Transmissions clicking...

[jayrat]

Hey guys, this is my first crawler but not my first build. I was doing some test runs today and crawling up some stairs, both front and rear ends were clicking. I'm assuming this is not normal. I took my time and was sure both transmissions were assembled correctly. I did add grease to the final drive gears, could this be causing the gears to slip? Bummer I have to dissect both trannys to figure this out...any suggestions?

[Harvo]

Make absolutely sure you got the right screws in the right holes on the tops of the axles. There is one that is just long enough to get into the gear if it's in the wrong spot.

[jayrat]

yup, all the screws were in the correct positions. They aren't clicking all the time, just when exceeding force is placed on the drivetrain...during the build, I had a problem with the gears being hard to turn by hand after installing the top axle case. I was able to check this as I didn't install the motor until after the axle tops were screwed to the trannys. Both gave me this problem, if I had the motors installed as the manual showed, I wouldn't of known the gears were binding. To remedy this I backed the axle top screws off a half turn each. Upon investigating, the trannys were dis and re-assembled multiple times, no screws protruding through any walls...

[SINister]

Not having the cases tightened down maybe causing the gears to pop. There's already an issue with the stock gears popping even when the cases are tight. The rough spot in the gears seems to be normal for some people when they first assemble the axles. It should run in quickly and not be a problem.

[jayrat]

Ya, I tried to tighten them down all the way and they were still clicking under hard load. They also click when stopping suddenly...

[SINister]

Originally Posted by jayrat

Ya, I tried to tighten them down all the way and they were still clicking under hard load. They also click when stopping suddenly...

Is it both axles?

[jayrat]

Yes.

[SINister]

There's a mod on here that shows how to shim up the gears to fix the popping, you might have a look at that. Most people that have it pop it's while under a heavy load not from something like a quick stop.

[jayrat]

K, thanks. I just went through that with my ft sc10 4x4!!! I wish these things would work properly from the beginning...now to research and wait for parts, if that indeed is what's going on. Thanks again. Maybe tomorrow I'll get some other suggestions as well.

[XJkid93]

My case stripped out where the screws when in and every time I pinned it they popped, so that could be the case

[jayrat]

I'm sure they're not stripped. I did leave them a bit loose though, when tightened all the way there was drag on the gears...I'll try and tighten them down all the way and see what happens. I greased my final drive gears, was wondering if people do this or not? Maybee that's the issue?

[HARDKNOCKZ]

I grease all my gears. It sounds like you're getting some deflection in your case halves &/or upper link mount. When under load...the cases &/or the upper link mount can start to separate, causing your gears to lose mesh.

If doing sudden stops, direction changes or quick starts on carpet...you can EASILY break teeth on the stock sintered gears. It's possible that that's the case. Your best bet is to try tightening the cases & upper link mounts to the point of ALMOST stripping & see if the click goes away. If not...time to tear down & see what you can find internally.

Good luck. There's a few mods to help shim up the gears also get a better clamp on the axle halves. Maybe check into em while ya have em torn down.

J.D.

[pitcher2103]

double check your pinions as well to make sure the set screw isn't catching the first gear.

also, if you take it all apart, i would clean the gears really good with some mek or something and see if there are any abnormal wear signs on any of the gears.. could be a bearing issue!!

stock gear case bearings don't last really long.. if you are not planning to upgrade cases and plates, i would check out bearing package deals from boca or avid. both are great. i have used both.

[jayrat]

Thanks for both replies...This is a real bummer for me. This is a new kit that hasn't been crawled with yet, just shaking it down in the front yard right now... I'm getting the clicking under hard acceleration and braking. Also under hard throttle loads, (climbing stairs). I don't make a habit of torquing down screws to hard but that makes sense and I'll give it a go...

[jayrat]

still supper bummed...torquing everything down made it worse. For some reason I can build multiple helicopters and have them fly perfect the first time up but I cant build transmissions on a crawler? What gives?

[HARDKNOCKZ]

Originally Posted by jayrat

still supper bummed...torquing everything down made it worse. For some reason I can build multiple helicopters and have them fly perfect the first time up but I cant build transmissions on a crawler? What gives?

If it's getting worse after torquin em down...It kinda sounds like ya got a screw in the wrong spot or a bearing is cooked. The set screw on the pinion's a good idea but I would think that it would click throughout the throttle range.

Sounds like it's time to break em down brutha. It sucks, I know. I destroyed a final gear about 2 minutes into my 1st pack when I built my 1st XR.

Did it EVER not click? A good thing to know...the illustrations of the hardware in the XR manual are 1:1 so you can just lay the screw down on the pic to make 100% sure you're getting em all right. From there...I'd disassemble & pay extra attention to the bearings, gear wear etc. Check the bearing on the end of the transfer gear shaft...the one in the upper link mount. I've had that thing come unseated, allowing the transfer gear to deflect off of the final.

If you're STILL stuck...take some pics & post em up. We'll get ya handled bro.

J.D.

[jayrat]

Thanks for all the input and the advice...I'ts greatly appreciated!!! Tore em both down and in both the front and rear the 22t gear was destroyed. Yes it didn't click when just driving in the house, as soon as some power was applied to the drivetrain, the clicking started. Didn't notice in the front but in the rear it looked as though the 22t gear was not quite straight. I remembered during the build that the axle case cap, (link mount), was hard to get straight. I was able to align it when installing the axle case top, but I thought at the time it was a bad set-up... Inside both case caps, where the 22t gear is, there was a wear mark where the gear had definitely been rubbing the case. This rig has like 10 minutes max on it, 5 of them chasing the dog around the house and the other 5 climbing a set of 5 stairs in the front yard. Soooo, I'ma order the machined gear sets front and back from ck crawlers, what else do you think I should get at the same time...? Vp trans cases? Axle tops? Transmission bushings? C hubs? I'm a noob to crawling and not sure what to get. I kinda wana hit the buy button tonight so I can start crawling soon...Thanks again for all the help.

Jay.

[Soulo747]

Something I noticed when building mine, the bearing that attaches to the 48p drive gear (part number AX30551 is the gear) needs to seat off from the gear.... I first had it right up against the gear on the shaft and obviously that's wrong... Gotta move it over into the little bearing seat.

Seems obvious, but I missed it at first.

Might wanna check it



Bearing AXA1213 in the pic.

[Soulo747]

Whoops didn't see page two haha... Too little too late. My bad

[jayrat]

Doood! It's never too late, you nailed it!!! Now I know why they both popped. Thanks a ton!!!!!!!!!!