Limited slip differential

Depends on the kind of driving you'll do. A normal (or 'open') diff gives all the torque to the wheel with the least traction. So, say you have one rear wheel in pavement and the other side in mud, the wheel in the mud will spin and spin and the wheel on pavement won't budge. An LSD prevents that from happening, transfering more torque to the side that has the most traction.

has great explanations of how all this goes on.

In 2WD, a LS diff can create some fairly undesirable handling problems on ice or mud. In 4WD, it isn't so bad, but can still be a problem in the wrong hands. So it really depends on the sort of driving you do most of, and the amount of finesse you are capable of contributing to the handling of the truck. A push-button locker has a lot more value.

if you are looking for some extra traction on occasional ice or gravel then go for it ... It will wear out over time.

You will be better off getting the electric locker from toyota

Don't all toyota 4x4s come with rear limited slip diffs?

Scotty schrieb:

Lucky us they don't!

Axel

Must have been lucky with the ones that Ive owned as all 5 have had LSDs.

Absolutely yes, there is a huge benefit. Get the limited slip and don't look back. Run, don't walk, to the sign up desk and get yours today.

Without limited slip (if you can get it in both axles, this is even better), you get drive torque to both tires on the same axle ONLY WHEN THERE IS GOOD TRACTION. When traction takes a bye under one tire, the Open Differential (this is what they call it when there isn't a limited slip) will divert all engine torque to the tire that hasn't got any grip, the limited slip will send torque to the tire that still has a chance of moving the car/truck forward.

Get the limited slip, and don't give it a second thought.

Another option is to get the TRD, which has a locker. The locker physically locks the left and right halves of the axle together, and this means both tires get full torque no matter what the traction is doing. One last option is the TRD with the Limited Slip. This is the most costly, but well worth it - especially if you intend to offroad.

I'm not sure, but I don't think they do. Limited Slip is an option on most

4x4s. I suppose it could be standard on the high end models, Land Cruiser and such, but most of us mortals have to order it.

I can't imagine why anybody interested in a 4x4 would not want limited slip. Snow and ice present special driving challenges, and dealing with these challenges with an open diff and limited slip certainly can demand differing approaches to driving style, I just can't imagine how anybody can take the position that they are LUCKY they don't have limited slip. Maybe they are crappy offroaders and have no business driving a 4x4.

I installed a LSD in my '01 Tundra so it would have better traction on roads where I wasn't using 4wd, in the rain, for example. Also, I've been parked in deep snow and had just the two wheels on one side spin. With rear LSD, I'd have the rear two pulling almost equally.

Ken

| >> Don't all toyota 4x4s come with rear limited slip diffs? | >

| > Lucky us they don't! | >

| > Axel | >

| >

| | I can't imagine why anybody interested in a 4x4 would not want limited slip. | Snow and ice present special driving challenges, and dealing with these | challenges with an open diff and limited slip certainly can demand differing | approaches to driving style, I just can't imagine how anybody can take the | position that they are LUCKY they don't have limited slip. Maybe they are | crappy offroaders and have no business driving a 4x4. | | |

If you ever get on a solid iced high cambered road you may discover one of the downsides to a posi-trac or limited slip dif. With all four wheels spinning on ice the vehicle will slide off of the road. Not too much of a problem if you just slide into a bar ditch. A big problem if you slide sideways off of a cliff. Also, with a limited slip it makes it hard to turn in the soup unless you are in well defined ruts. Testimony from one who has been there over 30 years ago.

If you have an open differential, the torque applied to either rear wheel is limited to the the torque that breaks one of the rear wheels loose. If you are on a consistent surface (level, equally slippery on both sides, the truck is uniformly loaded, etc.) this is not a disadvantage. The two rear wheel will break away with approximately the same torque applied, so you aren't loosing much. However, if you are on an inconsistent surface (one side slippery, or lower, or have an unevenly loaded truck), the maximum torque to either wheel is still limited to the torque that can be applied to the wheel that willl break away first, which, in this case, can be a very low value. A limited slip differential locks the two axles together so that the two axles spin together instead of letting the wheel on the slippery (or lightly loaded) side spin freely. In this situation the torque that can be applied to either wheel is no longer limited to the torque than can be applied to the wheel with the least traction. This is good when one wheel has good traction. However, if both wheels are on a slippery surface, it is very easy to break both wheels loose if you have a limited slip. This is bad becasue once both wheels have broken loose, they no longer will maintain the lateral position of the vehicle. This means the rear axle will most likely kick out. If you are on any sort of angled surface, the rear end will slide down the hill while the wheels are spinning (and once started sliding might not stop, even if you quit applying power). If you have 4wd drive, the front wheels will tend to pull you along and keep your truck pointed in the right direction (probably yawed somwhat). If you only have two wheel drive with a limited slip, you are likely to find you rear end slidding down the hill and end up with the front end pointing up the hill and be worse off than when you started.

The worst thing you can have on a really slippery surface like glare ice is 2WD, limited slip, and traction control that works by limiting engine power (and doesn't use selective application of the brakes).

A manually lockable differential is the best idea. You can select when you lock the rear axle and can therefore avoid loosing lateral location of the rear axle. However, on a consistent slippery surface, this is not going to save you. I have been driving farm tractors for most of my life. All of the tractors we have purchased in the last 40 years have included a manually operated rear differential lock. I have never once had this feature be of any use in a muddy field.

Traction control that selectively operates brakes on opposite sides of the vehicle while modulating the throttle is also probably a useful feature. I've never driven a vehicle with this feature. Some high end tractors actually include ground speed radar and modulate power to limit slip to the most desirable value.

I see that Toyota is playing up traction control for the Tundra. Anyone have details of how this sytem works? The TV commercials seems stupid, hopefully the actual system is a good one.

Ed

"Ed White" sez:

The missus' Sequoia has it and I don't like it. It may be a good system for those who don't have a feel for their vehicle (like the missus - she's a fine woman but definitely not a "driver"). If you do have a feel for your vehicle, it just gets in the way. I'm glad my Tundra doesn't have it or the Vehicle Stability Control (VSC).

Good drivin' to ya, VLJ

TRD sells one that's manufactured by Eaton, I didn't think any of the trucks had them - they usually push the electric locker withthe TRD package. I suppose you could have the dealer buy and install the third member Eaton from TRD though.

I have a 98 Tacoma and I bought the Eaton/TRD LS when it first came out - I think it was 2001 but I can't remember. Anyway, at the time it was $450 with exchange - complete third member. I don't think the price has changed much.

I love it. Sure a locker is better in some circumstances but for a daily driver that spends most of its time on pavement and then the rest in sand and dirt it's perfect - perfect for me.

Definitely - you havbe to be aware of the traction of the surface you're on and what your vehicle is doing at any given moment. No ice or snow here in Houston but plenty of rain and it can get squirrely if you're not careful on that - I can only imagine the finesse necessary on ice and snow.

Have a Detroit in the front/rear of my toyota pickup, open front/rear in my FJ6x.

It depends on how you drive and where you go. Limited slips are for pavement and dirt roads.

Serious 4x4 trails and rock crawling is Detroit/ARB time.

Salto: Serious question - Would you drop your 90-year-old grandmother in the front seat of your truck equipped with Detroit Lockers at both ends and ask her to run to the grocery store?

From my observations a Detroit Locker in a street driven vehicle can be a pistol - as in, deadly in the hands of an inexperienced driver. They lock up like a solid spool whenever you get on the gas halfway hard, even if you are turning a corner at the time, which can add up to some "severe handling and directional control issues"...

"When they're good they're very very good, but when they're bad they're rotten."

I've watched a Yahoo in their jacked-up-to-the-sky truck with a Locker in the rear go around a paved city corner and tap the gas - suddenly the tires start squealing and the rear end wants to go around that corner like it's square, and you could /very/ easily lose control if you weren't expecting it.

Detroit Locker differentials are truly For Off Road Use Only by experienced drivers, and I would be shocked if you can buy them as factory install on any car or truck without filling out a liability release form first....

If you want something in a Limited Slip that is still street drivable, you either use a clutch type LSD (available from Toyota), the ARB Air-Locker, or the Gleason Torsen worm-gear LSD. They either shift themselves into service gradually so you are always in control, or with the Air-Locker you only engage it when you really need it.

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Mind you all my previous have been Hilux based (Southern Hemisphere models, Tacoma I think that they are called in the US)

The 22R power curve of the in the pickup should not cause most of the drivability problems that you listed. The front hubs permit the locker to be disengaged. The front Detroit has been modified so that the ramp-up is different (mechanical engineer, ms level).

I do know that traditional limited slips will not function when one of the locked wheels is not bearing a load.

Usage of any differential traction device can be dangerous in the hands of a bad to poor driver ! If one cannot learn to drive with a traction device they should use tire chains.

Without added traction controls and lockers with proper tires in 2wd, I have driven to all but the most hard core remote locations in Colorado. In the majority of situations, skill, experience and knowing your vehicle really matter the most.

Lockers and traction control should only be considered as travel aids, not something that you depend on. They do break and they do fail.

In Colorado when its bad outside, its safer to stay home with the large number of bad to poor drivers on the roads. A large number of the drivers cannot remember driving on snow from one year to the next, and many have never driven on snow or ice in their lives.

My mother and mother-in-law both in their 80's travel around in my vehicles. They enjoy the fully locked Toyota rock-crawler and where it can go with the tsl swampers. The rock-crawler is my daily driver. The stock 85 Toyota 4x4 pickup is for hauling gear !

What can I say, opinions on traction devices vary as much as the number/types of them available and types of vehicles they are used in and for.