I must be completely incompetent...

[The Modfather]

Need to change my name to n00b or something....

Ended up picking up the SCX10-II kit. Finally had a chance to get building after work last night. Step 1 - axles. Awesome - just like my old Scorpion, but smaller ring & pinion. EZPZ. Followed the directions to a "T". When finished, I noticed that there is a small bit of play in the pinion, and when it compresses, it seems to be binding up on the ring gear. Makes sense - it's slightly offset, so that is to be expected. Disassembled the rear axle to make sure I didn't jack up the ring gear & locker - nope - that was good. Did I miss anytihng? Was there a shim or something? Nope. Maybe the locker & ring gear "snap" into the bearing recesses. Nope. Looked thru all the parts - maybe I missed a shim or something that wasn't noted in the book. Nada.

I gave it a rest last night and kept my mind off of it all day today. Got home and decided to give em a tear-down and rebuild (RC Mulligan) - same problem. I'm kinda at wits end here. When the pinion is pulled out, there is no binding. Also, when I spin the axle one way, it's smooth. Spin it the other way and it draws the pinion up into the ring, and causes it to bind up.

Sooooo....is this a defective kit? Maybe the axle housing is funky? Maybe I am over (or under) tightening something? ORRRR - is this why I'm not allowed to have nice things?! :mrgreen:

This is not my video, but it is what I'm trying to avoid (15 sec): https://www.youtube.com/watch?v=vkZAQlRKh3E

 

[Ditchrat]

If it makes you feel better, I tried to follow the directions on the transmission and had to take it apart 3 times before I got it right.

 

[Jboucher]

Same thing happened with my Bomber Kit.

After 2 rebuilds, i bought shims from locked up RC and the 3rd rebuild was perfect.

Some people on the forum got it right the first try.

Manufacturing variations i guess...

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[Inspector86]

It sounds like you need to shim the ring gear closer to the pinion gear in order to get a tighter gear mesh. How much will be a trial and error process.

 

[The Modfather]

It sounds like you need to shim the ring gear closer to the pinion gear in order to get a tighter gear mesh. How much will be a trial and error process.

The ring gear isn't the one that has play in it tho. If there was a way to keep the pinion pushed tightly into the bearing, there would be no issues. I just don't see how that can be a thing :shrugs:

 

[The Modfather]

If it makes you feel better, I tried to follow the directions on the transmission and had to take it apart 3 times before I got it right.

heh - looking forward to getting to that step LOL

 

[The Modfather]

It sounds like you need to shim the ring gear closer to the pinion gear in order to get a tighter gear mesh. How much will be a trial and error process.

The pinion 'floats' (for lack of a better term). There doesn't seem to be a way to keep it stabilized unfortunately.

 

[Inspector86]

The ring and pinion teeth are on a bevel. By moving the ring gear closer to the pinion the pinion cannot move forward. Alternatively you could shim the pinion forward into the ring gear by placing a shim between the pinion gear and inner bearing. In any case you have too much play between the ring and pinion.

 

[The Modfather]

The ring and pinion teeth are on a bevel. By moving the ring gear closer to the pinion the pinion cannot move forward. Alternatively you could shim the pinion forward into the ring gear by placing a shim between the pinion gear and inner bearing. In any case you have too much play between the ring and pinion.

Ahhh yes yes - I see what you're getting at. The binding occurs when the ring and pinion get too close. They are most happy when I am pulling outward on the pinion, forcing it into the inner bearing.

But for what it's worth, I agree with you - there is definitely too much play between the ring and pinion.

 

[Inspector86]

Also keep in mind that once you install the driveshafts they tend to pull the pinion back especially if you add shims between the driveshaft and outer bearing. It's all a matter of trial and error playing with shims until it feels right.

 

[The Modfather]

Also keep in mind that once you install the driveshafts they tend to pull the pinion back especially if you add shims between the driveshaft and outer bearing. It's all a matter of trial and error playing with shims until it feels right.

I was thinking about that also, but the concern I had was when the axles are articulating - will that affect the geometry enough that it could cause the pinon to get shoved back into the ring gear, and bind up. Could have the potential for busted metal pieces if so.

 

[HumboldtEF]

Also keep in mind that once you install the driveshafts they tend to pull the pinion back especially if you add shims between the driveshaft and outer bearing. It's all a matter of trial and error playing with shims until it feels right.

This is what I wanted to add too, yes without the driveshaft it wanders towards the ring gear but having the driveshaft attached should hold it in place.

I also was confused by this on my recent build.

 

[CR4NK]

FWIW, I wouldn’t think adding a shim between the drive shaft and outer pinion bearing, effectively pulling the pinion more toward the driveshaft would cause an issue. It helped on my scx10.2 and I’ve had no issues thus far.


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[The Modfather]

Wanted to say thanks to everyone who chimed in. I didn't have any kind of shims or anything, but decided to channel my inner redneck. I dug thru my old RC crap, and found a couple old RC10 Shock O-Rings. They're pretty small, but they slid over the top of the pinion and keep it from sucking up into the ring quite well!

Thanks again for such an awesome resource! Here are some pix, in case someone else in this world is as anal as I am

The O-Ring I used

The rear axle

Both axles

 

[Inspector86]

Just keep in mind that the driveshafts can spin at some pretty significant speeds and may throw the rubber O-ring off where a proper shim/washer will stay in place. Just sayin.

 

[The Modfather]

Just keep in mind that the driveshafts can spin at some pretty significant speeds and may throw the rubber O-ring off where a proper shim/washer will stay in place. Just sayin.

Valid point. For now, at least, my OCD has been put on time out :mrgreen:

 

[StomperCrawler]

The Scx10 ii kit should really include those shims and instructions on when and how to install them. A lot of folks seem to have this problem.

 

[thead]

i use the traxxas 5mm teflon coated shims for this.

 

[Jim85IROC]

When I built my bomber I ran into the same issues, and my fix for it was to throw a shim right where you put that o-ring, in order to pull the pinion away from the ring gear a tad. I doubt that o-ring will hold up long term, so make sure you order some shims, and when you get them, replace that o-ring. It's a great short term fix tho! I would only use as many shims as it takes to make everything work smoothly. Too much shim (i.e. the thickness of that o-ring) will pull the pinion too far away and can cause wear and deflection problems.

 

[midwest_rippa]

There is binding when the driveshafts are absent. once you put them on and have the truck built up I haven't had the problem since