Ultralite diff cases

[Brokenparts]

I would like to run the stock diffs in the Ultra Lite diff cases and I'm not quite sure what I'll need to do so... I know UE offered a kit for this but its not in stock.

Will the regular 7.5 cases work? Are the proper size bearings the only thing I will need to do this?

[suicideneil]

The diff case themselves are all the same, they only have different names depending on which 1/8 scale gears ( if any ) are included as part of a kit. I believe it is just a case of finding the correct sized bearings & shims in order to run the stock diff internals, but why on earth you'd want to do this is my question- the traxxas diffs are useless at handling BL power & proper 1/8 scale internals are not too hard to find ( Lord knows I've written enough guides which you can find in my sig on the useful links page/ emaxx upgrade guide )...

[Brokenparts]

well, I dont have $300 to spend on a set of 8 spyder diffs. The stock diffs are still holding the power of a Castle 1717 on 4s and I dont have any possible way to gear my truck any higher at the moment without having a custom pinion made. The motor is so big that it is actually resting on the transmission case so I do not have room to use a smaller spur gear. 1/8 diffs lower your gear ratio.

From what I understand, the only thing breaking the ring and pinions on the maxxes is the plastic diff housing separating and causing the teeth to skip, eventually destroying them. I would think that an aluminum diff housing and cup would help solve this issue.

Will Xray diffs fit the 7.5 housings? I have an old XB8 laying around in pieces is the only reason I ask.

[_paralyzed_]

Ultralite cases are way overpriced if you are just using stock traxxas diffs. There are a handful of companies that make aluminum diff cases for much cheaper, if that is the route you chose.

Using ultralite cases to run 1/8 scale gears is an easy bolt in solution, but expensive.

Super 8's are great and all, but they are just renamed ofna 8 spider diffs. "6 spiders" are just your average ofna diffs, as found in any hyper (pre hyper 9) buggy.

I have never seen a situation where a 6 spider broke that an 8 spider would have lasted. In the glory days of unlimited engineering 8 spiders were the most expensive, and now have a cult like following. In my opinion super 6 and super 8 diffs are about the same strength. That being said, ofna hyper diffs (same as super 6) can be had relatively cheaply. If I were building a bash proof maxx with budget in mind I would upgrade to super 6 (ofna hyper) gears.

Now to run 1/8 diffs you need either the ultralite cases, or Fastlane Machines combo hybrid bulks, which makes the bulkhead and diff case one unit.

With as much power as you have you need to consider 1/8 diffs. Even in aluminum cases maxx diffs get destroyed.

[suicideneil]

Indeed, if you upgrade the diff case to metal, then the next weak link is the tiny spider gears inside the traxxas diffs; there are only 4 of them vs 6 or 8 in 1/8 scale diffs. The plastic diff cup itself is also another weak link- do you have the older 3906 emaxx or one of the newer versions with a grey chassis ( 3903/3905/3908 )?

For cheaper 1/8 diff internals there are plenty of resources to look at:

http://www.rc-monster.com/forum/showthread.php?t=8012

http://www.beatyourtruck.com/forum/s...Best-1-8-diffs

http://www.rc-monster.com/forum/showthread.php?t=31594

bearing in mind Ultralites and the FLM Hybrids will use the same internals quite happily with a little shimming.

Really though, if you just want alloy diff cups and cases then look into FLM or GH racing options, but they will not fix the weak spider gear issue. If you want true 1/8 diffs, then either UE or FLM Hybrid bulks ( not the combo bulks ).

[Brokenparts]

I have Xray XB8 diffs. Any idea if they will fit?

I would also have to find other gearing options with 1/8 diffs. I am running a 31T pinion and 68T spur. I only have about 1mm of play between the motor and the transmission so a smaller spur is out of the question. I would have to have Dan @ Kershaw designs to machine me a custom pinion.

[suicideneil]

31/68?!?

What setup are you running that requires such a massive pinion ( tires, motor kv, voltage etc )? Running 1/8 diffs does tend to mean you need a pinion with about 3-4 extra teeth in order to get the same ratio as when running stock diffs, so it may not be an option unless you can alter the rest of your setup to improve things a bit...

[Brokenparts]

Its a 1717/1580kv

[suicideneil]

Running it on 6s?

[Brokenparts]

I am running it on 4s. I dont know what I would do with more power

[suicideneil]

That's your problem really- the rpms are too low so you have to use insnaely high gearing in order to get some decent wheel speed. You would be far better off with the 2200kv 1515 motor on 4s lipo, or an 1800kv 1518 motor if you can find one; the 1717 motor is really for 1/5 scale or heavy MTs on 6s lipo- you need the rpms...

[nitrostarter]

I would agree with Neil. You're only spinning 22,000 max at full throttle. You should at least run 5s on that motor with 6s being ideal. Just have to worry about the drivetrain with the extra power.

[nastety92]

Can't you just run 6s and gear down??

Nick

[suicideneil]

Originally Posted by nastety92

Can't you just run 6s and gear down??

Nick

I don't think he'd even need to gear down running 6s:

1580kv x 6s lipo = 39,816 rpms

2200kv x 4s lipo = 36,960 rpms

The 1717 will spin at a pretty close speed to a 2200kv on 4s ( = ideal rpms and speed for bashing in my eyes ), but will have much more torque; if he gears down it will only increase the drive-train shredding torque....

[MonsterMaxx]

I'm running 6s, 16/58 and the 1350 Tekin.
Batt and esc warm, motor cool (has castle motor fan.)

It's stupid fast.