Front diff stripped....

[Servohead]

Darned front differential gears stripped today. Common issue? I thought this truck was pretty robust??
Let's hope these parts become more readily available ....

 

[Caretaker109]

They are tough but stripped diffs just happen.
Landing on throttle after a big jump, brakes too strong, several causes possible.

i suggest you upgrade to the BulletProof diffs. they are a lot tougher..
And don't forget to shim the diffs properly.

 

[Bauerdog]

Completely agree on the bulletproof diffs, great upgrade, well worth the money. Just be sure to do front and rear diffs if going with the bp's. The gearing is slightly different. Be sure to inspect/replace bearings too. Bearing failure is a big cause of stripped diffs also

 

[Caretaker109]

I stripped the front diff on my Mugen truggy today and am checking if i can fit the Savage BP diff's. 🙂
The mugen diffs are spiral cut so i am very curious what happened.. Wasn't beating the sh*t out of it today..

 

[hpicelery]

Perhaps some folks got here from "new posts..." I'm not sure there is a "bulletproof" option for the XS. That being said, I will second the recommendation to shim your diffs. That will maximize the engagement between those gear teeth and make stripping them more difficult.

 

[Caretaker109]

Tnx @hpicelery, didn't see this was xs section. 😉

 

[Bauerdog]

Ah, I didn't notice that it was an 'xs' post either.

 

[Servohead]

Hey thanks guys for all the comment help! Is there a favorite source to get the "bullet proof diffs". And also is there a special link to "shimming" so I can do it properly?

 

[hpicelery]

There is no such thing as "bullet proof diffs" for the Savage XS. The kind folks who recommended them thought you were talking about the big Savage, not the XS.

Shimming the diffs will require you to disassemble them (something you were going to do anyway. Here's how I did it:

Get some of these shims from HPI:

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXGPA7&P=FR&gclid=CNPcjtXNts0CFQIcaQodUWMEOg

Remove the guts from the diff. Assemble just the diff casing with the new ring gear (no spider gears or output shafts). This will let you easily add or remove shims without having to take the diff apart each time.

Stick the new pinion gear onto the gear shaft inside the diff housing. This is a pain. If it won't stay, stick it in there with some grease.

Install the bearings onto the diff case and ring gear and pop it into the diff housing. Make sure the bearings are seated all the way in, then check for play between the pinion and the ring gear. If you can feel some, pull the diff case back out and add a shim between the ring gear and the bearing. Stick it back in and try again. Repeat until there is very little play between the ring gear and the pinion.

Play can also be lessened by putting a 5mm shim on the pinion shaft between the bearing and the cross pin. This is tricky to do, but it will reduce the number of shims you'll need on the ring gear. I haven't been able to get more than one on there, though.

http://www.dollarhobbyz.com/product...=10907151617&gclid=CLSEzK_Ots0CFQqsaQodXzIKQw

Once everything is shimmed to the point that adding another shim would cause binding, then make a note of how many shims you have added to your ring gear. Fully reassemble the diff, making sure to use the same number of shims on the ring gear as you did before.

Install the completed diff and you're off to the races. Once everything is assembled make sure that the diff can still spin without more than a tiny bit of binding. A tiny bit is ok because the new gears will loosen up as they break in. The diff should still be easy to turn.

I hope that helps. That's what I did when the truck was brand new, and I have yet to strip a diff despite all my enthusiastic (crazy and reckless) driving.

 

[Servohead]

I can't wait to try this out when I get the new ring gear!
AMAZING how helpful and friendly the forum folks here are.