy02

The factory limited slip is well worn out at 100k. Some people have claimed early as 50k. I remember seeing at one time, someone made a replacement clutch pack, that was higher in clutches (tighter) but cannot remember were. Only real solution to traction issues is to put a new carrier in your rear axle. I love my detroit, but a true trac is a quiet limited slip.

what would you reccomdend for a farm truck that sees the road 99% but will go off road a bit. I want to get rid of that junk LS in the rear end.

Sep 17, 2009 | 03:54 PM

#18

rebelchevy02

Posting Guru

Joined: May 2006

Posts: 2,274

Likes: 1

From: Milroy, PA

If its empty all/most the time, true trac. Its an all gear limited slip. Much more road friendly, and more like what your used to, other then more traction. If at any time one wheel is spinning (starting out from mud or wet grass, were the other tire gets no resistance) you simply slightly apply the breaks while on the throttle to get them to lockup. Most people who buy true tracs think they suck, because they dont understand how they work. Google torsen differential. They are very comparable in design.
linky
http://en.wikipedia.org/wiki/Torsen

However, if you ALWAYS want the rear axle locked when the pedal is applied anything more then slight, and I mean slight, then the detroit is the way to go. They are a little more "scary" at first untill you understand the noises it makes. When it randomly unloads, it sounds similar to an axleshaft breaking. (Yes I know that sound) It can happen at any time, even when coasting to a red light. But when I want two tires turning, all I have to do is apply throttle. The first couple times it unloads, you get a bad feeling, untill you hammer down the throttle, and realize your still tracking straight lol.

Sep 17, 2009 | 04:12 PM

#19

HH60FE

Thread Starter

Posting Guru

Joined: Jun 2008

Posts: 1,037

Likes: 0

From: Albuquerque

Mike, that makes sense to me now, about very little resistance on the left rear while spinning. I will try again before I do any oil removal/add and with slight brake application it "should" engage the limited slip. Thanks

Sep 17, 2009 | 10:10 PM

#20

rebelchevy02

Posting Guru

Joined: May 2006

Posts: 2,274

Likes: 1

From: Milroy, PA

Matt, what I wrote is for the Detroit True Trac limited slip. Not out factory LS. The true trac is an all gear limited slip, unlike our factory clutch type. If you have the factory LS you can try the extra braking, and at that point you may slow the spiining tire enough to get the other side to do something, however, more then likely it wont help much. Different type of differential. What I wrote was in reply to Deereman's question. Which reminds me, when I drove my truck empty once, when it had the detroit locker, it was a pretty jerky ride. Normally I have almost 50/50 weight distribution (scale verified, 45XX # per axle) and with that, I dont notice hardly any of the ill affects of having a locked axle. Unlike when it was empty. For that farm truck, I would go true trac.

Sep 17, 2009 | 11:49 PM

#21

KelVarnson

Fleet Mechanic

Joined: Feb 2007

Posts: 1,852

Likes: 39

Actually, some brake application might help with a conventional clutch-type LSD also.

In addition to the preload applied to the clutches by the springs, the pinion gears also push the side gears outward when torque is applied. This increases the drag on the clutches between the side gears and the case. The spring preload is really just to get things started when one wheel is in a zero traction situation.

In fact, some models of the True Trac also include spring packs for the same reason.

Sep 18, 2009 | 09:52 AM

#22

HH60FE

Thread Starter

Posting Guru

Joined: Jun 2008

Posts: 1,037

Likes: 0

From: Albuquerque

To quote other folks on here "learning every day!". Thanks

Sep 18, 2009 | 12:28 PM

#23

truckeemtnfords

Logistics Pro

Joined: Nov 2006

Posts: 3,679

Likes: 370

From: Fallon,NV & Bainbridge OH

Again somebody beat me to it, Kel is right, and it works sometimes on conventional diff's with no type of limited slip. I have used the "poor mans posie" several times getting people unstuck here in the snow when they take their 2-wd vehicle where it should not be going. Limited slip of just about any kind tightens (or locks) up the side gears of drive both axles whether it be by clutches or gears.