Hot Racing sealed differential review

[O.G.]

Just got the HR sealed diff in from Liquid RC for about $26 shipped. I've seen it a little less elsewhere but they were out of stock so...

Here it is, I'll take a few days to assemble and install in a truck. I'm a big fan of the FLM sealed diff so we'll see how this diff fares at about 1/2 the price.

[O.G.]

It was shipped in a bubble envelope and felt light as a feather. Some more pics of the packaging.






This is the opened package, note the ring gear still sealed up in what appears to be a bath of silicone. I'm not going to open it until assembly.

[O.G.]

The parts look pretty nice, well formed without too many swirl marks.

But I noticed one side of the case has some drilling AFTER it was anodized, and appears to be drilled deeper on the Left side for some reason. Maybe they test-fitted it and decided the depth was out of spec.



Here it is on the Right side of the pic. On the other hand, maybe the black didn't get down deep enough to coat the entire hole.

[O.G.]

Some more pics:












O-rings to seal up the unit.

[O.G.]

Then I began to doubt it is anodized, maybe just painted black so I gave it an un-scientific scratch test with my trusty pocketknife and some black came off on the blade but didn't expose any shiny metal.

They don't make any claims about anodized vs painted on the web site so I won't complain:

FEATURES:
CNC Aluminum and Steel Gear Sealed differential case
Sealed differentials allow it to tune to current track conditions by changing the weight of the diff oil.
Four O-Rings that seals against fluid leakage result in a very smooth differential that improves the performance of your vehicle.
YOU WILL RECEIVE:
One Sealed differential case (no gear inside)

[O.G.]

Here is a link to my Rustler build, scroll down to post #33 for pics of the Swami aluminum diff.

Link to a sealed diff discussion with pics of the FLM diff by kwitty.

[cunawarit]

WOW! This is exciting! This is the cheapest sealed diff for 2WD Traxxas RCs.

I've had very little issues with my Hot Racing tranny case, so I've just ordered one of this diffs It will take a while to arrive as it is being shipped internationally. But I can't wait to give this a go!

Thanks for the tip O.G.!

[scootroc]

Just got mine yesterday.

[cunawarit]

Just got mine yesterday.

Thoughts?

[scootroc]

Haven't had a chance to take a good look at it yet. I've been using the FLM diff in my other car, so I should be able to give a good comparison once I get to work with it.
Mine was $23.88 shipped from liquid rc.

[O.G.]

I decided to install new gears in the new diff so I'm on the way to the LHS, I hope they're in stock.

[cunawarit]

I decided to install new gears in the new diff so I'm on the way to the LHS, I hope they're in stock.

Decided the same thing, I didn't fancy cleaning out the old ones. So I'll just keep the other diff as a spare.

BTW, you are lucky, here in the UK I have to order my Traxxas parts online. It has been many many years since I find any in a LHS.

[scootroc]

I as well have a new set of gears for my new diff case.

With my dealings with the FLM diff, it does leak some. Not bad, but some.

I try to rebuild mine every 3 months or so.

[O.G.]

My LHS is about 6 miles from my house, or 9.6 kilometers European.

[O.G.]

Okay I have an update: new gears and fluid installed and everything is checking out.

New gears fresh from the LHS:






Planet gears:



Sun gears:



Planet shafts (sun gear alignment shaft is the short one):

[O.G.]

Now to the assembly.

First sun gear in place.





Planet shafts in place.



Planet gears in place.



Another view.



Ring gear seal.



The flip side.

[O.G.]

Ring gear in place, ready for some 30,000k silicone oil.





Test fit






Team Associated silicone oil




I like to fill the case about 1/2 way then work it in with the gears and top off.




Ready to be closed up



All finished. Dynamite 2.0mm hex wrench pictured (the best)

[O.G.]

So far the oil is holding and the gears spin tight and smooth. It feels about like my FLM.

I'll install in my truck tomorrow and give it a test run.

[dirty don]

Thanks for this informative thread about the new HR sealed diff. I just ordered one for myself. New gear Kit as well. Can't wait for it to come in.


Sent from Oser world

[rhardy60]

What's the benefits of a sealed differential over stock ?

[O.G.]

What's the benefits of a sealed differential over stock ?

The main reason is so you can 'tune' the differential with different weight fluids for track conditions. With my track Slash I settled on 30,000 wt fluid after testing 5,000 and 15,000 wt. 30k seems to be the sweet spot for that truck on a small dirt track.

The seals hold in the silicone oil which would spin out of the stock diff.

Reason #2 is they're a pretty cool addition to your truck and will hold in standard thick grease.

Sent from my Super-Kindle

[Stephan81]

You get to give it a run yet? Waiting on your review and thoughts before I order one up

[O.G.]

No I haven't ran it yet, I'm currently in the middle of the install on my Pede.
But, it does feel tight and smooth to my fingers and hasn't leaked yet.

[scootroc]

I just built mine today as well.
Nice piece. There doesn't seem to be any slop in the out drives. I use 120k lube and its very tight.
The one thing I did notice visually different from the FLM is the bolts that hold it together are longer. The HR diff has threaded holes that go all way through the case, where as the stock and FLM have dead en holes.

[harry697]

All finished. Dynamite 2.0mm hex wrench pictured (the best)

Your review had me convinced until I saw this. Throw that Dynamite tool in the trash and get a real one!


But seriously, looks like a nice piece. Think I'll get one. I've had a set of Robinson hardened planetary/sun gears new in the package for years and nothing to use them on. Pretty sure I just found a use for them. Weird thing is, I've never seen them before and can't find any info online. I guess there's one way to find out!

[O.G.]

Those tools are the best. Dynamite makes a black handled tool that strips out easily and I don't recommend them, but these wrenches are hard core.

[rag6]

Great write up Mr guinea pig(thanks!)!

I have 1 concern... Any info on a rebuild kit(o-rings)? I bent a motor plate on my first HR trans, and after trying to get a replacement for a year, I never got a response from HR. Could not find a way to contact CS that got a reply. I would try to source those o-rings before they wear out. They may last a lifetime, but who knows if you run in harsh hot and cold temps. If it starts to leak, you may have to buy another diff. Just thinkin'

Harry, some of the dynamite drivers are awesome, some suck. Once I found the good ones, they have been perfect for over a year, and I can get replacement shafts for 4$ if they ever round out. I am not afraid to put a little "crank" on them if I have to. Each wrench cost 8$ individually...

[scootroc]

Great write up Mr guinea pig(thanks!)!

I have 1 concern... Any info on a rebuild kit(o-rings)? I bent a motor plate on my first HR trans, and after trying to get a replacement for a year, I never got a response from HR. Could not find a way to contact CS that got a reply. I would try to source those o-rings before they wear out. They may last a lifetime, but who knows if you run in harsh hot and cold temps. If it starts to leak, you may have to buy another diff. Just thinkin'

Harry, some of the dynamite drivers are awesome, some suck. Once I found the good ones, they have been perfect for over a year, and I can get replacement shafts for 4$ if they ever round out. I am not afraid to put a little "crank" on them if I have to. Each wrench cost 8$ individually...

Just jumping in here...
I've rebuilt my FLM diff numerous times over the past two years with no wear to the o-rings.

However, I would any good auto parts store would have something if they have an o-ring assortment.

[rag6]

Your probably right. The smaller orings would be the ones exposed the most to drying out. I would make sure to find the small ones at least.
Dont get me wrong, I love HR stuff, but if you need help from them, you wont get it in my experience.

[rag6]

OG, was there any mention of using silicone sealant for the screws? If its just metal on metal, there may be room for thinner wt oils(under 100k wt) to seep out. Not trying to be a bummer, just that my mind always looks for the weak link...

[scootroc]

I tried emailing HR about 2 years ago. Still waiting on a response.

Another negative about HR: no instructions of ANY sort. Also just got the spring/shock checking tool. Still figuring a way to check spring rates with it.

[dirty don]

Just got my HR diff and new gears. Here goes another project. I should be able to get all these o rings at work. Those offshore oil and gas platforms all have a big assortment of o rings. I will let y'all know.

Sent from my MB886 using Tapatalk 2

[cunawarit]

Hopefully someone will figure out a part number from another manufacturer for the o-rings. How about the bigger gaskets? Any idea of how long those will last?

[rag6]

As mentioned above, you may never need them. My gearboxes rarely ever have dirt inside, even after a very long time between rebuilds. Dirt gets in easiest near the outputs, so I would assume that the smaller rings would see more dust and dirt...

[O.G.]

OG, was there any mention of using silicone sealant for the screws? If its just metal on metal, there may be room for thinner wt oils(under 100k wt) to seep out. Not trying to be a bummer, just that my mind always looks for the weak link...

As scootroc mentioned, there were no instructions included. It's been a while since I saw the inside of my FLM diff but I'm thinking the o-rings May be identical. Are the replacement o-rings available? If so they may fit.

Also, I think the screws seal up the diff pretty well and I don't think it'll leak through there.

[scootroc]

Also, I think the screws seal up the diff pretty well and I don't think it'll leak through there.

I filled my new HR diff up about 90% Saturday morning and bolted it together. Haven't touched it until tonight - a little 120k had bled through. I think that's to be expected when its very full though, which is why I let it set. Otherwise I don't see any issues.

[O.G.]

My 30k hasn't leaked a bit from several days ago.

[scootroc]

That's good!
I filled mine very full. Could probably tighten bolts more now that some of that thick stuff has been displaced. Lol.

[dirty don]

Just finished putting my HR diff together. Used 30K diff lube in it. It went together easy and it is very smooth. Not going to use it for a while, just had to have it. I just love the look of hr black and shiny parts. It will go in my bash p2de when I decide to do maintenance on the tranny. Running stock diff in it now. Well that's all for now folks.


Sent from Oser world

[O.G.]

I'm in the middle of my install. I'm going to put it into my spare HR transmission case, but I ordered new gears; the other day the LHS had the diff gears but are out of the other transmission gears. Mine are all filthy from the wheel bearing grease the PO stuffed into the diff... (This is why I use Bad Horsie diff grease in my unsealed differentials)