UNICYCLE Plymouth???

[Powerhouse]

So..I has a question....

HOW does a rear end work?

With the rear end jacked up and both rear wheels of the ground, If I turn my drive shaft .... only the drivers side tire turns. Is that normal? Or should they both turn??

[Don Coatney]

Try this. Spin the wheel that is not turning and see what happens. Most likley the opposite wheel will spin backwards. All is well with your differential.

[Merle Coggins]

Maybe this will help you understand how your differential works.

http://auto.howstuffworks.com/differential.htm

Merle

[Powerhouse]

Ahhhh....I was hoping it wasn't busted somehow. I kinda thought both wheels would turn by the differential. So all the engine power goes to one wheel? wow...

[Merle Coggins]

So all the engine power goes to one wheel? wow...

Not exactly... Power is equally divided between the two wheels. If one happens to have less tractive effort than the other, then all power can be directed to that one with the less traction.

Also, when turning corners, the outside wheel must travel farther due to it's larger arched path. So in this situation the differential will split the difference and allow the wheels to turn at slightly different speeds but still provide power to each.

With both wheels in the air, and turning the drive shaft, it's possible to have only one wheel turning. If there is more drag from the brakes or bearings on one wheel, the differential can reroute all rotation to the other wheel. If you hold the wheel that turns, the other wheel should then turn.

As Don mentioned, if you were to hold the drive shaft and rotate one wheel, you'll find that the other wheel will rotate in the opposite direction. This is due to the arrangement of the gears within the differential. This is all normal.

Merle

[Reg Evans]

Myth or Fact

I heard many years ago that on our rear ends you couldn't determine the gear ratio by jacking the car up and turning a wheel around 1 revolution while counting the revolutions of the drive shaft.

What I heard was that you needed to slowly roll the vehicle on the ground,one wheel revolution, while counting the drive shaft revs.

Maybe this is so for some differentials and not others. I don't know for sure.

Anybody?

[Merle Coggins]

There is typically a difference in size between the spider (cross) gears and the side gears in a differential. If both wheels are turning the same speed there is no movement of the spider and side gears, so the diff ring gear is essentially 1:1 with the axle shafts. When the differential is differentiating, due to each wheel turning at different rates, then there becomes another gear ratio change between the spider gears and side gears. In other words, at this time the ring gear to axle shaft is no longer 1:1 ratio. Without knowing what the tooth count is on the spider gears and side gears it's difficult to know what the ratio will be with only one wheel turning.

Merle

[Norm's Coupe]

All that you guys said, ok. However, I use an easier method of determining the ratio of the rearend gears. I scrape the crud off the housing and look for the stamp in the casting to tell me. :D

[Reg Evans]

Well Norm.... There have been a few times when I've transferred all the crap from my rear end to my face and I still couldn't find what I was looking for.

Oh God !.....Did I say That.

[Don Coatney]

There is typically a difference in size between the spider (cross) gears and the side gears in a differential. If both wheels are turning the same speed there is no movement of the spider and side gears, so the diff ring gear is essentially 1:1 with the axle shafts. When the differential is differentiating, due to each wheel turning at different rates, then there becomes another gear ratio change between the spider gears and side gears. In other words, at this time the ring gear to axle shaft is no longer 1:1 ratio. Without knowing what the tooth count is on the spider gears and side gears it's difficult to know what the ratio will be with only one wheel turning.

Merle

Merle;

You said what my thoughts were but I could not put my thoughts into verbage. Thanks for posting the facts.

[Norm's Coupe]

Well Norm.... There have been a few times when I've transferred all the crap from my rear end to my face and I still couldn't find what I was looking for.

Oh God !.....Did I say That.

Yep, you said that alright. For some reason it didn't come out just right. However, there are the times when someone may have put different gears in the same rearend too. In which case the stamp wouldn't mean anything.

[Niel Hoback]

If you have both rears off the ground and turn one side, the other side will turn the opposite direction IF you have the trans in gear, engine off, or in some other way, hold the drive shaft from turning.

When the trans is in neutral, the driveshaft will turn instead of the other wheel.

[Don Coatney]

Well Norm.... There have been a few times when

I've transferred all the crap from my rear end to my face and I still couldn't

find what I was looking for.

Oh God !.....Did I say That.

Reg;

I believe this picture is the best example of the condition known as $hit faced:D

Yep' date=' you said that alright. For some reason it

didn't come out just right. However, there are the times when someone

may have put different gears in the same rearend too. In which case the

stamp wouldn't mean anything.[/quote']

That is the case in my differential. I replaced the original gears with 3.55/1

ratio gears.