Ford Forums banner

LSD or not??

6K views 22 replies 15 participants last post by  94EF_Ghia 
#1 ·
this is pretty weird, and i dont know whats goin on!
ok.... on wet roads, i can get both wheels to bag up (stand still) and on the move, and on dirt i can get both wheels to go. on dry bitumen, it wont light up both wheels on a stand still, only the one.
this would surely have to be telling me that its an open wheeler?

also, im thinking of going 3:45 gears and a new LSD. better bottom end pick up with 345 gears i would think?
and would this change my rpm much?
 
#2 ·
Lie down and read the diff tag, that should tell you whats installed, most of the time.

By the sounds you have LSD as otherwise only one wheel would want to bag up in the wet, and you just aint got enought grunt in the dry to spin em.

Dellboy999
 
#5 ·
That's what I found out too. At 100kph it was stuff all difference in rpm, only 50-100 rpm. I say its definitely worth goin the 3.45's, the pick up down low is great.
 
#7 ·
The LSD in my EL XR6 is gone. It doesn't have a tag on the diff plug but I know it's LSD. I spun the wheel and the other one stayed still and sort of moved a tiny bit then stopped spining. If it was a single spinner the other wheels would turn in the opposite direction. I did a burnout last night and there was only 1 big black mark. I was dissapointed. I don't know whether it could just be the diff oil, or if the clutch packs inside the diff are fudged. Maybe I'll have to get it welded up again. I want LSD!

IS the standard EL LSD 3.23 and the XR6 3.45?
 
#8 ·
Well I’m gona go jack up my car in the morn. Its an EBII and I was sure it was NOT an LSD till the other night when I had a very excited mate run up and pound on my drivers side door screaming “Shit man, both wheels are going!” It was dry conditions and on normal road and time after time again I got both wheels to spin no problem. However later on that night at a completely different location I tryed again and although both wheels did begine to spin on the spot at first one side eventually stopped without leaving any real mark while the other kept going.

Another interesting thing is that the other day we swear my mates drive wheel changed! (also an EB II) LoL, any ideas on any of this?
 
#9 ·
Cobra said:
The LSD in my EL XR6 is gone. It doesn't have a tag on the diff plug but I know it's LSD. I spun the wheel and the other one stayed still and sort of moved a tiny bit then stopped spining. If it was a single spinner the other wheels would turn in the opposite direction. I did a burnout last night and there was only 1 big black mark. I was dissapointed. I don't know whether it could just be the diff oil, or if the clutch packs inside the diff are fudged. Maybe I'll have to get it welded up again. I want LSD!

IS the standard EL LSD 3.23 and the XR6 3.45?
Sounds like your diff is very rooted !
 
#10 ·
hot ef, mine does the same thing, in the wet both wheels go nuts, where as in the dry only one goes most of the time. The LSD is just worn out.As said above check it has lsd by the tag on the diff.

putting in 345's will help, and lsd is fun so i reckon it's worth it
 
#12 ·
There's a common misconception that non LSD or "open wheel" diffs only drive one wheel at a time - THIS IS SIMPLY NOT TRUE!!!

In conditions where there is grip available to both wheels a normal diff will be driving both wheels - but if one wheel loses grip it will spin and take drive away from the other.

An LSD is designed to keep drive force going to the slower turning (more loaded) wheel - instead of letting it all be lost to spinning up the one that's not gripping. A side effect of this is that yes, an LSD will generally leave two skid marks regardless of surface - or more accurately WON'T only leave only one.

In short - a normal diff can leave either one or two skidmarks depending on conditions but an LSD should generally leave two.
 
#13 ·
Cobra said:
I spun the wheel and the other one stayed still and sort of moved a tiny bit then stopped spining. If it was a single spinner the other wheels would turn in the opposite direction.
Who told you this little gem? Slap them in the head for me. The other wheel will only run backwards if the transmission is left in gear (manual) or in park (auto). Did you notice the tailshaft spinning while you did this?
 
#14 ·
Ouch! That hurt!

I told him and I am not alone. I first read this trick in a Chrysler Factory manual (which I still have; in fact its in the 1980 CM Valiant, and in the two KB and KC Centura factory manuals I have). But Chrysler and I am not alone also see:

http://www.geocities.com/MotorCity/Shop/1553/lsd/clintdiff.htm
http://www.kondratyev.com/porsche/ppi/man_trans.htm
http://www.miata.net/garage/vlsd.html
http://autos.groups.yahoo.com/group/nissanpathfinder/message/50
http://www.flash.net/~rjgeorge/tnotes.htm

and 1,001 other sites found in Google by entering the text "limited slip differential jack up". While this test is not foolproof I have never seen it fail with a Rear Wheel Drive Aussie Borg Warner or BTR transmission. Yes, worn out LSD behave like non-LSDs and some after market exotic diffs behave differently but has anyone out there got a Ford that fails this test (ie indicates they have an LSD when they have not or visa-versa)?

The jack up and spin the wheel test has also worked correctly for all the cars I have owned in the last 30 odd years.


There is a more dangerous alternative test here:http://zccw.org/Tech/Differential/LSD.html

and some workshop manuals describe a resistance torque test where you test by turning a rear wheel with a torque wrench. Hey there is one in the Ford manual. Elevate one rear wheel, remove wheel and brake caliper, refit wheel (not caliper) and attach torque wrench to a wheel nut at the 3 o'clock position, place trans in neutral with park brake off, rotate wheel in both directions until a consistent torque reading is obtained; this reading should be 36 nm or more.
 
#15 ·
It is ONLY a "L"SD and these B.W don't have clutch packs either and No adjustment[shims] thats for 9"..Even a brand new lsd B.W will spin one wheel if the traction is very different on each wheel.
 
G
#16 ·
When I take my EA for a hoon, and spin the tyres up around a corner in the wet, the ass end ALWAYS loses control. I know my car is a LSD and was wondering if this is normal? Can you get LSD's that don't do this or what?

Cheers
 
#17 ·
Aussiblue said:
but has anyone out there got a Ford that fails this test (ie indicates they have an LSD when they have not or visa-versa)?


BW 2 pin, 4 pin, and salisbury diffs, plus landcruiser, etc, can all indicate LSD in this type of test. Try at least 1 out of 3 failing or contra-indicating. This is why this test is a waste of paper, and webspace, it would appear. Generally more on manuals, as the resistance through the gearbox is low enough to allow the opposing wheel to follow the wheel you are testing.

Elevate one rear wheel, remove wheel and brake caliper, refit wheel (not caliper) and attach torque wrench to a wheel nut at the 3 o'clock position, place trans in neutral with park brake off, rotate wheel in both directions until a consistent torque reading is obtained; this reading should be 36 nm or more.
This test is much more reliable, and you can forego the torque wrench if you are only looking for confirmation of LSD, and not an indication of condition. I wouldn't bother with the brake removal though, will not be an issue unless they are dragging real bad, which is a problem in itself.
 
#18 ·
donuts2003 - that's exactly what LSD will make your car do.

It's another misconception about LSD's that they mean better grip - that's simply not true - they provide better traction. Traction and grip are different things - traction can be though of as the ability to make best use of the available grip. The LSD improves traction by reducing the loss of traction thru one wheel spinning (it doesn't MAKE traction - just controls it better) - so when the rear is pushed to the point where traction is finally lost it's more likely to be lost on BOTH wheels with an LSD - at that point there is also zero grip.

The idea is to be thinking about what that LSD is all about and drive it accordingly - then it can be a good thing - but if you drive it with the wrong idea then chances are you'll end up in a ditch or wrapped round a tree wondering what the hell happened. Essentially, an LSD actually requires better throttle/power control than a std diff - which is the exact opposite of how many people perceive the situation.
 
#19 ·
Cobra said:
The LSD in my EL XR6 is gone. It doesn't have a tag on the diff plug but I know it's LSD. I spun the wheel and the other one stayed still and sort of moved a tiny bit then stopped spining. If it was a single spinner the other wheels would turn in the opposite direction. I did a burnout last night and there was only 1 big black mark. I was dissapointed. I don't know whether it could just be the diff oil, or if the clutch packs inside the diff are fudged. Maybe I'll have to get it welded up again. I want LSD!

IS the standard EL LSD 3.23 and the XR6 3.45?
Same here , i dont know if i have LSD (i suspect not) but one of my wheels stays still when turning the other one. Its a 3.27 with no other tag that i can see on it..

james
 
#20 ·
Does the modified version of the test here as quoted in the box below http://www-unix.oit.umass.edu/~tcroy/articles/differential.htm get WTB56 good diff testing seal of approval?

Determining which kind of differential you have
1. The vast majority of cars have an open differential as it is cheaper to manufacture, has no clutches to wear out, and is generally better-behaved. But posi units are out there, sold under titles of "Traction-lok", "Sure Grip", "Limited Slip" and the like. The concept is to place a clutch pack in-between the left and right end-gears, trying to force both wheels to turn the same speed at all times. Of course, to turn a corner, the wheel speeds must vary - thus the clutch-pack friction between the two end gears cannot be set extremely high or you'll suffer from hard steering (the car will want to continue in a straight line) and accelerated tire wear. OK, I've said enough. You get the picture.


2. Secure the car from rolling forwards or backwards and place the car in Park (if you have an automatic) or first gear (if you have a manual trans). Raise the rear end of the car so both rear tires are off the ground. Place jackstands under the car to safely support it.


3. Try to rotate the left wheel. You have "locked" the driveshaft from turning by placing the car in Park (or in gear), thus posi or no posi, the other wheel MUST turn the opposite direction at the same speed. If you have an open differential, this will take minimal effort. The wheels will rotate in opposite directions at the same speed. If you have a limited-slip differential though, the clutches don't like to let this happen so they'll fight you. A lot. A tight posi might take over 100 lb-ft to get the wheel to turn. By this point you'll know which procedure below you should use.
 
#21 ·
Didn't try the link, but the detail and test as quoted by You is the best description I've seen in print, and the most reliable test, short of a visual inspection. This test is better than the other torque resistance test as it removes transmission resistance from the equation, which can be deceptively high in an auto.
 
#22 ·
Mines not LSD and I can get both spinning rather easily on dry bitumen doing a stand still. But one wheel will dominate the other. The one with the most weight on it seems to spin the most in my car if I am the only one in the car the passenger one will spin but if I have someone in the passenger side its usually that one that spins the strongest. Very weird :|
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top