500MX Rebuild

[superrmario]

Any ideas on up an down slop in a 500mx??

I had a pretty bad crash unexpected and didn't hit hold till after impact.



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[davehour]

Mine is brand new and has an axial play of about 0.5mm.

I think this might be the culprit of bearing/shaft problems being reported. I'll take mine off and apply green loctite between the bearings and shaft, or just a shim to fix the axial play.

David

[superrmario]

Originally Posted by davehour

Mine is brand new and has an axial play of about 0.5mm.

I think this might be the culprit of bearing/shaft problems being reported. I'll take mine off and apply green loctite between the bearings and shaft, or just a shim to fix the axial play.

David

Right on.

My motor has about 2mm of play.

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[davehour]

Ok guys,

Went through the whole process of disassembling and assembling the 500MX to fix the axial play it had. As shown in the pictures, the axial play of my 500MX was 0.23mm. You can check the amount of axial play by first measuring the gap between the top of the motor and pinion bottom at rest, and then pull the rotor case and the startor apart, and measure the resulting gap.

To fix the axial play in my 500MX motor, I installed a 5 X 7 X 0.2mm shim (this shim is one of the shims that come in the 600EFL Pro kit to eliminate the axial play in the elevator arm shaft). Please note I didn't use green anaerobic compound between the shaft and bearings because with the use of the shim, the shaft will be tight between the bearings and will not slip on them. As we know, the rest of the MX motors family (600MX, 700MX, etc), don't exhibit the problems the 500MX has with the shaft and bearings. In fact, those motors don't come with axial play nor anaerobic compound between the shaft and bearings.

Here is an explanation of the process and pictures:

1. Measure the gap between the top of the motor and pinion bottom at rest, and then pull the rotor case and the startor apart, and measure the resulting gap. The difference is the amount of axial play present. Find a shim with the approximate thickness of the amount of play.

2. Remove pinion from the motor.

3. Looking through the cooling slots of the motor, locate the grub screw. Using a 2.0mm Allen wrench, remove the grub screw. Make sure the Allen wrench holds the screw securely while removing it from the motor casing to avoid loosing it due to the magnets force. In the disassembling steps, this is not critical because if it's taken by the magnets, you can recover it when the motor is taken apart. But, in the assembling steps, it's critical because if you loose it, you will have no other choice but to take the motor apart again to recover it.

4. Using an arbor press, position the motor as show in in the pictures. Use a shaft to push the motor shaft from the casing. If you don't have an arbor press, a vise and a set of sockets can be used.

5. After pulling the shaft off the motor, pull the startor and rotor apart carefully. You can rest both in a table to have a stable pulling force.

6. Pictures show the lower and upper bearings. Now you can remove the bearings using the appropriate items to pull them from the motor.

7. My 500MX had only two flights at the time I disassembled it. You can see the mark produced due to the shaft slipping on the top bearing. No doubt they were going to fail later on.

8. The bottom of the shaft of my 500MX doesn't have a flat surface on it, but a hole made where the grub screw goes in.

9. Find a shim with the thickness of the amount of axial play present.

10. If you want, you can use the R48 anaerobic compound between the shaft and the bearings. Please, make sure the remove any oil/grease present. The T43 is lock threading compound to be used in the grub screw.

11. Make a mark at the top of the shaft collinear with the grub screw hole at the bottom. This will be used to align the shaft and motor casing grub screw hole when putting back the shaft in the motor case.

12. Install the shaft with the shim. Make sure the mark made in the previous step is in-line with the grub screw hole of the casing.

13. Using an arbor press or similar device, start pressing the shaft onto the motor assembly. Make sure the shaft is started aligned on the casing.

14. Press the shaft in until the shaft collar bottoms out on the top bearing. Do not apply excessive for when pressing the shaft, or the top bearing will be damaged.

15. Using compressed air, clean the inside of the motor to remove debris.

16. Install the grub screw. Use T43 or equivalent thread locking compound. Make sure the Allen wrench holds the screw securely to avoid loosing it due to the magnets force. If it's taken by the magnets, you will have no other choice but to take the motor apart again to recover it.

17. Viola! Motor without any axial play.

18. The use of a magnifying device helps a lot in the process. Shown is my OptiVisor with a 5X len.

Hope this help.

David

[davehour]

Continuation...