Results 1 to 11 of 11
  1. #1
    RC Turnbuckle Jr.
    Join Date
    Jul 2010
    Location
    England
    Posts
    5,788

    Unlimited Engineering option for Upgraded diffs in the Emaxx ( all models )

    Instructions for building & installing UE Ultralite diffs ( NB: same part numbers are required for installing FLM Hybrid bulks, regards differential internals ).


    Step 1:

    Either buy the full 6 or 8 spider Ultralite Diff kit from Unlimited Engineering ( or ebay if you get lucky ), or just purchase the Ultralite cases.

    6 spider kit SKU 13540
    8 spider kit SKU 13540B
    Left & Right side Housing ( case only ) SKU 13551

    If you buy either full kit, skip to step 3.

    Step 2:

    Option A: head to ebay and purchase a couple ofna hyper 7 buggy bulkheads and differentials- you will only need the internals so the bulkheads themselves can be discarded or sold.

    Option B: Head to ebay and purchase some Losi LST / LST2 differentials- case will not be needed so alloy or plastic option makes no odds.

    Option C: Hit up google and locate the following part numbers:

    HBSC8178 Hotbodies hardened differential x2
    HBSC8028 Hotbodies 43t front/rear bevel ( ring ) gear x2
    HBSC8030 Hotbodies 13t bevel ( pinion ) gear x2
    XRA962081 X-Ray 8x10x0.2mm washers/ shims ( any brand will actually be fine, just that size ) x1
    PTK-688-RSZZ Protek R/C 8x16x5mm bearings ( any brand is fine again, best quality you can afford ) x1

    Step 3:

    You will also require the following if using Traxxas stock driveshafts or cvds:

    Rc-monster 1/8 diff output shaft ( or make your own by cutting the threads off of Traxxas part #5454 )



    If you plan to use the stock center driveshafts then you will also require:

    Rc-monster revo driveshaft coupler V2 steel ( 8mm bore ) for the differential input shaft x2



    If you plan to use Traxxas center cvds you will require instead:

    Rc-monster drivecup hardened steel- 8mm bore x2


    NB: you can find the same type of item from many different brands such as Hotbodies and Ofna etc.

    Step 4:

    Admire all the parts you have purchased & remove from packaging ( I suggest you use a clean & tidy workbench or desk to work at, placing the parts on a sheet of white paper so small parts don't vanish ), or open up your Hyper 7 bulkheads and layout all the internal parts:



    Step 5:

    undo the 4 screws holding the ring gear to the diff cup:

    before


    after


    Step 6:

    Remove spider gear from shaft, slide out pin & remove shaft ( which has the built-in drive cup ). Replace pin into modified #5454 shaft or RC-M output shaft.



    continued..
    Keeping the Mods busy is my specialty...

  2. #2
    RC Turnbuckle Jr.
    Join Date
    Jul 2010
    Location
    England
    Posts
    5,788
    Step 7:

    Slide O-ring seal onto shaft, insert shaft into ring gear:



    Step 8:

    Replace spider gear onto shaft:



    Step 9:

    Remove grubscrew from diff cup, this allows you to slide out the pin & withdraw the output shaft; not all diff cups will have a little grub screw in the side so some nimble fingers are required:



    Step 10:

    As before, slide O-ring seal onto the new shaft, insert pin into the shaft, drop it into position, and replace the spider gear. Replace remaining spider gears, fill cup with your favourite brand / thickness of diff fluid, and screw ring gear back into place. A generic setup is 7k front & 3k or 5k rear, but it is worth researching & testing various weights depending on your driving style:



    Step 11:

    Take the pinion gear and place a couple of the 8x10x0.2mm shims onto it- you may need more or less depending on how the mesh feels once the diff is assembled, there is no absolute correct number of shims due to manufacturing variances. Ideally the shafts shoudl all spin smoothly with no tight spots, and no excessive play inwards or outwards ( once the drivecup or coupler is fixed to the 8mm input shaft ). Shims may or may not be required on either side of the diffcup to reduce side to side play once the diff is assembled, I didn't find the need for any, YMMV:



    Step 12:

    Place diff into case, observing the little engraved 'E' which shows which way round to place diff depending on whether it is for Nitro or Electric use- do the same for the other diff ( you may need to reverse the motor direction regardless by swapping 2 wires around on BL systems, isn't an issue ). Slide 2 of the 8x16x5mm bearings onto the pinion gear's shaft and insert also, checking the amount of contact between ring & pinion gear ( tip of pinion should not rub against the diff cup itself ). Apply some light grease between the ring and pinion gears and rotate a few times, you do not need massive amounts as this will only cause excessive drag:



    Step 13:

    Tighten the 3 screws holding the case halves together, et voila, one completed UE Ultralite diff with HotBodies, Ofna, or Losi LST 1/8 scale internals, complete with standard size output shafts, stock diff for comparison:



    Repeat steps for the other diff.

    With any luck you will find the diff spins nice & smoothly, without any tight spots or grinding, and without the shafts moving in or outwards by much.

    Step 14:

    Install the revo coupler onto the 8mm input shaft of each diff, and attach the other driveshaft parts ( you will need to remove the yolk from one end of the shaft to attach it to the coupler instead, see the traxxas exploded views for a diagram HERE). You may need to place a few of the 8x10x0.2mm shims on the outside of the diff, between the outer bearing and the coupler, to prevent the pinion moving inwards too far after setting the depth in step 11.

    If using center cvds then install the drive cup with the 8mm bore onto the diff, making sure to align the set screws with the flat spot(s) and use a small amount of blue threadloc.

    Congratulations, you now have 99% bullet proof diffs.
    Last edited by ArmyofDarkness; 09-13-2011 at 07:02 PM.
    Keeping the Mods busy is my specialty...

  3. #3
    RC Turnbuckle Jr. 87 GN's Avatar
    Join Date
    Mar 2010
    Location
    kansas
    Posts
    7,907
    Wow look at that. impressive.
    Would you go flip my truck back over??

  4. #4
    RC Racer
    Join Date
    May 2011
    Location
    Peekskill NY
    Posts
    232
    AHH, so I see you took your address out of the pics

    On these particlar ^^^UE diffs^^^ is that dif cup UE??? It looks like it has ridges on the outside
    EMBE BANDIT VXL SASSY CLOD RC10L RC18MT

  5. #5
    RC Turnbuckle Jr.
    Join Date
    Jul 2010
    Location
    England
    Posts
    5,788
    No, as per the pictures further up it is a hotbodies lighting buggy diff ( including cup )- back in ye olden days you could buy the diff + pinion + bearings as a kit from RC-Monster, but it is impossible to find the buggy diff on it's own these days, so you have to buy the truggy version + a separate buggy ring gear ( which is always out of stock, hence the ofna hyper diff being a better option ).

    I didn't hide my address intentionally, just how the photos turned out really- fan mail can be sent to me via PM
    Keeping the Mods busy is my specialty...

  6. #6
    RC Qualifier
    Join Date
    Aug 2011
    Posts
    271
    Mate thats an awesome guide.

    How much ballpark figure was that all up? I'm going to assume a diff like this is fairly bulletproof compared with the standard unit?

  7. #7
    RC Turnbuckle Jr.
    Join Date
    Jul 2010
    Location
    England
    Posts
    5,788
    The 1/8 diff options are much, much more durable- rare to ever see one fail.

    Price wise, something around $200-250 maybe, the diff cases / hybrid bulks being the most pricey part- the internals can be had much cheaper these days thanks to ebay chop-shops.
    Keeping the Mods busy is my specialty...

  8. #8
    RC Racer
    Join Date
    Jun 2011
    Location
    Northern Europe
    Posts
    205
    6 spider kit SKU 13540 = $260
    8 spider kit SKU 13540B = $299
    FLM17700 Front Hybrid Bulk = $70
    FLM18700 Rear Hybrid Bulks = $70

    Pricey...

    It is unclear to me if the UE kits includes both diffs or just one? When looking at the product pictures 2 complete diffs are shown:


  9. #9
    RC Racer
    Join Date
    May 2011
    Location
    Peekskill NY
    Posts
    232
    Quote Originally Posted by gumleguf View Post
    6 spider kit SKU 13540 = $260
    8 spider kit SKU 13540B = $299
    FLM17700 Front Hybrid Bulk = $70
    FLM18700 Rear Hybrid Bulks = $70

    Pricey...

    It is unclear to me if the UE kits includes both diffs or just one? When looking at the product pictures 2 complete diffs are shown:

    Those are the $299 Spider 8 diffs ... 2 complete diffs im presuming....

    What you can do is use the UE cases that are pictured above and some HB or Ofna Hyper 7 diffs as laid out in step 4 for a $75 6 gear setup..
    EMBE BANDIT VXL SASSY CLOD RC10L RC18MT

  10. #10
    RC Racer
    Join Date
    Jun 2011
    Location
    Northern Europe
    Posts
    205
    Yeah, I'm thinking 2 diffs too, but not sure at all... If it's two complete diffs the price is "ok" I think.

    About your suggestion with the UE cases - the SKU 13551 alone is $60, so I doubt it you'll be able to build a diff for $75. Please correct me if I'm wrong.

  11. #11
    RC Turnbuckle Jr.
    Join Date
    Jul 2010
    Location
    England
    Posts
    5,788
    Please don't post stuff in this thread, PM me any questions you have if something isn't clear.

    As stated though on the UE website, it shows a pair of differentials & says 'these' rather than 'this' can be installed in the emaxx or tmaxx- these is plural, meaning more than one = sold as pairs in order to upgrade both diffs at once.

    /English lesson

    If you look on ebay, you can find Ofna Hyper 7 diffs for about ~$20-30 each, so $75 per diff is a little optimistic; you can however find complete pairs of UE diffs for sale occasionally for $150-200, but you have to keep a eye out for them.
    Keeping the Mods busy is my specialty...

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •