1717 vs LST XXL diff
 

1-0

http://www.br-motor.no/bilde/diverse...00335small.jpg

Both pinion bearings blown to pieces. Happened after 10min run on my new installed 1717, in a e-revo.
On snow, paddles rear, 6s and only acceleration/wheelies.. No jumping. Geared for 35-38mph.

The diff was brand new, only ran 3 packs 5s on it with a tekin 2000kv before this happened.

I want bulletproof diffs, not this cr@p :lol:

so didnt that xxl some with a slipper?

http://www.kaazusa.com/products_lsd.html
might need some custom outdrives :lol:

If you read the text ;) i say it`s a E-revo, and it happened under accelleration, not from landing jumps or backflips, so the slipper wouldnt do anything about this..

Actually, i had alot of speed to.. Probably 25mph, and still accellerating..
Flat ground, loose snow with paddles...

Haha, might be a tight fit in the bulks :lol:

Looking at the pic of your broken diff case, I can see that you shaved some material in the right place to fit the diff in the E-Revo bulkhead. But it looks like you also shaved some material where the screws are which I think, this is just my opinion here, made the diff case a little too weak in the front where the pinion shank is. The case cracked, the bearings of the pinion started wobbling a tiny bit making the pinion move slightly until the pinion stopped meshing correctly with the ring gear and that's when it all failed. Also, did you shave off just a half a mm or more than that?
I measured a stock, untouched LST XXL diff case and the thickness is 26.85 mm. If 0.5 mm is taken off on each side than you should be left with 25.85 mm.

Also seeing you have a cvd cup on the pinion. Did you shim the pinion correctly to remove any slack when you installed this cup?

I`ve removed 0.5mm on both sides, and the diff is a very tight fit in the bulks.. No slop at all sideways.. Almost needs alittle force to close the bulks together.
I have to remove alot of material of the bulks, in the pinion/screw area, and therefor i did "soften the corners" around the diff screw arrea some, so i didnt have to make huge holes for them in the bulks....

I dont think i`ve removed more from the screw area on the diffs, than you did MC (ref. youre pics).

Lincpimp: Im think you got a good point :( I did not shim this. The drive cup lays into the inner ring of the bearing, and MIGHT be alittle tight.. The pinion axle isnt flat where the grub screw sits, it has a bump for it to sit. And i think the grub screw didnt line up 100% on this, and forced the cup harder against the pinion bearing...

I got a new diff on the way, and alot of shims, so i`ll try to shim everything perfect this time.. Both spyder gears, pinion mesh, and all the cups.
And ill flatten the grub screw area on the pinion axle this time.

I`m just learning the hard way i guess ;)

We need those RC Monster Hybrid diffs to get back in stock. How much longer do we have to wait!?

What diffs where used in the hybrid diffs? I havent payed attention to them, but i thought they where special diff housings to fit normal 1/8 diffs? Or was it only special diffs that fit in them as well?

I want FLM bulks, that fits strong diffs.. CEN diffs looks beefy, maybe they would work?

I just picked up 3 1717.. I'm glad the 1717 is winning.. LOL I can't wait until they arrive..

Hybrid diff cases are made for regular 1/8 diffs.

My CEN GST diffs are holding up fine with the 1527 installed...

My LST diffs are holding up fine with the 1527 installed... (but I don't have to shave any material away from the cases, since I have them installed in LST bulkheads)

Well, i`m getting more and more sure that lincpimp hit the nail right on, so i expect them to hold up longer when i rebuild new diffs with the correct mods and shim job.

I hope they do, My lst diffs that I built a few years ago have been thru a variety of motors inc a 1717 and they feel as smooth as the day I built them.

Ok, i`m doing a new diff now.. The new diff that came, was somewhat tight just as the other one`s been.. When rotating the pinion, i feel every tooth touching..
I can turn it with my fingers easy, but it feels alittlle notchy. No slack, ofcourse.

How tight should this mesh be, when i do my shimming now? Should i shim less tight, so everything runs silk smooth, or is it OK for a new pinion/ring gear to be this tight?

It had one shims on the cup side, none at the ring gear side. And one shim on the pinion. Just as every other LST diff i bought.

I know that the pinion shim is the one that has to go to get it smoooooth, but i`ve read about letting new part be alittle notchy too, so i want some opinions from you guys..

I feel that as long as it is rolling all the way around without catching, it will wear in and become free. If the pinion can make the ring gear do a full revolution and you don't feel any of the teeth suddenly catching like they want to lock up, just the same kind of rubbing all the way around, they will wear into each other and become free rolling. I would however take it easy on the throttle at first as a ''break in'' procedure to give a chance for those teeth to wear into each other.

Sounds fine, I like the diffs to feel like that so they wear in and still have a tight tolernace.

Ok, it got tighter when greased and screwed together, so i removed the pinion shim now.. Now i can barely feel some teeth in one short spot on the ring gear, so i guess i`m all set.
Absolutely no slack between pinion/ringgear.

I`ve also shimmed all spyder gears (0.1 on the 4 small, 0.2 on the 2 bevel gears), and they got nice and tight, but still run smooth..

Greased everything everywhere, twice, so i should be done now.
Also made the pinion axle flat where the grub screw is going, and should be able to just set it against the bearing without any shims, and tighten the grub.

Tomorrow i will open my front diff as well, and give it the same treatment, just in case..

I might open the rear diff again after a few packs, and reshim it after it wears in..

If this diff blows up now, i dont know what better to do :)

I found this guide helpful for shimming LST diffs (XXL diffs come with the HD cups installed) : http://hdrcvideos.com/forums/viewtopic.php?f=18&t=15378

I`ve been through that one the first time i did the LST conversion.. :)

But its a great thread!