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Old 12-25-2010, 10:02 PM   #1
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Default just got one

i just got a mrc for x mas and am looking to do some mods. i just need some feedback on what to do and what works the best. thanks
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Old 12-26-2010, 04:16 AM   #2
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Default so much you can do (if you wish)

CONGRATS on the new mini crawler. They are such fun.

Have a browse round the losi mini crawler section of this forum, there is so much advise.
Try to step back occasionally, it can get confusing and contradictory when reading the posts.

A good starting point with the MRC is simply to use it stock setup.
Get some good time practising, finding the limits of balance, climbing etc. Learn how the truck handles.

First simple steps to start with are re distributing the weight, mainly the battery. In stock form the battery is high up and throws the centre of gravity (COG) off. Moving the battery to over the servo (double sided foam tape / servo tape sticks it well!) lowers the COG and also places weight over the front axle (helps with grip on climbs). You will need to lengthen the wires a few inch. I would cut and lengthen the battery (cut one wire at a time to avoid shorts!) wire - solder if poss, crimp connectors will work ok too.

Next I would modify the front wheels (add lead wire inside the wheel (requires the tyres (glued) removing carefully (CAREFULLY cut between plstic rim and rubber tyre with a hobby knife/scalpel etc), and wrapping lead wire in the rim (about 2 oz per wheel is a starting point). Reglue the tyres once done. This will aid traction.

Soften up the shocks a little: remove the c clip spacers from above the spring. Maybe a drop of super glue to the spring cup to prevent it popping off and getting lost.

Limit articulation (seems a shame to lose all the super flex they MRC has, but it helps greatly). Add a piece of fuel tubing or similar soft tubing to the shock shaft (about 1/4inch is a start). This prevents the axles articulating too far and leaving the truck ina bind. Also helps with predictability whilst driving.

There are hundreds more stuff, some free to do, some require new parts.

Just try and enjoy each change, find the improvments and practice driving.
If you find you want to improve the rig greatly, some recommended upgrades (in rough order of preferance):
New tyres (Fit some comp tyres: dont come much better than HB Rovers ) will help MASSIVELY. The stock rubber is ok, but limited in grip. Fitting some Rovers will surprise you with how much a stock-ish rig can do.
New shocks - some alloy threaded ones allow smoother movement and adjustment.
Metal diff lockers (both axles and centre trans diff). With more grip, the plastic locker plates in the axles (and tranny) will strip out = no drive.
New servo - stock one is fine when the truck is standard, but with more weight over the front, more grip and more driver skill from practise(!) it will eventually either give up or not provide enough torque to turn when in a bind. There are many servos, check out people threads. A good mini (direct fit over the stock) is the HiTec HS-5245MG (metal gears high torque (5.5kgs)).

Hope this helps.
Just read some threads, don't worry about doing everything straight away.
Half the fun is learning, practising, finding a mod/change that improves your rig.
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Old 12-27-2010, 09:38 AM   #3
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WOW!!!!! i moved the battery, added weight to the front tires(2oz. per), and softened up the suspension so far. it made a WORLD OF DIFFERENCE! thank you so much.


anyone else have any cheap/free mods other than these???

even if they are expensive just list them

thank you
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Old 12-27-2010, 09:44 AM   #4
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Add weight to the front, but instead of gluing the tires back on cut four, 3/4" pieces of 2" PVC to slide over the inner flange on the wheels to make the wheels into an almost free set of beadlocks. Do a search for some pictures and write ups.
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Old 12-27-2010, 12:14 PM   #5
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ok will do

anyone else want to add some thoughts!
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Old 12-27-2010, 01:06 PM   #6
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Default where to start . . .?

There are so many things you can do, some require buying new bits though.

I modded my old stock MRC as far a I could, before buying a new chassis. Then the new chassis only made a small difference.


For the free mods:

My suggestions are (in no particular order)

remove the servo saver (the spring arm on the servo) and replace with the solid one that came with you MRC (Should be in the psares bag). This will improve steering a fair bit (within the limits of the stock servo). Just be a little more forgiving when the steering is bound up (eg, wedged between rocks) as there will be no "give" in the steering setup now and can strain the servo.

Flip transmission 180. Easy to do on a stock model, this mod simply gives more room to the front area above the upper link. To do: unscrew four bolts each side from lower edge of chassis side plates (twin vetical plates TVP), drop skid and tranny together, flip round 180 and refit. This makes the next mod a tad easier.

Remove the battery tray, cut out the middle section just leaving about 1/2 inch of the end (the idea is to ditch the plate's weight, leaving the ends to keep the chassis plates joined, and keep the shocks mounted.). You will need to rehome the ESC and Reciever (RX). A good place is to make a plate for the ESC to sit on (take some old body shell, DVD case, Butter tub etc, cut a triangle to fit on the upper triangle link (glue or punhc holes and zip tie in place). Stick ESC on upper link (front preferrably). This gets weight down - lowering COG. Stick receiver ontop of transmission casing (RX weighs very little).

Check all links and shocks move freely. Sort any binds (jamming, stiffness, touching of components) to keep suspension supple.

Four link. This is getting a bit further out of simple mods but can help reduce torque twist. It helps to do the rear mainly. I did mine by simply removing the rear triangle upper link (a 3link setup) and replaced by two links (3mm/3mm rod end at each end, 3mm all thread bar between). I made a plate from 2mm alloy sheet, which replaced the rear axle plate. this new plate extended forwards by about 1/2 inch (tapered/cut to clear shocks) with holes for new links' rod ends to fit to.

four link for rear:


fitted,
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Old 12-27-2010, 01:25 PM   #7
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The bead lock tip mentioned above is a great one to do (I never found any tubing the correct diameter , but it would save regluing tyres ever time you change foam or weights).

Bent lower links (mainly for the rear) helps clear rocks and ledges. A free method ( a little redneck method but hey it works) is to take the stock lower link, put in a vice (so the flat at the mid point is just sticking out of the vice) and bend the rod (carefully) to about 30 degrees. Now when refitting the this bent rod, note it will be slightly shorter eye to eye than it was straight (by about only 1.5mm) so you need to wind out the rod ends a couple of turn s each (remember one is a reverse thread!) to retain the original suspension geometry.

Lower the shell. Drill new body holes about 1/2 inch higher up the shell, to lowe it when fitted. You may need to also trim the fender/wheel arch areas to prevent tyres and battery touching during articulation.

By now your crawler should be getting pretty sorted. You may need to start spending money to see improvements. a good place to start is some new tyres (the stockers will hold you back now). I am sure everyone will recommend the HB rovers, they grip better than any. Don't look much different, but fit some and you will be amazed.
Servo - new metal geared high torque (mini or full size - which requires a new servo plate and some faffing with steering links but easy to do).
Eventually consider a move to a LiPo battery (much bettery "punch" and power delivery. SLightly higher voltage (fine) gives better wheel speed too.


there you go my two pennys worth
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Old 12-27-2010, 07:25 PM   #8
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so i did the motor and tranny 180 and moved my electronics and now my esc will flash orange for a second (2-3 flashes) and go out. i had to unplug everything to do this transformation and i plugged everything in its corrective spots (checked 3 times). i tried to bind them again and it didnt work. i also have no power to the servo or the motor, any ideas???
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Old 12-27-2010, 09:36 PM   #9
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not my thread but thanks to all who replied, helped me a ton. I also got one for xmas, my first crawler btw, i thought it would be a good start, it was bnd and smaller, little cheaper parts and so forth and so far i love this thing so much potential it seems!
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Old 12-28-2010, 02:42 AM   #10
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Quote:
Originally Posted by 98sahara View Post
so i did the motor and tranny 180 and moved my electronics and now my esc will flash orange for a second (2-3 flashes) and go out. i had to unplug everything to do this transformation and i plugged everything in its corrective spots (checked 3 times). i tried to bind them again and it didnt work. i also have no power to the servo or the motor, any ideas???
There is no problems unplugging things and then plugging them back in (the RX and ESC keep their settings).

Sounds like you have a plug in the wrong way round.

Unplug everything.
First you need to swap the motor wires round (forgot to say - as flipping the tranny , has the motor running in reverse (not a problem)) or flip the Transmittor switch (throttle reversing switch on top).

Now plug in the leads into the RX:
Looking at the RX head on, have the pins/socket in the bottom right corner as you look at it.. Now plug in the throttle (ESC) plug and Steering (servo) plugs, make sure the black wire (or brown on some) is to the far right position (i.e. near the edge of the box).
[looking left to right, the wires run: SIGNAL / POSITIVE / NEGATIVE. or WHITE / RED / BLACK or YELLOW / RED / BROWN]

You should not need to rebind. Once bound a rx and tx will not lose their binding. (If you have messed up the binding, fit the bind plug and perform a bind as per the instructions.)

It should be fine. The orange LED is the ESC powering up, not finding the RX properly, then shutting down. To confirm this, try plugging just a battery into the esc (i.e. unplug from the RX) it will do the same when switched on. When the RX is plugged in correctly it will light flashing Green (on the RX). Solid green when bound to a switched on TX.

Post back with how you get on.


G
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Old 12-28-2010, 03:04 AM   #11
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plugs must have been backwards, thanks man


p.s i need to learn more i guess haha
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