i need a indestructable rear diff, please help

[George16]

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:


Side by side with the hyper 7 cup:



Various diffs; Hyper 7/8/8.5, mutilator, savage I tried during my experimentations last year.


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.

[blueb8llz]

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

[suicideneil]

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.

[blueb8llz]

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

[George16]

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.

[blueb8llz]

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.

[George16]

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.

[blueb8llz]

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.

[blueb8llz]

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

[jayjay283]

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

[blueb8llz]

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.

[Just go Play]

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.

[George16]

Originally Posted by Just go Play

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...

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

[blueb8llz]

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

[George16]

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.