Which rear end gets more abuse? Open or Sure Grip?

[Super Blue 72]

Just a weird question I was thinking about:

What gets more abuse when you spin the tires?  An open rear end (one legger) or a Sure Grip rear end?

This is an 8 3/4 unit.

The reason why I ask (I'm no rear end expert, well, maybe except for women  ) but when I used to work for Acura years ago, on the '86-'90 Legends we used to have a lot of tranny problems.  Moreso in the winter. 

This usually stemmed from people spinning thier tires in the snow and then the diffeential gears would heat up then somehow the bolt holding the differential shaft would shear off and send the differential shaft flying.  Worse case made a 1" diameter hole in the casing.

Would this apply to the 8 3/4 rear ends too?  Would an open rear end suffer more heat and wear vs a Sure Grip under abuse?   

Thanks for any replies!

[tactransman]

I say open rear end...when you are spinning one wheel , the spider gears in the diff are rotating a lot (more wear/more heat) and  "sure grips" are built heavier duty to begin with.

[Super Blue 72]

Cool, thanks for the fast reply!     Makes sense!

[Chryco Psycho]

 

[Super Blue 72]

 

[Carlwalski]

Suregrips are more hard to drive though. With one leggers you can get sideways (or "S" turn burnouts) easily, one tyre to the next. With a SureGrip you get out too much and the diff will bite hard and if you don't know exactly what you're doing (and if you do) you can quite easily become a passenger. 

[Super Blue 72]

Thanks for the reply, NZ! 

I was always curious about this matter just because of what I saw at Acura.

I won't be changing the rear end anyhows, if it ain't broke I'm not gonna fix it.

Besides, with only 240hp (I have HP envy!  ) once I put on the wider tires I'll be lucky to be able to spin up one tire, let alone 2! 

[oldkimmer]

When an open diff is spinning 1 wheel it is rotating at twice the speed, so 50 mph=100mph.

[Super Blue 72]

Hmmm... I never thought of that.  Good point.

I wonder if I'm correct to say then that wheel gets twice the hp and torque? 

[moper]

No, I think it has to be geared up to get double the speed. Meaning the hp and torque "felt" a the tire would be 1/2 as much as if it was measured with a limited slip unit. Any physics guys care to comment? I'm making a guestimate...

[v8440]

Limited slip differentials attempt to keep wheel SPEED EQUAL.  They don't, of course-you have to go around turns.  Open differentials keep wheel TORQUE equal.  This may not make sense at first when you consider one tire spinning, so lemme explain it this way...


Let's say you have one tire on ice, and the other on pavement.  The car has to go uphill, and the differential is an open style.  You're not going anywhere, because the tire on ice is gonna spin.  The tire on pavement is actually trying to move the car forward, but it only applies as much forward torque as the other tire is absorbing as it spins.  Wanna quick way to get out?  Apply the parking brake moderately.  What happens is, the brake will exert a fairly large drag on the spinning tire.  The brake will also be applied to the stationary tire (the one on pavement), but since that tire is not already spinning, it's not having to overcome as much friction as the spinning tire does.  This means that the torque applied along each axleshaft remains equal, but one side is using more of that torque to overcome brake friction, since the other side is not spinning.  So, the non-spinning tire has more torque left over after brake drag to start moving the car.  Make sense now?

[Jacksboys]

 
Sounds interesting, but have you ever tried this?  I am not sure it would work exactly that way.

[v8440]

Actually, I have tried it.

[Super Blue 72]

Thanks for the reply!

Sounds like it should work in theory.  Wish my E-brake worked so I could try it! 

[Carlwalski]

Speaking of E-Brakes, anyone ever thought about converting to a handbrake?
Makes it a little easier and you can pull off more, uh, illegal turns...makes it smoother.