Fallen's 2nd UDR

[Gula]

Huh, even with the sticky icky runny E6K that seems to glue and hold anything together, amazing.

Have you tried the heavy duty version, called shoe goo? I've glued servos onto axles, as I broke an alloy mount (deployed to Afghanistan in 2011, and brought a wheely king rig)

As others sez, try packing everything that doesn't rotate full of grease, especially where two parts join.

What other brand alloy housing than vitavon, gtb? gpm and the cheap chinesium ones made from questionable material are there?

 

[ferp420]

axle flex is why i only buy metal axles
ive stripped to many gear sets with plastic axles

metal axle housings cost less than gear sets so it made sense

the dirt never caused a problem in my opinion but the only clamshell axles ive ever runwere on my scx10 and it dident go fast enuff to really cause a problem

 

[Fallen]

My 1st UDR used the GPM axle housing. It turned out to be durable enough, and everything inside of it spun smoothly.

For my 3rd UDR I'm trying this one:

https://a.co/d/gkBqf2O

It's nice that it's cheaper than the Vitavon housing, but the problem with Vitavon is getting ahold of one. Apparently they aren't shipping. The Amazon one was in stock in the US, ready to ship.

 

[Fallen]

Finished! I gave up on waiting for those Vitavon parts to arrive and bought some Hot-Racing parts from a different LHS:

Upper & lower A-arms
Trailing arms
Rear upper shock mounts
Front & rear sway bars
Hexes with brake disks













Non Hot-Racing upgrades:

Some Chinese, no-name aluminum axle housing from Amazon. Only one of the upper link mount bolt holes wasn't tapped all the way. I was able to solve that by using a spare bolt to finish tapping it.

MIP center rear driveshaft









The only thing left is to put some batteries through this and see how much of my painting holds up.

 

[MAC FAB]

Looks great! Driving at scale speeds is just fine. If I ever get around to putting on races, FPV and scale speed + a fuzzy. MY scratch build 1 car went 45 mph, Bomber sized, and could blow through most anything and not break anything. Kinda like going to Glamis and running the sand drags all day. Hard pack at a realistic speed and a video setup is more fun. Truck is bitchen, two thumbs up. Aluminum tape on the panels is genius if you don't have a sheet metal shop. Let's be seeing some run footage. You realize that to finish this off you are going to get another set off those shocks and bypasses, Fox, in black and polished. Amazing how quickly the build price turns scale. I believe an awd Mason goes for about $1.5 m, just saying.

 

[Fallen]

Thanks man!

I had considered buying some of the LX bypass shocks for this truck and I still may. The suspension is tuned pretty nicely though stock and I don't want to screw that up.

Since the rears already have the fake bypasses, maybe I'll just get some for the front. Especially since I really only want them because of how rad they look.

This UDR is probably sitting around $1,500 and I do expect it to go up a bit more. Eventually someone will release some different bodies for this thing.

I figured those AWDs were in the millions of dollars. It looks like it's still just the professional teams running those.

 

[durok]

Thanks man!

I had considered buying some of the LX bypass shocks for this truck and I still may. The suspension is tuned pretty nicely though stock and I don't want to screw that up.

Since the rears already have the fake bypasses, maybe I'll just get some for the front. Especially since I really only want them because of how rad they look.

This UDR is probably sitting around $1,500 and I do expect it to go up a bit more. Eventually someone will release some different bodies for this thing.

I figured those AWDs were in the millions of dollars. It looks like it's still just the professional teams running those.

BittyDesign makes UDR bodies AND interiors:

Bittydesign - Carrozzerie Off-Road Trasparenti

 

[Fallen]

Thanks, I didn't know they made clear ones. I'll probably end up with a clear Pro-Line body as they're a bit cheaper ($76 VS $99).

This UDR got a good shakedown on 6S with throttle limited to 75%. I actually need to go down to 67% to make it comparable to 4S. The nice thing about 6S limited is the increase in runtimes over 4S unlimited.

Boy TSM (Traxxas Stability Management) is a real performance upgrade. There is one section of my track where I can hold full throttle for about 2 seconds if I stick the right line. With TSM at 50% I can get up to speed and hold it as the suspension dances under the chassis. With TSM off I can't even get up to full throttle without the rear end stepping out and I have to lift.



I added this 1.55 Baja MTZ to my steering wheel. I glued it on to the stock Traxxas wheel. I like it because it's soft and grippy while dramatically increasing the diameter of the wheel. It makes it so that my steering inputs become much smaller when the truck is at speed.

My paint held up except in the few spots where the chassis flexes and flakes the paint off. Those are all fortunately inconspicuous and hidden by the body.

 

[Fallen]

My choice to buy a cheapie Chinese axle housing definitely had consequences. The 2 piece housing includes the planetary housing and the axle housing itself. The planetary housing wasn't machined properly so parts of the metal gears / hardware were rubbing on the inside resulting in this metal dust filling up the housing.





The solution: run the stock plastic planetary housing on the aluminum axle housing.



A local seller was selling the Vitavon front bulkhead and a ThreeDPrint Designs vertical tire holder. I scored both of those. The tire holder is a stiff rubber that I'm hesitant to paint. I think it bends enough that it's not realistic to expect paint to survive the flexing.





While replacing the front bulkhead I also swapped in the Savox SB2274SG Black steering servo. The faster servo should help out the gyro assisted steering at speed.



While I was replacing the front bulkhead I replaced the plastic front center driveshaft with a Hot Racing steel driveshaft. Apparently the stock plastic front driveshaft is a weak point.

I installed the Traxxas Variable damper kit in the rear unsprung shocks. But I switched to Losi shock oil instead of Traxxas as my LHS doesn't stock a good supply of Traxxas oils. The Losi oil feels thicker, so it's hard for me to tell what difference the variable damping kit is making. A shakedown over rough terrain will hopefully help me sort that out.

 

[Fallen]

About one month later, and I've put about 30 battery packs through this truck. A lot of suspension tuning happened in that time. The time for a "race prep" had come. Not because I have a race coming up, but maybe in the distant future. More on that later...

The UDR got cleaned. I used S100 motorcycle spray then hosed the truck off. Then needed some oil on the screw heads to prevent rust. The result:



You'll notice a few asthetic changes as well. Mostly in red. Red aluminum panels, red aluminum steering links, red upper links and red letters on the tires. A bunch of my Hot Racing parts had red so I decided to carry that theme on, even though the truck has a bright orange body.

The front sway bar set screws kept coming loose even with Loc-Tite on them. So I swapped them out for longer 2.5mm button head screws and used rubber bushings under the heads to absorb vibration. And Loc-Tite also...





I'm considering starting a UDR race league in my city, so I don't want to give too many details away about my suspension tune, but man does it work. The UDR comes from Traxxas with killer suspension, but it's a bit too plush for high speed over seriously rough terrain.



Over big hits at speed the rear end would kick just high enough to dig the front bumper and it would be a catastrophe from there. Now even at higher speeds over the same terrain the front end floats so I can stay off of my roof. My stock UDR (the pre-runner) can't keep up.



The races I'm considering are supposed to be a scale version of the SCORE races in Baja. A 50,000MAH race with tire changes required and other rules to keep it desert.



I'll eventually run a rule sheet by you guys to gather feedback. The track is about as long as an outdoor 1/8 buggy track, but 25X rougher and less predictable. But first I'd need to get ahold of one of these to count 100 - 150 laps:

rc lap counter

RC lap counter / timer Best bang for the buck!!!

trackmateracing.com

And then figure out power, as my track has perfect terrain, but no electrical power to run the lap counting hardware.

I'm also trying Amsoil gear oil in the rear axle gears instead of grease for less rolling resistance and better performance in high temperatures. Hopefully things don't get dry in there.

 

[Gula]

YO! That bad ass. Where you located? That would be a blast. I have a udr and a hammer rey that I'd love to take out to a track once with some other peeps.

 

[Fallen]

I live in northern San Diego County. It seems to me like it would be a lot of fun.

Make it long enough to really tax your truck's components in terrain hard enough to really tax your truck's suspension.

How does the Hammer Rey compare in size to the UDR? Similar suspension travel? Does it use 1/10 or 1/8 electronics?

 

[JatoTheRipper]

What is the "error in designing the axle housing"?

 

[Fallen]

The stock housing just flexes too much. Which makes sense as Traxxas probably wants to avoid breakage, so they made it soft.

But that flexing allows a gap to open between the housing halves and dirt just comes sailing in.

You'll see / hear many UDR owners complain of dirt / sand in their stock rear axle and I believe that's why the dirt gets in there.

The cheap aluminum housing I bought had machining problems. The planetary housing allowed the ring gear to make contact with the inside of the axle housing, breaking the ring gear and causing metal dust to pile up in there.

The axle housing itself works, it just doesn't play nicely with the planetary housing. So I use the stock plastic planetary housing bolted to the aluminum axle housing. The aluminum housing provides enough stiffness to stop the flexing.

 

[Gula]

I need to get my ass in gear ang get my rigs running (re-assembled) and on my next trip down to TX, swing your way and have a overnight rest nearby you... Now, these aren't mine. However, i borrows the pic from here: Losi Hammer Rey

 

[MAC FAB]

Count me in, running this. Bomber sized car. 5700kv goes 33 mph, 2s, with the 2400kv it hit 43 with a 3s.

 

[Fallen]

Thanks for the comparison photo Gula. I was concerned that the Hammer Rey would be more like a 1/10 scale and therefore not really able to be competitive against larger, heavier models with more suspension travel. They appear more similar than I expected.

And MACFAB that Bomber would be right at home on this track. I was initially only considering running races for 1/7 scale, but that Bomber has me thinking there should eventually be a 1/10 scale class.

Both classes would require solid rear axles and both would be unlimited. Scale would be determined by what the manufacturer classified the original chassis as. Custom models (such as MACFAB's Bomber) would be evaluated by race officials for admittance.

There is one section on my track where you can get a UDR up to 40-50MPH. But that straight away spits you into the roughest and least predictable section. It gets ugly very quickly if you fail to thread the needle properly.

 

[MAC FAB]

Nice. Mine is a buggy, SCORE class 1 or 10 car, that is Bomber/Baja Rey sized. Have you looked at the NORRA series format? It is like a rally, variety of classes. Draws on older race rigs that aren't competitive with the latest hi tech stuff or the big sponsorship stuff. Vet drivers. Check that out. Is Fiesta Island a viable venue? Ocotillo/Plaster City are there too when it cools down.

 

[MAC FAB]

As for scale, if you run more than 1/7 UDRs, consider a Thunder Tiger Jackal. Capra sized at 1/10, vs a Bomber, vs the Hammer Rey. Someone can't read the tape measure....

 

[JatoTheRipper]

As for scale, if you run more than 1/7 UDRs, consider a Thunder Tiger Jackal. Capra sized at 1/10, vs a Bomber, vs the Hammer Rey. Someone can't read the tape measure....

That TT Jackal looks nice and it's cheap. Is it similar in size to the UDR? Any idea of the durability and quality on the Jackal?