HPI Savage aluminum diff case & assembled diff

[PeterV]

http://209.2.68.15:8011/pics/HPI_savage_diff.jpg

http://209.2.68.15:8011/pics/HPI_savage_diff_apart.jpg

Latest from www.hpiracing.com

How do you make the toughest Monster Truck even tougher? Here’s how! HPI Racing introduces a complete set of parts to build ALLOY GEAR CASES for the Savage! Made from high quality aluminum, these differential housings come with everything needed to install them in any of the Savage line of Nitro monster trucks and include features such as steel cross pin supports and extremely accurate tolerances to help all of your differential parts in alignment even under massive loads. After hours and hours of testing R&D has determined that these parts can take any amount of power that you can throw at them. So if you are ready to take your Savage to the next level, these are the parts that will take you there.

86827 Alloy Diff Case (Pre-assembled)

86826 Alloy Gear Diff Set (Complete)

[chukb]

interesting.....they need to make alum savx bulkheads too.

[twisted]

the lack of dependable diffs before these were out was the main reason i got rid of my savage x.

[chukb]

the lack of dependable diffs before these were out was the main reason i got rid of my savage x.
why? there were already aluminum diff cases long before this!

[Killerush]

Golden Horizon has been making them for quite a while now.

[bobf24]

i wanted to make cross in supports for mine, but never got around to it and then sold the truck, the cross pin supports are whats going to make the diff bullet proof,

[twisted]

why? there were already aluminum diff cases long before this!

i know, i ended up buying a cup for the rear of the truck. the spiders still went.

[HYPA]

I have blown about 5 diffs in my Savage and I have just recently bought a pair of these. I have run the car hard about 5 times after I installed them and they are still smooth as silk. Great diffs but hardened gears would be even better.

[chukb]

i know, i ended up buying a cup for the rear of the truck. the spiders still went.
the six gear ones? I went through a few diffs on my sav x, but once I switched from grease to diff oil I've had no more probs, and I still have the plastic cups.

[jocktheglide165]

the lack of dependable diffs before these were out was the main reason i got rid of my savage x.
could be wrong, but fastlanemachine makes them already and they have a great warranty policy...better than HPIs...

[Duster_360]

Nova makes cups also but 7075-T6 not 6061-T6 like FLM uses. FLM Is a great deal for Tmaxx since they include re-drilled ring gears and new pinion.

I just bought set of gpm alum cases too. I hope by complete (#86826) they mean diff cases and the diff?? Tower has that listed at $40.

That would be a good deal, especially if they've been shimmed correctly. They won't last if they're not shimmed.

[twisted]

the six gear ones? I went through a few diffs on my sav x, but once I switched from grease to diff oil I've had no more probs, and I still have the plastic cups.

i ran the savage x. the cups got egged out from the spider shafts and in return stripped the gears.i thought that an aluminum cup would stop that. i also went to diff fluid.i even shimmed the gears. this wasnt an every day occurance but it happened to me at least 3 times at the track.so i moved on to a revo 3.3..and a new head ache, lol.

[Natedog]

interesting.....they need to make alum savx bulkheads too.

Yes, they do...the X gearcases (what the diffs go in) are better plastic and a more rigid design than the original Savage, but still not good enough!!! The flex of the gearcases allows the ring and pinion mesh to move around and the gears strip quickly under hard use...especially jumping. The only way that I kept my Savage and kept diff gears in it was by using GPM aluminum gearcases and Maximizer 7075 aluminum diffcups (the first maker of QUALITY diffcups), my own four spidergear mod with Ofna and HPI parts, and lots of Kyosho steel shims...cost me alot of $$$...and I almost sold my brand new Savage SS due to this. FYI, silicon diff oil helps the spiders last longer than any grease.

Properly built and shimmed diffs like my setup last about four gallons and then the diff carrier bearings puke the cages, seals and balls out the side and then the ring and pinion gears strip anyways...I'm currently running Hot Bodies Lightning diffcups (harder plastic with a steel insert for the bearing) and stock Savage ring gears turned down on a lathe to fit the larger 16x8mm bearings and hoping that they last longer than the stock 16x10mm bearings that are too small to take the side loading that a ring and pinion diff puts on them.

It's a start in the right direction, but HPI needs to get it together....it's been years since the Savage came out and I had diff gear problems...and so did all my friends.

Duster,

Those complete GPM gearcases mean complete with screws...but they are well worth it and the only thing that will keep diffs in a Savage...when used with the other things that I mentioned.

[Duster_360]

I was favorably impressed with the GPM diff when I got them - they look to be quality work, def worth the $21/pr price tag and added s&h from HK. I'll change to hardened steel hex heads screws when I start buildup.

Thats pretty much where I'm headed, but using the Nova cups instead - they sent me a coupon and thats what I used it on, set of cups. Thanks for mentioning the brg mod - I'll look into that and see if my lathe (gunsmith)
will handle that. If ring is hardened steel (expect it is), I'd have to invest in the right cutters, so doubt I will go there, nothing in my gunsmithing work uses that kind of cutter.

Its so flat here, I just don't do that much jumping so these modded diffs should get the job done.

[SquirrelNutz]

I think that this will help alot of people out. A good shim job on the X is all you need but I would still like to see some alum housings for the x as well. At least HPI is listening to its customers!

[crazy voneR]

where can i get these diff cases and gears ?

[Natedog]

Duster,

The ring gear is pretty hard...you'll need a good cutting tool for your lathe and some patience. :)

[Old_School_RC_1]

hmm....been running my Savage .25 SS for nearly 3 years now with the original 2 gear diffs front and rear. I'm even on my 3rd piston and sleeve, (stock HPI .25) but no diff breakage yet at all. Was going to upgrade when they blew out as everyone told me they would, but so far has never happened, and they are still nice and smooth. Maybe cause i used silicone in them from the get go (5k front, 1k rear, another beauty of building your own kit...)

In this case, just waiting for them to plain old WEAR out at this point. Interesting. In fact, I usually never have to work on this truck at all. Tough as nails all around.

Sorry, based off what i read here, i know that's the exception, but had to throw it out there. :)

[sasonrally]

I've never blown a diff in my savage and I have been running for almost 4 years. The trick is to check the diffs once a year, depending on usage of course, to make sure the wear on the plastic diff cases is controlled. Once the diff cases wear out you are prone to blowing up a diff, so you need to replace them. I mean people forget that these are monster trucks and they need maintenance once in a while. I found it that properly filled diffs with proper maintenance will get you far. As for these cases, they are great to have. It will ensure longer runs before some up-keep is needed. I also find it that the bearings die faster for me than anythign else, so those I watch out for more often. Aluminum bulk heads help on th ewear and tear.

Way to go HPI!!! Now we need aluminum bulk heads.

[chukb]

hpi now includes a parts bag of these with new sav-x rtrs. :)

[Duster_360]

Duster,

The ring gear is pretty hard...you'll need a good cutting tool for your lathe and some patience. :)

Thanks, was afraid of that, its amazing, but gun barrel steels cut like alum but are cut at low speeds and feeds unlike alum. I won't risk using one of my cutting bits on a ring gear.

I had expected they were pretty hard, so I'm just out of luck. Guess I'll just have to watch them closely.

If GPM had been paying attention instead of just duplicating stock parts (except for the case split), they could have made a killer upgrade by making use of larger brgs possible with the cases. Oh well...