TrueTrac/Torsen vs OEM Open Diffs

[MarkinWMich]

I tried this in the "Off Roading" section and didn't get much traffic.

Application: 2006 SR5 w/ V6 4WD w/factory traction control system. Daily driver. Occasional light towing (less than 2000lbs). Snow, ice, sand, & mud. No rock crawling or hill climbs, except for sand dunes.

130K on the odometer. Looking to do a regear with 4.56's or 4.88's. Not a lot of highway driving, but when I do, it's under 70mph. Spends most of the time around town, under 45mph. Looking for some good, low-end torque via the new gears.

The OEM open differentials have provided good service, but it certainly has it's limitations in deep snow and on the dunes. Looking for a potential improvement in that area.

I like the Eaton TrueTrac/Torsen differential, I have one in my '89 Mustang (modified for autocross and roadracing), so I am familiar with it's potential "quirks" with the rear end grabbing and kicking out the rear end around corners...but that's in a high-powered vehicle without traction control.

This and other forums have suggested NOT using the TrueTrac/Torsen differentials, especially in the front, and especially in snowy, icy conditions. This is a consistent statement made by pre-4th gen owners.

What are people's thoughts on using TrueTrac/Torsen differentials combined with the 4th Gen's factory traction control systems?

 

[JEL]

I am interested in this as well, I go up into the mountains often and there is always DEEP sloppy snow up there after a long day of skiing, never had a problem but a true LSD would be awesome "just in case." I can understand why not having one in front is suggested often, I suspect it would create some odd handling characteristics, but a mechanical LSD in back could be a cool idea.

My parents have a '02 Tundra TRD 4x4 with the factory Toyota LSD and it's GREAT in the snow, even the deep stuff (as long as they have sand bags in the back), it's NEVER been stuck and may do even better than my 3rd gen in the snow; hell most of the time it can get up really steep hills (with good tires of course) in 2 wheel drive where even Audis and Lesbaru Outbacks are starting to struggle.

 

[RPS13]

I've never heard a torsen diff described as "grabbing" the rear end. By their nature they offer progressive locking based on how much torque is being input.


As far as off roading with one, I wouldn't think it'd work very well. A torsen will act like an open diff on very low grip surfaces. Basically if one wheel has very low traction, all power will go to it. It can only bias as much torque as the least gripping wheel can transfer. Good on the (dry) road, but bad in low grip situations.

 

[Jeremy556]

I'd just put an ARB in the rear.

 

[DC runner]

Deep mud, ARB would be great. As for sand dunes, isn't that more about floating than spinning?

I could be wrong, but I always thought the key to moving well through sand was in not getting bogged down. Once you start spinning and digging in, you get stuck. Hence why dune buggies have those huge ballon tires that displace weight over a large area and basically "float" over the sand.

At least, every time I have driven on the sand that is how I operate. Air down to as low as you can and just float. Heck, 4wd isn't usually needed. See tons of 2wd with air down tires that do fine. Usually once someone gets stuck, spinning is the last thing you want.

 

[BlackWorksInc]

I suppose a Torsen Diff wouldn't be bad? But unless its lockable I wouldn't really want to run it in the front or rear.

 

[MarkinWMich]

I've never heard a torsen diff described as "grabbing" the rear end.

You accelerate out of a corner in a 2700lb car with over 550 hp to the wheels and an "old school" ultra stiff suspension, throw it into a drift with the inside rear lifting, believe me, you'll understand what grabbing is as you start to straighten out the wheel. It can be fun if you are prepared for it. It'll leave a brown stain in your shorts if you aren't.

 

[MarkinWMich]

Deep mud, ARB would be great. As for sand dunes, isn't that more about floating than spinning?

I could be wrong, but I always thought the key to moving well through sand was in not getting bogged down. Once you start spinning and digging in, you get stuck. Hence why dune buggies have those huge ballon tires that displace weight over a large area and basically "float" over the sand.

At least, every time I have driven on the sand that is how I operate. Air down to as low as you can and just float. Heck, 4wd isn't usually needed. See tons of 2wd with air down tires that do fine. Usually once someone gets stuck, spinning is the last thing you want.

Exactly. You can check out the YouTube vids on Silver Lake State Park. Amazing machines, but sometimes stock vehicles with street radials run up those dunes much faster and better than a highly modded vehicles. Tire tread, width, and pressure do play an important role.

However, that said, if all your power is going to a single front and/or rear, you are at a higher risk of digging in and getting stuck. If your vehicle is traction limited, then the only way to make a run up a dune hill is as fast as you can, but that beats the #%^* out of your vehicle as you are bouncing over those ruts and undulations in the sand. If all 4 wheels are getting power, then you can approach those dune hills at a slower, safer speed. In which case, running front and rear lockers may be best.

 

[nivlak]

I have been looking at a locker myself and since money is an issue I am looking at an automatic. Either a Yukon or detroit...here is a link where a guy has an automatic in rear and selectable up front.

I am curious though the whole snow issue but maybe the cautioning is for people who do not have snow driving experience....?

http://www.toyota-4runner.org/4th-gen-t4rs/159351-2005-v6-rear-locker.html

 

[RPS13]

You accelerate out of a corner in a 2700lb car with over 550 hp to the wheels and an "old school" ultra stiff suspension, throw it into a drift with the inside rear lifting, believe me, you'll understand what grabbing is as you start to straighten out the wheel. It can be fun if you are prepared for it. It'll leave a brown stain in your shorts if you aren't.

I've been in faster cars with torsens, none had what I'd call "bad" habits. They offer the most progressive biasing of all mechanical LSD types due to their design.


The "grabbing" you're feeling is more likely lots of unloaded wheel spin causing understeer, then as you get traction on the inner rear wheel it biases over and jerks you to a new rear slip angle. Generally it's a sign you have insufficient droop travel in the rear and possibly a lack of front roll stiffness compared to the rear.