Diff carnage!

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stevrock

stevrock

Well-Known Member
Messages
126
Location
Edmonton
The front differential gears...

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What happened was the screws that hold the crown and cup together, well, 3 of them backed off, making them run in a manner that was not. good.

Got my new stuff today, so I'll get it back together to break some more soon enough.
 
Make sure you shim either the pinion gear tord the diff and/or the diff tord the opposite side of the ring gear. I have done this many of times untill I started shimming them better or learned how to, LOL. Now I get my diffs to hold togather for more than 5 gallons.
 
I just did the same thing

I was showing off for the neighbor kids doing back flips and tore out diff on landing

I was at about 5 gallons on these
 
Well, I was waiting on the machined heavy duty ones from smf, when I got them I was going to rebuild them.

The diffs failed while I had the parts on order so I could shim them...

What sucked is that the screws backed out on the diffs that came with it from hpi, it seemed like there was only threadlock on two screws for each diff.
 
are the diffs the alloy ones cause the screws that come wif them back even with blue thread lock lol i replaced them with allen head machine screws from traxxas with the same dimension and boy i can tighten down and thread lock with no worries.
 
Yeah, they're the alloy ones. However, on that diff, only one was in tight, on the other there were two in tight.
Putting them back in on mock-up, there were two tight ones.
Weird...

I may pick up some screws tomorrow, I have to pick up some shims and a couple seals anyway.
 
I also recently stripped one and am replacing it with the machined heavy duty gears. I already have the machined heavy duty gears in the front but will be putting them in the rear also when I receive them.
 
So far, all is good. I'm hoping to elimitnate diff stripping problems once I get the machined heavy duty gears in the rear. It would probably help if I had them shimmed right. I'll have to read up on that before installing them.
 
bwl2828 said:
i have never done anything with my diffs and i have about 10 tanks in my truck should i do something with them?
Click to expand...

I think most people recommend that you shim them up after your first gallon - and I presume to keep an eye on them from then on.

Of course, I've been to 10 different threads on shimming and I still haven't figured out the exact process...but once I get 1 gallon through mine I will look into it.

I have already read that from the factory, the diffs do not have a lot of fluid in them, but I will just take care of that at the 1-gallon maintenance point.
 
I put a shim on the front pinion and two on the rear... two ended up being too much and creating a bunch of friction, so I went back to one.

The diffs took 1-2 depending on where they were at.
It's so snug there, it slowed my truck when I came off the throttle for the first couple minutes.
Everything's fine now.
 
On my last overhaul they seemed just a touch too tight so I cut an old dog bone and ran them in with my drill at high speed for 10-15 minutes and lash was perfect.
 
Since I upgraded my savage to the 4.6, I haven't been able to keep the bevel gears (four internal) in one-piece. I have broken the rear gears several times and now the front. I have the maximizer lockers coming in this Friday for both the front and rear, so problem should be solved. I would rather replace dogbones then have to take the truck apart to replace bevel gears all the time.

I do have a question, though, for you guys. I have aluminum front and rear differentials and diff cups. If I ever do decide to go back to a limited slip system again (when road racing) what should I do to get more life out of these things. I have heard some about shimming the diff when putting it together, but where do the shims go? Should I also upgrade the diffs with gear oil instead of grease? Thanks guys!
 
It is suggested to run silicon oil in the diffs rather than grease. Many people use like 7000 or 10000 weight. I am running 10000 in the front and 30000 in the rear and I haven't had problems with the internals of the diffs since (about 5 gallons). My problem is the 13 tooth pinion and the 43 tooth ring gear. I need to figure out how to shim those suckers. But now I have upgraded to the HPI machined heavy duty diff gears.
 
I just purchased a new 4.6 aluminum diff for the front of my savy. How would you guys recommend cleaning the internal gears out before I install in the silicone fluid?
 
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