i need a indestructable rear diff, please help
 

so my rear diff blew out for the second time. the first time, the ring gear's teeth was chipped off. and now this time, one of the ball bearings (attaches to diff/pinion gear) broke into pieces. so the diff/pinion gear and ring gears tooth is shaved. now my plastic diff case is sorta warped and cant close tight.

can anyone suggest me the best options for me are. i think i will need a new rear diff case, maybe a aluminum diff cup, ring gear and diff/pinion gear, shims, and whatever else i may need.
oh...maybe stronger better ball bearings haha. dont even know how they even exploded like that.
thanks for all help guys!

oops forget to tell you guys. im running a emaxx 3905 with 7xl/mmm on 4s

Easy.

1) UE ultralite diff with 6 or 8 spider gears, or just use the case and get ofna 1/8 scale inards.
2) FLM hybrid bulks and use the ofna or hotbodies inards again (buggy, rather than truggy gears).
3) Modify some Muggy or LST2 diffs to fit.

You can find a how-to in my Emaxx FAQ (scroll down, you'll see it).

sorry neil . the diff section is totally all new to me. so your telling me i need the flm bulks to fit the UE diffs? whats the bare mininum i can get away with on making a better stronger diff? i sorta wanted one with no mods, just a direct fit. is there a place to just buy each thing seperatly since i dont need the whole set up. most places sell them with the front and rear diff.
sorry for the newb questions. like i said, the diff is all totally new to me.

The FLM HYBRID BULKS are what you need to use 1/8 scale diffs.

You could just use an alloy cup and case from FLM, but that wont fix the fact that stock emaxx diffs are rather shite, with only 4 spider gears, compared to 1/8 diffs that use 6 or 8 spider gears.

The cheapest solution would be the muggy/lst2 diffs which can be bought on ebay for like $20 each; a small amount of work is all thats required to have bullet proof diffs:

http://www.rc-monster.com/forum/showthread.php?t=9153

Much better and cheaper than messing around trying to make stock diffs stronger with an alloy cup and case.

FLM hybrids are similar to the UE VBS setup, or the UE ultralite case which fits any maxx bulks, and uses 1/8 scale inards. You can find a kit in the RCM store with hotbodies 1/8scale buggy diffs and the required pinion gear and bearings etc.

Interesting Neil, I am going to start making adapters to put the lst diffs/cases in maxx bulks. Just need to get a setup mocked up to get the correct dimensions.

wow, thats a very informative and interesting thread to read. thanks neil. surprised why i never bothered to read that thread. i think i may still just go with the AL casing and cup.
im never really good at modding things so the direct bolt ons are best for me. plus, my spider gears never had any problems, it was always just the ring gear and pinion teeth.
i think the AL cups and casing would solve the flexing and issues.
heres what someone recomended me:
http://www.rc-monster.com/proddetail...zerdiff&cat=47
http://www.greatassemblyrc.com/Differential_Cases.cfm

It's the flex of the plastic cups in addition to the flimsy 2mm screws that won't stand the power of brushless setups.

I'm running UE ultralite with 8 spiders on my diffs and they stand the power of the 1515 1Y on 6S.

If you don't want to spend a lot, just get the FLM or Nova-RC alum cup with 3mm screws.

hey george16, thats funny how you said that, i was just looking at those nova cups on ebay. are these the ones your talking bout

http://cgi.ebay.com/DIFF-CUP-S-Maxx-Aluminum-Traxxas-2-5-3-3-Differential_W0QQitemZ330271679759QQcmdZViewItem?h ash=item330271679759&_trkparms=72%3A1205|39%3A1|66 %3A2|65%3A12|240%3A1318&_trksid=p3286.c0.m14
but it says pick the 3mm hole mounts only if i have modified gears. which i dont, im using the stock traxxas gears. will it still fit or no. if not, should i still get this with the 2mm screw holes? i think as long as i get this case, the screws shouldnt matter tooo much would it.
one last thing, should i purchase a AL casing? i think thats also just as important, cus that flexes and causes the ring and pinion gear teeth to break.
heres one i found for cheap
http://cgi.ebay.com/T-MAXX-2-5-3-3-E...QQcmdZViewItem

Gotta drill out the stock ring gear if you go with a 3mm screw cup. $100 bucks a diff for the cups and the case sound like highway robbery. I could think of a better way to spend 200 bucks, myself. Or are you only going to do the rear diff?

Like Linc said, you still have to drill the ring gear t o accept 3mm screws. I can tell you that it's a pain in the ass to drill them unless you have a drill press. Traxxas ring gears are made of hardened steel.

Yes, those are the Nova alum diffs.

Here's the FLM diff drilled out to use 3mm screws. No drilling required. You can get a pair for $60 plus shipping.

http://www.2coolrc.com/detail.aspx?ID=93

i only need the rear. my fronts are holding quite well. wow. thanks for that link george! so that flm al cup will fit my 3905 correct? so do you guys still think ill need the al diff casing? i think i might as well get one, i think i read that, thats what causes the ring and pinion gear to break,because of the flexing of the plastic casing. the cheapest one i found was this one....you know if itll fit my 3905?
http://cgi.ebay.com/T-MAXX-2-5-3-3-E...QQcmdZViewItem
and this one:
http://www.2coolrc.com/detail.aspx?ID=382

will any of these fit my 3905 without any mods onto my stock traxxas parts such as the bulks, driveshafts, etc..
or do you guys have one that you wanna suggest me instead. the flm ones are $45 kinda pricey.

EDIT: after browsing around, those two are the only two AL cases i can find. i know the ebay one fits the 3905 , cus the seller said so. i would think the integy fits for the 3905 as well.
so now, which one would be more reliable?

Taking the time to properly shim your diffs will make them last a lot longer and costs little except the cost of the shims and your time. Aluminum cases may help but you still need to shim them if you want them to last.

My Line.
 

That was going to be my line. You can buy all the best aluminum parts, but if the gears are not shimmed properly they will still eat each other in a very short time. Everyone looks to save a few bucks trying to go with the cheapest parts they can find. If you truly want bulletproof diffs as you first said in the thread opener, then get a good setup the first time and shim the gears properly. You will have more time playing instead of rebuilding, rebuilding, & oh yea rebuilding. Personally I would go for the FLM hybrid diff cases, and put the Hot Boddy hardened gears inside, with an FLM aluminum cup. I believe that Mike sells all of this here in RCM.

Here's my reply to your email. Might as well post it here so other people can benefit from the info.

Ray,
Thanks for the kind words. Yes I’m using ultralite cases and ofna Hyper 7 diff on one of my trucks. The gmaxx uses ultralite cases with ofna 8 spider diffs (stronger than the 6 spiders). There will be no mods needed to fit them.

Here’s the link for UE’s Ultralite cases:
http://www.unlimitedengineering.com/...ore/13551.html

You’ll need 2 of these. You’ll need shims for use with the Ofna Hyper 7 diffs.

8x10mm in varying thickness (.05mm, .1mm, .2mm)
6x8mm in varying thickness (.05mm, .1mm, .2mm)
4x6mm in varying thickness (.05mm, .1mm, .2mm)

Bearings you need:
8x16x5mm (8)

You need rcmonster coupler (2)

For the diff output shaft, you can either buy those from RCmonster or make them like I did. You need the revo stub axles. Just cut the threaded portion off. That’s what Mike basically did. A pair of Revo stub axles costs $4.79 at Tower so you need 2 pairs.

http://www3.towerhobbies.com/cgi-bin...?&I=LXHFY7&P=7

Here are the Ofna Hyper 7 diffs. You can see the diff outputs I made in the foreground.
http://i256.photobucket.com/albums/h...Picture021.jpg

If you dont want to buy the coupler, you can drill the plastic yoke to 8mm like I did here:
http://i256.photobucket.com/albums/h...Picture020.jpg
But you also need to drill a 2.5mm hole on the pinion shaft so you can use the stock setscrew.

Here's what it looks like on the UE ultralite case:
http://i256.photobucket.com/albums/h...Picture028.jpg

http://i256.photobucket.com/albums/h...Picture030.jpg

GA 7075T6 bulks and UE ultralite cases:
http://i256.photobucket.com/albums/h...Picture026.jpg

I only recommend things I have personal experiences knowing that it will work :lol:. I researched all this stuff last year.

Here's the 8 spider diff and UE Ultralite cases I'm using on the Gmaxx:
http://i256.photobucket.com/albums/h...Picture093.jpg

http://i256.photobucket.com/albums/h...Picture094.jpg

Lito

wow. they look pretty damn strong. can u get the 8 spiders for hyper 8 buggies? how much are they? ive got the 4 gear ones at the moment (LHS guy made a bet that i couldnt break the stock diff and if i did he would replace it with a better one... :lol:

im afraid wheeling down the street may cause them to break and they just look so sexy!

The 8 spiders for the hyper 8 buggies will work too.

In fact, the diffs from hyper 7/8/8.5 are almost identical. I said almost because the only difference I saw is the following:
1. Hyper 7 diffs use an o-ring as seal between the ring gear and cup
2. Hyper 8/8.5 diffs use a paper gasket as seal between the ring gear and cup

Other than that, everything is the same. I have the 6 spider version of each of these.

You can also use the diff from a Kyosho ST-RR truggy.

Here are some pictures of the Hyper 7 and Kyosho diffs:

Kyosho diff:
http://i256.photobucket.com/albums/h...Picture466.jpg

Side by side with the hyper 7 cup:
http://i256.photobucket.com/albums/h...Picture467.jpg
http://i256.photobucket.com/albums/h...Picture468.jpg

Various diffs; Hyper 7/8/8.5, mutilator, savage I tried during my experimentations last year.
http://i256.photobucket.com/albums/h...Picture469.jpg

These pictures were taken for somebody in the UE forum asking if the Kyosho ST-RR diff will fit into the UE Ultralite cases. They will. I took measurements using my digital caliper. Anyone who wants these measurements can pm me their emaill address so I can send you the info as an attachment:whistle:.

whoa thanks plenty george! great pics as well. i hope you dont get mad at what im about to do....so i went onto UE site, and found a AL case that can be used with TRX gears and it got my interest. heres the link if you guys wanna check it out:
http://www.unlimitedengineering.com/...ore/13549.html
and i also found this FLM AL cup on rcm site:
http://www.rc-monster.com/proddetail...LM13010&cat=48
i believe this setup should be enough for my mild brushless setup. my spiders never broke, it was always just the ring gear teeth.
quick question for you guys, will these two items be compatible without any mods?
and do you guys know what size shims i need?

and george...my bad once again. but your replys did help me still...cus i would have never went this route if it wasnt for you. and i am sure this helped others.
for those of you that was interested in the ofna 7 diffs, here are two auctions i was looking at when i was originally gonna go with this setup:
http://cgi.ebay.com/OFNA-Ho-Bao-Hype...QQcmdZViewItem
http://cgi.ebay.com/OFNA-HOBAO-HYPER...QQcmdZViewItem

That route will work, but if you go to ebay, you can often find complete sets of UE ultralites and 6 spider diffs for about $160- cheaper than buying the cases, then FLM metal cups and modified ring gears probably.

The LST2 / muggy diffs would be much cheaper and almost as strong; all you have to do is dremel a small bit of plastic to make them fit, its not as hard as you imagine it to be....

http://cgi.ebay.com/robinson-racing-...d=p3286.c0.m14 $70 for 2x complete metal case and cup diffs.

i already checked ebay haha. thats always what i do before i make any purchases.
$160 for two complete sets is a very good deal. theres absolutely none on ebay as of right now. but i only need the rear set anyways...so the UE ultralite and flm cup with ring/pinion gear is about $100 not including shipping. and i wont need anything else because ill just throw everything else from my stock diffs into the new diff housings.
im just not sure about the shim sizes, and the fit with the ultralites onto plastic TRX bulks.
i found a very good link about a guy shimming his tmaxx, he uses this size shims...are these the exact same sizes i will need:
http://monster.traxxas.com/showthrea...=diff+shimming

It's okay. You're still going to use the UE Ultralites. I bought those before too but ended up going the 1/8 scale diffs. With what you bought, you still have to drill and enlarge the stock ring gear to 3mm. It's not included in the package. I know exactly what's in the package because I bought 3 sets of those before.

Drilling and countersinking the traxxas ring gear will be a pain in the ass especially if you don't have a drill press and carbide-tipped bit. It was easy for me to drill the ring gear because I have a drill press and carbide-tipped bits.

If you go with the UE for TRX gears, all the required shims and bearings are included. It may or may not include the aluminum cups (depends on availability). If you go with the FLM route, you need some 14x16mm, 10x12, and 6x8mm shims in varying thickness.

cool...glad you arent mad. i was afraid id erked you since you posted all them good pics and useful info.
but as far as drilling the ring gear with 3mm holes, im going to just purchase this from rcm instead:
http://www.rc-monster.com/proddetail...LM13010&cat=48

you stated that i need these 14x16mm, 10x12, and 6x8mm shims. so do i still need to purchase these cus you also stated that if i was to buy the UE ultralite for TRX, it comes with all the bearings and shims....?

ps. do you still have any diff sets for sale, since you had sooo many before haha.

If you go with the UE ultralite for TRX gears, you don't have to buy the shims. The kit will come with shims and bearings. Depending on the availability of the aluminum cup, it might be included too. When I bought my 3 sets, the aluminum cups were included.

You're all set if you buy the UE Ultralite for trx gears and FLM alum cup with modified traxxas gear.

I already sold the alum cups but kept all of the UE ultralite cases.

perfect, i will place my order some time tomorrow. just trying to get some last min. info and advice . one more thing, i forgot to ask you guys, if this new setup will change my diff ratio? because i am keeping my front diffs stock.
And are these new diffs sealed?http://www.rc-monster.com/proddetail...LM13010&cat=48 because im using diff oil in the front (85,000 wt) i was gonna use 50,000 in the rear.

i do have some gorilla snawt, but im not sure if thats heavy/thick enough to be packed in a diff cup. i have some super lube as well.

so i just placed my order for a UE casing and FLM diff cup. ill report back once they arrive.
just to let you guys, for those interested in getting the FLM diff cup, there are two versions. one for the 3906 and the newer version for the 3905. the 3905 is supposely stronger because it allows you to fit the stock 3905 spiders and that CENTER SPIDER GEAR SUPPORT. im not even sure if the 3905 spiders will fit inside the original flm cup.
heres a link that shows both FLM diff cups:
http://www.addicted2rc.com/E-Maxx.html
i purchased mine from rcm though, just be sure to tell Mike which one you need. the one thats on his website is the original version. hopefully he has the 3905 version.

while i wait for my items, can anyone suggest me some good lubes, since i found out that the flm cup is not sealed. for reference, i have 85,000 wt oil in the front diffs. the only lube i got are super lube and gorilla snawt which i dont think is heavy/thick enough to be packing inside a diff cup.
thanks all

Get some automotive grease, the black crud, lasts longer on the diff (ring and pinion) than white lithium (IMO) or get the snawt, never used it but hes "supercoolin" from traxxas and people say its good. I guess since youre sticking with stock 4 spiders id stay high weight lube in the diffs, maybe 75k front 50k rear. Just recommendations, it really doesnt make a difference when theres 42 cubic inches of space in the diffs

so after all this, i decided to cancel my order for the UE cases and flm diff cups. some people on the forums made me realize how retarded it would be for me to use a nice UE case but use a 3606 style diff. even though its a flm diff cup, the insides are still the weak spiders with no center brace.
i am just going to look for deals on ebay for a complete diff set.

LOL, I'm not going to comment on the retard thing but I personally do not think that the choice of a 3905 cup would make a bit of difference. The spider gears are not the weak link, it's the plastic diff cup that would flex and allow the cross pin to move around allowing the spider gears to bind and fail. The aluminum cup fixes that problem so on that point there is now difference between the 2. The only advantage to the 3905 cup IMO is that they have seals.

Ok now for the retard thing... why would you pay over $100 for a single diff setup that used stock gears when you could buy a far superior 1/8 setup for the same price? Your not even getting the advantage of having combined bulks (which I found to be one of the best upgrades I ever made on my emaxx) and diff cases that would help justify the price...

If you need diff oil let me know I have enough weights to mix about any weight you decide to use.

I agree. 1/8 diffs are the way to go.

someone from the traxxas forum said this to me and it makes sense.

get aluminum cases for your diffs if they are separating and causing your ring gear to strip.
get aluminum cups for your diffs if they are separating from the ring gear and causing your spider gears to strip.
if you strip spider gears with aluminum cups, then the gears are too weak for you and you need to get the 1/8th scale stuff.
that's my opinion.

so after reading that, i decided i should inspect my diff cases since it was my ring gear that got stripped twice and no where else. my spiders are in perfect shape.
and how do you know it, one of the screws of the 4 screws that hold the diff case together was stripped! so i hope that was the cause of my issues because my diff case was just flexing.
so now, i am probably just going to get a complete set of stocks diffs from a brand new 3905 for $20 and see if thatll work.
although i do want to get some aluminum cases to protect that ring and pinion gear.
the only 3905 AL case i can find is this one, and the company isnt too reputative.
http://www3.towerhobbies.com/cgi-bin...&I=LXVBZ0&P=FR

It's your choice. If money is what's holding you back, then buy what you think is good for you for the amount of money you're willing to spend.

If you really want to save money, just enlarge the holes on your plastic cup to 2.5mm so you can use 3mm screws. Enlarge and countersink the ring gear to 3mm also. You won't spend a dime if you already have a 3mm drill and countersink bit.

Best option by far, all things concidered:

http://www.rc-monster.com/forum/showthread.php?t=15256

Thanks Neil, I have a feeling that the LST setup will be very popular once I get a kit together...

Plus, depending on what driveshafts are being used it will cost about 110-150 to do both ends, all parts. The flm hybrid bulks are 140 for the pair, plus the diffs and pinions are at least 25 each... if you can find them that cheap.

I should be done with the testing next week.

yup i saw that thread that linc created. sounds awesome. i will be sure to check back on that thread for the report.