potential diff issue

[81exige]

I need your expert opinion on this one:

• Rear wheels struggle to move if I hold the front ones in my hand and roll the car on its rear wheels (and vice versa - front wheels can barely move if rolling the car along on those front wheels, holding the rears in place).
• Center diff outdrives for either the front or rear will also have difficulty spinning, depending on which wheels are making contact (rear outdrive if rolling on the rears, front outdrive if rolling on the fronts)
• When I take out the center diff and rotate its outdrives in opposing directions, however, it feels rather free (although it does feel somewhat heavy but that could be because my car's center diff has thicker oil). I don't hear any sort of crunching sound when spinning the center diff either
• I DID attempt to remove the spur gear to inspect the diff's content but I nearly stripped one screw that refuses to budge and that's where I stopped

I think the center diff in my car might need to be serviced entirely because without it, I can spin either just the fronts or just the rears fine, but I'm not too sure. Appreciate all of your opinions

 

[ohsnap]

What vehicle are you running?
Electric or nitro?
I seem to recall you running a nitro buggy but am making no assumptions...

I've run into similar issues, and they can be tricky to diagnose and I'm on my first coffee and not yet fully awake.
Besides the diffs internals, the problem could come down to shimming or even a CVD's grub coming loose.
I had a shafted grub work its way out enough to hit the engine mount (but still stay in place) and it acted similar to your description.

You might want to pull and examine each diff - spinning them by hand - pushing and pulling on the out-drive diff cups while you turn them.
I've had diffs with internal problems that "worked" when you pulled and spun the diff cups by hand, but they froze solid when pushing in on the diff cups. Chipped spider gear.

Weirdly enough, it could also be your clutch. I've encountered a froze clutch that gummed up the works making my truck act similar to your description. When you were doing your rolling test, was the engine (assuming nitro), in place or removed?

Theres probably other issues I can't think of, but that's where I'd start.

 

[81exige]

What vehicle are you running?
Electric or nitro?
I seem to recall you running a nitro buggy but am making no assumptions...

I've run into similar issues, and they can be tricky to diagnose and I'm on my first coffee and not yet fully awake.
Besides the diffs internals, the problem could come down to shimming or even a CVD's grub coming loose.
I had a shafted grub work its way out enough to hit the engine mount (but still stay in place) and it acted similar to your description.

You might want to pull and examine each diff - spinning them by hand - pushing and pulling on the out-drive diff cups while you turn them.
I've had diffs with internal problems that "worked" when you pulled and spun the diff cups by hand, but they froze solid when pushing in on the diff cups. Chipped spider gear.

Weirdly enough, it could also be your clutch. I've encountered a froze clutch that gummed up the works making my truck act similar to your description. When you were doing your rolling test, was the engine (assuming nitro), in place or removed?

Theres probably other issues I can't think of, but that's where I'd start.

It's an electric truggy, and to ensure it wasn't the motor's magnet getting in the way I did try moving the motor away so the pinion wouldn't mesh with the spur - same exact behavior

good call on the front or rear diffs (or both ) being a potential culprit, will get to those two and report back