Big Rock Help, there is some sort of slipage going on in my rear diff.

[SheaDog05]

Ok, so I have the Nero Big Rock, not the 3s version, and I have basically no drive in the rear under power. I though it might be the motor shaft spinning free from the pinion, but under further investigation, I found that the rear drive shaft was spinning, the front was too, but way less. I took the rear diff out and examined it, but nothing seemed off. I do notice, however, that when I move the output shaft on it, the input shaft does not move when under resistance, like my hand holding it. Would it be the planetary causing this or a lack of gear lube? Any help would be greatly appreciated.

Thanks,
Shea

 

[adidas303]

Yea if you're holding the Diff Cup in hand, turning the outdrives has resistance, you probably have to open it up and make sure the sun/planetary gears are all good. Alot of people break the sun gear. They do have diff repair ki8ts with just the gears or you can hit up Jenny's and purchase the whole housing unit. ?

 

[SheaDog05]

Yea if you're holding the Diff Cup in hand, turning the outdrives has resistance, you probably have to open it up and make sure the sun/planetary gears are all good. Alot of people break the sun gear. They do have diff repair ki8ts with just the gears or you can hit up Jenny's and purchase the whole housing unit. ?

Yeah, I opened it up and saw the smallest amount of metal shavings. The gears all look fine though. Where do you think the shaving are coming from?

 

[adidas303]

How much Diff oil seemed to still be in the diff? That's usually common with very low amounts of Oil and the gears not really getting a good lube, so metal on metal can create shavings like so.

 

[SheaDog05]

Inside the planetary, there seems to be a sufficient amount, but there isn't a lot on the input gear or whatever it's called, sorry I don't know what the gears are called, I can upload a picture of both.

Inside the planetary, there seems to be a sufficient amount, but there isn't a lot on the input gear or whatever it's called, sorry I don't know what the gears are called, I can upload a picture of both.

 

[Woodentop]

Is the slipper clutch adjusted correctly/damaged?

 

[SheaDog05]

It doesn't appear to be damaged, but how should I correctly adjust it?

 

[Woodentop]

Check the pads for wear or obvious signs of damage if none tighten all the way in then back off half a turn or so see if that remedys the situation obviously as the pads wear they need tightening up

 

[SheaDog05]

Check the pads for wear or obvious signs of damage if none tighten all the way in then back off half a turn or so see if that remedys the situation obviously as the pads wear they need tightening up

Ok, will do, thanks

 

[Monster-Crawler]

Inside the planetary, there seems to be a sufficient amount, but there isn't a lot on the input gear or whatever it's called, sorry I don't know what the gears are called, I can upload a picture of both.

Everything looks fine in those pics. Like Woodentop stated, try the slipper. The specs should be in your manual if you still have it. If not, maybe check the center diff as well?

 

[SheaDog05]

Ok, will do, thanks

The first picture is right side up, the second is upside down.

 

[Monster-Crawler]

Probably wouldn't hurt to replace the pads, then set it to factory spec.
Looking at the pics again, maybe the washers too.

 

[SheaDog05]

Ok, thanks, should I tighten the bolt holding everything together more or loosen it?

Everything looks fine in those pics. Like Woodentop stated, try the slipper. The specs should be in your manual if you still have it. If not, maybe check the center diff as well?

Yeah, I would but the screws are stripped to hell to get the thing out. Do you have a way to back them out? They are not counter sunk.

 

[Monster-Crawler]

Ok, thanks, should I tighten the bolt holding everything together more or loosen it?

Fully tightnen, then loosen it back out 1-1/2 turns, according to the manual.

Ok, thanks, should I tighten the bolt holding everything together more or loosen it?


Yeah, I would but the screws are stripped to hell to get the thing out. Do you have a way to back them out? They are not counter sunk.

The bolts holding the center diff housing don't need to be loosened, you could work the diff case out of the aluminum mounts by wiggling them apart.

 

[SheaDog05]

Fully tightnen, then loosen it back out 1-1/2 turns, according to the manual.

The bolts holding the center diff housing don't need to be loosened, you could work the diff case out of the aluminum mounts by wiggling them apart.

No, I mean the screws holding the whole motor and transmission assembly inside the car. I can send a picture.

No, I mean the screws holding the whole motor and transmission assembly inside the car. I can send a picture.

No, I mean the screws holding the whole motor and transmission assembly inside the car. I can send a picture.

There are four screws on each side of the car holding it in. Like 5 out of 8 are stripped.

 

[Monster-Crawler]

No, I mean the screws holding the whole motor and transmission assembly inside the car. I can send a picture.



There are four screws on each side of the car holding it in. Like 5 out of 8 are stripped.

Oh those screws, yeah they're pretty small. Maybe try a pair of needle nose pliers, if you don't have easy-out extractors.

No, I mean the screws holding the whole motor and transmission assembly inside the car. I can send a picture.



There are four screws on each side of the car holding it in. Like 5 out of 8 are stripped.

One of the drawbacks of this platform is they're kind of a pain to work on.

 

[SheaDog05]

Oh those screws, yeah they're pretty small. Maybe try a pair of needle nose pliers, if you don't have easy-out extractors.

One of the drawbacks of this platform is they're kind of a pain to work on.

Yeah, they are a BIG pain to work on. Also, can I substitute the diff grease with the stuff that is used to grease up machines? Like excavators or skidsteers. I don't have any diff grease on hand.

 

[Woodentop]

Absolute pig to work on that's why mine gets the least "air time" my money's on that slipper, diff looks fine, let us know how u get on once it's all re assembled ?

 

[Monster-Crawler]

Not sure about what grease to use as I've never opened up the metal case, just the plastic outer housings. The grease I've seen on the outer gears are dark-brown in color.

 

[Woodentop]

I used 200k last overhaul in ctr total pita to do left alone since lol