emax trans case

[coolhandcountry]

Is the top shaft hitting the back of the case threw the bearing. I not sure if some one has looked or not. Just a suggestion.

[Promod]

After about 5 hours work got this trans as smooth as GLASS!!
The case is too narrow as Gustav said.
I ground down the top gear to gain play. This did help but didn't solve the problem. I also took some material off the shaft where the idler gear rides. This also helped. What solved the problem was grinding some off the single speed case where the idler gear is.
The lower shaft was ok and even able to use the little shim/washer.

Here is a few pictures.

Thank you,
Promod

[Promod]

Here is where I took material off the single speed case. Sorry for the bad pictures but you get the idea.

Thank you,
Promod

[Promod]

Just to clear up the second picture. I took the metal off the flat surface where it would hit the idler gear. Not off the inside.

Thank you,
Promod

[Gustav]

I think FLM may have tried to take the play out of the shafts being able to move in and out ,however every tranny i've ever worked with needs this play to run free.I have the single speed running good now doing similar to what Promod has described.

The 2-speed is more of a problem though,the topshaft and output shaft are both too tight(case too narrow).This is with no shims on the output shaft too.There's not really enough material to make the bearings sit deeper but Boca make 6x12x3 and 5x11x3 bearings but they're open bearings so the case would not be sealed.

I could use the narrower non-sealed bearings in one side of each output gears (the outside)and narrow the gear slightly(the part that sticks out and meets the bearing in the case,making it flush with the narrower bearing),so still using the sealed bearings for the case,i think this is the best solution for those wanting to use the 2 speed.For the top shaft using one 3mm bearing on the sealed side and grinding the top gear should be enough and will keep the case sealed too.

[coolhandcountry]

You had the same problem on a two speed as well. I wonder if they made more than one like this. I got the single and two speed trannies. Both of mine went together great. stock shim and no grinding. some one should talk to fast lane about this. Sorry to hear the trouble

[Gustav]

Actually the output shaft is fine with the 2-speed too,so ignore what i said about the output shaft in my last post,i must be losing it.The topshaft is way too tight though,actually locks the tranny completely if you tighten the top half.I think the use of 5x11x3mm bearings on the topshaft will solve this though so i'm not concerned about it.I'll report back after i try the narrower top shaft bearings.

Coolhand,does yours spin free with the top screws tightened up then?I'm suprised if they're not all the same because they're machined by computer so the tolerences will be small.

[coolhandcountry]

My tranny is tight and in the truck. I have run about 8 packs or so on the single and 12 packs on the two speed.

[Gustav]

I got mine running really good now as a 2-speed.I'm not really sure what the problem was to be honest but all of a sudden it goes together perfectly.I got the topshaft bearing to sit just a fraction further into the case,though i'm not totally sure that's what the problem was,i removed a little bit of material in a few areas.Anyway it's fine now,mesh seems perfect,very smooth,i like it alot.

[RC-Monster Mike]

Great, informative post, Promod! I just built two single speed trannies yesterday and did EXACTLY the same things you did to make it work smoothly. I mean exactly the same stuff! It took me a little over two hours to figure out/build both trannies(well, once I figured out the first one, I knew what to do with the second one!). The lathe came in pretty handy to modify the top gear.
I will address this issue with FLM. It seems like if they added a simple 1mm to the width of the motor half(part that mates with G-maxx single speed), it would solve the problem for both applications.

[squeeforever]

why are some people not having problems then?

[coolhandcountry]

Originally posted by squeeforever
why are some people not having problems then?

I am curious of this my self. Mine went together like factory. Did they change something between the batches?

[RC-Monster Mike]

I imagine there are some reasonable explanations for this. All machine work has tolerances. R/c, generally, isn't required to be super tight on the tolerances(though the tolerances are very close..say within .005" or so). It would be reasonable to expect a few parts here and there to be on the outside of the tolerance, particularly from two different manufacturers(actually three, counting the Traxxas parts, and 4 if it had a steel idler gear). If the g-maxx case was out .005" one way and the FLM was out the other way, you now have .01" total "out" from the design. It is also reasonable to assume that the designs themselves may be within .01" or so from perfect alignment(which is close enough for most applications). Dull tools, a slight shift in the machine...who knows, really? The key is to make the parts so that they work within these factors. Adding a mm to the case thickness wouldn't make anything sloppy on the parts that fit flawlessly, and would probably free up the "tight" parts as well. I knwo the two trannies I built both had slightly different fit, and I built them both at the same time with the same parts. Remember, Traxxas parts also have tolerances(for example, one of the input shafts spun truer than the other) as well, so the aluminum single speed is a mix of parts from a few different manufacturers.