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HotShot and BigWig owners rejoice, MIP Ball Diff

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HotShot and BigWig owners rejoice, MIP Ball Diff

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Old 02-01-2018, 07:29 PM
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Default HotShot and BigWig owners rejoice, MIP Ball Diff

Tamiya HotShot and BigWig owners, it looks like MIP is going to show some love by updating the stock 1980's designed gearbox into today's realm of reality . http://www.miponline.com/store/mip17165.html. Of course you will need 2 sets of diff's, but it includes new dog bones, bearings, and the installation tool. This is a pre-order sale, so these will probably go up to $70-$80 when the sale ends. What does everyone think of this? My MIP Blackfoot ball diff has been nothing but stellar!
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Old 02-02-2018, 10:50 AM
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Old 02-02-2018, 02:39 PM
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I think this is great! I've pre-ordered!
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Old 02-02-2018, 03:16 PM
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Originally Posted by Tamiyadan View Post
having to modify the gear case is terrible. the original design was fine and worked in the blackfoot/MB directly.

personally i'm not interested.
I definitely get what you are saying, especially if your keeping your HotShot on the shelf as a display piece. However, a beefed up bearing along with a race quality ball diff has to be eons better when running anything other than a silver 540 can motor. I look at it this way: A 6 gear RC10 classic transmission makes it a decent running car, but when you put a Stealth transmission in with ball diff, it makes the RC10 a whole different beast. My hopes are similar with the Shot and BigWig, should make a good car into a great running car.
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Old 02-02-2018, 06:23 PM
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Old 02-02-2018, 08:46 PM
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Tamiyadan, Yep I remember using those old 1700mah Sanyo SCR cells. We use to push those old cars, and electronics (MSC's burning up) to the limits back then. I mentioned the old 6 gear RC10 because I had the original when it first came out, not the re-release. I wish a had an album with pics of all the R/C's I owned and raced....oh well.

Your absolutely right about the limited gear choices in the Hotshot line of cars. You get about 4 pinion choices to choose from, all pretty bad. But, these new brushless motors like the lower gearing. I have a Supershot with a 10.5 in it, and she gets along really nicely. I even managed to find an old Parma bump steer eliminator kit which almost removed all the toe out during suspension compression. She's not going to beat a modern racer, but up against another vintage runner, well, that may be a different story.

My Current 2017 BigWig has a Gt tuned motor, with 8.4v 3000mah cells that will be getting this MIP ball diff system first. It was the last in the line of the Shot series, and Tamiya finally fixed the steering, and actually has decent suspension, 4 shocks all the way around. It will serve as my Ginny pig to see what the ball diffs actually do. I personally like an almost locked up front end (spool), and hopefully these new diffs will allow for such an adjustment, or at-least get pretty darn tight (TA03 ball diff tight).

Tamiya has problem differentials, namely the ORV cars (Frog, Black Foot, Monster Beetle), and Wild One/Fast attack, and also the Hotshot series. They all have one thing in common, cheap pot metal used in the gear diffs. This unhardened metal wears out 2x as fast as the nylon gears, and with anything over a sport tuned 540 they wear out very fast. I really don't think a 3d printed part will hold up in the diff area, as this has been tried before with the ORV's. All kind of braces have been made to keep the gears tighter, but to no avail, crunchy gears after just a few runs. The MIP ball diff is nothing new, Thorp use to make ball diffs for these same exact cars due to the same situation. I welcome any hops ups we use to have available back when they were being raced.

And for the record RCCA is late to the game. Over at the Tamiya Club forums this has been discussed for months now. Alberto from AMPPRO Engineering has been the one who has been approaching companies like MIP to help promote and make available modern day parts for vintage modelers to enjoy.
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Old 02-03-2018, 11:51 AM
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Originally Posted by Tamiyadan View Post
I ran modified motors on gear diffs back in the 1980s. it could take it just fine.
the ball diff was just there to give you some posi action as the tracks turned from dirt to clay. but you still had current limiter ESCs back then. the 6 gear rc-10 was more a problem then any hotshot type gearbox.

for time that i ran big wigs and boomerangs they were fine they got outclassed as technology went forward. in fact we usually only ran a ball diff in the rear this was because 4wd understeered as is. so you wanted either a gear diff or a one way on the front end as a posi up front would reduce steering. next generation gave you a center diff to play with. most people today running brushless nuked the older ball diffs and went back to gear diffs.

tamiya back then had the better gearbox designs, but not really the best cars designed around them.

but as for eons better? no it won't magically make the cars lighter or find missing power.
if you are really having traction problems you would actually gain more from playing around with different tires before going to a ball diff.

really ball diffs are in this case will be more show then go.

in fact with modern 3d printers it would make more sense to design an undergeared replacement gear set for the hot shot so you could alter the internal gear ratio and lower it to be more inline with modified motors. tamiya always designed there ratios for super stock motors and nothing hotter then say 18 turns. so it was a total drag since 4wd class was always running hot modified motors and 8.4 volts and the gear ratio was wrong which resulted in literal melt down of the gear box.

I famously set my tamiya vanquish on fire at a race back in 1992. i was running a 15 turn and 8.4 1700mah pack and the motor got so hot by being over geared that it melted the gearbox which dumped the motor on top of my battery caused a massive short and set my buggy on fire.

hotshots and all the chassis that were designed off it through the big wig came from a time in 1984 where 800-1200 mah batteries couldn't handle hot motors so the gear ratio was designed for an earlier time.


just cause RCCA made you want to buy it didn't mean it was that great LOL!
Any cheap lipo pack today has 2x the capacity and way more voltage than a 1980's 7 cell. A decent 13.5 most likely far outclasses your 15t from 1992.

I would suspect most guys are playing around with these cars, but even if you take it to a track just for fun, I would rather have a ball diff just for the give in the driveline with no slipper in there.
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Old 02-03-2018, 01:21 PM
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Old 02-03-2018, 05:59 PM
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GAHHHH

I spent $250 on vintage Thorp ball-diffs for my Boomerang re-re after trying the MIP Blackfoot ball diff and discovering it wouldn't work. I sent an email to MIP about this and they said they'd look into it. I had no idea they'd release a new product so fast.
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Old 02-03-2018, 06:35 PM
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Originally Posted by fyrstormer View Post
GAHHHH

I spent $250 on vintage Thorp ball-diffs for my Boomerang re-re after trying the MIP Blackfoot ball diff and discovering it wouldn't work. I sent an email to MIP about this and they said they'd look into it. I had no idea they'd release a new product so fast.
Whats going on with your MIP diff in your Blackfoot? Is it rubbing or something? I seem to remember building mine about a year ago, and it was really tight and rubbing one of the transmission side plates. I believe the gear might be offset, so had to take it apart, flip the gear, and build it up again. Seems it worked fine after that. Also have to watch for proper alignment of the gears side plates, and the black plastic middle spacer. You almost need 3 hands to assemble the plates, spacer, and gears.

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Old 02-03-2018, 11:03 PM
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I don't have a Blackfoot. I have a Boomerang. That's why the MIP diffs for the Blackfoot didn't fit. The ring gear has the wrong number of teeth to fit a Boomerang. This new diff from MIP fixes that, though it seems they decided to keep the larger Blackfoot-style outdrives and include a special drill to cut new bearing sockets in the Boomerang's transmission housings.
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Old 02-04-2018, 07:23 AM
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Ok got it, I wonder if you could just get the new Hotshot diff gear and still use the Blackfoot outdrives. But the again, guess you would need the tool to make the hole for the larger bearings.....Hopefully MIP will help you to get things sorted out.
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Old 02-04-2018, 10:18 AM
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Nah, I bought my vintage Thorp diffs from private sellers, so they're mine now and that's that.

From what I can tell, the outdrives are the same on the MIP Blackfoot diff and this new MIP Hotshot diff. The only difference is the size of the ring gear. The stock diffs on the Hotshot use smaller outdrive bearings than the Blackfoot uses, that's why it's necessary to drill-out the bearing sockets on the Hotshot's transmission housings in order to fit this new diff -- because it uses those same larger Blackfoot outdrives.
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Old 02-04-2018, 12:20 PM
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I think it's great to see someone innovating new things for some of the Tamiya classics. I unfortunately think there will be a very small market for this specific upgrade but I'm glad to see someone investing time in this space.

I have a re-Hotshot that I'll be building soon. However, my goal was to finally get one of the two kits I always wanted as a kid. I don't plan to do much other than bearings (which I bought with the kit) and a tuned motor and tires. I suspect many will keep their Hotshots and Bigwigs fairly stock if they are being driven at all.
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Old 02-04-2018, 12:38 PM
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Yeah, it's a niche product. That's why MIP isn't going to make the diff unless they get 250 pre-orders.
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