Rams Trac Rite / Helical Gear Differential

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SyN

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For those that have always been curious as well as myself: what type of design does rams anti-slip differential use. Well I think I found my answer.

AAM 11.5 TracRite Helical Differential Case Available for Ram, Chevy Silverado and GMC Sierra Trucks | American Axle & Manufacturing | Aftermarket OE Parts

According to this design as I understand the operation of this anti-slip goes as follows: When one wheel begins to spin the pinion gears on that side are forced toward the Pinion brake shoes .
The Pinion brake shoes then cause friction drag on the opposite pinion gears and the side gear.
These friction forces transfer power to the opposite wheel. Once the frictional forces are overcome, differentiation will occur.
The torque will be continually biased by the frictional forces to the high traction wheel.

This set up consists of two side gears, 6 pinion gears and 6 Pinion brake shoes
 
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Cardhu

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Looks like a Detroit trutrac. Probably much more to read on those if your looking for more info.the brake shoe bit is new to me.

Its a good design as they seldom wear out and don't require LS modifier. Lots of times the DTT people run mineral instead of syn.

In the Jeep world like have had success running them with Brake locking differential setups as the brake on the slipping wheel ups the torque to the traction wheel. for the DTT thats 3.5- 4 :1 iirc. Our traction control will probably work similar.

Still waiting for Eaton to modify the current C9.25 for the ZF ring gear for when my clutch based LSD wears out.
 
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SyN

SyN

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I assume through reading that article.
Though it doesn’t concern me:—>This may not be the same design that is incorporated within the 1500?

I am so thankful for No clutch pack design Limited Slip as well as No BW44-44 transfer case.
 
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Cardhu

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I assume through reading that article.
Though it doesn’t concern me:—>This may not be the same design that is incorporated within the 1500?

I am so thankful for No clutch pack design Limited Slip as well as No BW44-44 transfer case.

rub it in why don't ya.

While i'd rather have a DTT, the BW44-44 is far worse option. I'm actually pretty happy with how my clutch based lsd works, as I also was with previous versions of a "posi" in a 94 gmc.

All of which work better than the traclok in previous generation 8.25's.
 
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SyN

SyN

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Cardhu: My 01 F250 7:3L PSD w/3:73 rearend had the clutch based LS.
At the 293K mile mark it was still performing flawlessly due to my very early install of a aftermarket cover w/drain & fill plugs to make Service very easy/fast/mess free. Total rearend service took me about 20 min every 45K miles.

This is one service that was taken very seriously. I depended on that LS many many instances & it never left me stranded. I feel due my focus on (U take care of it with good routine service. It will take care of U when you need it the most.

Neglect is what drastically creates a slow death for the clutch design.
I whole heartedly believe me using a Top Tier Very robust gear oil all those miles aided in the systems long life.

Come Spring: my New 11.5” AAM will be getting a aluminum finned cover with fill/drain plug for better cooling & easy/fast/mess free service & receive a combo of Red Line 75W-90/75W-140 gear oil.
The 68RFE will receive the same basic treatment & refilled with Fresh ATF.
(Both around the 10-20K mile mark)

The front diff will receive the same treatment but only around the 35K mile mark since it will only be used 3-4 times a year (During Snow/Ice storms). Our region receives more ice storms rather then snow.

My main goal with this New HD2500 (since it’s going to be called upon many times during the summer months to tow the families fifth wheel many miles safely).
Very Easy/Fast/Mess Free service for the Rear Diff/Transmission/Transfer Case/6.7L/Front Diff within a 2 hr time frame.

Fuel Filer/H2O separator are a different day.
This is a Ram I have intentions on keeping for 10-15 years.

I will be the Only One who does the routine services on this Ram.
This Ram is by far much more then just your average grocery getter —> Daily Driver.

I don’t have any Nasty bad habits that actually harm my body so this is by far NOT a waste of $$$. Compared to those I was referring so that is a worthless argument.
 
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WilliamS

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My last ram 1500 had a clutch pack and it chattered and bound its entire life regardless of service, fluid, or replacement. Im actually happy with my smooth and quite open rear differential compared to my previous truck. Im hoping around tax time to add a torsen based as my last few cars and trucks had them and they were amazing in every situation and never had an issue.
 
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VernDiesel

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I have a 14 Big Horn 1500 EcoDiesel that I tow TTs with commercially. 370,000 miles. After 100k warranty I've changed all fluids myself. Trans, front & rear diferential and transfer case. Rear LSD is I believe Torsten and itself always worked quiet & smooth with quick engagement.

Routine service at 300k I noticed the vent tube was torn. Rear had never been in water & is not used "off road." Never the less it was full of rusty water mixed fluid. Disappointed I figured it's doomed although the rear was still quiet & smooth. I changed it again at about 310k hoping to Dodge a bullit. Fluid looked good & operation was still quiet & smooth.

By the service at 350k it was still operationally smooth but making noise. You guessed it the fluid was full of metal. I located & acquired another identical rear out of a 2016 (3.92 LSD) scheduled to change it the next day at a buddys shop the ring gear broke at 358k.

Zip tie up your vent tube & pop the cap off & dip your finger in it for a periodic inspection. Might save you a chunk of money.
 
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SyN

SyN

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Vern: Thank you for sharing your personal experience.
 

ColdCase

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Unless they changed the 2500-3500 LS rear ends since 2016, if you have one rear wheel in the air, they will just sit there and spin that wheel. No power is supplied to the other. It needs some resistance on each wheel to work. Someone posted a pretty good description here awhile ago. They were quiet and worked well otherwise if I recall, no chatter. 1500s have had cone based LSD for years with some preload, I think, PW excepted.
 
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JPT

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Unless they changed the 2500-3500 LS rear ends since 2016, if you have one rear wheel in the air, they will just sit there and spin that wheel. No power is supplied to the other. It needs some resistance on each wheel to work. Someone posted a pretty good description here awhile ago. They were quiet and worked well otherwise if I recall, no chatter. 1500s have had clutch based LSD for years, PW excepted.

This is how all limited slips work. You can feather the brakes to get traction again. If you want traction with one wheel in the air, you need a locker.
 

ColdCase

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Most mechanical clutch type LSDs (like the one in the 1500) just need a difference between the two axle sides to pump up the hydraulics which compresses the clutch pack. So with a wheel off the ground, there is power getting to the wheel with traction. There are a few YouTube videos of folks accidentally launching their cars when they had one wheel jacked up... Lockers are more efficient, however. Feathering brakes usually is used when starting out, to try to stop wheel spin before LSDs can do their thing. For the gear type, this may lock them in enough to get you moving. So its not a big deal on the road. A cone typ typically has some preload so it wont free wheel.

In an ELSD, the traction computer see a difference in axle rotation and compresses the clutch pack. Also, because its not relying on wheel spin to compress the clutch, it can lock up the diff in anticipation, like when you mash the throttle or driving slow in a low range rock traction mode. :)
 
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JPT

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Most mechanical clutch type LSDs (like the one in the 1500) just need a difference between the two axle sides to pump up the hydraulics which compresses the clutch pack. So with a wheel off the ground, there is power getting to the wheel with traction. There are a few YouTube videos of folks accidentally launching their cars when they had one wheel jacked up... Lockers are more efficient, however. Feathering brakes usually is used when starting out, to try to stop wheel spin before LSDs can do their thing. For the gear type, this may lock them in enough to get you moving. So its not a big deal on the road.

In an ELSD, the traction computer see a difference in axle rotation and compresses the clutch pack. Also, because its not relying on wheel spin to compress the clutch, it can lock up the diff in anticipation, like when you mash the throttle or driving slow in a low range rock traction mode. :)

The bold part is true up until one wheel has no traction at all (one free wheel in the air). Once there is 0 traction on one side only a small portion of the power goes to the wheel with traction. Typically not enough to continue moving. This is true for a clutch style, or a mechanical style, I do not know much about electrical limited slips, so I can't speak from experience.

My experience is from setting up axles myself (gears, and carriers), rock crawling a jeep with a 4:1 transfer case. I have installed clutch driven LSD, Gear driven LSD, Lunchbox lockers, Detroit lockers and finally (should have from the start) ARB lockers.
 

ColdCase

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There are modern clutch type LSDs and cone type LSDs. The cone type needed some back pressure although I think they had a preload so they wouldn't completely free wheel like the gear type. The new clutch pack type does not need back pressure, it locks in with as much torque as its designed to provide. But then I only have experience building diffs for street, mud, ice, snow. When I get a chance I'll find reference material.
 
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