Modifying a HB 1/8 diff to use 3.3 sliders
 

This is one of those things that occasionally gets discussed but not in any kind of detail, so I thought it would be nice if we could thrash out a 'how to' for future reference.

So far as I understand, you just need to remove the output shafts that have the cups built into them (?), and replace them with the 3.3 stub axles (with the threaded portion cut-off). The only thing Im not 100% clear on is how the larger spider gears then attach to the new out put shafts- is there a set-screw or pin of some kind that threads into the spider gear and hold the shaft in place? A picture would be great to illustrate, though I appreciate it does mean ripping apart a diff to get one (or two).

My reasoning for all of this is that I have noticed UE 6 spider diff cases are only $69.99 for two (?)- which is meant for using maxx diffs but ignore that bit, its the cases that are important here. If you then buy the HB 1/8 diffs that come with the needed bearings and pinions, all you have to do is combine the UE case & the HB diff to get the ultamite 'drop-in' diff upgrade for your E-maxx. Price wise it would work out at about $190 for a total truck, which is cheaper than a new UE 6 spider set, and cheaper than the FLM hybrid route too (buy about $10-15). I like this UE & HB diff idea since it means I wouldnt have to sell my existing FLM bulks in order to upgrade the diffs.

Any thoughts, tips & info on doing the shaft mod is most welcome.:yes:

EDIT: http://i115.photobucket.com/albums/n...uff/shafts.jpg
These are the modified output shafts for the HB diff that Mike sells for the revo diff upgrade- I assume he might sell them seperately if I/someone asked nicely?....

According to the pic you posted, if those are modified 3.3 axles, then the threaded portion is cut off, then the groove is milled into the center, and then a hole is drilled at the other end(that goes into the diff). The diff out put gear is held on by a cross pin that slides thru the newly drilled hoe and the output gear has a slot milled in the backside that the pin engages onto. This is just the same as stock HB, so the pin and output gear are un-modified. It could be done by hand, however the hole would have to be drilled prescisely thru the center of the axle. Not sure if you really need the groove, but I think it has something to do with the o-ring that seals the fluid in the diff.

must.....resist.....commenting.........

:rofl:

Sorry meant to say "freshly drilled hoe"

Glad to see that people are reading my posts!

http://www.rc-monster.com/forum/show...ht=revo+slider


All you need to do now is shoot mike an email and ask him for 4 output shafts for 3.3 sliders for 1/8th diffs. He's got a bunch of them laying around.

You guys make my day...:rofl::rofl:

Boy... I must have missed that part.

It all adds:

your kermit in heat avatar.. A fresh drilled hoe..

One pervert typo for sure..

Hole man, its hole, not hoe! Im a bad influence around here. Anyway, thankyou Serum for that info- I knew I read/saw that thread a long time ago but couldnt find it for the life of me. In any event, I shall try and find some UE diff cases, then order the diffs & shafts from Mike; the 2nd part is easy, the 1st part isnt given UE wont sell to people outside the USA..... **grumble grumble**

and here i thought you were trying to be the bigger man by ignoring it. glad to see i was wrong...:lol:

neil, i'll shoot you a PM.

Ow, you got me. PM replied- I love this forum so much, everyone is so helpful!

Neil, why not just get some FLM bulkless? Probably about the same price as a used set of UE cases.

After I did my sums (again) I discovered the FLM bulkless route would have been cheaper, but not by that much so....
Im lazy is the trouble- I already have FLM bulkheads which I like alot, and I didnt really feel like selling them & buying whole new bulkheads & diff combo. Daft I know, but thats just me :P

My HB diffs for revo conversion had the threads already cut, all i had to do was install. On Ue diffs (Emaxx) i cut the threads off and put the pin through the hole on the thread side, install in diff then drop the gear on shaft and line pin to slot, then finish assembly. its really easy

Cool, does sound nice & simple. I emailed Mike and he said I could buy the needed output shafts for $5 each, so $20 to do two whole diffs, which is ideal for people who run 3.3 sliders/ cvds etc. I also bought some diff fluid - 7k for the front & 5k for the rear to get me started with-, some of the 10x12x0.2mm shims to adjust the pinion depth if necessary, and some cups for the centre dogbones that mount onto the pinion output shaft; the stockers are 6mm, but the HB uses an 8mm pinion shaft so I have that covered. Just have to wait a few weeks and hopefully I will have everything I need to bulletproof the drivetrain completely & enable future upgrades of the BL motor & esc setup.

It is done...
 

First off, a big thanks to Mike for the diffs and modified output shafts, they really are nifty little items. And a big big thanks to ClodMaxx for all his help with getting me the UE ultralite cases- life saver dude.

http://i115.photobucket.com/albums/n...Maxx/diff1.jpg
Thats a nice lot of parts.

http://i115.photobucket.com/albums/n...Maxx/diff2.jpg
Stunning quality; I was going to polish them, but there really isnt much need to be honest.

http://i115.photobucket.com/albums/n...Maxx/diff3.jpg
One HB 1/8 diff.

http://i115.photobucket.com/albums/n...Maxx/diff4.jpg
Remove 4 screws holding the ring gear onto the cup.

http://i115.photobucket.com/albums/n...Maxx/diff5.jpg
Remove spider gear from shaft, slide out pin & remove shaft. Replace pin into modified shaft.

http://i115.photobucket.com/albums/n...Maxx/diff6.jpg
Insert shaft into ring gear, O-ring seal holds it into place which is handy.

http://i115.photobucket.com/albums/n...Maxx/diff7.jpg
Replace spider gear onto shaft.

http://i115.photobucket.com/albums/n...Maxx/diff8.jpg
Remove grubscrew from diff cup, this allows you to slide out the pin & withdraw the output shaft.

http://i115.photobucket.com/albums/n...Maxx/diff9.jpg
As before, insert pin into new output shaft, drop it into position, and replace spider gear. Replace remaining spider gears, fill cup with diff fluid, and screw ring gear back into place.

http://i115.photobucket.com/albums/n...axx/diff10.jpg
I found that two 8x10 shims was perfect for setting the pinion depth.

http://i115.photobucket.com/albums/n...axx/diff11.jpg
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.

http://i115.photobucket.com/albums/n...axx/diff12.jpg
A Voila, one completed UE & HB 1/8 diff, complete with 3.3size output shafts. The stock 3.3spec diff is a piece of plastic crap by comparison.

The only issue I have encountered is that the rear RCM dogbone is about 2-3mm too long now, since the pinion shaft is longer than on the stock diff, causing it to bind up against the end of the dogbone. The solution is to dremel the end of the dogbone alittle on both ends and deepen the slots on the tranny output cup, allowing for a tiny bit of extra clearance & movement. The only mistake I made was not to order any set-screws to hold the HB dogbone cups onto the pinion shafts- I believe I need two 4mm set-screws (ordering now).

this thread just saved my but, thanks. i was about to gain 300lbs and turn green in the garage.

"BEEFCAKE!"

"Get in the kitchen and make me some pie" (said in Cartman's voice)

I too am learning from this thread as the bombproof racebomb that I am putting together has the hybrid diff cases and my cvds have a much larger ball end than the HB diff outputs. Mailman was kind enough to send me a pair of these modded output shafts so I will give them a try.

Lincpimp, I'm working on building a Racebomb as well. What chassis do you have? I got a lexan bottom with the 7075 top plate (#5 of 11 I think?). I wish I could find a CF one though...

Hmmmmm...

You want a carbon fiber chassis. I have the all lexan variation, with the al braces. I am actually going to buy some more lexan and make an upper plate that will use a dual steering setup like the new emaxx. I will be speaking to a cnc guy soon and should have the ability to replicate the upper and lower plates. I have torpedo braces that need a top plate too. Not too familiar with cf, is it hard to mill, or hard on the bits? I will question the cnc guy when I talk to him. I am sure that I can get the cf plates made, do you have an idea on desired thickness of the cf?

No, no idea actually...They made something like 4 carbon fiber ones and there pretty hard to find. I had the chance to get one, but couldn't afford the whole truck. I actually need to get some braces before anything. since I only have the decks. Anyway, at a guess, I'd say the lower would need to be a good 3.5-4mm thick.

Do you want the braces now? I will be getting the oportunity to acuire some new bpp parts soon. Let me know as it may be tomorrow if time allows!

FWIW, a kid on the traxxas forums has a BPP torpedo chassis, but he is missing the braces at the moment- Im sure he would be willing to sell if anyone was interested.

well, i have overlooked something on my build. i now have to locate a front driveshaft/dog bone. i went to the lhs and all they had was front and rear mip set and wanted $65 for it. i didn't buy those needless to say. i'm using the flm ext chassis, should that still use the stock length front shaft? anybody know where to get only the front one?

Yea, I kinda need/want the braces ASAP. I also need some battery trays for the BPP LSP chassis if you can acquire them.

Mike should have it.

i see that he has a 72mm one, but i'm not sure if thats the one i need. i guess an email should let me know.

72 should be the right one.

I may be able to get the battery trays for the 1/8 scale chassis, and you need the braces for the racebomb, correct? I should be able to get as many upper and lower lexan plates made as needed.

You will need to order the 72mm shaft, but leave a note for the proper shaft - the 72mm length is a touch longer than stock for use with the Gmaxx chassis. Stock is around 70mm and I generally use around 68mm for the FLM chassis - I have this size floating around, so simply request it in the order. :)

good news, thanks.

Alrighty. I'll probably get the braces and the battery trays, and maybe a new lexan lower plate depending on how much it will all cost. PM me when you find out.

Ok Neil, we need the big how to on how to do the mod with ofna hyper7 diffs and flm hybrid bulkheads all the way down to the oil weight for the front and rear diffs. I had all my subscribed pages deleted by a supermod on that other forum where you can't post links. I think we all should start a all out campaign to get corporate to shed themselves of this supermod that really don't know much more than the rest of us. Anyway any how to's, hints , tips or anything else you think could be helpful as this could be a learning experience. Will the diffs need to be shimmed? If so I'm guessing you have a thread covering that as well

This thread has all the info you need in the first couple pages.

The hyper diffs are no different to the HB diffs with regards how you swap the shafts, fill the diff cups & shim the pinion gear to set the mesh correctly. Only extra thing you might need to do is use shims on either side of the diff cup to remove any side to side play that is noticeable ( in the output shafts ) once the Hybrid bulks are assembled- I didn't need to personally. Just pretend the Hybrid bulks are the UE diff case, and then the principle is identical.

Oil weight is personal choice to suit your driving style, but generally guys seem to go for 7k front & 5k rear ( I did, pretty generic setup ), 7k / 3k, or 5k / 3k- I'm don't have a great deal of advice to give on what will be the best choices for any given surface or driving style, shock & diff tuning has never been my strong point; talk to some truggy and buggy racers though and they should be able to offer some helpful pointers.

Hey Neil,
I just was able to buy a set of UE diffs with the spyder diff gears in it. Will the UE diff cases fit in the regular FLM bulkheads? I'm thinking about swapping the spyder gears for the HB gears in my full metal Emaxx some day down the road. I would like to have the Spyder gears in my high end truck and the HB gears in my plastic basher. I almost have a complete spare truck as I only used the MMM and ESC from my brushless Emaxx. I don't want to have to buy another set of hybrids if I don't have to.
Thanks,
Mike.

Yes, I use the UE Ultralites with regular FLM bulks- the diffs will fit any brand of standard Maxx bulks so no worries there.