Bgredjeep Bomber build recap

[bgredjeep]

Ran into a new issue with the rear sway bar. I've had the bar on and off multiple times as I work through the build, and as I went the arms seemed to keep angling in more and more.

Well, big shock, the cheap Amazon sway bar that I already knew was junk (only using the aluminum arms) is in fact more junky than I even realized. The hole has ovaled out on the machined side of the arm causing it to angle in when tight. I'll be picking up a new sway bar (reefs or hot racing) to replace this.

 

[bgredjeep]

Here's the axles I picked up. I'm not sure if these are a clone of some other existing housing or not. I wanted wraith based axles for the bigger gear set (instead of the ar44 center wraith width axles I had on my capra). These are a true drop out 3rd member with aluminum bearing retainers. I'll get some internal pictures when I go through the front axle. I forgot to take any of the rear when I had it apart. The specs indicate they have underdrive gears in both (43/13) but I didn't count teeth. It should pair fine with the high ratio trans I ordered.

I happened to have some scale hardware on hand so it made good sense to try that. It looks great imo. The rear will be ready to install once get loctite on all the screws. Looking at them and guessing what might fail first, I'm suspecting the locker. It's not as tight on the shafts as I would like, but it'll work fine until it doesn't, then I'll upgrade.

 

[bgredjeep]

Got a couple detail shots inside the axle.

 

[Fallen]

While I'm unwilling to give up my unlocking diffs, I sure wish my Miller Motorsports had axle housings that beefy and good looking.

 

[bgredjeep]

While I'm unwilling to give up my unlocking diffs, I sure wish my Miller Motorsports had axle housings that beefy and good looking.

I hear that. I think if the aftermarket support was there for the miller we'd likely see more of them.

This one is shaping up and should make a pretty good u4rc racer. It'll be low and relatively light.

The rest of the parts I ordered have shown up so this morning I built the transmission. The ssd parts are nice as usual. Since I didn't have a donor trans I picked up a cheap slipper and gear set from Amazon and a bearing kit.

How it started

How it's going

I also found enough driveshaft parts in my toolbox to get those taken care of.

 

[themountain]

Those wraith copy axles are quite decent...I have a pair in my bouncer and beat the snot out of it for 2 years now....only weak spot are the shafts so far but that can be easily solved "thumbsup"

 

[bgredjeep]

Those wraith copy axles are quite decent...I have a pair in my bouncer and beat the snot out of it for 2 years now....only weak spot are the shafts so far but that can be easily solved "thumbsup"

That's good to hear. I hadn't seen these specific housings before but I liked the look. No complaints so far.

Today I made it a roller. It'll have to come back apart at least 1 more time. I had my buddy print an updated revision of the skid plate for me that I'll need to install and I will need to work out mounting the esc and radio again. I haven't given any thought into what esc and motor I'll run. I'm pretty sure I've sold off all my old brushless systems that didn't have a home. I've got some brushed stuff I'll probably throw in to make it move short term, but the goal is for this to be pretty fast. I still need to pick up a new sway bar as well. Probably going to get the reefs since I should be able to mount those arms with everything else I already have in place

The tires on these pics are the 5.25 hyrax 2.2. I'll be running something in the 5.75 range when it's done. Wheelbase is just over 15".

I threw in a battery, motor, esc, and rx to get a better idea on the weight.

 

[bgredjeep]

I decided to try a forward motor mount on this miller chassis. I eyeballed it and figured it would fit ok. I ordered the CCW scx10 mount. Unfortunately I found the ssd trans case is a bit different than the normal 3gear so the mount would not work. I drew a new plate to mount to the trans and make it work. I'll use this for now, but I'll probably have the plate made from carbon before I'm finished.

Test fit in the car confirmed it will sit under what I had planned to be the battery tray. Now I'm planning to mount the battery on the skid so some new parts are in the works for that.

Here's the ccw plate compared to the one I made.

 

[Fallen]

Good heavens, you weren't kidding when you said low.

Plus the battery on the skid? That's going to be one planted Ultra 4 car. 4S battery sending it through the whoops?

 

[bgredjeep]

Good heavens, you weren't kidding when you said low.

Plus the battery on the skid? That's going to be one planted Ultra 4 car. 4S battery sending it through the whoops?

The current battery tray I designed is for my 3s 4200 packs. I should be able to make a new tray easily if I use a different pack. For the esc I'm thinking I'll go ahead and spend the money for the mamba x and probably around 4000kv on the motor. I'm not there yet, but getting closer.

Here's a look at where it's heading.

 

[MAC FAB]

I’m loving this thing. One question I have for you is tuning the front shocks. They appear to be at about a 45* angle at full bump from a closer to 90* angle at full droop, so I wondered how you will overcome this “issue” in my mind. I come from the school of linear spring and progressive on the angle, go fast stuff. I am anxious to see your run feedback with your sweet innovations. Looks like a good candidate for fpv.

 

[bgredjeep]

I’m loving this thing. One question I have for you is tuning the front shocks. They appear to be at about a 45* angle at full bump from a closer to 90* angle at full droop, so I wondered how you will overcome this “issue” in my mind. I come from the school of linear spring and progressive on the angle, go fast stuff. I am anxious to see your run feedback with your sweet innovations. Looks like a good candidate for fpv.

I hadn't initially planned on mounting the shocks on top of the axle like I did. The chassis is wide in weird places so when I had them on the outside of the normal ar60 shock mounts the shock body was right against the chassis tube. The change in the angle between droop of bump isn't quite as extreme as you mentioned, but its a thing for sure. I do have the option of moving the upper mount forward about 15mm to sit the shock more upright. Once I get to the point of making it move I can test and make adjustments as needed.

For the suspension in general I've been more focused on getting a full range of motion without hitting the chassis. The rear sway bar has been fighting me on this but it's slowly getting there.

 

[bgredjeep]

I got the new skid installed and the cage back on. Still just mocking things up while I wait on the motor and esc to show. I'll finalize the front skid when I get the real motor, then I can send off for the carbon parts.

I also decided to make a new servo/upper link mount like one I did for my wraith a while back. This spreads the links a bit wider so I have extra clearance for the motor. While I was at it, I did move the front shocks forward 1 hole.

 

[bgredjeep]

Amazon warehouse deal got me today. I was looking for esc options and about to pull the trigger on the mamba x when I noticed they had a "used like new" option from warehouse deals for another $50 off. I've used the warehouse deals many times for stuff so I gave it a shot.

It showed up today (a day early). In my gut I half expected what I found. Original packaging was fine. I opened the motor and immediately notice red wires, also much shorter than castle uses, capped off with electrical tape and a missing screw. I didn't bother even touching the motor and set the box aside to check the esc. No surprise there aside from the esc being in even worse shape than the motor. Dirty of course, and blow/smashed capacitors.

So some dirtbag blew their stuff up, bought new, returned their trash as unused, and Amazon just puts it back on the shelf. Anyone could glance at either item and know they were not "used like new" which is Amazon for open box returned. Lol

I snapped a couple pictures and started the return process. Heading to the ups store to drop it off on a few minutes.

 

[broadside]

I've been running the Mamba X and a Castle 1410 3800Kv and 16/68 gears since I bought my Bomber long ago. Great combo. Programming the throttle curve helped a ton going between the slow low gear stuff and the full out high gear stuff. It's not super fast, topping out at 19 mph on 2.2's and a 80C 3S battery, but it's fun regardless.

 

[bgredjeep]

I've been running the Mamba X and a Castle 1410 3800Kv and 16/68 gears since I bought my Bomber long ago. Great combo. Programming the throttle curve helped a ton going between the slow low gear stuff and the full out high gear stuff. It's not super fast, topping out at 19 mph on 2.2's and a 80C 3S battery, but it's fun regardless.

I'm running a similar setup in my bomber as well (just a different motor), but with a 2spd wraith trans. I haven't measured the speed but it's enough that it's hard to control at full throttle for more than a few seconds.

This rig I'm not too worried about the low speed, but I figured it will be enough for the rocks on a u4 course. For now I'm stuck waiting for Amazon to process the return on this junk they sent me so I can buy it again.

 

[broadside]

I'm running a similar setup in my bomber as well (just a different motor), but with a 2spd wraith trans. I haven't measured the speed but it's enough that it's hard to control at full throttle for more than a few seconds.

It has so much to do with the throttle and braking programming you set up on the Mamba for high speed running. You need to fine tune it to the rig you build as the default is linear and sucks for low speed. I found a setup I can live with, but just need to remember to let off before starting a turn at full speed on asphalt or grass then getting back on it once the suspension settles. This thing grips and even being as low as it is, will hook sideways and roll pretty easily. I am sure I can spend more time fine tuning but I am not that dedicated to it anymore. I have much higher priority hobbies these days.

But it is so much fun watching it run full speed on semi-rough dirt seeing the suspension work, then going to low gear to crawl something.

 

[bgredjeep]

Amazon finally processed my return on the junk mamba x and I reordered new. That should be here tomorrow. I finalized the parts I wanted from send cut send and got those ordered so maybe by early next week I can start working towards final assembly.

I printed this spacer to use with the carbon motor mount plate I've got coming. The fmm came with spacers, but the ssd case being different, one of the spacers needs to be ~1.5mm longer. The second Pic shows the motor skid I made a bit wider to offer a little extra protection. The skid ties into the aluminum plate in the chassis so it should be plenty strong.

 

[bgredjeep]

I'm getting close now. Motor and esc came in Thursday, then my send cut send order showed up today. I made some good progress on assembly today.

 

[themountain]

You want to keep the skid as it is for U4 racing? You think it will hold ?