Swerve making crunchy noises when going to a stop

When stopping, our swerve makes these crunchy noises, and we aren’t particularly sure why.


  • Checked Loctite on all falcons for wobbly shafts. All shafts are loctited and spin w/o wobble
  • Greased all the gears again with white lithium grease and ran them
  • checked for carpet and debris in gears and bevel gears
  • Battery voltage looked fine

We swapped our PDH today, but this was an issue before we swapped our pdh as well, so we still aren’t sure what’s the issue.

All other robot functions are working smoothly with no issues (arm, claw, intake). Any help would be appreciated.

We are running SDS mk4i modules

Thank you!

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To me, that sounds like gears skipping. Do you see any wear on the gears? Is everything tight?

Also could be a breaker tripping. Take a look at the DS logs and look at the current draw for the various swerve pod motor channels.


Bevel gear skipping or worn out drive gear above bevel pair skipping.

We’ll check for wear tomorrow morning. I forgot to say that we were losing coms occasionally, but we were not sure if that was a byproduct of switching the PDH and a separate issue, or a part of the initial issue.

The bevels didn’t look worn when we were applying grease today though.

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Our team had a similar issue last week. The bearing which held the belt driving pully popped out and the belt was skipping a lot. Take a look at this shaft, how tight the belt is, and make sure all the bearings are still seated.

Wouldnt belt skipping impact turning instead of stopping?

In theory yes, but there can be a lot of forces in slamming the brakes on like this, with control loops expecting a certain predictable system things can go 0-100 real quick.

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I second guessed myself as well, but I think Skyehawk is spot on. As you slow the very powerful Falcon is trying hard to hold that module in place, that belt could totally start slipping. Even if its not that just something else to check.

I see. We’ll check for the belt then ASAP. Thank you!

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This probably isnt it but make sure that all the wheels have bolts attaching them to the bevel gears. We just found yesterday that only 1 of 20 bolts was actually still attached to the wheel/bevel combo, but all 4 wheels still spun as normal, even when there was nothing holding them to the bevels but hopes and prayers. The wheels could be not attached to the gars, so when they stop it could cause some… interesting issues.

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It sounds like the belt to me (this year we have had a lot of chance to hear belts skipping xD) and I do remember that particular bearing causing us some issues early on during assembly. I think people above have the right path here


We discovered it was due to two of our falcons missing bearings, which caused the crunchy sound.

We found replacement bearings that we transplanted from dead falcons, which seemed to fix the issue.

On the other hand, one of our falcons seemed to have a broken magnet, which caused it to lock up. We replaced it with a falcon from our alpha robot, which did the trick.

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Obligatory question for further reference: version# of the balky Falcons?