Macinnis

Restoring my old Big Bear

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Cleaning out a closet a few weeks ago, and I stumbled across my old RC Big Bear.  Last I remembered the differential gear was stripped and the truck was just retired.  I pulled the rear end apart and found everything in decent shape, except that differential gear was gone.  The three small pinion gears were just laying in the case.  I had left the AA batteries in the truck and controller. They leaked and left a mess in the electronics.  Soaked the affected parts in lime juice,  squeaky clean now!   So i head to feebay and find that new replacement differential gears are available at a very inflated price, but this is not a cheap hobby so I ordered.  The gears that I found were the double bevel style instead of the new upgraded tri bevel high torque gears.  I just wanted to get the truck running so I used two of my tri-bevel gears in the double slots and put the truck back together.  It worked!  The truck ran and it was just as awesome as i remembered.  I started pushing the limits of the truck to see what it was capable of and heard a slight grinding noise so I immediately stopped and disassembled the truck to see what went wrong.  I find the idler gear has some funny looking wear on it so back to feebay.  Nothing major to any of the other parts so I stopped to work on the body.  

As i was running the truck I hit something at a funny angle and cracked the front body mount.  This part was surprisingly easy to replace as the files are available online to 3d render and sent the files off to a 3d printing company.  Replacements much cheaper than original.  Should have them soon.  Same file included the running bar lights so go those ordered too. Pulled the body off and removed all the screws and started paining.  Going back to the original blue and have aftermarket stickers ordered.  Just going to add some detail to the new paint job until I can get it running again.  So for now the truck sits until the new parts come in. 

Sorry about the long winded first post, but I wanted to document what I have done as info on these trucks is scarce.  Maybe help someone else if others are having trouble.  

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Welcome! I have a soft spot for the Big Bear; it's the one classic RC model I would still like to find someday. I had one back in the 80s (or rather, my brother had one, but quickly abandoned it), and years later I had an actual Datsun/Nissan 720 pickup, which I loved.

The Big Bear was pretty fragile to begin with, and as you have discovered, Marui parts are neither plentiful nor cheap. In light of that, you may want to take it easy on the old truck, and pick up a more modern model to "push the limits" of. Plenty of excellent choices that we can all suggest if you choose to go that route.

In the meantime, nice work on the Big Bear, and keep us updated.

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Cool to see another big bear getting a new lease on life. Despite it's fragility, and its lack of working suspension, they actually go quite well. 

Should finish painting mine, regardless of whether I end up keeping it or not.

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Nice Bear , see that you also have the original v1 two gear rear diff.

I am still hoping to find more information about the Marui v2 replacement or the MIP ball diff .

 

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Mmm noticed you got a different pinion and spur gear interesting.

RcMgF8RSsYLaX0hr66II4d2hL0zKWSthbIhfv-euDAJCOebNWAmdocnGjcTnKwW1pUje0h4cxwgZt6uf

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berman I am jealous of the interior of your Big Bear.  The detail on the dash and driver look great.  I am not artistic what so ever so I don't know if I could recreate that.  I am missing the driver and windshield on mine.  Depending on the price, those are on my watch list.

waterbok I too would be interested in finding more information on the MIP ball differential set that I have seen online.  No one seems to have any info on what parts are needed or how it gets replaced.  My BB came with the version 2 differential gear that had three bevel gears, but the V1 with two bevel gears is all I could find as a replacement.  As you can see in the pic my idler gear has some wear, so that piece is on order.  After that, every gear in the rear end will be new with the exception of the pinion gear.  I hope this allows the truck to be "lightly" driven.  I don't know why mine would have a different pinion gear than yours.  

I finished up the weekend with a new coat of Gloss Blue on the body, and did some light sanding to bring the Datsun emblems back to the surface.  Next step is some detail work.  The body has some battle scars, but I think it turned out pretty well.

If anyone else needs parts and has access to a 3D printer I found this site http://www.thingiverse.com/thing:1079909 that has 3D rendered a few hard to find parts.  There are companies online that you can upload files to and the will print and ship them much more reasonable than finding replacements.  They have the roll cage, bumper, KC lights, and body mount.  I am waiting on the lights and body mount. I will update once those come in to see how they turn out.

I was also able to find stickers at www.mciracing.ca .  They charge $10 US + Shipping while originals go for $60 US and up so that was a no brainer.

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9 hours ago, Macinnis said:

waterbok I too would be interested in finding more information on the MIP ball differential set that I have seen online.  No one seems to have any info on what parts are needed or how it gets replaced.  My BB came with the version 2 differential gear that had three bevel gears, but the V1 with two bevel gears is all I could find as a replacement.  As you can see in the pic my idler gear has some wear, so that piece is on order.  After that, every gear in the rear end will be new with the exception of the pinion gear.  I hope this allows the truck to be "lightly" driven.  I don't know why mine would have a different pinion gear than yours.

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I think the difference between the improved v2 3 gear diff set is also it has a different pitch for the teeth (v1 48p and v2 32p?) thats why your pinion and idler have a different teeth count.

Or you have an upgraded thrid party idler and pinion, i think i read somewhere MIP made something like that.

Be carefull that you dont mess up the diff gears teeth you wont find a replacement that easy. I am however thinkering with the idea of making them out of 3D printed.

Do you still have the v2 3 bevel diff gear, could you post pictures of that one and any gears that came with it?

 

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This is from wikipedia:

Quote

Kit Revisions

Owners of the original version (v.1) of the Big Bear experienced problems with its differential gears. This kit used the same gearboxes and gears as the Marui Jeep CJ (MT-59-RC-7) and the Marui Toyota Landcruiser (MT-59-RC-8) kits and consisted of 2 large bevel gears, and a gear set of 48 pitch metric. This proved to be a major problem for the first version of the Big Bear, as the special black M480RS motor and the large tires designed for the Big Bear created increased load, causing the differential gears to break or heat up and melt.

Marui made a special replacement part "#048 - Strengthened Differential Gear Set" that consisted of a tri-bevel differential, larger 32 pitch gears, and a change to the gear ratios. This new differential gear set found its way into the re-release of the Big Bear (v.2) coupled with a new heat sink plate between the gearbox halves. There were some draw backs to the new gears; The added torque of the new gear ratios made the truck do wheelies more easily, and made the truck a little slower. In addition to replacement gears and heat sink, Marui replaced the original M480-RS motor with an RS540-SH motor, and a redesigned mechanical speed controller with covered contacts to eliminate contamination.

Spare Parts List

The following Marui RC Parts were used for the Big Bear, as well as other Marui kits:

Part # Description
#007 GEAR & MOTOR CASE
#010 OILLESS BEARING SET
#014 CONTROLLER SET (the original speed controller for v.1)
#016 CONNECTOR SET
#021 SERVO SAVER SET
#028 DIFFERENTIAL GEAR SET (the original gear set for v.1)
#029 PINION SEAR SET
#030 FRONT ARM SET
#031 REAR ARM SET
#032 REAR AXLE SET
#033 BUSHING SET
#035 FRONT TIRE & WHEEL SET
#036 REAR TIRE & WHEEL SET
#037 BUMPER SET
#038 ADJUSTER
#047 CONTROLLER SET (the new and improved speed controller for v.1)
#048 STRENGTHENED DIFFERENTIAL GEAR SET (the new and improved gear set for v.2)
M060 CHASSIS
M096 WINDSHIELD-BB
M097 ROLL BAR
M098 SEAT-BB
M099 BODY-BB
M132 IDLER GEAR
M133 BODY MOUNT

Aftermarket Parts

Many supporting manufacturers developed products for the Big Bear. Here is a list of known aftermarket parts designed specifically for this kit:

Manufacturer Part # Description
BO-LINK   BODY MOUNTING KIT
BO-LINK   FORD VAN BODY FOR BIG BEAR
BRU-LINE 4202 SUPER SYSTEM REAR HUB - BIG BEAR
BRU-LINE 5278 BIG BEAR BODY MOUNTING KIT
IMEX   DAWG TIRES FOR BIG BEAR
MOORE'S IDEAL PRODUCTS (MIP)   BBG HEAVY DUTY GEAR SET FOR BIG BEAR      
MOORE'S IDEAL PRODUCTS (MIP)   BIG BEAR BALL DIFFERENTIAL GEAR
MOORE'S IDEAL PRODUCTS (MIP)   CASE SAVER
MOORE'S IDEAL PRODUCTS (MIP)   IDLER SHAFT
MOORE'S IDEAL PRODUCTS (MIP)   TEFLON AXLE BUSHINGS
PRO-LINE 2512 CHROME HUBS (FRONT)
PRO-LINE 2513 CHROME HUBS (REAR)
RACE MASTER 701 BIG BEAR WHEELIE BAR

 

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1 hour ago, waterbok said:

This is from wikipedia:

 

Thats awesome info, I've have to check what I have on the two Big Bears diffs I have. I am pretty sure one is a v1 but not sure of the other.

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These are all the parts I have left of the version 2 three gear differential as well as the pinion gears that go on the axles.  The actual differential gear that holds the three bevel gears was gone. It was shredded and I think i remember taking it out in hopes of making it to a hobby shop to find a replacement and lost it. The complete v1 gear that I bought of ebay is shown for comparison.  The 3 bevel gears are much smaller and require a different pinion gear that matches their angle.  That's probably the reason for the increased torque and slower speed.

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Oh cool could you give some dimensions on the diff bevelgears and a tooth count. 

I am still going thru some YouTube vids on how to do 3D gears :)

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@MacinnisThanks for the link to MCI Racing, decals are so hard to come by and are usually wicked expensive too. I will definitely be using them in the future!

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11 hours ago, Macinnis said:

@waterbok i don't know how I would dimension them and they have a funny angle on them compared to the v1

Tooth count and maybe upper/lower diameter, height of the gear and width of a tooth. As they are supposed to be 32 or 48 pitch I might be able to guess the rest. :)

Do you happen to have the 'old' 3 diff gear wheel somewhere? 

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So I checked what I have and it turns out that one my diffs is missing the differential gear pieces :( 

However the version 1 diff set as far as I can tell looks exactly the same as the Galaxy and Hunter diff sets. See comparison photo, maybe the 3 gear diff set was also used in another Marui car (it might make it a little easier to locate one?).

I also found that I has NIP 029 - pinion gear set. You both sizes for the spur gear and a matching pinion gear. see below.

Galaxy diff on the right

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029 Pinion Gear Set Packet, 

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On 1/16/2017 at 6:02 AM, waterbok said:

Mmm noticed you got a different pinion and spur gear interesting.

RcMgF8RSsYLaX0hr66II4d2hL0zKWSthbIhfv-euDAJCOebNWAmdocnGjcTnKwW1pUje0h4cxwgZt6uf

@waterbokhow many teeth are on the pinion gear attached to the motor on the V1 differential? It looks like 16 but I can't tell for sure. 

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Well never mind I can see in your last post it is 16. 

 

Does anyone know why when I put the two halves of the differential gear together and bolt them in, the tires will not free spin.  they will spin opposite directions but you cant set the truck on the ground and push it.  Is that normal?

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I saved some money and went to the hobby shop today and bought a pinion gear that goes on the motor.  Just so others know, if you use the version 1 differential gear and idler gear, you can buy the pinion gear 48 pitch, 16 tooth cheaper than an OEM and it works perfectly. (EDIT THIS IS THE WRONG GEAR. ITS A .06 MOD)  All of the gears in the rear end are now brand new.  The only slight problem is the pin that holds the idler gear fits a bit sloppy.  The holes the pin fits in are a bit wore out.  I took it for a quick test drive and it sounded very smooth.  I will take it back out tomorrow when its daytime.  Version 1 gears are built for top end.  The truck is MUCH faster top end.  The improved version 2 gears are very low geared.  The truck takes off much faster but is a bit slower on top end.  I actually like the v1 better.

This week while I was waiting on parts, I added a bit of detail to the truck.  The 3D printed body mount and KC lights are at the post office and will be delivered Monday so I will get pics of those once they arrive.  Still waiting on the stickers from MCI Racing.

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Carefull with the V1 even when it runs smooths, the gears are under dimensioned and cant take the strain in the long term. Hard cornering will ruin the diff bevel gears.

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20 minutes ago, waterbok said:

Carefull with the V1 even when it runs smooths, the gears are under dimensioned and cant take the strain in the long term. Hard cornering will ruin the diff bevel gears.

I told the hobby shop I wanted grease for the rear end and they recommended Team Associated #6588 Black Grease - 4CC.  I put quite a bit on each gear in the back.  I have enough left over to do it one more time.  After a few battery cycles, I will pull it apart and see how everything looks and redo the grease. 

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I got the 3D printed KC lights and "body mount" today from Shapeway.  First thing I noticed was the body mount was not right.  The package had the correct picture from the company they just put the wrong part in the bag.  So waiting to hear from them on that.  Going to put a coat of paint on the lights and get them installed and wait for the next step.  Hopefully the stickers arrive soon.

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The Big Bear is complete for now!  It has an occasional slip in the gears under torque but its screaming fast top end with the v1 gear set and does very well cornering in chat covered asphalt.  The stickers came in from MCI racing today.  The gears in the rear end are all brand new.  Still missing driver and wind shield.  Shapeway has to resend the body mount.  My new Bush Devil 2 will arrive tomorrow. On to the next project!

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I have yet to see a sticker staying over a 3D printed piece. Did you sand and polish those lamps?

By the way, what is your opinion on the MCI stuff? Good or not?

And of course, Ohhh that BIG BEAR looks juicy. As Peter Criss would say THAT'S THE KIND OF SUGAR PAPA LIKES!! :lol:

 

 

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