Yeti XL weekend recap

[Deckard]

Since I didn't have the kids this weekend, my YXL spent most of the weekend getting upgrades and some tweaking.

I drove it a bit Friday evening and thought I lost the front diff. I was pissed. Opened the bulkhead, no visible damage, took apart the diff... perfect. Filled the diff with 500k (out of 100k). Put it all back together and still no power to the front wheels. I pulled the gear box and the grub screw for the front drive shaft had fallen out (doh). At least the front diff is fresh.
Saturday, the mailman dropped off a package from Dhawk....time to redo the front diff again!

I installed the Dhawk Racing aluminum front bulkhead, Dhawk bevel collars (front and rear), a Dhawk steel drive shaft (stock one looked twisted), and new ceramic bearings.

Having previously upgraded to the Dhawk bellcrank I have become a fan of Dhawk. The bulkhead install was a breeze and everything fit together perfectly. I like that it comes with new screws and shims. The collars went on with ease. The stock collar on the rear was fused to the pinion and was a bit difficult to get off. The rear drive shaft also came with screws. There's much less play than the plastic stock shaft. It's feels much more solid.

So, she's all back together and I can't wait to drive this bad mofo Sunday morning. I turn it on to test out the steering, forward and... doh, the front and rear wheels spin in opposite directions... ARRRGH. Take the front part, flip the diff, put it all back together...again. Tomorrow she will terrorize the neighbors.

Sunday afternoon...finally, time to drive this bad arse. She's crazy loud, even worse than my ex....this isn't normal. 10 feet and can tell the motor has slipped. I had to fiddle eff around with motor placement (this seems like a terrible design). If it's too tight, the spur rubs the front drive shaft. Too loose, the motor slips. Finally, it all seemed to click into place and it felt good. No rubbing on the drive shaft and the motor was only moving the parts that should be moving.

Time to drive in a park that's next to my house. Nothing fun there, just grass and a bit of dirt, but it's a good testing area. Wow, this thing is so much fun to drive even in the most boring of spots. Rolled it, flipped it, loved it.

My only concern is that my 8000 mah Helios batteries seems to be slowing down much faster than normal. They don't seem to just cut off, but slow down about 5 min before the cut off. Maybe the cutoff is too low? Could the motor be overheating? I checked the temp and it as 190 degrees and the motor had had about 5 minutes to cool before I got the temp gun out. Could the front or rear diff be binding due to the shims I added?

Anyway, I have all week to figure it out. Can't wait to drive it with the kids next weekend!

On a side note. I picked up a Latrax 1/18 SCT "for my son". Fun little truck. I had to order one for me. LHS will have it this week. I'm not addicted!

Sorry for the long post, but I had a fun with the YXL this weekend.

[mond]

It maybe the pinion is digging into the diff cup. Mine did this ever so slightly on the HR diff cups. Not a mark on the pinion but a small groove around the diff cup where they wore. Silky smooth now though.

[Tzicul]

On how many S's are you running?

[Deckard]

I'm running 4s. Sunday it was pretty hot here in north Texas. No pet bursting into flames, but it was close. I checked for any binding in the rear axle. Didn't find anything. I think I may have had the gear box and motor down a little to tight. Repositioned it a bit.

I think I'll order the castle fan and heat sink for the motor. I need to order another cable for the ESC so I don't have to open the receiver box when I want to reprogram.

Speaking of ESC. I can set the throttle curve on my radio (Futaba 4PKs). Is it better to set it on the radio or on the ESC?

[redsawacs]

IF you set the ESC wide open and make changes with the radio, you'll have a much easier time tuning it back up or down using your radio. If you tune the ESC, you'll have to go back into the ESC to make changes later if you choose....pain!

Sounds like you have had a few REALLY GOOD "shake down" runs. When you build a kit, you will always have to take it out a few times to get everything adjusted correctly. You're doing everything right.

I suspect the pinion gear on the motor is too tightly meshed into the spur gear. This will create excessive heat and amp draw (draining batteries faster). It would be best to have a video showing your mesh to be sure though. Just my initial guess.

[pro mod steve]

Serious question how tight is to tight on gear mesh? I have set all my trucks by feel for years (rocking spur back and forth against pinion) with no problems. I always thought too tight was when there was no gap or clearance at all?

[gregm412]

If you run a piece of paper threw the gears and the paper rips. It's to tight

[Deckard]

Thanks for the feedback guys. I had the mesh too tight. I finally had a chance to run it a bit after putting a 17t pinion on and adjusting the mesh. Feels perfect now.

Wild ass crazy fast for sure. I've been thinking about getting some more batteries to go 6s, but I'm afraid this thing will time travel.