I'm stumped please help

[Mustang63.1]

So I cracked the diff cup of my rear hyper7 diff and replaced it with a xxl diff but had to reuse the hyper7 ring gear because the losi was too big. So I got it all put back together and I still only have power to the front so I have looked at my diff multiple times and everything looks right so I finally decided to open up my transmission and there aren't any stripped gears in the tranny. I am so stumped on to what it could possibly be. Please help.

Thanks,
Mustang

[hatethmpr]

i would check the driveshaft in between the rear diff and the tranny. you may ahve stripped the shaft. just my thought.

[rc guy14]

^^ what he said earlier today i forgot to put my set screw in my center drive shaft and couldnt figure out what was wrong =P

And i esencially had the same problem your describing.

[f687s]

hmm check all your driveshafts and tranny

[Mustang63.1]

Yep im running the flm chassis and everything is tight and the cvd isnt broke

[M n M]

Sounds like the input pinion is not engaging the ring gear. Is there any in and out play of the input pinion when it's in the diff housing?

[Mustang63.1]

No not that i can see. I am just sooo stumped on what it could be

[EmaxxChris]

With the rear diff out can you turn the input pinion and the output shafts will spin as well? Have to you taken the diff apart after putting it together? Issue with the spider gears? Just throwing out ideas.

[Mustang63.1]

I dont think there is an issue with the spider gears because it is a brand new diff but ill check tomorrow

[Lazybum]

I have just got a set of diff's off a chop shop on e bay and had less then 2 runs on them and now the rear diff is not working when I removed it the main gear is showing wear and the spider cage is full of plastic chunks so I would pull it a part and clean it and check it you may have a diff out of the same batch

[Mustang63.1]

So i have narrowed it down to 2 things, the cup and ring gear is moving a little so the pinion isnt meshing all the way or a spider gear issue

[Mustang63.1]

So when i have the diff out and turn one cup, the other one doesnt really turn. The pin locking the gears are not broken and when i turn the cup all of the spider gears turn so i think that the spider gears and the other big internal gear are not engaging.

[M n M]

When you turn one of the output drive cups does the input pinion turn?

[Mustang63.1]

Okay here we go...

Diff in 2

But I think this gear

Is not engaging with these


The only problem I see is that there isn't really any room for shims.

[87 GN]

carrier open....turn the one drive cup on the carrier does it turn the gears.
then reassemble the carrier, turn both drive cups, what does it do?
one cup at a time, then both cups oppsite direction..

[Mustang63.1]

When you turn the drive cup on the carrier, it turns the spider gears but when you put the diff together, you can feel that there is a gear like slipping

[Mustang63.1]

Anybody? I haven't been able to drive my trucks since the beginning of the year

[M n M]

When you say the drive cup, are you referring to the input pinion that is connected to the driveshaft or the output pinions that connect to the wheel axle?

[Wolfslash16]

Um, you could try and get new parts and see if that fixes it, or could try putting in a stock traxxas diff and see if it will work that way.... Try putting a shim beheind the main gear, and see if that main gear with make contact with the sipder gears... Good luck fixing it!

[Mustang63.1]

When you say the drive cup, are you referring to the input pinion that is connected to the driveshaft or the output pinions that connect to the wheel axle?

The drive cup going to the wheel axle

[Mustang63.1]

Um, you could try and get new parts and see if that fixes it, or could try putting in a stock traxxas diff and see if it will work that way.... Try putting a shim beheind the main gear, and see if that main gear with make contact with the sipder gears... Good luck fixing it!

Thanks and is it difficult to shim a diff? I have never had to before.

[M n M]

Neither have I put from what I've read the hard part is a) Finding the right shims, then b) Stacking them in trial and error until you get the right fit.

[Wolfslash16]

Ironicly, I've never shimed before, but I have all of the stuff to shim my diffs, I just need to get around to it!