Sure Grip definition

[IroquoisPliskin]

Hello guys! I need your help on clarifying something. My cuda is factory equipped with the A36 option, which means it should be 8.75 axle with 3.55:1 ratio and sure grip. Recently I've found out that when the car has no ground contact and one wheel is turned, the other wheel turns the same direction. It's not possible to make the other wheel to turn opposite direction. It seems to work like a locking differential as used in off road applications, where the wheels turn in unison regardless the traction etc.  Is that correct that way? Is "sure grip" equal to a 100% locking differential?
Except that I'd like to know if there is another way to identify the rear gear ratio except the comparison of the wheel movement to the drive shaft movement. Maybe by some serial numbers or other marks on the gear housing etc.
Thanks for your replies in advance!

[anlauto]

Yes your rear end is acting normally for a Sure Grip rear axle.
There is no stampings outside anywhere to be found. The gear ratio is stamped on the ring gear inside the rear end.
One full revolution of your wheel should result in 3 1/2 turns of your rear yoke.

[PlumCraZRT]

Sure Grip uses clutches to tie the wheels together during straight driving (or unloaded movement).  When turning, the necessary differentiation should be enough to allow the clutches to slip.  So... the answer is "no", the Sure Grip is not a locker.

[HP_Cuda]

Alan

There is the tag on the outside of the 8 3/4 which notes the rear end gear ratio. A great deal of times folks take the tag off and lose it.

Looks like this...

http://www.google.com/imgres?imgurl=http://thumbs1.ebaystatic.com/d/l225/m/m-VbeUluVDdBdnkBhPfSL9Q.jpg&imgrefurl=http://www.ebay.com/bhp/mopar-differential-8-3-4&h=120&w=225&sz=6&tbnid=BVDZHjWJzCYk4M:&tbnh=90&tbnw=169&zoom=1&usg=__PeRX1CbDgG0WiBcOI9HDSN-xKIw=&docid=IKXeAH2DFMmW7M&sa=X&ei=v7eCUuTtG6SujAL2lIGwDA&ved=0CFEQ9QEwBg

[anlauto]

Really...wow learn something everyday...(sarcasm)

[72cudamaan]

Sure Grip uses clutches to tie the wheels together during straight driving (or unloaded movement).  When turning, the necessary differentiation should be enough to allow the clutches to slip.  So... the answer is "no", the Sure Grip is not a locker.

Of course some use cones and not clutches.

[Super Blue 72]

Alan

There is the tag on the outside of the 8 3/4 which notes the rear end gear ratio. A great deal of times folks take the tag off and lose it.

Looks like this...

Thanks for the info!  Didn't know that.


The GM guys had it easy, didn't they?  Weren't there tags on the GM rear ends that said, "Use limited slip differential fluid" or something like that? 

[IroquoisPliskin]

 Is there any possibility to verify if the sure grip is still working properly? At the moment I have the impression that it could have been modified to be 100% locked.

[anlauto]

Here's a thought...Jack up one side only and try and turn the wheel...

[Challenger6pak]

The only way would be to take the 3rd member out and see if it has a locker installed.  Is the car drivable? A locker will chirp the tires most of the time when a U-turn is made.  Does yours chirp?

[jimynick]

If it's a suregrip, not a spool, you could simply wet down the pavement under one wheel and get on it. The large difference in traction should see the wet side spin more. Use an observer and if both wheels spin at the same time and amount, it's likely got a spool in it. Just my 

[PlumCraZRT]

Here's a thought...Jack up one side only and try and turn the wheel...

My Sure Grip (which is new mind you) would be very hard to turn with one wheel on the ground.  Maybe with a torque wrench... even then I'm not sure.


Another thought... regardless of whether you have Sure Grip, it would probably be wise to add friction modifier if you're planning on replacing the gear oil.

[IroquoisPliskin]

Car is drivable. I could not notice any chirping when U-turning the car so far, but honestly speaking I don't know if it's possible anyway with 40 series flowmasters only under the car. We tried to turn the wheels against each other but this attempt was unsuccessful. I wanted to know if that's the behavior I should expect from sure grip.

[Challenger6pak]

From a good sure grip I would say yes.  It is very hard for you to duplicate the torque and make the unit slip like when your car corners, unless the sure grip is worn out.  Its' function is to act like a locker but be able to slip when it needs to, such as in corners.

[Chryco Psycho]

if you had a spool you would know , the sure grip should stay locked until there is enough different speeds at the wheel to cause the friction of the sure grip to be overcome . if you had a spool the inner tire would sqeal at almost any speed in a corner