Granite Am I having a diff issue?

[MCFCLen]

Have to change my spur gear so I was checking everything else while I have it open.
I have the drivetrain disconnected and when I lift up the front and spin the wheels the driveshaft output doesn’t move 100% of the time. Is that normal?
When I connect the driveshaft back on, the wheels move fine when I spin the driveshaft. Just want to make sure I don’t have to crack open the diff.

Also,when I roll it with all 4 tires on the ground both outputs spin just fine. I’m probably being paranoid but figured I’d ask lol.

thanks!



Edit: here is a video. https://streamable.com/gcq71b

 

[Surchaufeur]

Have to change my spur gear so I was checking everything else while I have it open.
I have the drivetrain disconnected and when I lift up the front and spin the wheels the driveshaft output doesn’t move 100% of the time. Is that normal?
When I connect the driveshaft back on, the wheels move fine when I spin the driveshaft. Just want to make sure I don’t have to crack open the diff.

thanks!

What happens if you move both tires of the front does the output gear turn?

 

[MCFCLen]

What happens if you move both tires of the front does the output gear turn?

On the ground or up in the air?
On the ground it moves perfectly.
Just added a video to my main post.

 

[suchtragedy]

It's normal for an open diff. When there is no resistance (tires in the air) when you spin one wheel the opposite wheel should spin the opposite direction and the drive shaft doesn't spin because there more resistance in the shaft than the opposite wheel in the air. If you spin one wheel while holding the opposite wheel in place the shaft should try to spin because the wheel is locked in place has more resistance than the shaft. When the drive shaft spins the wheels the rate at which each wheel spins is determined by the resistance (traction) of each wheel. When both wheels are on the ground pointed straight both spin at the same rate because the resistance is equal. In a corner the inside wheel slows down and the outside wheel spins faster because the outside wheel has less resistance. When one wheel is on the ground and the other on the air the one in the air will spin while almost no power goes to the wheel on the ground.

This where different weight diff oils come into play. Thicker oils add more resistance so wheel speed is closer to being matched in certain conditions. If you have heavier oil in your front diff the front wheels will pull through tighter corners better because both tires are getting a more even split of the power (this is called oversteer). If you have thicker oil in the rear the car will want to push forward and not turn as sharply (aka understeer). This is where tuning with diff fluid weights can be really beneficial for those who are trying to maximize their cars handling for various conditions and types of driving.

Anyways that's the 101 on differentials and what they do.

 

[MCFCLen]

It's normal for an open diff. When there is no resistance (tires in the air) when you spin one wheel the opposite wheel should spin the opposite direction and the drive shaft doesn't spin because there more resistance in the shaft than the opposite wheel in the air. If you spin one wheel while holding the opposite wheel in place the shaft should try to spin because the wheel is locked in place now has more resistance than the shaft so the shaft. When the drive shaft spins the wheels the rate at which each wheel spins is determined by the resistance (traction) of each wheel. When both wheels are on the ground pointed straight both spin at the same rate because the resistance is equal. In a corner the inside wheel slows down and the outside wheel spins faster because the outside wheel has less resistance. When one wheel is on the ground and the other on the air the one in the air will spin while almost no power goes to the wheel on the ground.

This where different weight diff oils come into play. Thicker oils add more resistance so wheel speed is closer to being matched in certain conditions. If you have heavier oil in your front diff the front wheels will pull through tighter corners better because both tires are getting a more even split of the power (this is called oversteer). If you have thicker oil in the rear the car will want to push forward and not turn as sharply (aka understeer). This is where tuning with diff fluid weights can be really beneficial for those who are trying to maximize their cars handling for various conditions and types of driving.

Anyways that's the 101 on differentials and what they do.

this was super helpful! Thank you so much. Glad to hear it’s normal and now I know all about diffs hahaha.

 

[suchtragedy]

this was super helpful! Thank you so much. Glad to hear it’s normal and now I know all about diffs hahaha.

Lol this is the video I watched ages ago that made it make sense to me back when I was confused about it.

 

[northeastflyer]

haha i thought i noticed a wheel wobble and then thought the same thing. noticed the inverse rotation and tested it to make sure i wasn't crazy.

getting into the diffs and the deeper parts of the car seems a bit intimidating to me right now but i'm sure the need will arise.