V5 Motor mount

Has anyone found any shoulder screws similar to the the Vex 276-1408, but with the shoulder shorter than 0.046 material thickness? This might be an alternative to the breaking brass nubbin on the V5 motor. We have a lot of motors with the brass alignment bent or missing.

Does it matter? As long as you put a shaft through before you tighten the screws, you shouldn’t have to worry about alignment.

Some people have found 6-32 alternatives. For 8-32 right now I think the only option is to lathe down 0.5" standoffs in order to create the insert for holes.

For those who feel the inserts don’t matter… putting a shaft inside the motor before you screw it in is not enough to properly align the motor. Additionally, the inserts are quite necessary because otherwise the motor will not maintain a centered position, likely migrating to the edges/corners, especially when the screws loosen and are tightened by you.


Loosening screws isn’t a problem if you loctite them.

Loose screws aren’t completely eliminated by the use of loctite. Additionally, mounting motors with the insert is just objectively better–a robot without the inserts, I can guarantee you, will have friction or alignment issues that the robots who do have the inserts will not. It’s important to note that even if you can align the motor perfectly so that the axle does not touch the edges of the hole and also use enough loctite/let it settle for long enough that it will never come out through regular use (lol), it will not be aligned with bearings that are on opposite ends or even with a bearing that you put on the motor side. Personally, if a motor’s inserts are destroyed I either replace them or never use the motor.


Even with the inserts, motors can become slightly misaligned, but if you put the screws through bearings, this isn’t a problem, with or without inserts.

A bearing isn’t required on the motor side, unless you plan on cantilevering the shaft.

Granted the vex bearings are more of a bushing, so adding additional bearings will just create unnecessary friction

Not necessarily for the shaft, but to keep the screws stationary.

@railrhodes, this issue of broken inserts was also discussed here: VEX V5 Motor Threads - #4 by technik3k
The best alternative that I was able to find last year was the 6-32 threaded insert:

However, if you couldn’t get those, the next best solution could be to screw a 1" standoff coupler into a broken insert and use a nut on the other end to secure a motor. It is possible, but tricky to secure the coupler with Loctite without further damaging the loose threads. Here is an example:

As @M8R and other have said you don’t want to leave motor dangling on the broken inserts or shifting under even the smallest of the loads, because that could add a lot of friction to the shaft and possibly damage plastic motor base.


Are these legal? I’m thinking no because they’re not an identical replacement to anything that VEX makes nor is there a special allowance for them in the manual, but I’m admittedly not up to date on the Q&A since the end of February (my last event as a EP).


I don’t know, because I never had a role with permission to ask under new Q&A system and, I don’t believe, anyone else did. The only insert related question I’ve seen last season was by @lacsap about legality of replacing motor inserts with standoffs, which was ruled legal.

I don’t think GDC will be comfortable answering the question about 3rd party inserts anyways. Making them legal will make people demand more freedom on similar parts.

And, if they have to rule them illegal, then they must sell replacement inserts or accept responsibility and replace full motors if the plastic base is ruined as the consequence of using it with the broken inserts.

It has been almost a year (more if beta program counts) since people had first complained and there is still no official solution.

Standoff coupler solution is definitely legal, but how many people will be proactive enough to implement it before their motor inserts become unusable?

So, I feel, that linking to this 3rd party replacement part is preferable to watching $40 motors slowly getting irreversibly damaged in large numbers.

Also, we miss your forum integrated Q&As, @Karthik!