Blown Diffs Question - ET48.3
 

Hi Guys -

I posted this up as part of another post in the EB48.4 thread, but figured I might want to post here as well given it's specific to the truggy....

*I have x2 of these... and both blew a diff* - One truck blew a rear diff, the other a front diff. At least... that's what I'm assuming it is right now. I haven't torn them apart, but one was RWD only, and the other FWD only. the center drive is spinning to both ends - but the outdrives aren't.

A lot of people were puzzled by this at the track as they haven't seen a Tekno do that before. I'm confused as to what I did wrong on these? When I got the kit I had to contact Tekno because the spider gears were not moving freely on the cross pins what-so-ever. At first, Tekno denied that could even happen, but after sending them a video they sent me replacement spider gears and cross pins for both trucks. I confirmed the replacements spun freely and installed them, but yet this? Did I shim incorrectly? Is there something else I'm doing wrong?

I plan to tear them apart tomorrow. I'll update what I find but sheesh... I've never had x2 blown diffs on x2 cars in the same day! I've been building these things since my first Futaba FX-10 - not to say I didn't do something wrong, but unlikely IMO. Any ideas?

PS - I'll check when I get home to see if a set screw may have backed out. I should have spun the tires on both of the vehicles to see if the diffs were good before I rushed to ordering parts. Oh well - I'll have extra's if it's not the diffs :). Thank you in advance for your responses guys!

My Own Stupid Fault
 

Set screws on every single outdrive on every single one of my vehicles was backed out, or in the progress of backing out. It does not appear I used enough loctite, or none at all. Stupid mistake, but a quick fix!

On a fresh kit it's best to motor spray the metal parts you intend to put thread lock on. This will clean off any residual oils leftover from the machining process.

I had the same issue with a couple of the spider gears too, I just flipped them around to the cross pinst they rotated the most freely on. They seem ok now and I'm sure they will wear in smoothly.
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​​I also had to add shims in a couple places that we're not in the instructions/kit. I added .25mm shims under the wheel hexes, and in between the front spindles and the spindle carriers. The front a arms had to be sanded to allow the spindle carriers to move freely, and in the rear I sanded some of the spacers to get the rear hubs to fit nicely in the a arms and move freely.

Still overall very happy with the kit, and the result of this extra work is a very tight car.

I'll work on putting in my electronics in tonight, and I still have to see if I can get these 155mm batteries to fit.

Motor
 

Swapped over to the emulsion caps. I think who ever designed the o ring for the TKR8207 emulsion caps, should be kicked in the nuts! Those things are a pain to install in the caps. Almost like they are to large for the cap? I would just about get to the point I would give up, and it would just plop down in there like it was suppose to. Took me an hour and half to get the 4 o-rings in the caps!

Haha oh yea i had the same problem when i built my EB48.4 a while back. I was certain the o-rings were too big...