I burned out my motor. overgeared?

[Trike]

I went out for my 2nd race with my Z-car conversion on saturday. Had a great day, Made 3rd in the B-main and got bumped up to the A main. 15mins into it, the motor seized.

my setup.
Medusa 30-60-1600
Gearing: 15/44
MMM ESC
6s 2650mah 20-30c

To start off, I knew it was running a little warm during the qualifying rounds, the motor hit 160F, the ESC hit 160F'ish, battery was 98F. During my 20min main, I came in to change the battery at around 10mins. The ESC wouldn't re-arm, I think it overheated/thermaled. Took about two mins to re-arm. After the race, I ran back to my table and temped the motor. 216F . The ESC was at 168F, battery was at 98F. I knew the motor was done for. But figured I run it during the A-main anyways, it finally seized 15mins into it.

During the qualifying rounds, I changed the timing to its lowest and moved the throttle curve a lower, hoping it would help a bit during the main.

During my 1st race a month ago, I never had any temp issues.

This is what changed since the first race.
Rebuilt diffs with heavier oil 5-7-3. The center and front had leaked out.

ESC settings:
Punch control set to 100%
drag brake set to 20%
Timing set to low.
start power set to low.

The only thing I can think of that may have caused it is the heavier diff oils, and the drag brake set to 20%. That combined with more consistent lap times may have caused it.

So.... What could I have done to fix this? Smaller pinion?
The next question would be. I still have my 6s packs. Should I stick with the medusa 1600kv so I can continue to use them?

Thanks! This has been a good learning experience for me and its been fun to tinker and to see how the changes affect the performance.

Thanks!

[lincpimp]

Personally I would think the drag brake was a not needed and could have caused some heat issues. Putting heavier oil would not cause any issues that I can think of. I have the same motor in my hyper8 on 6s. I also had a 1500kv medusa motor that it used on 6s.

You may have just had a bad motor, try giving medusa a call and see if they will warranty it. Worth a try. Bar that I will sell you my 1600 medusa motor for a good price, I am not using it and have too many motors hanging around...

it a good motor to i used to own it i think!

[Trike]

I finally got a chance to remove the motor off the buggy and found out why it burned out.
As I was taking the grub screw off, I noticed it was a little loose, then I noticed that I couldn't get the pinion off. Looking around some more, I noticed that the pinion was right up against the can. *doh*. After prying it off, it looked like the pinion was spinning on the motor shaft then somehow worked its way to rub against the motor can. The motor spins freely now, but i'm sure has de-magged a bit due to the temp. I got a new 1600kv 36-60 and comparing the two by spinning it by hand, the new one feels like the magnets are stronger. I'm going to see if it's worth it to have medusa rebuild it, depending on the costs.

All in all.. user error....

What's the easiest way to slot the shaft?

[BL_RV0]

Medusa will repair for free, usually.

[Trike]

I had my 3rd race this past saturday, thinking that the pinion rubbing against the can and the low motor timing on the medusa was causing my heat issues. I put in a 14t pinion and changed the timing to normal and turned off the drag brake.

I ran into the same problems again. After my first qualifier, My temp hit 155ish and the ESC was at 150ish, battery was still around mid 80's. I borrowed a heatsink and slapped it on, temps dropped to around 140ish after the 2nd round and I thought I was ok.

During the Main, I came in for a battery change at around 15mins, The ESC wouldn't re-arm again. The motor was hot to touch. took a couple mins to re-arm. After I finished the 20min main. It took me a couple mins to find my temp gun and the motor was at 170ish, the ESC was at 150ish. Battery still under 90.

I just sent in an email to castle to see if they have any suggestions.

[Arct1k]

How much airflow do you have into body - There is a reason nitro motors have a big head sticking out of the body... Electrics need air too...

[Trike]

I thought airflow may have been an issue as well. When I noticed the issue couple races ago, I cut out the front and rear windows to get some better circulation through the chassis. I think airflow should be pretty adequate through the body.