J8 Build

[summerof95]

I decided to start a build-tread to track future upgrades and modifications to my J8.

This started as a RTR Wrangler Unlimited.
I converted it to a J8 style body by cutting out the rear seats, installing a flat deck, and building the rear of the cab from styrene.
All of the small scale accessories are also built from styrene, except the fire extinguisher, which is steel.
Originally, I was really impressed with the looks of some of the super-scale C1 builds, and I wanted to go a similar direction with my SCX. But after beating on this for a while, I've decided I'm more interested in performance and durability, and am willing to sacrifice some degree of scale-ness to the cause.


Current Specs: (As of 07-25-14)

Wheels: Axial 8-hole beadlocks
Tires: 1.9 Trepadors
(Front wheels are weighted with 2.25oz, each)

Suspension:
All lower links, steering linkage, and rear-upper links are all-tread and brake line with Traxxas ends. Both front and rear axles are four-linked.
Shocks: Stock
Wheel Hubs: Standard
Wheelbase: Standard

Drivetrain:
Pinion: 15t
Idler: Robinson Racing Hardened Steel
Dig: Vanquish Hurtz 3-Position
Shifter: Hitec HS-311

Protection:
Sliders: 20ga bent steel, 10 degree boat side
Rear Bumper: Brake line
Front Bumper: Stock, trimmed

Electronics:
Battery: GForce 3S 2200mah Lipo
TX: RC3S
RX: R4EH-H
ESC: Holmes Hobbies Torquemaster BR XL (Waterproof)
Motor: Axial 27t
Steering Servo: Bluebird BMS-660DMG+HS
Winch: RC4WD Warn 9.5cti
Winch Control: HeyOk 4-amp Relay-driven

[summerof95]

Here are some recent (6/23/14) pictures of it:





Actual J8 for comparison

[summerof95]

Here's a few pictures from the conversion.

[summerof95]

Subtle boatside job.
Bent the sliders up 10°, and removed the bottom 6mm of the body for a minor increase in side clearance.
Note very noticeable at a glance, though.

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[summerof95]

The transmission had gotten rather noisy recently, so at the suggestion of a few members here, I order a new RRP idler gear. It's shipping from a couple cities over, so hopefully I'll have it pretty quickly.


I rearranged a few things on the chassis in anticipation of new parts.




The weather was decent today, so, after stopping at ACE hardware for some M3 bolts and all-thread, I took the Jeep out for a little hike by the lake.

Aside from an accidental tumble down a 20' hill, everything went pretty well. I did notice, part-way through the hike, that the throttle response seemed a little... off.
Here's what I found:

Yikes.

Here's a few shots I got today:

[summerof95]

So I've ordered parts from LiquidRC, Vanquish, and WowRCModels in China.

I've gotten shipping confirmations from all but Vanquish. They're obviously reputable, since there's tons of folks on here with their parts, but how long does it usually take them to ship an in-stock item?

[sjc115]

Looks great!

All except that fishing line, that looks like it could cause a heap of problems.

[raceeng18]

I like the body work, nice job.

[Johnnysplits]

Originally Posted by summerof95

Battery: Onyx NiHM

What made you go with a nimh battery?

[summerof95]

Originally Posted by Johnnysplits

What made you go with a nimh battery?

Initially, it was cost.

I gave myself a budget of $300 for a new RC car. Everything I've owned previously was 1/24th, but I wanted something bigger. Something easier to work on.
The local RC shop, Maximus, had the SCX RTR on sale for $289. "Well," I though, "this looks like fun."
Things were going great until we started talking batteries. $65 for a Lipo, and another $30 for a basic charger. Way over budget!
So I ended up leaving with a used HPI NiMH.
Nothing fancy, but I was thrilled to have my new toy!


Now I'm in a place where I could afford to switch to Lipo, but why?

Right now, more power just means spinning the slipper-clutch even faster. I think there's a number of upgrades to left do before the rig would really benefit from the higher voltage.

I've got nothing against Lipo, I ran 2S in my Micro SCT (and a poor Xmod), I simply feel that it's not the right time to make the switch.

[summerof95]

Between getting wedged in between rocks, and tumbling down hills, the driver-side mirror has started to tear through the lexan body.

I tried removing the mirrors, but that left two huge holes; not very scale, and just plain ugly.
I decided the solution was to make foldable, removable mirrors.


After cutting off the base of the mirror, I drilled a hole, and pressed a small metal rod into it.



I attached a small servo mount to the body, where the mirror had been.



Viola!
Folding mirrors. They can also be removed by simply pulling them up and out of the mount.

[sjc115]

I am constantly amazed by the great ideas I see on this board. The mirrors are very nice!

[summerof95]

First shipment of goodies!



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[summerof95]

RR idler gear

Vanquish Hurtz Dig



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[summerof95]

Well, the good news is that my parts are coming in...

The bad news...
I drove down to a local spot to crawl around, powered on the car, and only got one set of beeps ESC. Red LED on constant, green is flashing like mad.

Drove back to the house and started opening things up.
Tried everything I could think of, then finally called Axial customer service.
Tried all the same things again, then the rep said the ESC is shot.
He offered to send me a replacement if I can find my receipt, but I haven't a clue where it is.

Don't know what happened. It was working fine this morning, then this afternoon, dead.
Guess I need to find that receipt.

EDIT:
Found it. Email sent. Now to wait.
Not looking forward to being unable to drive it.

[Johnnysplits]

Originally Posted by summerof95

Right now, more power just means spinning the slipper-clutch even faster. I think there's a number of upgrades to left do before the rig would really benefit from the higher voltage

First off, the slipper should be locked up. Second, a 2s lipo has the same voltage as a 6 cell nimh (by .2v) ...close enough. It's the long runtime and full power until lvc is what you benefit from. You know, soon as you start using a nimh battery, the power gradually goes down...completely the opposite of a lipo. You can get great quality lipo's for around $30. A charger however, is where you want to spend some money. A $30 charger is not gonna cut it.

[summerof95]

Originally Posted by Johnnysplits

First off, the slipper should be locked up. Second, a 2s lipo has the same voltage as a 6 cell nimh.

Correct, 2S is essentially the same voltage as a 6 cell NiMH, which is why I was only considering 3S. If I'm going to make an upgrade, I'd like to gain something from it.
Considering I may have damaged a stock gear using NiMH, I don't think that switching to 3S Lipo and LOCKING the slipper would be a very good idea right now.

When I said:

Originally Posted by summerof95

there's a number of upgrades to left do before the rig would really benefit from the higher voltage

I was referring to things like HD ring/pinion, steel transmission, etc., things that would allow me to lock the spur and not grenade my driveline.

[summerof95]

I might not be able to drive it, but I can still work on it.

Installed VP Hurtz Dig and the RR Idler.



No servo for it yet, but it seems to shift very easily.
An FYI for anyone considering this dig, it requires a 1.3mm hex driver for assembly. I drove all over town trying to find one. Finally ended up with a cheap-o 30pc bit set, just to get that one size.

Can't wait to get my new TX and ESC, and take this for a spin.

Speaking of the ESC... I wonder how long it'll take to receive a replacement from Axial.
I've got a 10-day vacation starting on the 18th, and I'm going to go nuts if my rig is still out of commission.

[CrawlSD]

I like the body on this Jeep. Sweet!

[summerof95]

Thanks!
I wanted something a little different, there's too many plain silver RTR bodies out there.
Plus, it provides a good place to carry a spare. Keeping it on the bumper wasn't very practical.