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Old 12-11-2007, 12:18 PM   #1
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Default Hopicomponents: the universal diff. solution

Here I am to introduce you a new hop-up for both our off-roads models, buggy and truggy. Born out of the mind of Domenico Mezzabotta, an Italian modeler and devised in order to answer the problems of bindings and fast wear that plagued the differentials of its 8ight...may be of everybody’s 8ight!!!
Domenico has put “bearings” in the outdrive cup pivots, a not easy job considering parts small sizes, but not impossible… how? By using high quality steel.



The kit is made by Hopicomponents and its under patent pending.
Each kit contains two special diff-outdrive cups made by high quality steel, produced with high precision CNC machine tools and many steel rolls of 1 mm diameter each one.
When Domenico has decided to begin this adventure, he phoned
me asking if I could take care of the reliability and durability tests.
He sent me a set of prototypes so I could start my job!
Well, I treated them badly for one month both on buggy & truggy and now I can
tell You … those stuff is extremely reliable and give You a great increasing on overall traction performances: I never had failures of the product and the wear is not still percepibile.

Which are the PROs?

-remarkable low friction between diff housing/ring gear and the outdrive cup pivot
-long lasting of the new outdrive cups made by high quality steel
-less stressed areas on satellite and planetary gears, they works firmly
-lower temperature when differentials works
-less alteration of the viscosity of the silicone oil thanks to minor overheating of the case
-a better torque distribution on the three differentials

How to install the kit?
Simply put a film of high quality graphite grease on the outdrive cup pivot, then insert 15 rolls for each cup. The outdrive cup pivot is ready for being inserted in the diff housing and/or in the ring gear.

this is what’s happened to me in
The A-Main of the Italian Truggy Nats....



It will not happen any more!

Currently only the kit for Losi 8 is on sale, but Domenico is working on many different brands: so You will find in short time more kits for Jammin/HN, Hobao, Kyosho, etc.

You can buy the kit directly from www.hopicomponents.com.

Notice that the product has been positively reviewed on the Italian RC magazine
"TRUE MODEL", in the December 2007 number.



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Old 12-11-2007, 02:04 PM   #2
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That's a great design. I was just talking with a friend the other day about the problem of metal on metal contact on the diff cup/out drive.
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Old 12-11-2007, 02:09 PM   #3
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I like the idea! How does the internal seal for the diff still work? Is the o-ring riding on the needle bearings, or on the shaft? Has there been any breakage of the very narrow shaft where the needle bearings sit?
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Old 12-11-2007, 02:49 PM   #4
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I fail to see how it will fix the issue of the cross pins wearing out the cross pin slots. Also, is there any type of cage to keep the needle bearings spaced? Otherwise they will just bunch up and cause more problems...
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Old 12-11-2007, 06:05 PM   #5
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Using a metal diff housing would have probably prevented that blown diff. its an interesting design, but like rezenclowd3 said how do you keep the bearings from bunching up?
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Old 12-11-2007, 06:10 PM   #6
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IMO using block attached to the crosspins that slide into the pinslots in the diff cups is a much simpler idea.
also arn't needle bearing prone to fail if they stop moving.
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Old 12-11-2007, 07:23 PM   #7
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alloy diff housings and cross pin blocks add a lot of un-needed weight to your drivetrain, they are ok for MT's or bashers, but for true race kits they are about the worst thing you can do,

the only thing I wouldn't like about this set up is putting all those needles together, I would need the kit to come with 4 or 5 extra for the ones I lost on the floor, lol
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Old 12-11-2007, 08:16 PM   #8
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I think this was an excellent idea, and It could be even better with the feedback posted here. People have mentiond that the needle bearings laid loose like that could bind. Maybe it would be better for him to cut 6 precision half circle cuts into a stock outdrive and place the needle bearings in that, so he would be using the outdrive as a race as well. then he would also only need 6 needle bearings instead of 15 and it should perform the same.
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Old 12-12-2007, 03:47 AM   #9
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Im doing more pics, and I'll post them soon, to explain You all better.

Thanks
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Old 12-20-2007, 04:06 AM   #10
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here below few images about the packaging of Losi 8 kits with bilingual
instructions







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Old 12-20-2007, 06:34 AM   #11
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There wont be any binding with loose needle rollers.... Automotive manufacturers have used them in drive shaft universal joints for the past 40-50 years without any problems....
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Old 12-20-2007, 09:14 AM   #12
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Will someone sell them in the USA?
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Old 12-20-2007, 11:32 AM   #13
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within few days, paypal payment will be available too,
I have just discussed it by phone with Domenico

And I am doing an installation tutorial with my camera, so.... stay tuned


Mugen & Kyosho kits are still on track testing
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Old 12-20-2007, 11:39 AM   #14
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Good idea but IMO you will need a better finish on the lathed section of the cup to get rid of those chatter marks, polish them up and they would last alot longer, or tell your mate to sharpen his cutting tool.
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Old 12-20-2007, 11:49 AM   #15
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The Losi has aluminum inserts in the diff cups for the diff shafts doesn't it? That is why they wear right? Other brands use steel though. I know that I have not noticed any excessive wear through an entire season of running my Xray car.
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