Scorpion / Tomahawk re-re tight transmission?

[Jim85IROC]

Has anybody experienced a tight gearbox in the Scorpion/Tomahawk re-release? I was putting mine together last night and with the cover screws backed off 1/4 turn the gears spin nice and free. When I add that last 1/4 turn to snug it up, the gearbox tightens up and gets hard to turn. I took it apart and didn't see anything obvious. I need to take it apart again, but before I did I figured I'd ask in the hopes of somebody else having experienced the same thing being able to point me to something specific.

[Jim85IROC]

I found the problem when I took the transmission back apart. The bearing on the plastic side if the diff housing was a BEAR to remove. The plastic was too thick, which was preventing the bearing from fully seating. It took quite a lot of filing to remove enough plastic for the bearing to be able to be installed and removed by hand. After that, I reassembled and the diff turns freely with the cover installed tightly. The outer trans gears are a little crunchy through part of the rotation, but hopefully that will smooth out once I run it.

[Jim85IROC]

Speaking of problems, it appears that the alignment marks on my front arm mount are completely wrong. I initially installed the arm mount as the directions showed, aligning the marks on the rod to the marks on the frame clamps. When I installed the arms, the geometry was all wrong, and I had a massive amount of toe with all of the links at the lengths specified in the instructions. Going back to look at other pictures, it's clear that the "handle bars" should be facing forward & up, where mine were facing closer to straight up. I had to experiment with how to clock the mount until my toe & camber came into a more correct alignment. Now all of that looks good... I think. The control arms still seem to be pointing down more than I would have expected.

Here are some pics that I took. This first batch shows the front suspension with the bar installed with the alignment tabs aligned:




Here it is with the bar titled forward more like it appears in pictures:

This pic is dark but you can see how the mount is clocked forward:




What do you guys think? Is my geometry still off?

[Coelacanth]

While I can't advise you as I don't have any Scorpions (or variants), when the re-re Scorpion was first released, I seem to recall incorrect positioning of that front bar was a common problem. I'm pretty sure that was brought up a few times in the original re-re topic, here...but unfortunately it's now 68 pages long.

https://www.rc10talk.com/viewtopic.php?f=30&t=35178

[XLR8]

To be honest, when I built mine, I didn't even pay attention to the marks. I've adjusted the bar until I had the correct suspension movement (or as correct as it can be considering how funky the suspension geometry is). Mine appears to be adjusted like yours. Sorry I can't be more helpful.

[Jim85IROC]

While I can't advise you as I don't have any Scorpions (or variants), when the re-re Scorpion was first released, I seem to recall incorrect positioning of that front bar was a common problem. I'm pretty sure that was brought up a few times in the original re-re topic, here...but unfortunately it's now 68 pages long.

https://www.rc10talk.com/viewtopic.php?f=30&t=35178

Thanks. I've got some reading to do!!!

To be honest, when I built mine, I didn't even pay attention to the marks. I've adjusted the bar until I had the correct suspension movement (or as correct as it can be considering how funky the suspension geometry is). Mine appears to be adjusted like yours. Sorry I can't be more helpful.

No, that's actually very helpful. I just wanted to hear that I was correct in determining that it was wrong when built to the manual.

[coxbros1]

Even on my mid 80s Assault, when i followed the manual instructions and rod lengths, mine was way off, i just moved it all around until the geometry looks decent. Yours look the best i have seen

[Jim85IROC]

Thanks! I'm anxious to get this done and drive it! I'm also putting together a worlds-ish RC10 buggy, so it should be fun to compare the two cars.

[klebinger]

Got my Tomahawk to days ago and I experience the same problem with the tight gearbox. Really annoying
Plus: I also struggle with the front arm mount. Will turn mine forward also - I hope that the clamps holding it will finally sit flat. Because right now they look like your's in the "before"-pictures:
https://photos.app.goo.gl/vuSPAHM93muQpxmw5

[mikem65d]

I know this is an old topic, but speaking of the front bar that the arms attach to, The manual is way off. The marks have you set the bar in a backward position that ends up with way too much neg castor and toe in.
Mine was hideous looking until i dug up the old original manual that showed the proper setup.
The bar is to lay flat in line with the upward bend in the front of the main rails.
The marks on the new re re line up no where within the guidelines of the new manual.

[XLR8]

I agree, those factory marks make no sense.
Also, be aware if you run your car that suspension beam will bend upon impact. I went a little wide coming out of a turn and clipped a corner post on my deck and now I get to take the front end apart and try to straighten a bent beam.
I didn't think it was going very fast at the time.
One disadvantage of having an all metal RC.

[mikem65d]

Yep i remember straightening a time or two with my original Tommy.
I was teaching my son how to drive and ended up being a mechanic....LOL

So i was going to buy another Tommy to have, but decided to just buy some of the optional pieces that are available.

I know I know, better things to spend money on, but it's an old nasty habit of mine to trick out models and then leave 'em on the shelf....