Topic: Rear Wheel Lugs Mismatched?

[S.P.]

I went in to rotate my tires this afternoon. When I went to install the rear two I noticed that the position of the lugs on the left rotor don't match with the right. Bear with me while I try to describe this:

When I went to put on the left rear tire I had 1 lug at top, two on the sides, and two at the bottom. But when I went to put on the right rear tire the pattern was upside down: two lugs at top, two on the sides, one at the bottom.

Since the rear rotors don't turn independently of each other like the front rotors do, how would I go about matching both sides up? Not a big issue obviously, but I would like to have all four tires uniform.

[TomatoSoup]

Your joking right? 

Just in case you're not - the left and right rear wheels *can* move independently - that what the differential is for.  If they didn't one wheel would skip every time you went round a corner!

[S.P.]

Unfortunately I'm not. Forgive my lack of mechanical know-how. Every time I went to turn one side the opposite wheel would also turn with it. It seemed strange to me at the time, but since I'm not two keen on the mechanics of the suspension I shrugged it off. Perhaps I was doing something wrong? Or maybe there's a problem with the diff?

[DaveOC]

You're not doing anything wrong, that is exactly how our differentials are supposed to work when they are up in the air. As a matter of fact, all differentials work that way.

[S.P.]

Oh, okay. That's a relief. When in the air both will spin simultaneously. Got it.
So If I only jack up one side, that tire will spin freely while the other remains planted?

[Gentleman Jack]

Oh, okay. That's a relief. When in the air both will spin simultaneously. Got it.
So If I only jack up one side, that tire will spin freely while the other remains planted?

Not if the emergency brake is on.  I only say that because I have done that to myself a few times...

GJ

[S.P.]

Lol. I made sure that the e-brake was off, and trans in neutral.
I'll fix my tires tomorrow then. Thanks everybody. I learned something new today!

[timlange3]

But the first time you take a turn, they will become unmatched, one wheel will go a further
distance than the other, so one will rotate more.  As for differential, since ours is a posi-trac,
both wheels should rotate in the same direction when they are both off the ground.  When one can turn 'freely' it will turn, but with effort due to the friction plates in the differential.  A non
posi-trac, one without friction plates, and both wheels off the ground, will have both wheels spin, but in opposite directions.  This video on the Prelinger Archives,
http://www.archive.org/details/Aroundth1937 will show you how a basic differential works.

Tim.

[SHiNY]

Not if the emergency brake is on.  I only say that because I have done that to myself a few times...

GJ

Dumbass!

[Sly Bob]

S.P. don't hesitate to ask any question here. There are many here that have likely wondered the same thing. Here's a good site that explains how a differential works.

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

Ya' know what they say, " The only dumb question is the one that doesn't get asked."

[Gentleman Jack]

Dumbass!

SP,

Please note, SHiNY's comments were directed at me, not at you.  I think you probably realized that, but I want to make sure you know you can ask anything here anytime.  SHiNY owed me one, and I think she delivered it with perfection.... 

GJ

[S.P.]

Gentleman Jack: Yes, I did see that she quoted you lol

Sly Bob & WanderingSol: I'll look into those articles to help me learn how our cars operate. Thankfully I kept tabs on this thread before running back out to 'fix' my tire lol

You guys are great help. I think I'll stop lurking for a while and get more involved here.

[Sol Asylum]

Dumbass!

Don't sugar coat it Shiny tell GJ what you really think.

[SHiNY]

Don't sugar coat it Shiny tell GJ what you really think.

Actually I do plenty of dumb stuff myself. I just try not to put it in writing for all to see.

S.P. - never referring to you. I don't know you well enough to be mean to you   Oh, and welcome!

[Sly Bob]

What amazes me is that the technology in a rear differential has been basically unchanged since it was first invented and yes, welcome S.P.!