Slipping LSD

[superj]

now, with all the talk on this, when i open the site and see this thread at the top again, i keep thinking we are slipping lsd to drinks in the club.

 

[gw33gp]

My 89 STX had the clutch type LSD in the rear. I did a lot of off-road trips with it, and it was still working well when I sold it with almost 200K miles on it. I did the Ford recommended process of checking periodically and had a little loss in performance but was always in spec. I always used Ford LSD additive when I did a lube change.

I can say though the Torsen in my 02 FX4 is a much better LSD. I have 284K miles on it and it still works like new. No additive is required either, just 90W-150 gear lube.

 

[RonD]

For maintenance the gear driven Limited slip are 100% better, but they are not actually "limited slip", they are RPM matching above a certain point

They are OPEN type differentials until the axle RPMs get far enough apart, i.e. a slipping wheel/axle, then they come alive to match axle RPMs, transferring power/torque from the higher RPM axle to the lower RPM axle
Its a good differential setup but not limited slip

Clutch pack type are true "limited" slip
They are always Locked full time, the friction modifier allows the clutches to slip a little, so "limited slip", when cornering
So with fresh clutch packs both rear wheels should have equal power/torque in a straight line acceleration, instantly

 

[00t444e]

For maintenance the gear driven Limited slip are 100% better, but they are not actually "limited slip", they are RPM matching above a certain point

They are OPEN type differentials until the axle RPMs get far enough apart, i.e. a slipping wheel/axle, then they come alive to match axle RPMs, transferring power/torque from the higher RPM axle to the lower RPM axle
Its a good differential setup but not limited slip

Clutch pack type are true "limited" slip
They are always Locked full time, the friction modifier allows the clutches to slip a little, so "limited slip", when cornering
So with fresh clutch packs both rear wheels should have equal power/torque in a straight line acceleration, instantly

A gear driven limited slip is an actual limited slip just a better one.

https://www.eaton.com/us/en-us/catalog/differentials/eaton-detroit-truetrac-differential.html

"The Detroit Truetrac is a helical-gear style, limited-slip differential that maximizes wheel traction and enhances driving characteristics. Maintenance-free, it features smooth, automatic operation in forward and reverse. Its versatility makes Detroit Truetrac the ideal traction solution for almost any type of vehicle."

https://www.powertrax.com/product-info/powertrax-grip-pro-traction-system/

"The POWERTRAX® Grip Pro is the latest design in traction adding differential technology. It combines the smooth operation of a limited-slip differential, with the strength of a fully machined, forged steel case. "

Strengths & Advantages Of The Spartan Helical LSD

When you’re driving in a normal manner a positraction limited slip differential is pre-loaded and provides equal traction to both wheels.

www.randysworldwide.com

"Advantages Of Gear-Type Spartan Helical Limited Slip Differential

The Spartan Helical LSD limited slip differential provides smooth engagement, quiet operation, and requires no maintenance because there are no clutches to rebuild. The unit’s 10-pinion design has a strength advantage over an equivalently sized 6-pinion or 8-pinion gear-type unit because it has more points of contact and a greater surface contact area to deliver optimal load distribution. This LSD is built tough. The Spartan Helical LSD is a fully assembled unit featuring a forged 8620 grade steel case and stout 8620 alloy internals for superior durability."

 

[gw33gp]

A gear driven limited slip is an actual limited slip just a better one.

https://www.eaton.com/us/en-us/catalog/differentials/eaton-detroit-truetrac-differential.html

"The Detroit Truetrac is a helical-gear style, limited-slip differential that maximizes wheel traction and enhances driving characteristics. Maintenance-free, it features smooth, automatic operation in forward and reverse. Its versatility makes Detroit Truetrac the ideal traction solution for almost any type of vehicle."

https://www.powertrax.com/product-info/powertrax-grip-pro-traction-system/

"The POWERTRAX® Grip Pro is the latest design in traction adding differential technology. It combines the smooth operation of a limited-slip differential, with the strength of a fully machined, forged steel case. "

Strengths & Advantages Of The Spartan Helical LSD

When you’re driving in a normal manner a positraction limited slip differential is pre-loaded and provides equal traction to both wheels.

www.randysworldwide.com

"Advantages Of Gear-Type Spartan Helical Limited Slip Differential

The Spartan Helical LSD limited slip differential provides smooth engagement, quiet operation, and requires no maintenance because there are no clutches to rebuild. The unit’s 10-pinion design has a strength advantage over an equivalently sized 6-pinion or 8-pinion gear-type unit because it has more points of contact and a greater surface contact area to deliver optimal load distribution. This LSD is built tough. The Spartan Helical LSD is a fully assembled unit featuring a forged 8620 grade steel case and stout 8620 alloy internals for superior durability."

I have to agree. Both types (clutch and gear) serve the same function. Both transfer a percent of torque to the axle with least traction. Both want equal torque to each axle but accommodate that in a different way.

I have Torsen in my Ranger and a Truetrac in my 69 Fairlane Cobra. I find they are almost like a locker when accelerating. I have to be careful when accelerating around corners because the inside tire starts chirping. This never happens with a light throttle while going around a corner. The nice thing about Torsen or Truetrac is they have a higher torque bias to each axle than a clutch type typically has. This in combination with the locker affect makes for good off-road traction.

 

[RonD]

You guys believe all the ADS, "Just as good as", "better than", "checks in the mail"

Come on, a Locked differential or a "going to lock" differential those are the two choices

I will take the locked differential, lol

 

[gw33gp]

You guys believe all the ADS, "Just as good as", "better than", "checks in the mail"

Come on, a Locked differential or a "going to lock" differential those are the two choices

I will take the locked differential, lol

I have learned not to trust any advertisement if that what you are referring to (ADS). I do trust my experience though. Locked differentials have drawbacks and are not the optimum in drive axles.

I sometimes run a locked differential on my race car. On the track at speed, it works fine but pushing it around in the paddock is very difficult. This is due to the axle binding when turning. This is hard on the axles also when driving. I much rather use some type of LSD on my race car when off or on the track. A good LSD runs freer in corners too.

A selectable locker works well, but a good LSD like Torsen is still my preference for off-road. I believe it causes less strain on the axles.

I am not saying everyone should do what I do, but I know what works best for me.

 

[superj]

i like limited slip too, same reasons. locked sucks on road and eats tires too

 

[00t444e]

You guys believe all the ADS, "Just as good as", "better than", "checks in the mail"

Come on, a Locked differential or a "going to lock" differential those are the two choices

I will take the locked differential, lol

Full case auto lockers like the Detroit locker or Yukon Grizzly are the way to go for sure, or a lunchbox locker if you are on a budget.

 

[RonD]

Ford Trac lok is a full time Locked differential, as its natural state
It only "slips" because of the added Friction Modifier which makes it more street worthy

That is what I was referring to, VS the full time UNLOCKED(OPEN) gear driven lockers, like the Torsen

 

[00t444e]

The track lock is never locked, clutch plates putting pressure on spider gears is not locked, a locked differential would have no clutch plates.

 

[RonD]

Trac lok is always locked same as GMs posi-traction
Try not adding the Friction Modifier and see what happens, pops/jumps like crazy when going around a corner, lol, like a manual locker(when locked) or welding axles together

 

[gw33gp]

Ron, I don't know where you are getting your information, but that is not true. It is my understanding that limited slip differentials without the friction modifier get chatter in the clutches not tires hopping like you get with a locker or a welded differential.

An LSD is in essence locked when going straight but they are no longer locked when not going straight.

 

[RonD]

Yes, its the clutch disks making the noise because they are locked and can't "slip" smoothly without the friction modifier, but if you were on gravel/dirt a tire would slide/skip without the friction modifier, like a welded axle

They are locked full time, just have "limited" slip as needed on PAVED roads

 

[gw33gp]

You obviously do not understand how an LSD works. Look up the Ford specs how to test an LSD if it is functioning properly. You lift one wheel off the ground and check how much torque is required to make the lifted wheel turn. You will find it is way lower than it would take to make a loaded tire slip on dirt.

Until you do that, I am not discussing this anymore.

If you think an LSD is locked, you must also think if one tire is in the air, the LSD will still drive the other tire.