Why (not) to do the LCC tranny flip

[Olle P]

Introduction
I’ve just done the “tranny flip” and as of now, before having done a test run, I wish I had it undone!

Background
About me
I’m an engineer and MSc. I don’t like doing things just because someone else says it’s good to do it. I want solid arguments what makes it good. Unfortunately I went on with this flip without many positive arguments...

Why do it? Arguments for and against.
In the case of the tranny flip the arguments I’ve found for it are
a) it straightens the drive shaft (eliminating problems where the drive shafts and suspension links occasionally get in physical contact with each other), and
b) it moves the motor (and thus CoG) forward.

With the LCC suspension very much in stock shape I’ve found absolutely no situations where the drive shafts can touch the links, so that argument is moot unless you’ve messed with the links.
A straightened drive shaft does reduce drag from the joints though, which is a good thing!Moving the CoG forward is also welcome.

The very obvious downside to doing the flip is that the motor and tranny package is also moved some 3mm up and about one centimetre sideways, exposing the motor to the environment and shifting the CoG marginally up and considerably to the side.

My LCC before the flip
The parts that matter are:

• Generally stock parts, with some exceptions.
• Battery plate (home made) on the forward upper links. (I’m pretty sure the stock battery plate can’t be used with the tranny flipped.)
• RC4WD motor with 49mm straight can.
• 12T pinion, the smallest advisable.
• Having spent more than half a year tracking down and minimizing all sources of friction I’ve made it run quite well on a brushed motor!

Doing the flip
Parts required
3mm (1/8”) spacer(s) to make the tranny go clear of the lower links’ ends.
Two UNC 4-40 x ½” screws, countersunk, to replace the stock screws holding the tranny.

What to do

1. Remove the tranny and the left side plate.Make sure the spacer(s) fit without interfering with anything. (I made my own spacer from scratch to have a tailored fit.)
2. Mount the tranny (and motor).
3. Here’s the part I really didn’t like: Remove material from the side plate (to open it up for the parts that will protrude.
   1. Start by removing the two diagonal bars forming a V across most of the plate.
   2. Then remove quite a bit of the vertical part below the inner opening.
   3. Try to hold the plate in place.
   4. Realise that it won’t fit until you’ve removed quite a bit more material.
   5. Use a felt tip pen to mark what to remove.
   6. Do the removal.
   7. Repeat from c. until the plate actually does fit.
4. Mount the side plate.

So, what’s wrong with it?
I ran into a couple of problems, current and foreseen future ones.

• I had to remove quite a bit of material at the lower part of the side plate just to be able to force it into place. This results in reduced structural integrity.
• The tight fit of the side plate prohibits the use of a larger pinion, unless combined with a smaller diameter motor.
• My current motor is designed such that one of the connectors is pushing against the side plate. I had to put a piece of plastic tape in between to isolate it electrically from the chassis.
• The forward drive shaft is more elevated now than before, which is good for ground clearance but forces me to raise the battery plate a bit more above the links.
• I’ve previously made a very nice elevated stand for the crawler, where it hangs by the body posts. Now the motor gets in the way for the stand and it can’t be used.

Still remains to be seen how bad the exposed motor and side-shifted CoG is for business… and if there’s some unforeseen goodness making it worthwhile.

[Dini]

"If it ain't broke, don't fix it"

This should have come to mind with your Losi. If you had it dialed in, you should have left it that way and learned to drive it.

[SHOtime]

Ill admit it isnt entirely ideal, as simply centering the driveline for the hell of it doesn't net you much because of the moved weight. However the big advantage for me to flip the tranny was to run bent lowers, the trade off is there, but the improved clearance in the rear was much more worth it to me than the slight effect a weight shift made. Im not sure how you did yours, however i dont know why you are saying there is no room to run a larger pinion. I have plenty of room, however you are correct about it being tight in the rear. Im not worried about that however because aluminum does not conduct, and the chassis plates are all aluminum. There are definitely reasons to do it, whether its worth it or not is up to the one hacking up their crawler.

[thomass14]

can I fit my titan motor 550 can if I do the flip? I started to hack the chassis and now i'm thinking it doesn't have enough room to fit. I like my titans and don't really want to run a different motor has anyone tried a 550 with the flip?

[Duuuuuuuude]

Originally Posted by SHOtime

Im not worried about that however because aluminum does not conduct

Oh yes it does.

[Dini]

Originally Posted by Duuuuuuuude

Oh yes it does.

X2! Guess you haven't done much electrical work, eh?

[losikid]

The rubbamod was originally done so bent links could be run.

Rubba's TLR Comp Crawler Prototype

If you don't intend to run bent links then why flip the tranny?

I personally don't like having that much weight hung off the side of the chassis, i don't like having less off camber ability when the motor is on the lower side. But talking to quite afew other losi drivers last night, i guess its something that you get used to.

[losikid]

Originally Posted by Duuuuuuuude

Oh yes it does.

Originally Posted by Dini

X2! Guess you haven't done much electrical work, eh?

x3, all metals are conductive

[SHOtime]

To an extent, but i havent had any short problems whatsoever. Almost anything can conduct under the right conditions. Irregardless the tranny flip is useless if you arent planning on bent links.

[losikid]

To an extent? its aluminum wire running the 100 amp service out in our shop...

I'm not 100% positive on this, but the anodized aluminum (a thin layer of an aluminum oxide) will make the surface non conductive. But the tranny flip requires you to todo alot of hacking and chances are that there is plenty or raw aluminum there to short stuff out...

But i doubt something will short out...

[NFG]

I flipped my LCC a few months ago and it was to allow me to run bent links. The bonus of straightening the drive shafts and moving the CG forward helped in the decision. Then again I have three spare frames so I can always go back.

Although I will admit the motor takes a few hits but so do the MOA rigs out there. I run a curved body that helps but my Rockstar is showing some nice scatches. Can't say that the offset motor has a noticeable effect on the CG.

All in all I like the "flip" mod' for what it does for me. I did not do it just to be like the others. But like a lot of crawler related mod's it's a personal thing.

[ghtpdm5]

for running the stock chassis, the rubbaneck mod is the way to go. the motor hanging off the side is a concern, but placing your electronics and a bit of weigh in the chassis will offset the motor hang. i honestly considered doing this before doing the cdw rails and my v1 chassis. still considering it for a sporty honestly.

the aluminum that the chassis plates are made of is some stout stuff, the structural rigidity is no more compromised than it would be with the common weight loss cutting that many do. my concern on this is and always will be the transmission mounting holes. i'd personally brass insert the holes used to ensure a solid mount for longer. the losi plastic wallows out pretty easily with impacts and repeated dis-assembly.

the motor hanging out there is not a big concern to me overall with proper balance weight and inserts. the phoenix runs the motor half outside the chassis, and i've never had an issue with it that truly annoyed me.

and it being useless outside of bending the links is false. the straightened driveline angles reduces wear and tear on the cv joints and the dogbone cups on the lnc shafts. along with that, it smooths up the driveline motion, less binding in the joints and cups is always a good thing. its a good mod all around to those that like the stock chassis and can make it work for them.

the other option is custom fab at this moment in time. building a chassis that suits you will perform better in the end. i tweaked and modded the stock chassis and i couldn't make it work like i wanted, so i made my own, the difference was immediate after 20 minutes of driving it. while custom making a chassis may look difficult, i can tell you with first hand experience that it is to a point. if you are good with tools and with your research, it is fairly easy to make a working chassis. my v1 chassis was made with a coping saw, files, a drill press, a hand drill, and time.

[Duuuuuuuude]

Originally Posted by losikid

x3, all metals are conductive

Except for unconductimium.

[killswitch]

Originally Posted by losikid

I'm not 100% positive on this, but the anodized aluminum (a thin layer of an aluminum oxide) will make the surface non conductive.

Only the hard anodizing we see in the RC world is non conductive. 95% of the colored stuff is conductive.

[NFG]

My tranny flip on the LCC. Works great!

[Olle P]

Originally Posted by losikid

If you don't intend to run bent links then why flip the tranny?

Originally Posted by Dini

"If it ain't broke, don't fix it"
This should have come to mind with your Losi. If you had it dialed in, you should have left it that way and learned to drive it.

Let's face it, the ten or so latest threads discussing the tranny flip (disregarding the single one posted after I wrote this thread starter) says nothing or very little about a (strict) correlation between tranny flip and bent links.
It's much more in terms of "tranny flip the single best mod I've ever done to my LCC!", very much like the common practice to replace the stock front worm drive with a HD one. (That mod also seemed a bit strange to me. Still I did it and now I can tell the world not only just to do it, but also why to do it. The LCC is by no means "broken" without that mod, but it runs a lot better with it.)

Originally Posted by losikid

... the anodized aluminum (a thin layer of an aluminum oxide) will make the surface non conductive. ... plenty or raw aluminum there to short stuff out...

- Aluminium oxide is pretty much non conductive, yes.
- A very thin layer (a few molecules deep) of oxide will form spontaneously almost instantly when raw aluminium comes in contact with air. Not enough to prevent electrical contact.
- Aluminium as such is the material of choice for high voltage power lines, because of its low density and its cheaper than copper.

As to why I can't use a larger pinion: The shape of the motor I use doesn't allow it (unless I go for a much larger pinion). I had to shoehorn the connector in, as hinted in this picture:

The red motor cable connector squeeze against the side plate between the two upper holes for the upper link.

[JohnRobHolmes]

Originally Posted by killswitch

Only the hard anodizing we see in the RC world is non conductive. 95% of the colored stuff is conductive.

Now I must test!!

Black, green, orange, and blue show no conductivity on the surface, but testing along edges show conductivity with minimal pressure. A visual check shows the coating is breaking a bit.


I wonder what would happen at 500v though!

[Olle P]

Originally Posted by Dini

"If it ain't broke, don't fix it" ... If you had it dialed in, you should have left it that way ...

To me "dial in" is exactly the same thing as "fix what ain't broken".

Starting with a brand new, factory mounted, LCC there is (AFAIK)...
... exactly one "fix" required:
- Adjusting the tightness of some screws. (They're mostly too tight at delivery.)

Then there are three "dials" available:

1. Choice of electronics (including motor).
2. Choice of pinion.
3. Choice of suspension settings.

Any change outside of this..., like

• Not using the stock battery plate.
• Adding weight to the wheels or knuckles.
• Replacing the tires.
• Using HD worm drive in the front.
• Running bent links.

... is a matter of "fixing" what by definition isn't broken, but it makes the LCC perform better.
I've done all of them but running bent links, and that's on the short list of future "fixes of what ain't broken"...

[Dini]

What I meant by that (maybe it was lost in translation?) was if your LCC was running and driving great, you should have left it that way and not done the tranny flip. I'm well aware that this hobby is all about constantly tuning and tweaking.

[Olle P]

Originally Posted by Dini

What I meant ... was if your LCC was running and driving great, you should have left it that way ...

I sort of understood that.
The problem is that I can't tell how well my car performs compared to what's expected, since I have neither prior experience nor any other crawler available for a head to head comparison.

The nearest I've come this far is running with an SCX10, and that seemed fairly close in obstacle negotiation...