How to adjust rearend gear mesh?

[tomc5179]

I'm a newbie RC person and this is my first post here. I just retired a year ago and the RC car bug bit me a couple weeks ago, so I ordered a Yeti from Tower Hobbies over the weekend and just received it this morning. Boy Howdy, these things are a lot different from the ones I was used to playing with 30 years ago!

Anyways, I did the pre-run check and checked all the bolts for tightness, spur gear / motor mesh and just generally looked everything over while I was charging up a couple new batteries and everything appeared fine.

So, for my first run, I put in a 2S 5000 battery and take it easy for about 10 minutes or so and then I stop and give everything the once over again and it all looks fine. So then, I proceed to flog it a little as in doing donuts in a gravel driveway, a couple top speed runs, a few burnouts on gravel / sand and then I run it through some tall grass in an ditch. It's getting close to lunch by then, so I bring it back down the driveway and do a couple of donuts before I go in. I notice a clicking noise somewhere underneath during power, but I just assume it is some brush from the ditch catching on something.

After lunch, I throw in a 3S 5000 battery and go out and set it down in the driveway. As soon as I hit the power, I hear the unmistakeable sound of gears stripping. I stop and go inside to check it out and after looking at a couple other things, I take the rear diff cover off, and sure enough, the ring gear is about halfway stripped off. I can't believe it's only lasted for basically 1 battery worth of run time!

I googled for setup / adjustment info and searched the forum and found some info for the wraith, but nothing really specific to the yeti. Have any of you had this problem and if so, do any of you know where to look for adjustment info? I noticed in a search that Axial had HD replacement gears for the wraith, so I will check to see if it's the same for the yeti.

I can't say it's a deal breaker for me, I just thought that rear gears would last a little longer than that. I can't believe that I was too hard on it. I wasn't getting shock loads, just a lot of wheel spinning. Other than that, this thing is a blast and I'm sure I'll have lots of fun flogging it.

Thanks for any help

 

[altd896]

You'll be fine with the HD gears, all axial axles use the same gear set.
If you can pickup yourself a shim kit in the 5mm size for the pinion shaft & whatever the carrier bearing size is, 10mm I think from memory, check your manual.
I got yokomo ones from a-main. You'll be able to shim your gear mesh nice then, it can be a little sloppy stock.
You might need 1 or 2 under the pinion to pull it in slightly & similar on the back of the ring gear to move it closer to the pinion, till they're snug & smooth not tight, almost no backlash between them.

Just an observation but its funny how times change, once upon a time ”it died after 1 battery" meant 4 minutes on a 1200mah nicad, now with a 5000mah lipo one battery of running could be an hour or more, ahh the good old days, who needs em.

Donuts, even in gravel, is still pretty hard on the drive train.

 

[tomc5179]

Thanks, mate. I'll order a set of the HD gears and some shims and try that.

BTW, what type of grease do you use for the gears?

 

[SteveC6R]

Suggestion, get an Avid thrust bearing for the rear inner pinion bearing and kill two birds with one stone. The Avid bearing is sized 5x11x4.5mm so it takes out any slop and you also want have to worry about blowing out the inner pinion bearing and ruining your HD gears.

Also Mobil 1 synthetic grease is a great choice for RC use.

 

[altd896]

Any good quality automotive grease should be fine.
If you have to go buy a grease a synthetic like the Mobil 1 has the advantage that if a little water gets in it shouldn't emulsify (mix & dilute) the grease.
I hear good things about the cowrc udder butter grease.
Personally on my wraith & scx10 I've used some Redline automotive synthetic grease we had at work, I wouldn't go out & buy it especially.

 

[DTB1]

Green grease is the only grease I use. I use it in the yeti, polaris Rzr, on our boat, all my trailers, and my tractors.

I use Mobil 1 synthetic on my Chevrolet truck. That's only because it is never submerged and doesn't have a chance to be submerged.

 

[tomc5179]

Update - missing caps

Thanks to everyone who replied with info. I'm going to be ordering shims and thrust washers along with HD gears for front and rear, BUT -

I haven't even looked at the thing again till this afternoon to see what size the ring and pinion gears were so that I could order them, but when I looked at the thing again, it slapped me right in the face - THEY NEVER PUT ANY CAPS ON TO HOLD THE DIFFERENTIAL TO THE HOUSING! I knew I couldn't have been that hard on it to strip them out so quick.

Anyway, I called Axial's warranty phone and they didn't even question me about it. I told them I thought I better get a new housing along with all the other bearings and miscellaneous parts as the pinion was real sloppy and I didn't know if the plastic in the housing may have been gouged out from the ring and pinion flopping around in there. I had to get all the part numbers and quantities for them, but the guy said that they will send it right out.

Anybody else buying a new one might want to take off the diff cover and just check to make sure you have caps on it before you run it.