Center Diff...

[Paul]

So while running my kit at the track yesterday I crashed like 10 times, nothing spectacular but flipped a few times and nose dived into the opposite side of a few jumps. Sooo today I decided to rip it apart and make sure everything held up good. Have everything apart and so far I've disassembled both the front and center diff. The front diff wasn't bad at all, just a tad low, but the center diff was almost on E. Both look fine inside, no metal shavings or anything. Haven't gotten to the rear diff yet but already know its been leaking a little like the front. This is an Associated RC 8.2 FT. Question is what can I do to keep my center diff from leaking if by some chance taking it apart and refilling it doesn't somehow solve the issue? I'd rather not have to tear down the center diff after every track day. Thanks in advance for any help.

 

[SchrodeMode]

First, you have to figure out where it's leaking from. Check the O-rings and gasket, replace any that are damaged/tweaked. It may have just needed this teardown and rebuild, maybe an o-ring wasn't seated correctly and pulling it out and putting it back fixes it.

 

[Paul]

Yeah thats my hope, that rebuilding fixes it. Did find others that said to sand the diff housing's where the two join and replace black o-rings with clear. Don't have any extra gaskets for the ring gear but some say to doubble up on those and or shimms. I didn't do anything but inspect and refil. We shall see. I will say that rebuilding all the diffs took FOREVER! I need to get a little mini cordless drill, seriously have blisters on my fingers this morning.

 

[Paul]

So after disassembling my diffs topping them off and reassembling, the leaks appear to be gone. Could be that the ring gears hadn't been tightened equally (and enough) all the way around and I was really careful of that this time around.

 

[Kris407]

what weight oil did you use?
i use my Dewalt impact gun to remove the screws and to tighten them but i dont allow the gun to drive them all the way in, i use the screw driver for the final turns to tighten them down. i use a tooth brush to clean the diff gears and it's fast and easy, the inside of the diff case is a pain but i use a bowl full of paint thinner to drop it all in and then i just rinse out the case with water and blow it dry with my air compressor. i do get in there with Qtips and paper towels for the corners in the casing. glad to hear it's better now!

 

[hotrodrob]

They would absolutely leak if not tightened proper ,opposite applies, but fluid can so leak from the 2 output gear shaft seals

 

[ninnon]

Try these:
1) Check crews
2) Check where it leaks from
3) Check for bad washers.
4) Check for damage
Hope it helps

 

[Paul]

Try these:
1) Check crews
2) Check where it leaks from
3) Check for bad washers.
4) Check for damage
Hope it helps

All seems to be good now after working on them. Could be a case where (at least with these Associated diff housings) they need to be broken in a little and then reassembled after a bit of use? More likely I just hadn't assembled them perfectly the first time. The front and rear always leaked a tiny bit (found shortly after assembling my rc8.2 kit) but the center was good. The car did sit for almost 2 years before I started the break in process on my engine but that's neither here nor there. I knew the front and rear diffs were leaking just slightly and had read this was somewhat common. Decided to break in my engine before addressing those diffs and after taking the car to the local track for a couple hours found that the center diff had leaked really badly, the front and rear not nearly as much. Car needed to be cleaned and the diffs needed to be rebuilt so I took EVERYTHING apart, topped off diff fluid, reassembled, no leaks yet and I've done a little bashing since reassembling.

It was impossible to tell where exactly the leak(s) were coming from as the transmission cases and diff housings pretty much had at least a thin film of oil all over (center diff was basically dripping).

 

[ninnon]

All seems to be good now after working on them. Could be a case where (at least with these Associated diff housings) they need to be broken in a little and then reassembled after a bit of use? More likely I just hadn't assembled them perfectly the first time. The front and rear always leaked a tiny bit (found shortly after assembling my rc8.2 kit) but the center was good. The car did sit for almost 2 years before I started the break in process on my engine but that's neither here nor there. I knew the front and rear diffs were leaking just slightly and had read this was somewhat common. Decided to break in my engine before addressing those diffs and after taking the car to the local track for a couple hours found that the center diff had leaked really badly, the front and rear not nearly as much. Car needed to be cleaned and the diffs needed to be rebuilt so I took EVERYTHING apart, topped off diff fluid, reassembled, no leaks yet and I've done a little bashing since reassembling.

It was impossible to tell where exactly the leak(s) were coming from as the transmission cases and diff housings pretty much had at least a thin film of oil all over (center diff was basically dripping).

Thats good then

 

[WinnersCircle]

I also add synthetic wheel bearing grease to the output shafts to further help 1) stop leaking past the o ring and 2 provide lubrication in the event of metal to metal contact.

Lee

 

[hamz9561]

I also add synthetic wheel bearing grease to the output shafts to further help 1) stop leaking past the o ring and 2 provide lubrication in the event of metal to metal contact.

Lee

Actually I've found that Green Slime works better for this. I use it wherever oil/O-ring contact.

 

[Greywolf74]

+1 for green slime

 

[Paul]

They don't have it at my LHS! Do need to get some of this wonder lube though Happy to report that none of the diffs are leaking at this point though and I drove it hard today. Good thing too, cause you know what they say about leaking diffs?

 

[SchrodeMode]

They don't have it at my LHS! Do need to get some of this wonder lube though Happy to report that none of the diffs are leaking at this point though and I drove it hard today. Good thing too, cause you know what they say about leaking diffs?

If you can't get the Green Slime, you can always find alternatives.......

For sharing___________________________________________For Winter​

 

[ninnon]

If you can't get the Green Slime, you can always find alternatives.......

For sharing___________________________________________For Winter​

lol

Personally I wouldn't do it, because when you are driving in dirt, it will turn into slimy sandpaper, and will end up being worse.

 

[Paul]

Hmmm warming liquid. Wonder if that would work on the head?

 

[ninnon]

Hmmm warming liquid. Wonder if that would work on the head?

Hmmm- that comment could be taken 2 ways, I like the second, wronger one, better...