smirkracing

iTrader: (19)

Hi All,

My USA-1 snapped an axle tube on the very first run (in the first 5 min). Very disappointing. I splurged for the vitavon axle for the USA-1, but I cannot for the life of me get the diff to fit. I am a pretty experienced modeler, and I don't *think* I'm missing anything obvious (which is of course when you make the dumbest mistakes) but I am at a loss right now...

Anyone have this axle? Here are pics of my USA-1 diff NOT fitting into the axle. Specifically, the diff seats nicely into both the main axle body and into the diff cover / 3rd member separately, but when you bring them together, the cover has no hope of ever fitting. It has little arms to the left and right that mate with the axle tube, and those slide 5mm or more into the tube. But the diff sits flush with the outer surface of the tube, so there's zero millimeters of space for those arms to drop in.

It isn't like the fit is close within say 1-2mm. It is off as if the part is for a different vehicle almost.

Here's a set of pics I sent to vitavon service... but not sure how helpful they will be.




Thanks in advance for any assistance.

1995 Monster T

Either the diff gear is too big or the bearings are? Or the bearing slots are too small? Send it back. I looked at it but hated the design. No axle supports to change it to 4 link.

smirkracing

iTrader: (19)

Thanks!

I figured it out - the fit is extremely tight, and you have to push VERY hard to get the diff seated correctly (much harder than I was pushing initially). I am a little worried about having to take things apart - not sure I can figure out where to put a screwdriver or other tool to actually get the diff back out without damaging anything. Oh well.

Can you explain what you means in terms of not liking the design? I haven't bolted everything back together but from what I can tell the Vitavon design has the same mounting points for the links as the stock axle does. From the pics it looks identical and you get the same parallel 4-link set-up (which in turn requires a panhard bar - I actually prefer triangulated links for this reason but it is what it is). Is that what you mean, that there aren't supports on the Vitavon axle to change to a triangulated 4 link design?

1995 Monster T

You shouldn't have to push hard to get it in. It should just drop in. I prefer the mounting points over the diff to triangulate and lock out the 4 link. The panard bar get is the way of mounting the servo direct for steering. Which you will see with the Vitavon steering upgrade kit. I made my own steering kit direct mount to the axle and it was a tight fit. Now i have 4 wheel steering/

which truck you have EP or nitro? the nitro has a problem with the gear rruning tight on the 3 speed. You can't adjust the motor to set the gear mesh properly.

smirkracing

iTrader: (19)

Thanks for the tips and insights. I do indeed have the Vitavon steering kit. I would have thought they'd have designed around the panhard bar, so I guess I'm in for an unpleasant surprise. Vitavon customer support was extremely responsive (they even cut a video showing how the diff should drop right in, as you suggest) and sent it to me. We're debugging together (checking fit, etc) to figure out why my axle is so tight.

So did you find an alternative that you like better? There's a hot racing axle (also quite pricey) which also maintains the stock design. Or did you design something totally custom on your own?

1995 Monster T

I plan on making my own 4 link setup when I make my own center diff housing. My diff housing will be in 3 parts .A center and two side covers and will include the upper link mounts and will work the stock parts. I will ditch the panhard bar for more clearance for the axle steering servo.

swerv512

iTrader: (21)

I've been itching to pull the trigger on an LMT but have been going back and forth between the Vitavon and Treal upgrades. Let us know how Vitavon handles this

smirkracing

iTrader: (19)

sounds awesome. Looking forward to seeing pics and getting some inspiration.

I installed the vitavon axle-mounted servo steering setup today on a stock axle and I see what you mean. Even with the new vitavon panhard bar mount, which pushes the panhard bar forward maybe 5mm, the panhard bar hits the top of the servo saver when the shocks compress. So you can clearly see that the left side of the front suspension loses at least half an inch of travel.

I added a bunch of washers (at least 5-8mm worth) and that pushed the panhard bar further forward, and now it clears the servo saver just barely.

All in all I am surprised at the vitavon parts for this truck. So far nothing has worked perfectly for me.

are you adding a center diff to your USA-1? Please do share what you build. That would be pretty cool.

1995 Monster T

I plan to leave the stock drive line alone. I did improve the shock set up. I raised the back up and added a new front shock mount to raise the front up and changed the angle to match the angle in the back. Truck sits higher and drives better, I added a full light kit channel operated to turn on/0ff by remote. Sadley I have to switch to a 4 channel radio.

smirkracing

iTrader: (19)

1995 Monster T

Have you seen this article?
https://www.rccaraction.com/modding-kyosho-mad-crusher/

This is from Kevin Hetmanski who designed the Losi LMT. He triangulates the links on the USA-1 and ditches the panhard bar (which I would also like to do). He makes it seem very easy - just adds a few aluminum spacers to switch the links from parallel to triangulated.

I'd be curious what you think of this.

1995 Monster T

I plan on doing the same thing but adding mounts to the center gearbox above the diff section when i machine it. That's the true way of doing it. This is how I did it on my 1/5 scale monster truck. I haven see Kevin Hetmanski's design yet? Right now, I'm working on my Tribute Usa-1 body for my 1/5 scale monster truck and fixing and cleaning up a Prather fundraiser 1/4 scale gas boat. I just bought.

smirkracing

iTrader: (19)

Have you ever thought about adding a center diff to the USA-1? I am tempted to try to figure out how to add one...

1995 Monster T

A center diff would be the worst thing you could do to the truck. All the power would be transferred to the wheels with the least resistance which would be the front as the front is lighter. You would lose acceleration and traction. I know for a fact as I have the original truck and it has a center diff. It sucked on takeoff and lost power to front wheels. I locked it and WOW a big difference. I can now pull wheelies with it. same thing with the buggies. The fronts would always spin on takeoff. I locked every one of my buggies. Even on my 1/5 truck I have no center diff.

Brokenparts

iTrader: (6)

You can fill the center diff with different weight oils to control how much power is lost to the front wheels...

Just ordered a USA VE for myself, cant wait to start tearing into it!

1995 Monster T

You can fill a center diff all you want with oil. it will still send power to the wheels with the least resistance. I run all my 1/8 buggies locked. No loss of power or traction.

Worst time of year to buy anything now. No coupons or discounts of any kind.