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Use this area as your personal project pages or blog! Each thread belongs to one user as a project page!
By 66deuce
#132587
Hi all. Despite my post count, I'm not new here. Had an account before, some of you may remember project barbie crawler: viewtopic.php?f=3&t=13167

Anyway, I'm now re-registered and going to share my latest project!

I actually picked this jeep up for $40 right around the time I was finishing Barbie crawler, but it's been on the back burner, as the girls took quite some time to get used to the smaller ones and I had other irons in the fire. But I finally got motivated when I spotted a stack of brand new 15" Kenda snowblower tires at my friend's shop, of which I purchased 4. That night the wheels in my head started working out the details, and the parts ordering began. I got the frame built last week, and some of the bits I ordered are starting to trickle in. We're still ~ a month from completion, on account of the 120 tooth steel 1 module main gears and 1.5 module bevel gears for the diff had to come from China, but I have most of the suspension and electronic parts now. It will be 4 link suspension 4 wheel drive, powered by a pair of UB12120 batteries running volts and amps through a 3,000 Watt PWM controller to the 68x92mm DC brush motors.

Here is a comparison of the stock motors vs. the new units:

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This is the frame, made from 0.083" wall 1"x2" square tube, MIG & TIG welded:

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This is the approximate finished ride height:

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It will ride on coil-over shocks, made from 1" OD x .120" cut-to length coil springs over 100N lift struts. Still waiting on the M6 metal heim joint ends, but the plastic bits were fine for mocking it up. Machined 416 stainless low spring mounts, and used some vinyl tubing over the strut body to help keep the spring straight (pic before tubing was added):

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Front axles consist of 1/2" round bar with a ball machined on the end, the stubs I turned from 1" stock to 5/8" diameter except for the rear flange. I went with an impact wobble type joint because it is simple, and because it allows me to move the joint and knuckle pivot closer to the center of the wheel to mitigate tire swing during turns. Cross pins are 1/8", and are held in place by the bearings (double row 5/8x1-3/8x7/8):

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I do have the first bearing housing made, although the knuckle and steering arm portion are not yet fabbed. The bearings are retained by snap rings on both sides. The wheels are 1" keyed, so I will be machining inside and outside keyed adapters 5/8" ID & 1" OD. The entire stub axle, adapter & wheel assembly will be retained by a 5/8-18 castle nut.

Axle housings are 1" ID schedule 40 steel pipe. The gear boxes will be made from two pieces of 1/2" plate in a tear drop shape, which a friend of mine will water jet the external profile, then I'll mill the internal dimensions. Each housing half will be welded to the axle tubes, then they'll bolt together with five 5/16-24 socket heads. The differential carriers will bolt to the main gear. Out drives will be 12mm 12 point sockets, welded to the bevel gears, with corresponding male triple square cut into axle shafts. These will be oil filled diffs as well.

The suspension won't be anything fancy, basically what you'd find under a real Jeep TJ or JK, with 4 links and a track bar on each axle. LH and RH threaded 5/16 heim joints with 1/2" OD bar for the links, steering linkage will be 1/4" heims. I have not yet decided if I'll stick with a simple arm pattern for steering or make a gear box , will probably wait and see how difficult it is to turn on the aggressive pneumatic tires under the (estimated) 135 lb curb weight.

These motors clock 4188 RPM at full tilt on 12V, so the no-load wheel speed would be 12.4 MPH; I expect speed with 80 lb payload to be 8-10 MPH.

Will update as more progress is made, hope ya'll enjoy this one!

And no, aside from water jetting the gear box housings, none of this is being farmed out or done on CNC equipment. All the custom parts you'll see here are machined manually on a Lagun FTV-2 knee mill and Hardinge HTC lathe, all welding in-house with a Snap-on MM250SL MIG and Simadre 5200DX TIG/Plas.


#132589
:shock: :shock: eagerly awaiting the next update 8-)
#132672
Wired :D

Still don't have the LED head and tail lights, but the switches showed up yesterday, so I got all the wiring done sans the DPDT switch for the forward/reverse modes, as I have not yet found one I like. I didn't take a pic before installing, but the foot pedal is modified with a slightly longer screw for the necessary travel, then a return spring added. The 100K ohm 35mm linear potentiometer is in a housing I carved from 1-1/4" ABS, and moved via a simple music wire link.

It was a long night of measuring, fitting and soldering, but the end result is a clean wiring job with not a single crimped connection. Dug through my bin and found both halves of a GM 10 pin connector, which is perfect for connecting the dash harness to the chassis in a way that the wind screen frame can be removed easily with just two connectors and the 5 screws (second connector for the not-yet-present brake light switch). There are two unused terminals in the connector, and I did run separate brake lamp wires for left and right, so I may add turn indicators later.

We did go a little overkill on power wires with 10 ga fine strand silicon, but why not. The 10 ga stuff isn't that much more than 12, ($1.66/ft), and there's no question it'll carry the load.

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Had to do a second pic for the power switch, as the LED in that one is far too bright for the camera to show anything but a starburst in a head-on shot

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I thought these 5 pin switches would allow the LED in the switch to illuminate without any voltage output from the contacts, but alas, I was wrong. All the extra terminals do is allow different switch illumination configurations (always on, on when depressed, on when extended). Since the ESC switch simply closes an internal circuit but does not apply voltage, I had to use the switch to control a micro relay, and the relay to close the ESC "on" circuit. A small draw I didn't want, but oh well. Had to have the big chrome 19mm illuminated switch!
#132749
Made some progress on the differentials today, as the first part of my gear order with 4 bevel gears came in (no idea what the hold up is on the rest, since they were ordered same day).

The parts individually: Mod 1.5 16 tooth 8mm bore bevel gear, I counterbored them .500", .375" deep. 5/8x1-3/8 bearing. 12mm 12 point socket, the rear .710" I turned down from .671" to .625". Oil seal, 17mmx26mmx6mm. Coupler, machined from 5/8" 0-1 drill rod. .312" stepped to .500", then a .375" square to fit the socket.

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Mocked up:

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The coupler TIG welded to the sockets (out drives):

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And a pair of out drives with spider gears as they will exist in the carrier that I have not yet machined:

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I initially planned to weld the bevel gears directly to the sockets, and then try to find .671" ID bearings or make sleeves. But after staring at the pieces for a little while, I decided to make use of the square drives in the sockets and the set screw provisions of the gears. The couplers are spot-drilled for the set screws.

The carrier will be a hybrid, part full size vehicle and part RC in design. It will be open on the sides and use a through-carrier cross pin for the gears like a regular automobile, but the main gear will comprise the rear of the carrier, as in an RC. The bearings on the out drives will also support the whole assembly like an RC car.
#132773
Got one carrier done (except for the main gear mounting holes, which will be done with the main gear in place once I have it to ensure perfect hole alignment). It started life as a chunk of 3" x 6-1/2" steel bar stock. 217 passes on the lathe and a couple hours of mill work later, it is 2.178" long, 2.600" diameter with a 1.850" cavity 1.733" deep.

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Also added a volt meter to the dash and a 40mm cooling fan to the ESC:

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#132939
Main gears finally showed up, so one carrier is now complete. Just have to build another that is identical!

A gear as received on the right, one I've finished machining on the left. These are 4.8" diameter 120 tooth module 1 gears, .400" thick, surface hardened:

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Tapping the six #10-32 x .600" holes on the carrier:

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And assembled:

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The final weight of the carrier and gear assembly is 4.29 lbs. Motor is 2.4 lbs. That means we are more than five times the weight of a standard PW gears & motor. Just slightly more substantial than stock parts :D
#133844
Well, mother nature's wrath caused some delays on this project, as cleaning up flood water and mold in the house is more important than modifying BPROs, but I finally had some time to get back after it. Yesterday I sat down with my buddy to do up the water jet CAD file for the gear box housings, and I've made some other progress since my last update.

Got the rear spool made:

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Got the splines cut on the rear axle shafts (a bit of a headache, as 12 point sockets aren't just triple squares nor a double hex, with the points being an obtuse angle of 110°)

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Re-did the front axle shafts out of 5/8" O-1 drill rod, hardened after machining. The shaft will be cut in two and the ends splined once I determine lengths.

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Bearing housings are done, as are the keyway cuts in the spindles

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Bought 5/8" ID x 1" OD 1018 steel bushings to adapt the wheels, which I had to broach inside for 3/16 woodruff keys. The adapters I TIG welded into the wheels to simplify installation and spacing off the bearing race:

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Also got lighting done

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And modified a 150A winch relay to toggle forward/reverse using one stock DPDT on/on switch:

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That's it for now, but hopefully I'll have those housings done sometime next week, and then I can move on to setting up suspension. Also have mod 1.5 gears on order for a 3:1 steering gearbox I plan to build
#133952
Still making progress on this, but there seems to be little interest in this build from the community here. I'd like to poll those who visit to see if I'm wasting my time uploading images and updating the thread.
#133953
66deuce wrote:Still making progress on this, but there seems to be little interest in this build from the community here. I'd like to poll those who visit to see if I'm wasting my time uploading images and updating the thread.
Your going to have to learn to be patient :lol:

400 views in 2 months is actually pretty high. There isn't much discussion because to be honest, machining your own differentials and shafts is well above the skill and budget of the majority of power wheels modders. We are all enjoying your build, just don't have much we can contribute to it. ;)
#133956
Little interest??!! I have never been so interested in a build here before. You also haven't asked for opinions or asked any questions so I thought it was pretty normal to have low replies. Also keep in mind that people will be reading these posts Years from now. I have been searching posts here and on other boards and learning from other guys that were building years and years ago.

Please Do Not Leave Us Hanging!!
I will now return to patiently waiting for future updates.
#133958
400 views in 2 months is actually pretty high.
Guess I'm just used to higher traffic boards; when I started my miniature AR-15 build thread on AR15.com, we were at 12 pages after 2 months. But then, guns are a more popular subject than modifying ride on toys.

As long as I know that at least a couple of folks find it entertaining, I enjoy posting about projects like this. Not looking for pats on the back or anything, just to know that I have an audience to justify the time spent uploading photos and explaining what's been done.

That said, my buddy got the pieces of 1/2" plate cut out on his water jet for me over the weekend, so yesterday I got after it and have one housing done, save for the axle tubes. Yeah, I could have cut them myself with the plasma torch, but there is much more accuracy and virtually no clean up with the jet. I do still have to make spacers and drill holes to mount the motors, but that's easy.

Pieces fresh off the water jet:

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Insides machined:

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Welded up:

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And assembled:

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Housing with guts weighs 11.4 lbs; this thing is not gonna be light!

For the record, I'm a pretty decent machinist, but a mediocre welder-especially when it's circumferential welds with multiple tacks and no fixture. I'll probably go back over it with the TIG, try to flatten out and blend those fugly areas where tack and bead meet.
By edac
#133967
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Can you show some detail of the steering linkage? I'm thinking 2wheel drive.
Last edited by edac on Wed Jul 22, 2015 5:26 pm, edited 1 time in total.
#133970
Can you show some detail of the steering linkage? I'm thinking 2wheel drive.
I will when it's done, but we're not quite there yet, and, as with many things, I don't fully know how it'll be done until I'm doing it. I start with a vision in my head, and then it evolves based on availability of parts and materials, changes in geometry or available space, etc.

This is going to be a 3.17:1 gear reduction steering, as the weight of the chassis combined with the traction of the tires would make it nigh impossible for a young kid to turn the wheel with a stock type arrangement. I was initially thinking ring and pinion gears that I stole out of an angle grinder, but decided I'd rather keep it linear, so ordered three 1.5 module gears, 2x 12 tooth and 1x 38 tooth. Straight cut gears are also more forgiving of tolerances than spiral cut bevels, which put quite a lot of strain on the pinion bearings, and will skip teeth if there's much play in bearings or housing.
#134009
Getting there!

Front axle tubes (1-1/2" 0.025 wall DOM, turned to 1.375" OD and bored to 1.023" for the 1.025" seals on the diff end) mocked in place:

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Cutting the motor adapter on the rotary table. Not just a spacer; provides O-ring sealing on the shaft to keep oil out of the motor, and changes the mounting from 3x M5 screws to 2x 5/16-18 bolts. This way, I can run the bolts all the way through the housing so that the motor can be removed without having to split the axle.

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Tubes welded and motor attached

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Axle completed:

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And with tires (weighs 45 lbs!):

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Used 3/8" heim joints to act as ball joints. Tie rod is 1/2" 0.080 wall tube with 1/4" heim joint ends, obviously bent to clear the gearbox. Everything is working great!

It does all have to come apart again to loctite all the set screws in the diff, install the axle seals after I'm done welding control arm and shock mounts, and to fill with gear oil (no fill plug, will simply be stood on end and filled, then sealant on the case halves and bolted together).
#134018
Took the motivation I had today and ran with it, got mounts and links built, axle is under the Jeep! Still have to get the shocks and trac bar done, but I really feel like I'm making progress now.

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And, though sluggish, it was able to get rolling with me on it. Of course, that's just one motor driving, batteries that were only at 11.8 volts with no load, rear wheels riding on steel tube (no bearings) and my 190 pounds as payload.
#134040
Front coil overs and trac bar mounted. Compresses pretty good under my weight (~185), but I'm definitely gonna have to clip more coils to make it compliant with only the body, batteries and a couple of small kids (32 & 36 lbs).

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#134042
The front axle setup is looking wicked! However, it's nearly impossible to get a spring rate that can sit neutral on a power wheels. Automotive Vehicle payload is usual under 35% of total vehicle weight. On a power wheels vehicle payload is usually 200-300% of vehicle weight, and can change dramatically if there are one or two riders. This means your suspension sits at full extension all the time with only some limited compression available.

I bring this up because years ago a "founding" member designed his front axle without springs. The 5 link axle rested on a "soft" bump stop with free down travel limited by straps. He found it had enough compression give to provide a decent ride, and yet followed the terrain with down travel to maintain excellent traction. I thought I'd mention it here
#134043
Yeah, I've been thinking about that, and the most likely solution is going to be either annealing a portion of these springs, or going to a dual spring set-up, with some very soft ones that are about 1/3 the total length and compress almost fully under static load + 60 lbs. That way there will still be downforce on the axles during articulation, yet compression available for impacts.

definitely challenges in addition to the sheer amount of machining and fabrication (I'll probably exceed 200 hours on this build). As you noted, the majority weight of a normal vehicle is body & frame, with relatively little payload and unsprung weight. By contrast, the unsprung weight will be about 60% of this vehicle's total weight, which I now estimate will be ~150 lbs, vs my previous 135 pound guess (axles & tires coming in at about 90 pounds, negligible amount in partially sprung weight of links and shocks), and occupants will double or more the load.
#134052
I've struggled quite a bit with the issue. Shorter springs or a dual spring setup with a very soft second spring can lead to a very tippy ride, especially if there is only one rider. That can be overcome with a sway bar, but then articulation is nearly eliminated. Perhaps some very careful sway bar tuning could make it work
#134059
It'll really just come down to playing with it. One thing that does change the game with this build is the use of shocks, not just springs. Specifically, they are gas charged lift struts, which are valved to extend slowly. When the suspension is fully compressed under my weight, if I suddenly jump off, it doesn't just spring back up; it takes the better part of a second to return.
#134091
So, I decided to spend pretty well the entire day Sunday on this, and then I've thrown quite a few hours at it the last two evenings. Made a lot of progress, though. The rear axle build became a little more involved than I'd originally planned, as I decided to use pocketed bearing flanges, as you'd find on many full scale rear wheel drive vehicles. However, the bearings are not a pressed fit as you'd find on a full size. Rather, I welded up a ring and then machined it down to create a shelf. The bearing rides against that, followed by the brake rotor adapters (I used 2219-T651 aluminum for those), then the 5/8" ID x 1" OD sleeves, which I cut for 1/4" key stock to match the wheels, and attached them to the axle shafts with 0.207" hardened pins. The wheel bores retain the pins, and the axle nut is tightened, that tension locks down the inner bearing race and rotor adapter, and pins the rotor against the adapter, as I machined the shelf on the adapter 0.005" shy of the rotor thickness. The rotors are cut for the key stock as well, but it's really the friction between adapter and wheel hub that keeps them from spinning.

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I also managed to find little CV boots for the front axle joints :D They're for an HPI B5, cut down to fit in my application.

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#134096
The little CV boots are a nice touch :lol:
#134125
Well, today was quiet around the shop, so I tore it completely back apart to install axle seals, fill diffs and paint.

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That is final assembly. I was pretty close on my weight estimate, too: Chassis with tires is 116 lbs, body with batteries is 44 lbs for 160 lbs total.

From here, it's just sorting out the steering gear, which I got started on today. Primary housing machined (it is pocketed for bearings, running 8x14x4mm on the pinion and idler, 12x28x8mm on the spur). Gotta do the cover, then drill and tap holes, and whip up a shaft and arm.

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Those are module 1.5 gears, BTW. HUGE teeth, as large as you'd find on the gears in a full sized car transaxle. The spur is 2-1/2" in diameter and just under 3/4" (actual 18mm) thick. Had to counterbore it 4mm on either side to keep the box dimensions narrow enough to fit underneath, forward of the battery compartment.

Unfortunately, however, I've discovered that these 180 watt 68x92mm motors just don't quite have the torque needed with only 15:1 reduction. It'll move, even with me on it (188 lbs dressed), but empty, it couldn't crawl over a 5" tall block. So, I've ordered some 76x88mm 250 watt cans, and a couple of 24 tooth spur gears. I'll be ripping the shafts out of these motors to become pinions off the 3:1 gear box that will be fitted to the new motors, giving a final ratio of 45:1. To keep speed decent, we'll be going 24V, so these motors will actually be putting out closer to 500W each. The motors are rated at .4 Nm on 12 v, so at 24v and after 45:1 reduction, the combined torque of both axles should be in the neighborhood of 50 ft lbs. There won't be any modification to the axle housing for the new motors; I'll machine identical mounting points into the gear box, and the motor will simply be offset slightly. The beauty of DC motors is, of course, that no idler gears are necessary to achieve correct rotation, just switch polarity when you add or subtract a gear.
#134134
Unfortunately, however, I've discovered that these 180 watt 68x92mm motors just don't quite have the torque needed with only 15:1 reduction. It'll move, even with me on it (188 lbs dressed), but empty, it couldn't crawl over a 5" tall block. So, I've ordered some 76x88mm 250 watt cans, and a couple of 24 tooth spur gears. I'll be ripping the shafts out of these motors to become pinions off the 3:1 gear box that will be fitted to the new motors, giving a final ratio of 45:1. To keep speed decent, we'll be going 24V, so these motors will actually be putting out closer to 500W each. The motors are rated at .4 Nm on 12 v, so at 24v and after 45:1 reduction, the combined torque of both axles should be in the neighborhood of 50 ft lbs. There won't be any modification to the axle housing for the new motors; I'll machine identical mounting points into the gear box, and the motor will simply be offset slightly. The beauty of DC motors is, of course, that no idler gears are necessary to achieve correct rotation, just switch polarity when you add or subtract a gear.
I was curious on how it was going to do with so little reduction. Stock gearboxes, even the 24v ones run 100:1 to nearly 300:1 in certain applications. And yes, we are jealous that you can just machine another gear into the adapter to quickly switch up ratios :evil: :lol: :lol: :lol:
#134145
I was curious on how it was going to do with so little reduction. Stock gearboxes, even the 24v ones run 100:1 to nearly 300:1 in certain applications.
There was really only one way to find out. In theory, it would have similar axle torque to a standard PW 550 motor geared a little high; a typical ~15K RPM 550 makes 0.04-0.05 Nm torque, where these cans are rated at .3 Nm, or about 7 times as much. So, 15:1 would theoretically give me the same wheel torque as 100:1 with 550s. Granted, that's still a little light, but 15:1 was the highest ratio I could achieve direct driving the spur with the motor pinion using readily available parts.

Like I said, it will get moving, and it'll even carry me, but crawling ain't gonna happen as it is. 15:1 with these motors on a relatively stock 60-80 lb BPRO with plastic wheels would probably work just fine, but at 160 lbs with the traction of 4 pneumatic tires, these cans really strain to get started, with momentary spikes in current draw up to 68A on my Fluke meter.

The new arrangement will have about 8 times the wheel torque, and though the calculated free wheel speed on 24V @ 45:1 is lower than current set up on 12 (12.4 vs 8.5 MPH), I think the real world speed on flat ground will be about the same.
#134190
Got the steering gear done. Major brain fart on that one; I finished the housing pictured above, mounted it, and then realized that I'd gone from originally planning to run the steering on the back side of the axle to where it ended up on the front, which means the arm needs to pivot in the opposite direction that the wheel is being turned, hence no idler gear. So today I made another housing, this time with just the two.

I decided to use a pressed fit on the pinion gear, but selected a cross pin arrangement for the spur.

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The arm & shaft are obscured when the front bumper is attached. All that's left for steering now is to make a universal joint to couple the stock steering shaft to the gearbox input shaft. I was going to make a bearing plate to live just behind the wheel, but I'm not sure that's necessary.
Last edited by 66deuce on Sat Aug 01, 2015 11:44 pm, edited 1 time in total.
#134193
What is the actual steering ratio? How many turns lock to lock? Looks like you nailed it perfectly keeping the drag link parallel with the track bar :)
#134197
The gearbox is 3.17:1 (12T & 38T gears), the ratio of the pitman arm (2.375" CTC) to the knuckles (2.875" CTC) is 1.2:1. The input shaft rotates 260° lock to lock right now, although I can shorten the pitman arm almost an inch if effort is still too high.

I'd like to have gone with a higher ratio, but space was pretty constraining. There's only 1.3" between the battery compartment and grill backing. I'd have had to step down to module 1 gears or cut the 1.5 modules in half to double up, and the latter would have meant running much smaller bearings on the spur gears. The kind of hits steering parts can take, there's a reason I went with these really husky gears and output bearings.
#134203
We have steering! In retrospect, I probably should have just bought the dang $20 U-joint, but it's done now. Yokes cut from 5/8" 0-1 drill rod, cross is 5/16" key stock with smooth profile 4-40 socket head screws. There's a bit of play, but no more than a stock PW. It was expected, as we're tying a lot of things together here, some of which I just didn't feel like taking the time to bring to tighter tolerances than +/- 0.003", given the application. That may not sound like much, of course, but stacking tolerances and exponential increases as you move away from a pivot point add up to about 20° play at the wheel.

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Last edited by 66deuce on Sun Aug 02, 2015 1:57 pm, edited 1 time in total.
#134225
Got the brakes finished up

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It's actually a somewhat complex pedal assembly, though it doesn't really look it.

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Also went ahead and ran in series for 24 volt; on the passenger side is the 10 amp voltage regulator to run relays, lighting, etc. Also added a pair of 30A automatic breakers in parallel.

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And another volt meter in place of the CB radio channel sticker

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And got the OEM wheel covers trimmed to fit the 6" steel wheels

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Still waiting on the new 250W motors, although my 24 tooth gears came. Unfortunately, we also discovered that winch solenoid isn't adequate for this application; after about 5 or 6 minutes, the coils get hot, weaken, and can no longer overcome the spring. Soooo....I have a pair of 80 amp DPST relays en route to replace it.
Where did you get the coil springs for the struts.
http://www.ebay.com/itm/331316359941?_t ... EBIDX%3AIT
#134284
Well, seller has been slow to ship those motors; I might see them by Saturday. Unfortunately, because I don't have specific dimensions, I cannot build the gear boxes until I have the motors in hand. However, I did get the electrical upgraded. These motors are rated at a full load current of 35 amps each, but I know that the load can go higher under certain conditions-like, double. While I do have circuit breakers, they may not react fast enough to prevent smoking the ESC. Solution? Add another ESC in parallel to share the load. That's 6,000 W total capacity, or up to 250 A @ 24V. Of course, 10 ga wire cannot handle that, so we're running 10 out of each battery to each ESC, and also from the relays to the motors. But between ESCs and relays? Rather that run four 10 ga cables, I opted for a pair of 6 ga.

One of the batteries is out right now for patterning the mount for the two that will live under the seat (total 4x UB12120):

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Not enough room in the body channel for three 18 ga, four 10 ga and two 6 ga wires, so we had to go under the body:

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Last edited by 66deuce on Wed Aug 05, 2015 9:04 pm, edited 1 time in total.
#134290
Wow, this is a crazy awesome build. I don't have anything to offer due to the fact that this is way beyond my ability, but I do read and enjoy it!
User avatar
By taz11
#134291
Moderator Pick.... :D 8-)


I link to this build has been added to the Moderator Pick thread.
#134302
Other two batteries and two of the relays came today, so I zipped down to wally world to pick up a container for these new bits, then spent my down time while waiting on parts for a customer vehicle to set it all up. Opted for studs and eyelets to connect everything, since insulating is not really a challenge on plastic BPRO bodies. No spade connectors on the relays; soldered 10 ga wires directly to the terminals. There is a 1/8 x 1" steel strap supporting the container.

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My impatience cost me a relay, though. Just had to try it out, even though I knew the load would be to high for just one relay per pole. I was proved right after about 12 seconds.
#134303
Absolutely awesome! And thanks for all the posts...sorry it has taken me so long to sign in and post a few compliments...you're really gone over the top on this. Plus, finding the time to do all this is hard enough, then you have to post it, too.

So...I'm sitting here thinking about all this work you've done...eventually the kids will out-grow just about anything electric (maybe not a certain mustang)...are there plans for a 2-stroke motor? I was in the barn looking at our stock 14" wrangler and I have no idea where you'd fit that it...but I bet you could figure it out :)
#134306
are there plans for a 2-stroke motor? ? I was in the barn looking at our stock 14" wrangler and I have no idea where you'd fit that it...but I bet you could figure it out
Nah. Fitting an engine would be the easy part; getting it to drive the wheels would be much more difficult, especially if trying to incorporate reverse. Would have to use a crazy chain set up with jack shafts galore or build bevel gear boxes that could use drive shaft inputs........something like that. And then there's not really having any room for such a drivetrain under the body. One of my initial concepts for this build was a single motor with a central gearbox running drive shafts to each axle, as in a real Jeep. But that system would have been far more complex than dual axle-mounted motors, with the added disadvantage of parasitic loss through more drivetrain. Only upside would be cool factor.

No, we'll just upgrade them to go karts, quads and dirtbikes, mothball this thing until they have kids of their own (no way I'm selling it, wouldn't even be able to recover parts cost)
Last edited by 66deuce on Thu Aug 06, 2015 9:54 pm, edited 1 time in total.
#134335
Motors came in yesterday! Wrapped up work for the day and immediately got after this. By 1am, I had one gearbox finished and installed, gotta do the other today. I now know this: 250W 12V motors on 24V with 45:1 reduction have plenty of torque! It lurches pretty hard with me on it and only the one motor, will spin both rear tires if you restrain the vehicle with no payload (too much traction to do a free standing burn out).

Anyway, inside view of the gearbox, which is pretty husky (1/2" & 1" 7075-T6 plate):

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the jack shaft, made from the shafts out of the 180W motors with the modified Boston Gear 24T gears pressed on:

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And installed:

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#134339
And done. Well, except for the taller roll bar and the winch I'm going to make with an 80 RPM planetary reduction 700 series motor I snaked out of a GM transfer case shifter assembly.

It's a powerful little beast now, able to hit the ~8 MPH top speed with me on it in just a few feet. If you try to hold it back by the roll bar, it'll just pull a wheelie.

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The other relays showed up today, too. A five pack. Since I still had one good one from the first order, I decided to just split the load between 6 instead of four.

The draw with the more powerful motors at greater reduction is much lower, although it will still spike over 100 amps if you smash the pedal to the floor from a stand-still or stall the motors. Granted, that's with me on it, so 120 lbs less with my two daughters riding together may not get that high. At moderate load, however, the draw is similar to a stock power wheels; on flat ground and part throttle, it accelerates drawing 20-32 amps, and will run full throttle full speed on level ground pulling just 34 amps. Motors and wires did build some heat (warm, but comfortable to hold my hand on), but again, that's with a heavy load and me playing with acceleration to see what kind of peak draw we're looking at.

I'll be curious to see what kind of battery life the rugrats get out of her. 24V and 24Ah with the quad batteries, so I'm thinking if they aren't nailing the throttle non-stop, probably 45-60 minutes. I know that seems kinda poor with 4 batteries when compared to a normal PW seeing similar play time on a single battery, but remember how much more weight, traction and torque this thing has. At some point I'll try to find another little driver, hook a pair of stock PW to this thing and video the tug-of-war. I'm quite confident this little monster will drag the others with little trouble.

FYI, anyone considering these tires for their ride, beware: they are VERY high traction, both on dirt or grass and on pavement or rocks. Stands to reason, given what they're made for. Just figured I'd mention it, because I've no doubt that this much traction with plastic PW gears would result in crunchy goodness real quick.
And yes, we are jealous that you can just machine another gear into the adapter to quickly switch up ratios
I dunno about the quickly part; I have about 10 hours in machining the two gear boxes and jack shafts...........
#134346

And yes, we are jealous that you can just machine another gear into the adapter toquickly switch up ratios



I dunno about the quickly part; I have about 10 hours in machining the twogear boxes and jack shafts.....
Beats the slow boat from China! :lol: :lol: :lol:
#134354
Well, might be a little bit before I get video to share. Boy is too small to drive it, and the power scared the girls.

Also gonna have to re-do some of the electrical; unanticipated was the completely paralleled system diverting the majority of power to the axle with least resistance. Right now, when one of the front wheels loses traction, there is very little driving force from the rear motor. I would have expected that if they were in series, but not sure why it's doing it in a parallel system. Didn't have that problem with the mini jeep using 540 motors. Will have to add relays and run wiring to drive one motor with each ESC. Not a big deal, just means more spaghetti to tie up.
#134424
Got the wiring re-work done, but we smoked a rear motor. Might have had something to do with adults playing on it, though...........me being one of the lightest to give it a go. That rear spool puts a lot of strain on the motors, especially when surface traction is high and there's a 180-235 lb passenger sitting directly over the rear axle. Anyway, I've ordered a replacement motor, and we'll keep the payload to miniature people from here on.
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If it burns another motor, we'll be scrapping the brushed system altogether in favor of two 56x92mm 730KV brushless cans with a pair of 200 amp ESCs at ~100:1 reduction. That's another $600 I don't want to throw at it right now, but I'm working up to it. Two of those monster BLDC cans on 24V would be putting out 5-6 Kw, or 7-8 horsepower!
By nepbug
#134449
Well, well done.

One thing I'll add. Earlier you mentioned clipping some coils off the springs to soften them up. That will actually make the springs stiffer. Less coils means for a given compression the wire will twist more, thus they will be stiffer.

I hope the girls get back on-board with driving it, can't wait for videos. Maybe take it to a dirt/low friction surface to make it less scary to start out in?
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