Auto gurus: what is the rear differential?

[axelfox]

I went to get an oil change for my 98 Toyota RAV 4 and the guy said I needed maintenance of the rear differential.

What exactly is the/a rear differential? How would I maintain it myself? The guy said that the fluid was dark and that it should be a honey color.

thanks

 

[Argo]

Differential is a slope of a curve at a given point. So draw a line through the rear of the car and its slope is rear differential.

 

[Anubis]

Originally posted by: Argo
Differential is a slope of a curve at a given point. So draw a line through the rear of the car and its slope is rear differential.

LMAO

 

[ElFenix]

is it 4wd?

 

[Nocturnal]

I'm pretty sure he's talking about the rear axle?

 

[Heisenberg]

A differential splits the power from the driveshaft and sends it to the wheels via the axles. I assume since you said the rear one your RAV 4 is four wheel drive - 4WD's have two, one front, one rear.

 

[ElFenix]

Originally posted by: Heisenberg
A differential splits the power from the driveshaft and sends it to the wheels via the axles. I assume since you said the rear one your RAV 4 is four wheel drive - 4WD's have two, one front, one rear.

3 usually

 

[Heisenberg]

Originally posted by: ElFenix

Originally posted by: Heisenberg
A differential splits the power from the driveshaft and sends it to the wheels via the axles. I assume since you said the rear one your RAV 4 is four wheel drive - 4WD's have two, one front, one rear.

3 usually

2 differential's, 1 transfer case

 

[Peetoeng]

Originally posted by: ElFenix

Originally posted by: Heisenberg
A differential splits the power from the driveshaft and sends it to the wheels via the axles. I assume since you said the rear one your RAV 4 is four wheel drive - 4WD's have two, one front, one rear.

3 usually

2 in front for better steering in slipery surface?

 

[Tominator]

The differential allows the opposing wheels to turn at different speeds. A four wheel drive normally has two of these, but many autos are front wheel drive assemblys with the back axle drive assembly added as an after thought.

If this was the case with the RAV 4, the front differential is serviced at the time the transmission is as they are the same assembly. The rear differential needs a service at the recommended interval. That is found in the owner's manual. It contains a lubricant than is drained and replaced. If it is due, the service should run less than $20.

There is no need to get it serviced at a more frequent interval than recommended in your owner's manual.

 

[ElFenix]

Originally posted by: Peetoeng

Originally posted by: ElFenix

Originally posted by: Heisenberg
A differential splits the power from the driveshaft and sends it to the wheels via the axles. I assume since you said the rear one your RAV 4 is four wheel drive - 4WD's have two, one front, one rear.

3 usually

2 in front for better steering in slipery surface?

never heard of a center diff? maybe its awd i'm thinking of

 

[Antoneo]

What is the purpose of a "limited slip differential" if I may ask since it sorta goes inline with this thread?

 

[HappyPuppy]

It would do no harm to change the lubricant in the diffenential, but it probably isn't necessary. Check your owner's manual or call a Toyota service department.

 

[CraigRT]

ever seen a big jacked up pickup truck?
u know that round ball looking thing in the middle at the back in the middle of the axle?
that's your differential.

power goes in through driveshaft, power comes out to rear axles to wheels.

i think you can figure out the rest.

 

[ElFenix]

Originally posted by: Antoneo
What is the purpose of a "limited slip differential" if I may ask since it sorta goes inline with this thread?

so that your car doesn't fsck the hell up when drag racing.

 

[edfcmc]

Park your vehicle and look at from the rear and bottom. Look for a metal housing that connects to the rear wheels and at the center of this metal body is a large oval shape container that should be surrounded by 10 or 20 bolts.

REAR DIFFERNTIAL GEAR
|

|||=======0=========|||

^---------------------------------^
|-----------------------------------|
Tire------------------------------Tire

The center oval shapped thing contains the real differential gears.. That is the part that is normally serviced. There should be a metal plate that covers the housing and the metal plate is held in with many bolts and a gasket in between. Somewhere on the housing itself, is a square filler plug that you can open up and stick your finger in it to check the the Gear oil. If you housing isnt leaking, then to service the differential is easy. You unscrew the square filler plug, pump out as much of the old gear oil, and then fill up the rear differntial with the appropriate gear oil for your vehicle. Then screw back the filler plug....

If you are going to attempt to do this, shell out the money for the Haynes or Chilton Manual for your vehicle and it will tell you the appropriate method for servicing your rear differential but it shouldnt differ too much from I stated.

 

[Heisenberg]

Originally posted by: Antoneo
What is the purpose of a "limited slip differential" if I may ask since it sorta goes inline with this thread?

A normal open differential will allow one wheel to spin and one to stop completely. This is bad because if the spinning wheel has no traction, you're going to get stuck. A limited-slip only allows so much of this before locking and sending the power equally to both wheels.

EDIT: ElFenix - I've never heard of a central diff. in a standard 4WD. They always have two diffs. and a transfer casing. Maybe some of the newer AWD systems have them. There's so many variants and hybrids of 4WD and AWD I lose track.

 

[Zenmervolt]

Originally posted by: Heisenberg

Originally posted by: Antoneo
What is the purpose of a "limited slip differential" if I may ask since it sorta goes inline with this thread?

A normal open differential will allow one wheel to spin and one to stop completely. This is bad because if the spinning wheel has no traction, you're going to get stuck. A limited-slip only allows so much of this before locking and sending the power equally to both wheels.

EDIT: ElFenix - I've never heard of a central diff. in a standard 4WD. They always have two diffs. and a transfer casing. Maybe some of the newer AWD systems have them. There's so many variants and hybrids of 4WD and AWD I lose track.

AWD systems typically use a Viscous Coupling to link the front and rear driveshafts, this allows them to drive only one axle until there is a speed differential between the front and rear driveshafts, then the VC begins to transfer torque to the other driveshaft until the speed differential is eliminated or the VC reaches maximum lock. A lot of times the VC is referred to as the "center differential".

ZV

 

[Evadman]

Originally posted by: Antoneo
What is the purpose of a "limited slip differential" if I may ask since it sorta goes inline with this thread?

The main type of differential is an "open" diff. This means that power is sent to both wheels, but if one looses traction, all the power will go to that wheel, and be wasted. This is bad.

Then there are limited slip diffs. These use clutch packs, springs, etc to make sure that both wheels get power, but the "limited slip" bart will let the wheels rotate at different speeds when you turn a corner. ( the inside wheel turns less than the outside one )

Then there are lockers. these physicly lock the 2 wheels together, and the power is split 50/50. There is no slipping whatsoever. They can be disengaged for turns. In this one, you can see the teath around the outside edges that come apart for turns.

Then the racing spool. this locks the wheels together no matter what, turn or not. Handling = suck anywhere except the drag strip or off road. Only insane people use these on road This pic is actually a mini-spool, not a full spool. But they do the same thing.Full Spool

There are many variations, and this is hugely oversimplified, but you should get the idea.

This is a pic of a 12 bolt Differential. from GM.
Inside a Diff Dana 44 I think. (anglefire pic. cut and paste into address bar to see.)

 

[Bignate603]

Differentials

Read that, it explains what it is, and how it works.

 

[Antoneo]

Then there are lockers. these physicly lock the 2 wheels together, and the power is split 50/50. There is no slipping whatsoever. They can be disengaged for turns. In this one, you can see the teath around the outside edges that come apart for turns.

These were the ones used in early versions of quattro by Audi correct?

 

[KenGr]

I believe some of the more advanced 4WDs (like the high end Audi's) have an electronic center torque distribution differential. With full time 4WD, you will get better driving under normal conditions if the power goes to the rear wheels. Under slick conditions, it electronically senses slippage and sends the power where it belongs. I thiink the newer Jeep Quadra-trac systems may also do this.

 

[iamwiz82]

Originally posted by: Antoneo

Then there are lockers. these physicly lock the 2 wheels together, and the power is split 50/50. There is no slipping whatsoever. They can be disengaged for turns. In this one, you can see the teath around the outside edges that come apart for turns.

These were the ones used in early versions of quattro by Audi correct?

No, Audi's had Torsens, i believe. they shared it with the Hummer

I have a locker in my Jeep and the most ungodly noises can be made while getting on the gas during a turn.

EDIT: This is not what you want to see when you open up your diff. . Thats

 

[B00ne]

Originally posted by: Heisenberg

Originally posted by: Antoneo
What is the purpose of a "limited slip differential" if I may ask since it sorta goes inline with this thread?

A normal open differential will allow one wheel to spin and one to stop completely. This is bad because if the spinning wheel has no traction, you're going to get stuck. A limited-slip only allows so much of this before locking and sending the power equally to both wheels.

EDIT: ElFenix - I've never heard of a central diff. in a standard 4WD. They always have two diffs. and a transfer casing. Maybe some of the newer AWD systems have them. There's so many variants and hybrids of 4WD and AWD I lose track.

I have heard of the center differential - I think distributes the power between fromt and rear - could be wrong tho

 

[LAUST]

Originally posted by: Evadman

Originally posted by: Antoneo
What is the purpose of a "limited slip differential" if I may ask since it sorta goes inline with this thread?

The main type of differential is an "open" diff. This means that power is sent to both wheels, but if one looses traction, all the power will go to that wheel, and be wasted. This is bad.

Then there are limited slip diffs. These use clutch packs, springs, etc to make sure that both wheels get power, but the "limited slip" bart will let the wheels rotate at different speeds when you turn a corner. ( the inside wheel turns less than the outside one )

Then there are lockers. these physicly lock the 2 wheels together, and the power is split 50/50. There is no slipping whatsoever. They can be disengaged for turns. In this one, you can see the teath around the outside edges that come apart for turns.

Then the racing spool. this locks the wheels together no matter what, turn or not. Handling = suck anywhere except the drag strip or off road. Only insane people use these on road This pic is actually a mini-spool, not a full spool. But they do the same thing.Full Spool

There are many variations, and this is hugely oversimplified, but you should get the idea.

This is a pic of a 12 bolt Differential. from GM.
Inside a Diff Dana 44 I think. (anglefire pic. cut and paste into address bar to see.)