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Lightning Pro Diff Gear Replacement

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RobH

Gone - bye bye.
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Last Sunday, race day ended for me with a blown rear diff in my Hot Bodies Lightning Pro. I've read and heard from others on the track that the light-weight HB diff gears were soft and problematic. The LHS had three sets of Kyosho Inferno MP 7.5 diff gears (direct fit on Lightning Pro). I jumped on it.

I opened the rear diff and, as expected, the bevel gears looked like someone had flatened the edges with a hammer. I tried to get pic of the roasted gears, but they were too fuzzy. I installed the large bevel gears, the small bevel gears and the respective shims. Bam. That was it. It wasn't that had. I put in my 1000wt silicone diff oil and put it back together. It was easy.

I removed the mill and ripped into the center diff with some confidence. The center diff is sooo easy to take out. I think I had the new gears ready for oil in a matter of 15 minutes:

582centerdiff.webp

ain't them shinny diff gears purdy?


I put the center diff back on the buggy for whatever reason and proceeded to remove the front end. After the front end was off, it didn't look like much:

582apart.webp


I was removing the last of the faggot from my buggy (that would be purple anodizing) and I was tempted to take everything off the chassis and turn it into a pure silver buggy. I amost did it, but I was running out of EZ-Off and the brown/goldish colored chassis didn't bug me nearly as bad as the remianing purple ano on the front end.

It was also at this time that I noticed the Lightning Pro (and RR) comes with a servo saver as standard equipment. I had never noticed before:

582ssaver.webp


I tore into the front diff and it was just as easy as the rest:

582frontdiff.webp


I removed the very very last of the purple ano and felt much better because of it. I then put the whole thing back together: (well almost)

582together-med.jpg


Look between the cooling head and the reciever box and you'll see that I forgot the rear chassis brace. Would I have to take the mill out again? Nope. That's why I love my hemostat:

582hstat.webp


All in all, the project seemed more scarey than it really was. I have yet to build an RC froma kit. Seeing my expensive toy in so many pieces made me a little nervous. It really wasn't until I had run three tanks of gas through the buggy that I'd realized that I'd put it back togethre correctly.

The Kyosho Inferno MP 7.5 diff gear upgrade is well worth it for anyone tha races the Hot Bodies Lightning Pro. $22 is cheap for peace of mind.

-Rob
 
Nice work!

I'm considering a Kyosho Inferno or an XXX-NT. I would imagine the Inferno mp-7.5 would have these beefy diff gears to begin with.

I was at a contractor's tool supply house looking for a reamer when I saw a couple things I didn't plan on getting. One was a set of dental picks which remove e-clips like a dream. The other was a two-pair set of hemostats. I carry the larger pair in the box to grab the copper gasket after removing the glow plug. It also grabs that piece of zip tie that falls into your chassis after you cut it off the air cleaner.
 
Yeah, working on r/c's really isn't that hard. Even working on the savage. It's all about knowing the layout of the chassis.
 
I hate to ask dumb questions.. but.. What is the little set screw on the side of all the diff housings for? I had thought you could add diff oil there.. but when I remove it, I see no way of getting the diff oil in there.. any help would be great!

ummm.. please disregard this last post.. amazing what you can learn by just looking at the instruction manual.. :) sorry.. Peace!!
 
it's appears to be where you slide the center pin through to hold gears in place.. After looking again.. I'm still not a 100% sure.. Is there a diff expert in the house??????? :)
 
i know what it's for. i had the rear diff apart and i couldn't get the one pin out. the pin holds the one end of the diff together. i checked the manual and if you remove that allen screw, it makes a hole in the diff case that you can slide the pin through. this way, there isn't enough clearance for the the pin to slide out while the diff is spinning at high speeds.

I also forgot to mention something in the original post.

If you buy the Lightning Pro diff gears, you will get a diff gasket. There is no gasket in the stock diff. This sounds weird and you'd think the diff oil would leak out, but it doesn't. As long as the surfaces are clean and you wrench the case down tight, they won't leak. Furthermore, if you install the diff gaskets into the Lightning Pro diffs, your diff will self-distruct! Putting the diff gasket in changes the spacing in the diff and the gears will not mesh right. Hence, you would blow your gears almost instantly. This is why the Lighning Pro ships without diff gaskets. Don't install them!
 
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