Question about backing up

[WDaniels]

Ok, now I don't want to start anything and I don't want anyone mentioning anything about the closed thread, but... ... ... ... ...



As I am a manual transmission type of guy and not really too bright at that, would someone enlighten an old man on why backing up a hill would do harm to the reverse bands? Wouldn't going in first up that same hill hurt the same bands????

WD

 

[Joe G.]

There are no bands in the OD unit.



There is a overrunning clutch in the OD unit. It only holds in forward so reverse only uses the clutches in the clutch pack. The overrunning clutch is a set of steel rollers on ramps so they jam in forward which takes the load off the clutches in the clutch pack.



The clutches in the OD unit are smaller than the rest of the clutches in the transmission so they are the weak point if something slips in reverse. Those clutches are not engauged by fluid pressure. Instead they are engauged by a strong spring.



The result of all this is that if you really pull hard in reverse, like pulling out a heavy vehicle that is stuck, can slip the OD clutches while using a forward gear allows the overrunning clutch to take the load.



If I have any of this wrong, I hope someone chimes in.

 

[WDaniels]

Wow! And I thought women were complicated.

WD



Thanks Joe.

 

[BMH95]

They are. Trucks come with a shop manual and a maintenance schedule. Imagine if every time you opened you shop manual it showed the turbo in a different spot in the engine bay, and the maintenance schedule changed constantly. You know, this time the key fob opened the door, next time it didn't.

 

[BMH95]

And to answer the question, the reverse gear is not made to handle load. So backing up a hill puts a lot of strain on internal components. That's why people say don't back a heavy load up a hill without using 4low, if possible.

 

[Joe G.]

4low does not change the strain on the direct clutches in the OD unit.

 

[MA2LA]

4low does not change the strain on the direct clutches in the OD unit.

Actually yes it does, you are using gearing to you advantage and it doesn't take as much power to do the same amount of work

 

[Joe G.]

Oops. I was thinking about the torque at the end of the transmission not after the transfer case. It's still not a good idea to pull hard in reverse.

 

[johncameron]

And to answer the question, the reverse gear is not made to handle load. So backing up a hill puts a lot of strain on internal components. That's why people say don't back a heavy load up a hill without using 4low, if possible.

I guess I'm screwed with my 2WD

 

[CKelley1]

that is why we do not own any automatics, and if you keep the cost of fuel and maintenance of the two over the 1,000,000 mile life of the trucks you are going to kick yourself for buying the junk auto

 

[grasmo]

Trust me if you can damage a 2wd truck reversing a heavy load brother you are making some serious traction. My experience is that it would slip the wheel before it could damage the transmission.

 

[Joe G.]

There was a post about that exact failure a couple of months ago. I don't remember if it was on the TDR or another forum.

 

[catoiler]

First thing; if you worry about everything someone says will harm your truck you better park the truck and ride a donkey! second; if you are backing up a 20* hill well yeh, backing up the driveway or into a camp site no. use common sense and you will be OK!

 

[DieselDoghouse]

Ahem, backing up a donkey under load can result in neck injuries depending on the harness AND if done in severe hard ground could injure the toes of the hoof:-laf